The present invention relates to a microscope . More particularly, although not exclusively, the invention relates to a microscope with auto focusing function,

BACKGROOND OF THE INVENTION

Microscope requires fine adjusting operation and skills for observing samples to be observed in sharp image formation. It has been difficult to observe the objects rapidly and in large quantities. Therefore, nowadays, focusing is automatically performed. However, these auto- focusing microscopes have complicated outer profile and are usually bulky.

Also, microscopes usually allow various magnification of the sample to be performed. Different sets of lens are provided in the microscope for different magnifications. The sets of lens take up a lot of space and make the microscope even more bulky and complicated to use.

OBJECT OF THE INVENTION It is an object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages and/or more generally to provide a microscope with auto focusing function which is compact and user friendly.

SUMMARY OF THE INVENTION There is disclosed herein according to a first embodiment of a first aspect of the invention, a microscope comprising a housing having an axis; a lens module within the housing including at least one optical lens, the lens module being arranged to slide relative to the housing; an optical sensor provided behind the lens module for sensing light through the lens module; an auto-focusing mechanism for focusing the light from an object outside the housing; and a controller for controlling the auto- focusing mechanism based on information relating to light sensed by the optical sensor; wherein the microscope includes a magnification selecting mechanism to select between first and second optical magnifications, which includes a magnification selection control circuit to automatically position the lens module to one of first and second predetermined positions along the length of the housing corresponding to the first and second optical magnifications .

Preferably, the auto-focusing mechanism includes a first part comprising the lens module and a second part to which the first part is engaged for movement about and along the axis, the second part having one or more piezoelectric elements which upon excitation generate a traveling wave on the second part to cause movement of the first part relative to the second part about and along the axis, the movement along the axis achieving auto-focusing.

More preferably, the first and second parts are engaged through inter-engaged threads, and excitation of the piezoelectric elements drives the threads of the first part through the threads of the second part by frxctional force to bring about movement of the first part relative to the second part about and along the axis .

It is preferable that the second part has eight piezoelectric elements positioned around its periphery .

Advantageously, the second part is of copper material.

More advantageously, the controller is adapted to identify one position of a plurality of different angular positions of the first part of the auto-focusing mechanism relative to the second part, at which position the contrast ratio of the light sensed by the optical sensor is the highest . Preferably, the controller is adapted to compare contrast ratio of the light sensed by the optical sensor, at different segments of angular position of the first part of the auto-focusing mechanism relative to the second part, and to identify the segment at which the contrast ratio is the highest.

Yet more preferably, the controller is adapted to compare contrast ratio of the light sensed by the optical sensor, at different sub-segments of the identified segment of angular position of the first part of the auto-focusing mechanism relative to the second part, and to identify the sub-segment at which the contrast ratio is the highest .

Advantageously, the first part includes an annular arrangement of magnetic poles which are rotatable with or by the first part relative to the second part during auto-focusing .

Preferably, the auto-focusing mechanism includes a magnetic sensor fixed relative to the second part for sensing the magnetic poles to generate a signal indicative of the angular position of the first part relative to the second part .

More preferably, the auto-focusing mechanism includes an annular arrangement of magnetic poles on the first part rotatable with or by the first part relative to the second part during auto-focusing, and a magnetic sensor fixed relative to the second part for sensing the magnetic poles to generate a signal indicative of the angular position of the first part relative to the second part, each magnetic pole representing a corresponding one of said segments or sub-segments for determination of the angular position of the first part relative to the second part .

Yet more preferably, the magnetic poles comprise alternating north and south magnetic poles. It is preferable that, the magnification selecting mechanism includes an electric motor to drive the lens module, and a transmission connected to the motor for transmitting and adapting output of the motor to the lens module to cause sliding of the lens module relative to the housing in a direction along the length thereof.

Advantageously, the transmission includes a threaded shaft meshes with threads in a threaded through hole of the lens module to cause sliding of the lens module relative to the housing in a direction along the length thereof, in response to the drive of the motor.

More advantageously, the lens module is caused to move between the first and second predetermined positions in response to the drive of the motor.

Yet more advantageously, the lens module is caused to move between the first and second predetermined positions in response to rotation of the threaded shaft driven by the motor.

Preferably, the magnification selecting mechanism includes first and second detectors positioned separately along the length of the housing for detecting presence of the lens module at the first and second predetermined position respectively. More preferably, the first and second detectors comprise infrared detectors.

Even more preferably, the first and second detectors are positioned on same plane as the first and second predetermined positions respectively.

Yet more preferably, the lens module includes a projection for cutting infrared beam of the respective infrared detectors when the lens module reaches the first and second predetermined positions.

Advantageously, the threaded shaft has a first gear fixed to its end, the first gear being meshed with a second gear fixed to a shaft of the motor to bring about rotation of the threaded shaft when the shaft of the motor rotates .

It is preferable that the microscope includes a guide extending along the length of the housing to guide the sliding of the lens module .

It is preferable that the microscope includes a manual focusing control arranged to replace or override the auto-focusing mechanism for performing manual focusing.

Preferably, the lens module includes a set of lenses including the first-mentioned lens, all the lenses being in fixed relationship relative to one another.

