CAMERA AND LIGHT SOURCE

This invention relates to imaging apparatus of the kind including a housing, an imaging device within the housing, an optically-transparent window mounted with the housing through which the imaging device receives radiation from a field of view externally of the apparatus, an illuminating device also within the housing and arranged to provide illuminating radiation through the window onto the field of view.

The present small size and relatively low cost of video camera modules has made them more common over recent years. In some applications, such as for medical imaging used inside the body, the imaging apparatus requires some means for illuminating the field of view of the camera, such as one or more LED lamps.

There are various problems associated with apparatus where a camera and illuminating means are contained in the same unit, especially where size needs to be kept to a minimum. In particular, it can be difficult to achieve both a safe level of electrical insulation and keep to a minimum leakage of light within the apparatus directly from the lamp to the camera. Plastics materials may be used for the window to increase electrical insulation but these tend to lead to more internal reflection within the apparatus.

It is an object of the present invention to provide alternative imaging apparatus.

According to one aspect of the present invention there is provided imaging apparatus of the above-specified kind characterised in that the apparatus further includes an optical barrier between the imaging device and the illuminating device, that the optical barrier is in the form of an optically opaque compressible material located in the housing in compression and in contact with an inner surface of the window such as thereby to reduce the amount of radiation emitted by the illuminating device that is incident on the imaging device without passing through the window. The optical barrier is preferably of a radiation-absorbing material. The optical barrier is preferably of a material selected from a group comprising: rubber, foam or silicone and is preferably of a black colour. The optical barrier may be held in compression between the floor of a recess in the housing and the inner surface of the window. The optical barrier may extend across the housing between the imaging device and the illuminating device such that it divides the housing into two optically-isolated regions in which one contains the imaging device and the other contains the illuminating device. Alternatively, the optical barrier may be in the form of a ring compressed between the window and a surface around the imaging device such that radiation from the field of view passes to the imaging device through the centre of the ring. The illuminating device may include one or more LEDs. The housing may include an inner part having an open end and a cap fitted over the outside of the inner part, the cap including a wall extending around the outside of the inner part and sealed with it, and an end face of the cap providing the window of the apparatus. The cap may be formed entirely of an optically-transparent material.

According to another aspect of the present invention there is provided an endoscope including a bendable elongate support and imaging apparatus according to the above one aspect of the present invention mounted at one end of the support.

Imaging apparatus in the form of an endoscope will now be described, by way of example, with reference to the accompanying drawings, in which,

Figure 1 is a side elevation view of the endoscope;

Figure 2 is a cross-sectional side elevation view of the forward, patient end of the endoscope showing a first arrangement of the imaging apparatus;

Figure 3 is a forward end view of the endoscope of Figure 2; Figure 4 is a cross-sectional side elevation view of an endoscope with an alternative arrangement of imaging apparatus; and

Figure 5 is a forward end view of the endoscope of Figure 4

With reference first to Figures 1 and 2, the endoscope, introducer or bougie 1 includes an elongate, bendable support or rod 10 comprising an outer plastics sleeve 11 and an inner core 12 having a coaxial passage 13 extending along its length. The forward, patient end of the rod 10 supports an imaging unit 14 that is connected by a cable 15 extending rearwardly along the passage 13 to a low profile electrical connector 16 at the rear end of the endoscope. In use, the connector 16 is connected to a display unit 17 via a cable 18 and mating connector 19. The endoscope 1 is used to insert an endotracheal tube 20 or the like. The endoscope 1 is first inserted to the patient's trachea while monitoring the image on the display 17. When correctly positioned, the connector 19 at the end of the cable 18 is uncoupled from the connector 16 on the endoscope 1 and the endotracheal tube 20 is slid over the connector 16 and along the endoscope from its rear end. When the tube 20 has been fully inserted the endoscope 1 is pulled out rearwardly leaving the tube in position. Further description of the method of use of the endoscope can be seen in WO2010/136748 and WO2013/ 124605.

With reference now also to Figure 3, the imaging unit 14 is contained within the forward or patient end 30 of the endoscope 1. The forward end of the inner core 12 terminates short of the forward end of the sleeve 11 to leave a cylindrical recess 31 within which the imaging unit 14 is contained. The forward end of the sleeve 11 provides an inner part that is closed by a moulded cap 32 having an inverted can shape with a cylindrical side wall 33 and a lateral end wall 34. The side wall 33 fits onto a reduced diameter recess 35 at the forward end of the sleeve 11 with its rear end abutting a forwardly-facing step 36. The cap 32 is sealed on the outside of the sleeve 11, such as by means of an adhesive or solvent. The thickness of the side wall 33 is equal to the height of the step 36 so that there is a smooth continuation between the outer surface of the cap 32 and the sleeve 11. The cap 32 is preferably moulded entirely of an optically-transparent plastics material although it is only essential that its end wall 34 be transparent so as to provide a window for the imaging unit 14. The imaging unit 14 comprises an imaging device in the form of a conventional video camera sensor 40 and an illuminating means or device such as in the form of one or more LEDs 41 mounted side-by-side. Typically, the LED 41 emits radiation in the visible spectrum although this is not essential since it could emit at wavelengths beyond the visible part of the spectrum providing that the camera were sensitive to these wavelengths. The camera 40 is oriented to receive radiation from a field of view through the end wall or window 34 of the cap 32 forwardly of the endoscope 1.

Similarly, the LED 41 is oriented to emit radiation forwardly through the window 34 onto the field of view of the camera 40. The imaging unit 14 additionally includes a barrier, partition or screen 42 arranged to prevent or reduce the amount of radiation emitted by the LED 41 that is incident on the camera sensor 40 directly or by internal reflection within the recess 31, that is, radiation that passes from the LED to the camera without having first passed through the window 34. The barrier 42 is of an optically-opaque, radiation-absorbing, compressible material, such as a matt black rubber, foam or silicone. The surfaces of the barrier 42 could have small ribs or other surface textures to reduce reflection and are preferably of a black colour. The barrier 42 is held in compression between the inner, underside of the window 34 and the floor of the recess 31 provided by the forward end of the inner core 12. As illustrated, the barrier 42 extends diametrically across the recess 31 in a straight line but the barrier could divide the recess into two optically-isolated regions in other ways, such as along a chord displaced towards the camera or LED, or it could follow a curved or angled path.

Because the barrier 42 is compressible it makes close contact with the underside of the window 34 and with the end surface of the inner core 12, thereby accommodating any imperfections in the surfaces and any misalignment of the surfaces. The compressible nature of the barrier 42 facilitates assembly and does not require close tolerances in order to achieve intimate contact. In this way, the leakage of radiation around the barrier 42 can be very low.

Figures 4 and 5 show an alternative configuration where the barrier 52 is in the shape of a circular ring and is located between the underside of the window 54 and the forward-facing surface of the camera 50. Alternatively, the barrier could sit on the floor of the recess and extend around and along the camera. The open centre or bore 53 of the ring 52 provides a light path along which the camera 50 can receive radiation transmitted through the window 54 from its field of view. A ring- shape barrier could instead, or additionally, be provided between the LED 51 and the window 54. These ring-shape barriers need not be circular but could be of other shapes, such as oval or square, to match the shape of the camera or illumination source with which they are used. The present invention is not confined to endoscopes but could be used advantageously in any imaging apparatus having an illumination source mounted close to a sensor.