JP3768280B2 - Optical data collection device for paper - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention collects optical data of conveyed paper sheets and detects the presence / absence, double feed, width, etc. of paper sheets based on the optical data, and paper sheets based on the optical data In particular, the present invention relates to an optical data collecting device for a paper sheet discriminating apparatus that discriminates the type of paper, and in particular, an LED (light emitting diode) can be used as both a light emitting element and a light receiving element, and stable optical data can be collected even if the bill passage position changes. The present invention relates to an optical data collecting apparatus.
[0002]
[Prior art]
In a banknote discriminator, it is common to specify a banknote by measuring the width of the banknote (the length in the direction perpendicular to the transport direction). In such a bill discriminator, generally, a combination of an LED array and a photodiode array, or a combination of an LED array and a linear CCD constitutes a line-shaped sensor, which is shielded by bills conveyed laterally. The length of the bill is measured by detecting the length of the light shielding portion of the sensor.
[0003]
By the way, LED can be used not only as a light emitting element but also as a light receiving element. That is, the LED operates as a light emitting element in the forward bias state, but operates like a photocell in the cello bias state, and operates like a photodiode in the reverse bias state. An example of using such characteristics is a bidirectional transmission (duplex communication) system using an optical fiber. For example, Japanese Patent Application Laid-Open No. Sho 62-198234 discloses an optical communication device in which an LED is used as both a light emitting element and a light receiving element. This optical communication device provides a forward current corresponding to a transmission signal to an LED, and a photoelectric conversion circuit that detects and receives a reverse current that flows when the LED receives light from an optical fiber, and a transmission operation during reception By providing a transmission prohibiting circuit for prohibiting transmission, bidirectional optical communication can be performed through a single optical fiber.
[0004]
Japanese Patent Application Laid-Open No. 60-248067 discloses an original reading apparatus that reads an original using an array type sensor (hereinafter referred to as “LED array”) in which a plurality of LEDs are arranged in parallel. . FIG. 20 shows an example of a cross-sectional configuration of the main part of the document reading device. This reading device emits LEDn in the LED array 2 to illuminate the document 1 on the transparent protective layer 4, and the LEDn The adjacent LEDs n-1 and LEDn + 1 are turned off, and the reflected lights a and b reflected from the document 1 in the region R corresponding to LEDn are received by the LEDn-1 and LEDn + 1 and converted into electrical signals. The reading operation is sequentially repeated for all the LEDs of the LED array 2 arranged on the substrate 3 so that the document 1 is read.
[0005]
However, in the device that collects optical data of conveyed paper sheets and detects the presence / absence of paper sheets, multi-feed, width, etc., and the device that discriminates the type of paper sheets, As described above, a combination of an LED array and a photodiode array or a combination of an LED array and a linear CCD is used as a detection sensor, and there are the following problems.
[0006]
Photodiodes and phototransistors generally have a light receiving spectral sensitivity wider than that of light-emitting LEDs, and thus have a characteristic that they are easily affected by external light. In such a combination, since one side of the passage is the light source and the other side is the light receiving sensor side, there is a certain gap in the bill passage, so that the way the shadow is made by passing the bill through the light source side or the light receiving side. Since it is different, the bill length detected differs depending on the bill passage position. Further, when measuring the thickness by the amount of transmitted light for the purpose of detecting double feed, there is a problem that the output fluctuates depending on whether the bill (paper sheet) passes through the light emitting side or the light receiving side.
[0007]
[Problems to be solved by the invention]
As shown in FIG. 21, a transmissive sensor using an LED (light emitting diode) and a Ph-D (photodiode) or Ph-Tr (phototransistor) is provided between the LED and Ph-D (or Ph-Tr). The received light output varies depending on the passing position x of the medium 1 at. That is, the distance between the LED and the medium 1 is x, and the Ph-D (or Ph-Tr) detection output is e._OThen, the detection output is e_OIs expressed by the following equation 1, and the passing position x of the medium 1 and the detection output e_OThe relationship is expressed as shown in FIG.
[0008]
[Expression 1]
e_O= K / x²
Here, 0 ≦ x ≦ d and K is a coefficient.
That is, the detection output e_OFluctuates in inverse proportion to the square of the distance x between the LED and the medium.