More preferably, the set of lenses has two focus points.

There is disclosed herein according a second embodiment of the invention, a microscope substantially as described hereinbefore with reference to the accompanying drawings Figures 1 to 27.

There is disclosed herein according to a third embodiment of a first aspect of the invention, a microscope comprising a housing having an axis; a lens module within the housing including at least one optical lens, the lens module being arranged to slide relative to the housing; an optical sensor provided behind the lens module for sensing light through the lens module; an auto- focusing mechanism for focusing the light from an object outside the housing; and a controller for controlling the auto-focusing mechanism based on information relating to light sensed by the optical sensor; wherein the auto- focusing mechanism includes a first part comprising the lens module and a second part to which the first part is engaged for movement about and along the axis, the second part having one or more piezoelectric elements which upon excitation generate a traveling wave on the second part to cause movement of the first part relative to the second part about and along the axis, the movement along the axis achieving auto-focusing.

Preferably, the first and second parts are engaged through inter-engaged threads, and excitation of the piezoelectric elements drives the threads of the first part through the threads of the second part by frxctional force to bring about movement of the first part relative to the second part about and along the axis .

More preferably, the second part has eight piezoelectric elements positioned around its periphery.

Even more preferably, the second part is of copper material .

Yet more preferably, the controller is adapted to identify one position of a plurality of different angular positions of the first part of the auto-focusing mechanism relative to the second part, at which position the contrast ratio of the light sensed by the optical sensor is the highest .

Advantageously, the controller is adapted to compare contrast ratio of the light sensed by the optical sensor, at different segments of angular position of the first part of the auto-focusing mechanism relative to the second part, and to identify the segment at which the contrast ratio is the highest . More advantageously, the controller is adapted to compare contrast ratio of the light sensed by the optical sensor, at different sub-segments of the identified segment of angular position of the first part of the auto-focusing mechanism relative to the second part, and to identify the sub-segment at which the contrast ratio is the highes .

Yet more advantageously, the first part includes an annular arrangement of magnetic poles which are rotatafole with or by the first part relative to the second part during auto-focusing.

It is preferable that the auto-focusing mechanism includes a magnetic sensor fixed relative to the second part for sensing the magnetic poles to generate a signal indicative of the angular position of the first part relative to the second part . Preferably, the auto-focusing mechanism includes an annular arrangement of magnetic poles on the first part rotatable with or by the first part relative to the second part during auto-focusing, and a magnetic sensor fixed relative to the second part for sensing the magnetic poles to generate a signal indicative of the angular position of the first part relative to the second part, each magnetic pole representing a corresponding one of said segments or sub-segments for determination of the angular position of the first part relative to the second part .

More preferably, the magnetic poles comprise alternating north and south magnetic poles .

There is disclosed herein according to a first embodiment of another aspect of the invention, a method of auto- focusing an image of an object utilizing the first, second or third embodiment of the first aspect of the invention, comprising the step of identifying one position of a plurality of different angular positions of the first part of the auto-focusing mechanism relative to the second part, at which position the contrast ratio of the light sensed by the optical sensor is the highest .

There is disclosed herein according to a second embodiment of another aspect of the invention, a method of auto-focusing an image of an object utilizing the first., second or third embodiment of the first aspect of the invention, comprising the steps of comparing contrast ratio of the light sensed by the optical sensor, at different segments of angular position of the first part of the auto-focusing mechanism relative to the second part, and identifying the segment at which the contrast ratio is the highest .

It is preferable that the method further comprising the steps of comparing contrast ratio of the light sensed by the optical sensor, at different sub-segments of the identified segment of angular position of the first part of the auto-focusing mechanism relative to the second part, and identifying the sub-segment at which the contrast ratio is the highest.

It is preferable that the method further comprising the steps of assigning a magnetic pole to each segment or sub-segment, sensing the magnetic poles, and generating a signal indicative of the angular position of the first part relative to the second part .

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of an embodiment of a microscope in accordance with the invention;

Figure 2 is an exploded diagram of the microscope of Figure 1;

Figure 3 is an exploded diagram of the microscope of Figure 1 taken from an angle different from that of Figure 2;

Figure 4 is a diagram showing internal construction of the microscope of Figure 1;

Figure 5 is an enlarged diagram showing a transmission of the microscope of Figure 1

Figure 6 is an operation block diagram of the microscope of Figure 1; Figure 7 is an enlarged perspective view of the microscope in Figure 1;

Figure 8 is a diagram of an lens module in the microscope of Figure 1 at 500X magnification;

Figure 9 is a diagram of the lens module in Figure 1 at 50X magnification; Figure 10 is a diagram of the lens module in Figure 1 at 200X magnification;

Figure 11 is an enlarged cross-segmental view of the microscope of Figure 1 taken along its length;

Figure 12 is a right perspective cross-segmental view of the microscope of Figure 1 taken along its width; Figure 13 is a left perspective cross-segmental view of the microscope of Figure 1 taken along its width;

Figure 14 is a circuit diagram of the microscope in Figure 1 ;

Figure 15 is a circuit diagram of the microscope in Figure 1 ; and

Figure 16 is a circuit diagram of an optical sensor and a controller of the microscope in Figure 1.

