In the prior art, various reflective sensors have been known, using a reflected optical beam emitted from a light emitting diode (LED) and which photo is sensed by using a light sensing element positioned (Darlington phototransistor) adjacent the LED. However, it has been difficult to use a single sensor for determining the position of two separate, overlying components that are to be positioned precisely aligned along at least one plane.

SUMMARY OF THE INVENTION The present invention utilizes a single optical sensor that has a light emitting diode light source and an adjacent light sensitive component, such as a phototransistor, that senses the amount of light reflected from an object. The light sensitive element provides an analog output that is a function of the amount of intensity of the light received. The element output sign is supplied to a circuit that provides identifiable signals when the voltage level generated by the reflected light back to the light sensitive transistor is at, or below, two separate threshold levels. The sensor also can be used in its normally intended mode, which is for sensing when one object overlies the sensor.

In the process for determining the position of two different overlying objects, the light emitting diode projects a light beam along a line that identifies the reference position to be sensed. A first object such as a web of film is spaced farther from the light source and sensor than the second object, such as a substrate or card, and the film moved by a drive over the reference or light line to intercept the light beam.

The film will thus overlie the substrate. When the film intercepts the light beam, a reflected light signal is provided to the light sensitive element or phototransistor. When the reflected light level causes conduction of the phototransistor current that exceeds a set first threshold level, and causes collector voltage to drop to or below that threshold level, a first signal is provided to circuitry including a controller indicating that the film or first object is properly positioned and the drive for moving the film will be shut off.

When the substrate is moved by a drive in a path between the film and the sensor, when the substrate aligns with the sensor, the reflected light will be greater or more intense, causing the phototransistor to conduct more current, and provide a voltage on the phototransistor output that is lower than the voltage caused by light reflected from the first object or film.

When the voltage is at or below a second threshold level, there is a signal from the phototransistor that the substrate is properly positioned and the drive for the substrate will be shut off or discontinued.

This can be done for alignment of leading edges of two or more stacked, generally planar surface objects, or for any other desired positioning where two or more objects that are to be associated are at

different levels or spacings from the sensor and where the positioning of the objects, or an edge or part of the objects, relative to a known reference point or line is to be sensed.

In the form shown, a printed identification card is the substrate and a laminate film material which is to be placed over the card is above the card. The sensing is to first sense the position of an edge of the overlying laminate film, and subsequently move a card or substrate between the laminate film and the sensor so that when the sensor provides a second signal, the card will be properly positioned along the same line or plane as the edge of the laminate film. The edges of the laminate and the card will be precisely aligned. The two parts are then driven in unison to a lamination station for laminating the laminate material onto the surface of the card that faces the laminate material.

A"home"or"zero"position for the sensor can be established using standing techniques so the edges of the film and substrate are located properly.

The parts can be aligned laterally by providing a fixed guide for the card in registry with a sensor, and adjustably moving the feed mechanism for the laminate until the laminate laterally aligns with a fixed line along which the card side edge moves. Then the card is advanced so the leading edges are aligned as described.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic side view representation of a lamination station including a laminate feed mechanism and an alignment sensor for

sensing the position of a leading of the laminate and a card on which the laminate section is to be laminated.

Figure 2 is an enlarged side elevational view of the leading end portions shown in Figure 1, again schematically shown; Figure 3 is a simplified circuit diagram of a typical LED sensor and a reflected light sensing transistor; Figure 4 is a schematic top plan view of the alignment device in position for aligning the laminate feed mechanism laterally and a sensor position for sensing the leading edges of the laminate and card; Figure 5 is a typical output current curve from the circuit of Figure 3; Figure 6 is a schematic diagram of the sensor with a modified sensing circuit including a controller.

Figure 7 is a process flow block diagram of the present processor; and Figure 8 is a control loop flow diagram using the present sensors in a card lamination process.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS Referring to Figure 1, an apparatus that is used for laminating sections of laminate material onto a substrate such as an identification card is illustrated at 10, and is shown only schematically. A source of laminating material or film 12 is separated into individual lamination shown schematically at 14 is used to feed material into a laminate drive represented only schematically at 16. The laminate drive moves a laminate film section 14 along a guidewall 18, which has an end surface or edge 18A. The laminate section 14 is moved until at least a short portion 20 protrudes beyond the end edge 18A. Portion 20 is spaced above a card guide, as shown a supporting platform 22 in the

apparatus 10. The card guide 22 supports a card 24, and also supports the front edge sensor shown schematically at 26 below the plane of the card guide. The sensor 26 includes a focused light source or LED 28 (see Figure 3) and a light sensitive element or phototransistor 30, which is connected in a circuit to provide an output voltage as a function of the light received. The more light that reflects on the base of phototransistor 30, the more current is conducted by the transistor and the lower the voltage signal the collector, as will be described. The sensor 26 may be a Honeywell Inc. sensor HOA 1180-003.