Figure 17 is a perspective view of a third embodiment of a microscope in accordance with the invention; Figure 18 is an exploded diagram of the microscope of Figure 17; Figure 19 is an enlarged diagram of a transmission of the microscope of Figures 17 and 18;

Figure 20 is an operation block diagram of the microscope of Figures 17 to 19;

Figure 21 is a schematic cross-segmental view of a connection relation between a first part and a second part in a first embodiment of an auto focusing mechanism of the microscope of Figures 17 to 20;

Figure 22 is a schematic top view of the auto focusing mechanism in Figure 21; Figure 23 is a schematic cross-segmental view of the auto focusing mechanism in Figure 22 with a set of lens;

Figure 24 is a schematic cross-segmental view of a second embodiment of an auto focusing mechanism of the microscope of Figures 17 to 20;

Figure 25 is a schematic cross-segmental view of a magnetic ring of the auto focusing mechanism of the microscope of Figures 17 to 20;

Figure 26a is a schematic illustration of five segments of angular position of the first part of the auto- focusing mechanism relative to the second part in Figure 21;

Figure 26b is a table showing a first stage of auto- focusing conducted by the auto-focusing mechanism;

Figure 27a is a schematic illustration of six sub- segments of an identified segment of angular position of the first part of the auto-focusing mechanism relative to the second part in Figure 21; and

Figure 27b is a table showing a second stage of auto- focusing conducted by the auto-focusing mechanism; DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to Figures 1 to 16, there is shown a first embodiment of a hand-held microscope 1 embodying the invention for magnifying an object 70 (e.g. skin) . The microscope 1 has a number of basic components: a housing 2, an optical system 3, a controller, an optical sensor 4 and an auto-focusing mechanism 5. Electrical auto- focusing is made possible by a set of basic components. These basic components include an electric motor to drive a lens module 11a in the optical system 3, and a transmission 17 connected to the motor 15 for transmitting and adapting output of the motor 15 to the optical system 3 to cause sliding of the optical system 3 and/or the lens module 11a relative to the housing 2 in a direction along the length or main axis thereof.

In the first embodiment, the microscope 1 has a fixed magnification 500X, as shown in Figure 8. In a second embodiment, the microscope 1 is capable of switching between two magnifications namely, 5OX and 200X, as shown in Figures 9 and 10. In Figures 1 and 2, which are generally applicable to both embodiments, the housing 2 of microscope 1 is substantially cylindrical and has three segments . Segment 2a is telescopically insertable into segment 2b and segment 2b is connected with segment 2c. At a front end of the segment 2a there is an aperture 7 defined by an iris 7a. On the iris 7a there are eight LEDs 8 which act as light sources in addition to the ambient light when the microscope 1 is in use . The LEDs 8 are white LEDs . A hood 29 is attached to or integrally formed with the front end of the segment 2a and around the LEDs to protect them.

At a rear end of the segment 2c, there is an opening through which a cable 16 runs. The cable 16 connects the microscope 1 to a DC power source {not shown) .

In a preferred embodiment, there are three windows 9 on a panel 90 that form part of the housing 2 and extend across the segments 2b and 2c. The window 9 furthest away from the rear end accommodates a button 9a which if pressed allows snap shot of the object 70. The middle window 9 has a button 9b for locking and unlocking the auto-focusing mechanism 5. The window 9 closest to the rear end encompasses a turning dial 9c. The dial 9c is a user interface of a manual focusing mechanism.

In the preferred embodiment where the microscope 1 is capable of switching between 50X and 200X, a switch 51 is provided at the rear end of the housing 2 next to the cable 16 as shown in Figures 2 and 3, permitting the user to manually select between the two magnifications . Inside the housing 2, there is the optical system 3 which includes a casing 11 that has three portions 11a, lib and

The first portion, the lens module, 11a has an opening 7b on its front end. Light enters the optical system 3 through the opening 7b. Inside the lens module 11a, there is a set of stationary lenses 12 that comprises two lenses 12a, 12b for converging light that enters the optical system 3 through the opening 7b.

The optical system 3 and/or the lens module 11a is slidable along a central axis X along the length of the housing 2 to bring about focusing of image of the object 70. The sliding of the optical system 3 and/or the lens module 11a is brought about by the motor 15 and the transmission 17. The third portion 11c of the casing 11 has two holes 14 and a nut 30 arranged equiangularly around the periphery of the casing 11, for removably connecting certain parts of the transmission 17. The nut 30 is internally screw-threaded.

The controller 6 includes a motor control MCU and a main controller DSP / controller mounted on the main control board 6a. The motor control MCU controls the motor 15 and a motor driver.

The optical sensor 4 is attached to a front side of a sensor PCB 4a as shown in Figure 3. The sensor PCB 4a is placed perpendicular to the central axis X to maximize the amount of light collected. The PCB 4a is connected to the main control board 6a as shown in Figure 2 at right angle to one another.

The aperture 7, the optical system 3 and/or the lens module 11a and the optical sensor 4 are arranged co- axially along the central axis X. Light that enters the microscope through aperture 7 is focused by optical system 3 and/or the lens module 11a and lands on the sensor 4 for detection. As mentioned above, the auto-focusing mechanism 5 includes a motor 15 and a transmission 17. it also includes a pair of guide rods 13. The motor 15 is stowed inside a motor housing 15a. In this particular embodiment, the motor 15 is a 2.5V DC motor with a normal speed of 103 rpm.

The transmission 17 includes a finely screw-threaded shaft commonly known as the lead screw 17a, a first gear 17b fixed to an end of the lead screw 17a, and a second gear 17c fixed to one end of a shaft of the motor 15. The first gear 17b meshes with the second gear 17c thereby connects the motor 15 to the lead screw 17a. The lead screw 17a runs through the nut 30 of the optical system 3. The threads on the lead screw 17a cooperate with the internal threads of the nut 30, thereby enabling driving of the optical system 3 and/or the lens module 11a by the motor 15.

The transmission 17 transmits and adapts output of the motor 15 to the optical system 3 and/or the lens module 11a. The motor 15 rotates at a relatively high speed, which is inappropriate for slower and fine movement of the optical system 3 and/or the lens module 11a. The transmission 17 reduces the higher motor speed to a considerably lower, linear speed for the optical system 3 and/or the lens module 11a. This permits fine adjustment of distance between the optical system 3 and/or the lens module 11a and the object 70 for focusing. The first gear 17b is m0.4 X 14T and has a rotational speed of 132rpm for rotating the lead screw 17a at the same speed. The second gear 17c is of m0.4 X 1ST and rotates at a speed of 103rpm.

When the motor 15 is activated, the motor shaft and the second gear 17c rotate at 103rpm. This brings about the rotation of the first gear 17b at a speed of 132rpm. The lead screw 17a rotates by or with the first gear 17b at the speed of 132 rpm. As shown in Figure 3, the optical system 3 and/or the lens module 11a is slidable forward in direction A and backward in direction B along the axis X as the lead screw 17a rotates clockwise and anticlockwise respectively .

Referring to Figure 2, the guide rods 13 are two cylindrical rods . One end of each of the guide rods 13 is fixed in a corresponding hole 14 and the opposite end in an aperture 34 of the sensor PCB 4a. There are two opposite apertures 34 on opposite sides of the sensor PCB 4a, one for each guide rod 13. The other end of each of the guide rods 13 is inserted into corresponding apertures on the third portion 11c of the optical system 3. The guide rods 13 are connected to the apertures. These guide rods 13 guide the optical system 3 when it slides axially along the axis X, and prevent angular displacement of the optical system 3 when the motor 15 is on .

Referring to Figure 6, during operation of the microscope 1, light of the object 70 in front of the microscope 1 enters through the aperture 7 and is converged by the lens 12a, 12b of the optical system 3 and then falls on the optical sensor 4. The microscope 1 can be connected to a computer. An image of the object 70 is displayed on a display such as the screen of a computer monitor.

Data/information is collected by the sensor PCB 4a. The sensor PCB 4a is connected with the main controller DSP . The data/in ormation collected by the sensor PCB 4a is sent to the main controller DSP. When the image of the object 70 is not in focus, the main controller DSP informs the motor control MCU to cause the motor driver to drive the motor 15. The shaft of the motor 15 is driven in a clockwise or anticlockwise direction to bring about focusing of the image.

When the motor shaft rotates clockwise, the second gear 17c rotates clockwise and the first gear 17b is caused to rotate anticlockwise. The lead screw 17a then rotates anticlockwise to cause sliding of the optical system 3 and/or the lens module 11a towards the object 70 in direction B as shown in Figure 3. When the motor shaft rotates anticlockwise, the second gear 17c rotates anticlockwise and the first gear 17b is caused to rotate clockwise. The lead screw 17a then rotates clockwise to bring about sliding of the optical system 3 and/or the lens module 11a away from the object 70 in direction A as shown in Figure 3.

Once the image is in focus, the sensor PCB 4a will inform the main controller DSP and then the motor control MCU to stop the motor driver and the motor 15. The focusing system will continue hunting until a focused image is obtained or in case there is change in the image distance, thereby maintaining the image in focus .

In a preferred embodiment, a snap shot of the image can be taken by pressing the button 9a, which is a switch connected to the motor control MCU. The button 9a once pressed triggers the motor control MCU to instruct the main DSP to inform the computer which in response captures a snap shot of the image.

The focus can be locked, or unlocked, by pressing the button 9b which is a switch that connects to the motor control MCU. By pressing the button 9b, a signal is sent to the motor control MCU to disable the motor 15 thereby locking the optical system 3 and/or the lens module 11a at a particular position and hence the focus. Pressing the button 9b again releases the optical system 3 and/or the lens module 11a by re-enabling the motor 15. Auto- focusing will resume once the motor 15 is enabled.

Manual focusing is activated by turning the dial 9c. Manual focusing mechanism 10 overrides or replaces the auto-focusing mechanism 5 when the dial 9c is stroked. This is to allow the user to manually adjust the position of the optical system 3 and/or the lens module 11a for focusing if it cannot be achieved by the auto-focusing mechanism 5.