The sensor 26 is supported on the card guide 22, and the LED 28, preferably a focused light source, projects light upwardly through an opening 32. The phototransistor 30 receives reflected light through the opening 32 in the card guide platform 22.

It can be seen that the end portion 20 of the laminate film section is offset or spaced from the plane of the card guide platform 22 by a distance indicated by the double arrow at 34. A card 24, which is driven along card guide platform 22 with a card drive 25 (generally a drive roller 25B and a pinch roller 25A as shown) will be moved under control of a controller 49 to a position where its leading edge 24A is in line with the light beam from the LED 28 in sensor 26, and then will be aligned with the leading end edge 20A of the laminate section 14.

The laminate film section 14, and its end edge 20A is moved into position first by the laminate film drive 16 under control of controller 49, and its end edge position is sensed before the card 24 is moved into alignment. When the laminate section 14 overlies the light beam from the LED 28, light is reflected back as

indicated by the reflection lines 38 in Figure 3, and this will cause the phototransistor 30 base to become conductive and the voltage output will drop across a resistor 34 below the full voltage (5 or 3.3 volts) at the collector to a selected level or threshold that is proportional to the intensity of light that is being reflected onto the phototransistor 30. As soon as the threshold level is reached, the controller 49 receives the signal and stops the laminate drive. The drive includes a controlled motor, such as a stepper motor.

In the schematic diagram of Figure 3, the voltage will be sensed at line 40 and is an inverse of current flow. The more light, the more current and the lower the voltage at point 40. The voltage with no light being sensed is the supply voltage, which may be a standard 5 or 3.3 volts. When the voltage at point or line 40 is below a set threshold level, for example, 3 volts, it is known that the end edge 20A is directly overlying the light beam, and the precise position of the edge 20A is indicated by this lower voltage sensed at the controller 49, which controls the functions.

The card 24 will then be moved forwardly under control of controller 49 along card guide 22 so that its end edge 24A comes into alignment with the light from the LED in sensor 26, and because a greater amount of light will be reflected due to the difference in the offset or spacing of the card from the sensor relative to the film, the voltage output at point or line 40 will be further decreased. When that voltage output is down below a second threshold level, for example 0.8 volts, the controller 49 receives the signal and the drive to the card 24 is stopped by stopping a stepped motor driving the drive roller 25B. The controller 42 then has the indication that the edge 20A and the edge 24A

are precisely aligned. The alignment plane is indicated at 24C in Figure 2. In Figure 3, a threshold detector 90 is illustrated and includes a control 88 to set the first threshold voltage for the film and a control 92 to set the second threshold level for sensing the substrate.

As shown in Figure 2, when alignment occurs, the controller will start both the laminate drive and card drive and the film and card will be driven by their respective laminate drive stepper motor and card drive stepper motor. This drive is using stepper motors that are precisely driven so that the same amount of movement is achieved with the stepper motors from the card drive and the laminate drive. The stepper motors used can be controlled to move in very small increments, and can be controlled to include micro stepping. The end edges will merge together in drive rollers shown at 44, which comprise a powered lower roller 46 controlled by controller 49, and a spring loaded idler roller 48, so that the card and the laminate section will be driven precisely together to the lamination station. The laminate section 14 and the card 24 will be in contact with each other or contiguous, for the laminating operation, and that is the way the film and card will be passed through the rollers 46 and 48 forming the 44.

A plan schematic view is illustrated in Figure 4, and the support platform 18 for the laminate is mounted on a laminate drive shaft 50, that is mounted so that it can be slid laterally in direction indicated by the double arrow 52. A worm 54 drives the shaft 50 and the platform 18 relative to the frame 10, when a DC motor 56 drives the worm through a gear drive 55. The lateral position of the support 18, and thus the laminate section 20 held thereon can be adjusted to

align the side edges of the laminate section and the card side edge. The laminate section end portion 20 will be overlying a lateral alignment sensor 58 and the position can be precisely adjusted.

The sensor 58 is adjusted initially to be positioned accurately with respect to a fixed card side guide 57, against which the card is held under a spring- loaded guide 59 when the card is driven. The side to side or lateral location of the sensor 58 is then preset.

The end portion 20A of the laminate section as it is fed by laminate drive 16 under control of controller 49 will extend beyond the edge 18A of the laminate support wall, so that the sensing for the lateral position of the laminate film section takes place on the end portion. The mechanism and platform 18 can be moved laterally by driving the motor 56 and rotating worm 54 to precisely align the lateral edge shown at 20B in line with the edge of the card, that is being fed into the system. The side edge of the card 24 is guided with the fixed side guide 57 so its position is known, and is used as a reference for positioning the laminate section laterally.