The dial 9c is connected to the motor control MCU. Turning of the dial 9c to the right activates the motor 15 to bring about sliding of the optical system 3 and/or the lens module 11a in the direction B, Turning of the dial 9c to the left will reverse the motor 15 to bring about sliding of the optical system 3 and/or the lens module 11a in the opposite direction A. The dial 9c can be released when the image of the object 70 is in focus. In this embodiment where there is only one magnification 500X, the lenses 12a, 12b in the optical system 3 and/or the lens module 11a for 500X magnification have only one focus point. The sensor 4 is 1/3" in size. As shown in Figure 8, when the wavelength is 400nm to 1100nm and the focal length is 8.47mm, the back focal length is 45.55mm and the flange back length is 36.41mm. Auto-focusing commence once the microscope 1 is electrified. When the wavelength is 00nm to llOOnm and the focal length is 8.47mm, the back focal length is 45.55mm and the flange back length is 36,41mm.

In the further embodiment where the microscope 1 is capable of switching between 5OX and 200X magnifications, the optical system 3 and/or the lens module 11a has two predetermined positions along the length of the microscope 1, one for each magnification 50X or 200X. The default position for 200 X magnification (hereinafter known as the 200X default position) is much closer to the aperture 7 than that for 5OX magnification (hereinafter known as the 50X default position) .

The microscope 1 includes a magnification selecting mechanism 5a which includes a magnification selection control circuit to automatically positioning the lens module to first and second predetermined positions along the length of the housing corresponding to the first and second optical magnifications. Electrical auto-focusing and the magni ication selection are made possible by the same set of basic components. These basic components include an electric motor to drive a lens module 11a in the optical system 3, and a transmission 17 connected to the motor 15 for transmitting and adapting output of the motor 15 to the optical system 3 and/or the lens module 11a to cause sliding of the optical system 3 and/or the lens module 11a relative to the housing 2 in a direction along the length thereof. As shown in Figures 11 to 13, there are two infrared interrupters 18a and 18b located at the 20OX and 5OX predetermined positions respectively within the housing 2. The optical system 3 has a plate 18c extending from its casing 11, which blocks infrared beams of the interrupters 18a, 18b when the optical system 3 and/or the lens module 11a reaches the respective 200X and 50X default positions, thereby stopping the motor 15 briefly.

The optical system 3 and/or the lens module 11a is caused to move to the respective 50X and 200X predetermined positions by sliding the switch 51 to corresponding sides . The switch is connected to the motor control MCU. Sliding of the switch 51 causes the motor control MCU to activate the motor 15 and motor driver to bring about movement of the optical system 3 and/or the lens module 11a.

Assuming the optical system 3 and/or the lens module 11a is at the middle position along length or axis X of the housing 2, when the user slide the switch to the 200X magnification, a signal is sent to the motor control MCU. The motor 15 is activated and causes the optical system 3 and/or the lens module 11a to slide in the direction B to a 200X predetermined position. The plate 18c on the optical system 3 blocks the infrared beam of the infrared detector 18a once the optical system 3 and/or the lens module 11a is at the 200X default position. Blocking of the infrared beam stops the motor 15 and indicates to the main controller DSP that the optical system 3 and/or the lens module 11a is now in the right position. Auto- focusing may then commence.

When the user slides the switch 51 to the 5OX magnification, a signal is sent to the motor control MCU. The motor 15 is activated and causes the optical system 3 and/or the lens module 11a to slide in the direction A to a 5OX default position. The plate 18c on the optical system 3 blocks the infrared beam of the infrared detector 18a once the optical system 3 and/or the lens module 11a is at the 5OX predetermined position. Blocking of the infrared beam stops the motor 15 and informs the main controller DSP that the optical system 3 and/or the lens module 11a reaches the right position, ready for auto-focusing to commence .

As shown in Figure 9, for the 50X magnification, when wavelength of the light is 400nm to llOOnm and the distance between the object 70 and the lens 12a is 43.62mm, the back focal length of the optical system 3 and/or the lens module 11a is about 18.06 mm, the flange back length is 16.43 mm, the focal length is 15.2 mm.

As shown in Figure 10, for the 200X magni ication, when wavelength of the light is 400nm to llOOnm and the distance between the object 70 and the lens 12a is 23.37mm, the back focal length of the optical system 3 and/or the lens module 11a is about 38.3 mm, the flange back length is 36.67 mm, the focal length is 15.2 mm. In this particular embodiment, the sensor 4 may be a 1/4" Ml20102Mega sensor. The lenses 12a, 12b inside the optical system 3 and/or the lens module 11a have two focus points, for the 50X and 200X magnifications respectively .

In a different embodiment where no manual focusing is provided for, the location for the dial 9c is taken up by the switch 51. Various detailed circuit diagrams of the microscope 1 are depicted in Figures 14 to 16, the operation of which would be apparent to persons skilled in the art .

The overall size of the microscope is significantly reduced while permitting auto-focusing in more than one magnification .

In a preferred embodiment, a snap shot of the image can be taken by pressing the button 9a, which is a switch connected to the motor control MCU. The button 9a once pressed triggers the motor control MCU to instruct the main DSP to inform the computer which in response captures a snap shot of the image. The focus can be locked, or unlocked, by pressing the button 9b which is a switch that connects to the motor control MCU. By pressing the button 9b, a signal is sent to the motor control MCU to disable the motor 15 thereby locking the optical system 3 and/or the lens module 11a at a particular position and hence the focus. Pressing the button 9b again releases the optical system 3 and/or the lens module 11a by re-enabling the motor 15. Auto- focusing will resume once the motor 15 is enabled.

Referring to Figures 17 to 28, there is shown a third embodiment of the microscope 1. The third embodiment preferably includes a magnification selection mechanism 5a which includes a magnification selection control circuit to automatically position the lens module 11a to one of first and second predetermined positions along the length of the housing 2 corresponding to the first and second optical magnifications . The motor 15 and the transmission 17 are responsible for electric magnification selection only. The auto-focusing mechanism 5 includes the lens module 11a which forms the first portion (a first part of the auto-focusing mechanism 5) , piezoelectric elements 52 on a neck (a second part of the auto-focusing mechanism 5) of the third portion 11c of the casing 11 and a magnetic ring forming the second portion lib of the casing 11. The switching between 50X and 200X magnifications by the magnification selecting mechanism 5a is carried out in the same way as described in the second embodiment of the microscope 1. However, focusing is conducted by the auto- focusing mechanism 5 which allows a wry fine axial/linear adjustment of the position of the lens module 11a relative to the third portion 11c along the axis X or the length of the housing 2. The lens module 11a contains a set of stationary lens 12. More specifically, the lens module 11a is moveable towards and away from the third portion 11c linearly/axially to bring about the auto-focusing.

The focusing mechanism 3 includes eight piezoelectric elements 52 which may be piezoelectric ceramics and may foe flake-shaped, arc-shaped column-shaped, or various polyhedron-shaped, overall ring-shaped, cone-shaped, or piecewise circular piezoelectric elements . The advantage of using piezoelectric elements for bringing about rotation of the lens module 11a relative to the third portion 11c is that the arrangement involves less mechanical parts. This is cheaper, easier to maintain, lighter and less susceptible to damage due to wear and tear. These piezoelectric elements 52 are respectively adhered to exterior of each of the eight surface segments of the neck of the third portion 11c, in the form of a regular octagon. The neck of the third portion 11c is preferably separable and made of coppe , The third portion 11c is a connector for connecting the piezoelectric elements 52 and the lens module 11a to the lead screw 17a of the transmission 17 and the guides 13. The neck of the third portion 11c may be a separate part glued to the third portion lie.

In the preferred embodiment, the lens module 11a is rotatably connected to the third portion 11c through inter-engaged threads. External threads are fabricated on the neck 11a of the lens module for connection with internal threads on the inside of the neck lie' of the third portion 11c, such that the lens module 11a can be screwed into the neck 11c' of the third portion 11c. The rotation of the first and second portions 11a and lib along and about the third portion 11c causes an axial/linear movement relative to the third portion 11c due to the characteristics of screw motion, such that the distance between the stationary lens 12 in the lens module 11a and the sensor 4 on the sensor PCB 4a is changed to achieve focus adjustment. Preferably, the maximum axial/linear movement of the lens module 11a relative to the third portion 11c is about 3mm. The width of the threads is 0.5Mmm. The lens module 11a and the third portion 11c are substantially cylindrical in shape. The lens module 11a (first part of the auto-focusing mechanism 5) has different segments 111 to 140 of angular positions relative to the third portion 11c (second part of the auto-focusing mechanism 5) . The threads connecting the lens module 11a and the third portion 11c are helical threads with a total of sis turns/ six pitches, each about 0.5mm thick. Each turn is divided into five segments 111 to 115, each segment takes up 72 degrees and each segment 111 to 140 in all six turns is divided into six sub-segments 211 to 216 each 12 degrees, as shown in Figures 26a, 26b, 27a and 27b. There are thirty sub- segments 211 to 240 in each turn. Each sub-segment 211 to 240 in one turn aligns axially with the corresponding sub-segment 211 to 240 in the following turns . For example, the first sub-segment 211 in the first turn is aligned with the first sub-segment 211 in the second, third, fourth, fifth and sixth turn and so on. The lens module 11a go pass thirty sub-segments which is five segments by rotating 360 degrees relative to the third portion 11c. The second portion lib in the form of a ring is preferably fixedly attached to or formed integrally with exterior of the neck 11a' of the lens module 11a to rotate with or by the lens module 11a. The second portion lib forms a complete ring around the periphery of the lens module 11a. The ring lib has a thickness covering the six turns, i.e. 3 mm and comprises an annular arrangement of magnetic poles and preferably alternating north and south magnetic poles 311 to 340. There are preferably thirty magnetic poles 311 to 340. Each magnetic pole 311 to 340 represents and aligns radially with a sub-segment 211 to 240 in each turn. For example, the first north magnetic pole 311 represent the first sub-segment 211 of the first to sixth turn and aligns axially with the first sub-segments 211 in the first to sixth turns . The lens module 11a, by rotating 360 degrees relative to the third portion 11c, moves pass 30 magnetic poles .