The sensing for lateral position is then carried out. If the edge of the laminate section is not precisely aligned, the platform 18 is shifted by motor 56 and worm 54 until the proper signal is received.

Referring to Figure 5, a plot of voltage at line 40 versus current of the phototransistor 30. The voltage at the transistor output along line 40 is on the vertical scale, which is indicated at 61 and the on zone of the system, when both the laminate drive and card drive will work is indicated by the region that is defined as a block 60. The voltage at line 40 will be

a full scale value of 3.3 volts. When light is reflected from LED 28 to the base of phototransistor 30, the transistor conducts and the voltage at line 40 will drop, when the current is passed through a suitable resistor. The current can be made to follow a first slope of decreasing voltage indicated at 62. When light is reflected, such as when the first sensed device (the laminate section) moves and the reflected light increases, there is a point 64 along the line 62 where the voltage at line 40 is in the range of 3 volts. A command signal is given by the controller 49 to the laminate drive 16, usually a stepper motor, to stop the feeding of the laminate section 20. Then the lateral adjustment can take place.

As more light is reflected as the card 24 is moved over the sensor, the current through phototransistor 30 increases, the voltage at output line 40 becomes less. When the voltage signal is approximately 0.8 volts as at point 66, a signal is given to stop the card drive and the ends of the laminate film and the card are perfectly aligned. The slope of the voltage signal can be changed to that shown at 70 by modifying the resistor through which the voltage is divided. The slope can be made to adjust the sensitivity of the sensor as desired. The zone where threshold settings can be selected is indicated by the arrow 72. The voltage threshold signals for shutting off the laminate drive and the card drive are separated sufficiently so distinct commands are received.

While the specific embodiment has been shown in connection with the laminating a printed ID card, the control can be used for substantially any type of operation where there are two overlying or registering objects that need to be precisely aligned, and which can

be spaced apart at the location of sensing. In other words, the difference in distance from the sensor is a direct function of the amount of light reflected, and when the light reflected from two different parts or objects is different, the different voltages that are sensed can be used as signals for providing action through the controller that is shown at 49. The controller 49 controls the laminate section drive 16, the card drive 25 and also a printer and laminator drive 77 (Figure 4), as well.

In the process, therefore, obtaining the necessary reference position of two objects that are spaced a different distance from a sensor is provided.

The basic concept is to set the threshold for the front alignment sensor to first sense the alignment edge of the object that is farthest away from the sensor.

The threshold for the lateral assignment sensor, if it is used, is set, and the lateral adjustment devices are activated once the laminate film is held in position, with its end edge has been sensed until lateral alignment is completed for the film or which is farther from the sensor than the card. The same sensor can be used for lateral adjustment as for the end edge, and when the sensor output reaches the desired level, lateral adjustment is stopped by the controller. The sensor 56 can sense direction to adjust laterally as well.

The film is then driven forwardly, which in this form of the invention comprises the film or laminate material, until the front alignment sensor 26 output reaches a selected active threshold, and then the laminate drive or film drive is stopped by the controller.

The threshold for the front alignment sensor to sense the components that is closest to the sensor is then set, and the drive for the second object is activated to move the second component, which in the form shown is a card on which a laminate is to be placed, until the front alignment sensor 26 indicates that the different threshold is reached, in this case a lower voltage output.

The card drive is then coordinated by controller 49 with the film drive until the two parts, the film and the card enter a common drive which in this form of the invention comprises drive rollers 46 and 48 that will hold the two parts in a proper relationship as they are driven forward into a laminator or other processing section 81.

In this form of the invention, as shown, there is a constant monitoring of the output voltage, which is dependent upon the current conducted by the phototransistor, so that it is not a straight on-off sensor. However, an on-off sensor could be used, which essentially would be a comparator that would be used to turn on or off a circuit when the voltage from the sensor met or exceeded a certain level.

The ability of obtaining different voltage signals from the sensor, as a function of the distance of the sensed object from the sensor permits its use for sequentially sensing a plurality of objects at decreasing spacing from the sensor for determining when the objects are precisely aligned with a reference position.

Figure 6 is a schematic showing of a modified sensing circuit. A flat object such as card 24F is shown over sensor 26, which includes the focused light source 28 and phototransistor 30. Other flat objects

include a laminate or a card and a laminate. The line 40 is connected to one input of a comparator 96 that has an output connected to controller 49, which is a microprocessor. The controller 49 is used to set the thresholds and the threshold level is provided on a bus 97 to a digital-to-analog converter 98, which provides the reference or threshold signal to the second input of the comparator. When the signal on line 40 is at the threshold level, the comparator provides an output on line 96A to the controller 49. The controller 49 then carries out other control functions.