The magnetic poles 311 to 340 on the ring lib are sensed by a magnetic sensor, preferably a hall sensor 51 which is fixed relative to and preferably supported by the third portion 11c. In the preferred embodiment as shown in Figure 19, the Hall sensor 51 is provided on an auto- focusing PCB 55 which is fixedly attached to and preferably on the side of the third portion 11c. The hall sensor 51 is placed next to, but preferably spaced from the magnetic ring of the second portion lib. The hall sensor 51 generates a plurality of alternating signals that corresponding to the number and nature of magnetic poles that go pass it when the second portions lib rotates with the first portion 11a. In the preferred embodiment, the peak of the signal represent a north magnetic pole in the ring lib and the floor of the signal represent a south magnetic pole in the ring lib. The number of peak and floor equals to the number of alternating north and south magnetic poles sensed by or went pass the hall sensor 51. Each segment or sub-segment that has been sensed will has a corresponding signal generated by the Hall sensor 51 for identifying its angular position on the lens module relative to the third portion 11c.

During operation of the auto-focusing mechanism 5, an alternating voltage of a certain frequency is applied to the piezoelectric elements 52 to excite mechanical vibrations on the neck lie' of the third portion 11c where the piezoelectric elements 52 are attached to, so as to generate the traveling wave circularly. The third portion 11c is fixed and the traveling wave around the circle of that casing drives directly the threads of the lens module 11a through the surface of the internal threads on the neck of the third portion 11c with frictional force, so as to propel the first and second portions 11a and lib to rotate relatively to the third portion 11c. The rotation of the first and second portions 11a and lib also causes axial movement relative to the third portion 11c due to the characteristics of screw motion, so that the distance between the optical lens 12 fixed in the lens module 11a and the image sensor 4 fixed on the sensor PCB 4a is changed to achieve focus adjustment.

In the preferred embodiment, auto-focusing is a two stage process. To initiate auto- ocusing, an auto-focus button 9b is pressed. Referring to Figures 26a to 27b, in the first stage, the lens module 11a is moved to the home position which is the front of the first segment 111 in the first turn, if it is not already at the home position Then the lens module 11a and the ring lib start to rotate relative to the third portion 11c. The lens module 11a and the ring 11 stop briefly after turning 72, 144, 216, 288 and 360 degrees reaching the sub-segments 216, 222, 228, 234 and 240 in the segment 111, 112, 113, 114 and 115 of each turn for obtaining the contrast ratio of the light sensed by the optical sensor at these segments 111, 112, 113, 114, and 115 of each turn. Five contrast ratios are taken in each turn. There are in total thirty contrast ratios in all six turns . By then the lens module 11a will have traveled 3 mm linearly or axially away from the third portion 11c . All of the thirty contrast ratios are sent to the main controller DSP (controller) which compares the contrast ratios of the light sensed by the optical sensor 4, at different segments 111 to 140 of angular position of the first part of the auto-focusing mechanism 5 relative to the third portion 11c, and to identify the segments 111 to 140 and the segment 121 at which the contrast ratio is the highest . The hall sensor 51 senses the number of the magnetic poles {6, 12, 18, 24, 30) that went pass it until it stops at the magnetic poles 316, 322, 328, 334 and 340 that represent the segments 111, 112, 113, 114 and 115 in each turn. A signal for each segment 111, 112, 113, 114 and. 115 is generated by the hall sensor 51 which contains information concerning the angular position of each of the segments 111, 112, 113, 114 and 115 in each turn. For example, the sub-segment 216 and the magnetic pole 316 represent the segment 111. The hall sensor 51 go pass 6 sub-segments to reach the sub-segment 216 and the magnetic pole 316. A signal with three peaks (north magnetic poles) and three floors (south magnetic poles) will be generated representing the segment 111. All the signals generated by the hall sensor 51 are sent to the main controller DSP to determine the angular position of each of the segment and the segment at which the contrast ratio is the highest.

For example if the segment 121, which is the first segment in the third turn has the highest contrast ratio of 17, the main controller DSP will be able to determine the angular position of the segment 121 by interpreting the signal correspond to that segment 121 and calculating the number of magnetic poles (sixty six) that went pass the hall sensor 51.

In the preferred embodiment, the lens module 11a is returned to sub-segment 211 after the contrast ratio of all the segments are obtained. The lens module 11a is then rotated clockwise to the segment 121 by passing sixty six magnetic poles (passing some of the magnetic poles two times and some three times) to reach the magnetic pole 316 in the third turn which is radially aligned with the sub-segment 216 in segment 121. Alternatively, the lens module 11a remains at the last sub-segment of the last segment in the last turn after the contrast ratio of all the segments are obtained. It is then caused to rotate anti-clockwise to reach sub- segment 216 in segment 121. At the second stage, the lens module 11a is moved to the front of the first sub-segment 211 of the segment 121. Then the lens module 11a and the ring lib start to rotate relative to the third portion 11c. The lens module 11a and the ring 11 stop briefly after turning 12 degrees at the end of each sub-segment 211 to 216 for obtaining the contrast ratio, of the light sensed by the optical sensor, at these sub-segments 211 to 216 of the segment 121 in the second turn. Six contrast ratios are taken. By then the lens module 11a will have traveled 0.1mm linearly or axially away from the third portion 11c. All of the six contrast ratios are sent to the main controller DSP (controller) which compares the contrast ratios of the light sensed by the optical sensor 4, at different sub- segments 211 to 216 of the identified segment 121 of angular position of the lens module 11a of the auto- focusing mechanism 5 relative to the third portion 11c, and to identify the sub-segment 214 at which the contrast ratio is the highest. The hall sensor 51 senses the number of magnetic poles ( 1, 2, 3, 4, 5, 6) that went pass it when the lens module 11a stops at each sub-segment 211, 212, 213, 214, 215 and 216. A signal for each sub-segment 211, 212, 213, 214, 215 and 216 is generated by the Hall sensor 51 which contains information concerning the angular position of each of the sub-segments 211, 212, 213, 214, 215 and 216. The signals generated by the hall sensor 51 are sent to the main controller DSP to determine the angular position of each sub-segment and the sub-segment at which the contrast ratio is the highest .