Figure 7 is a block diagram showing a process flow chart with the steps for alignment of an ID card and a laminate section that is to be placed on the ID card, as shown in the drawings. A first step is to set the threshold of the alignment sensor 26 for the film as indicated by the block 100, then the drive for the laminate is energized and the laminate section is driven forwardly as indicated by block 102. The sensor is coupled or shown at block 103, at intervals of 100 microseconds or so, and when the threshold is not reached the drive continues. When the threshold is reached the reflected light indicates that the front edge of the laminate is aligned with the sensor. The laminate film is stopped by controller 49 as indicated by block 104.

When a lateral alignment sensor is used, which can be, in some instances, not used, the lateral alignment sensor would be set. The support for the laminate or film is moved laterally for the lateral alignment and the lateral alignment drive is stopped when the threshold for the lateral alignment sensor is reached. The lateral alignment, which may be optional is indicated by block 106.

If suitable guides are provided for both the laminate section and the card, there are instances when the lateral alignment step would not be needed. Also, it should be noted that the fixed side guide for the card would be used, and the lateral alignment sensor 56 would be properly positioned relative to the line defined by the side guide edge prior to starting operation of the printing and laminating apparatus.

After the front alignment sensor has positioned the film and the film is stopped, the front alignment sensor threshold for the card is set, as shown at block 108. The process would proceed. The card is driven forwardly as indicated by the block 110 until the threshold is reached. The sensing is indicated at block 112, and the sensor is sampled at intervals until the threshold is reached. This is the second threshold, and the card is between the laminate section and the card support, so that it is closer to the sensor.

The card is stopped by controller 49 as indicated by the block 114, and in the lamination process the card and the laminate film section that had been aligned or"married"are then moved forward simultaneously to the next processing station, which is the lamination station in the form of the invention shown. This is indicated by the block 116.

Referring to Figure 8, a simplified flow diagram for the controls functions carried out by controller 49 is illustrated.

The step in the process, after the film has been properly loaded into the film drive is to drive the film as indicated by the block 120. The film is driven until the edge is sensed at the reference position as shown by the block 122. The film is then stopped by the controller 49 as indicated by block 124 and the

substrate or card is driven along its path (which is preselected) as indicated by the block 126.

Both the film and the substrate have edges that are to be aligned, and in this instance, consideration is given for the front edge. The substrate then is moved to overlie the sensor and its edge position is sensed as shown at block 128. It was previously noted that the sensor will be set at different thresholds, for the two different levels of the film and the substrate.

Once the substrate position is sensed, as explained, the substrate or card drive is stopped by the controller as indicated by the block 130, and then the controller 49 will drive both the film and the substrate to a further processing station as indicated at 132.

Variations of these drives can be made, but the controller 49 controls the functions as a direct result of the sensor input for the objects at two different levels that are being married or positively aligned along one edge.

If the two objects being aligned are not a card and a laminate film, the process shown in Figure 7 would be followed but with different overlying objects.

Multi-level sensing can be used with a wide range of products or objects that have edges along surfaces that reflect (or transmit) light and that need to be "married"or precisely aligned along a reference plane or line. Several overlying substrates or films can be aligned in sequence at different levels using these techniques.

The sensing shown can be carried out if the substrate and/or the film are light transmissive, by providing a light source on one side of the set of light transmissive sheets or substrates that are to be sensed.

That is, for example, the sensor 26 is shown below the card path and thus also below the film. A reflecting mirror could then be positioned on the top side of the film, or a directly mounted phototransistor could be positioned on the top side of the film. The light that is transmitted through the two or more layers that are being sensed provides the sensor output. The light, as stated, can be reflected from a mirror above all of the layers, if the light source is below the layers, or a phototransistor can be mounted on the opposite side of (above) all of the layers and sense the light transmitted through the layers.

The method also can include sensing a plurality of layers one of which partially blocks light and then subsequent layers fully block a light beam, particularly where transmissive sensing is utilized as discussed above.

It is also apparent that two or more webs of film which are continuous webs can be fed and aligned as discussed. For example, a thicker web of plastic material can be sensed, and two or more layers of such web can be aligned and moved to a laminator, to make a composite card. This method could be used for constructing a multipart card such as the 3M secure card'. The alignment sensors will precisely align the edges of material that is on a continuous web, after which the material can be cut to size. The controller can be used for driving the webs in place of the laminate drive and the card drive.

A laser diode can be used as the light source, but requires slightly different, but known, sensing circuitry.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.