Referring to Figure 27b, for example if the fourth sub- segment 214 of the segment 121 has the highest contrast ratio, the main controller DSP will be able to identify the sub-segment 214 of the third turn by calculating the number of magnetic poles that went pass the hall sensor 51.

In the preferred embodiment, the lens module 11a returns to the front of sub-segment 211 after the contrast ratio of each sub-segment has been obtained. Thereafter, the lens module 11a is rotated to sub-segment 214 by passing three magnetic poles 311, 312, and 313 to reach the magnetic pole 314 which is radially aligned with the sub- segment 214 of segment 121. Alternatively, the lens module 11a remains at sub-segment 216 after the contrast ratio of each sub-segment has been obtained and rotates anti clockwise to reach the magnetic pole 314 and sub- segment 214. The lens module 11a has moved axially or linearly relative to the third portion 11c and 1.06667mm away from the sensor 4.

In the preferred embodiment, auto-focusing is completed in 14 seconds. When the auto-focusing button 9b is re-pressed, the lens module 11a will return to the home position and the aforementioned auto-focusing procedure will start all over again. In the preferred embodiment, the buttons 9b and 9c are replaced by an auto focus button 9b and two manual focus, up and down, buttons 9c as shown in Figure 17. Referring to Figure 20, the auto focus button 9b when pressed initiates auto focusing. Signal is sent to the main controller DSP which then informs the motor control MCU to proceed with auto focusing. Auto focusing will stop when the distance travelled by the lens module 11a reaches the predetermined desired distance. The position of the lens module 11a relative to the third portion 11c will remain unchanged until the button 9b is re-pressed to restart auto-focusing .

A manual focusing control is arranged to replace or override the auto-focusing mechanism 5 for performing manual focusing. The manual focus buttons 9c are used to manually control the auto-focusing mechanism 5 to conduct manual focusing when the user finds necessary. By pressing anyone of the manual focus buttons 9c, the manual focusing overrides the auto-focusing. A voltage is then applied to the piezoelectric elements 52 initiating movement of the lens module 11a relative to the third portion 11c. Releasing the button 9c will break the voltage supply and stops the movement of the lens module 11a relative to the third portion 11c. In a preferred embodiment, pressing the up button 9c causes the lens module 11a to rotate clockwise increasing the distance between the lens module 11a and the sensor 4. Pressing the down button 9c causes the lens module 11a to rotate anti-clockwise reducing the distance between the lens module 11a and the sensor 4.

Figure 20 shows the electric connection of various components in the third embodiment of the microscope 1. This is different from that of the first two embodiments. The auto focus button 9b, the snap shot button 9a and the switch 51 are connected to the main controller DSP while the buttons 9c are connected to the motor control MCU. The motor control MCU is connected to the motor driver for the motor 15 and the motor driver of the auto- focusing mechanism 5. The infrared detectors 18a and 18b are connected to the motor driver of the motor 15. The Hall sensor 51 is connected to and on the auto-focusing PCB 55 which is connected to the motor driver of the auto-focusing mechanism 5. The sensor 4, preferably a CMOS image sensor and the sensor PCB 4a are connected to the main controller DSP. The main controller DSP is connected to the USB and the USB may be connected to a PC for displaying the image of the object 70.

The auto-focusing mechanism 5 in the third embodiment of the microscope may be referred to as ultrasonic motor.

Figure 24 shows a different embodiment of the auto- focusing mechanism 5. The distance between the lens 12 can be changed. One lens 12a is fixed in the third portion 11c and the rest of the lens 12 remains in the lens module 11a. Movement of the lens module 11a relative to the third portion 11c changes the distance between the lens 12a and the rest of the lens 12. This brings about focusing of the image of the object 70.

It should be appreciated that modifications and alterations obvious to those skilled in the art of microscope, manufacture and use, should not be considered as beyond the scope of the present invention. For example, instead of stationary lens, the inter-distance between the lenses in the optical lens module can be changed. For example, there may be only four LEDs on the iris. As a further example, the hood may be made transparent.

In the described embodiment, two magnifications are selectable by the optical system or the optical lens module being movable between two positions using the motor. In a different embodiment, there can be three magnifications selected by moving the optical system or the optical lens module to three respective positions along the length of the housing.