[0009]
For example, when two sheets of paper are transported in an overlapping manner, the detection output e when passing through the LED side_OAnd a detection output e when passing through the Ph-D (or Ph-Tr) side_OIs a waveform as shown in FIG._OIn a simple comparison, it was not possible to detect the overlap of two sheets. In addition, the photodiode or phototransistor has a wide spectral characteristic and is affected by disturbance light. The 5000 yen banknote in Japan does not have a watermark at the center of the banknote, and if there is oil stain, the light transmittance is high, and when the bill width is detected by the transmitted light, the received light amount when the banknote approaches the light source side In many cases, it was detected that there was no banknote and it was difficult to detect the presence or absence of a banknote.
[0010]
The present invention has been made under the circumstances as described above. The object of the present invention is to collect stable optical data even if the passing position of the paper sheet changes, and to share a light source and a light receiving sensor with a common member ( It is an object of the present invention to provide an optical data collection device for paper sheets that can detect the width, double feed, type, and the like of paper sheets at low cost.
[0011]
[Means for Solving the Problems]
  The above object of the present invention is to collect two optical LEDs in an optical data collection device of a paper sheet detection device that collects optical data of paper sheets being conveyed and detects the presence and / or multifeed of the paper sheets. Are provided to face each other for light emission by passing a light emission current, and for the other, a current-voltage conversion resistor is connected in series for light reception.When one LED operates as a light source, the other LED operates as a light receiving sensor, and when the other LED operates as a light source, the one LED operates as a light receiving sensor.Switching means for switching between light projecting and light receiving, storage means for storing light reception signal values from the light receiving LEDs before and after switching by the switching means, and light reception before and after switching stored in the storage means Comparing means for adding or averaging signal values and comparing with a predetermined value is achieved.
[0012]
  Further, in the optical data collection device of the paper sheet discriminating apparatus that collects optical data of the conveyed paper sheet and discriminates the type of the paper sheet, a direction transverse to the transport direction of the paper sheet Light-emitting / light-receiving sensor means having LEDs arranged in a substantially straight line on both sides of the passage surface and arranged in parallel with a predetermined interval;In the first modeWhen the LED on one side of the passage surface operates as the light emitting light source side, the opposing LED serves as the light receiving side sensor.MoveMakeIn the second mode, when the facing LED operates as the light emitting light source side, the one LED operates as a light receiving side sensor.The light emitting light source side and the light receiving side sensorAndA light emission / light reception switching means for switching; a read AD conversion means for sequentially reading and A / D converting the output of the light receiving side sensor in the first and second modes; and a LED for reading a digital value from the read AD conversion means First and second storage means for storing in correspondence with the first and second modes together with address information for identifying the same; the same address stored in the first storage means and the second storage means This is achieved by providing an average value calculating means for calculating the average value of the stored values.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a configuration example of a first embodiment of an optical data collection device for paper sheets of the present invention. In FIG. 1, a sensor means 10 for reading optical data of a paper sheet conveyed on a path is composed of a pair of LEDs (light emitting diodes) 11 and 12 that serve both as a light emitting element and a light receiving element. And the LED 12 are installed facing the top and bottom of the passage surface. LED 11 and LED 12 are LEDs of the same member. When one LED operates as a light source, the other LED operates as a light receiving sensor, and the light projecting / light receiving switching is performed so that the light projecting side and the light receiving side are alternately switched. Controlled by means 20.
[0014]
  As shown in the configuration example of FIG. 2, the light projecting / light receiving switching means 20 is composed of two light projecting / light receiving switching circuits 21 and 22, and an inverter 23 is connected to one of the switching circuits 21. Switching between the light emitting side and the light receiving side is performed by inputting the signal CHG and its inverted signal. In the light projection / light reception switching means 20, when the light projection / light reception switching signal CHG is "0" (mode 1), the switching circuit 22 causes the LED 12 to flow in the forward direction to operate the LED 12 as a light emitting element. When the switching circuit 21 applies a reverse voltage (reverse bias voltage) or 0 V (zero bias) to the LED 11 to operate the LED 11 as a light receiving element (photodiode), and the light projection / light reception switching signal CHG is “1” ( The mode 2) is configured to operate with the LED 12 as a light receiving element and the LED 11 as a light emitting element, contrary to the above operation. The switching between the mode 1 and the mode 2 by the switching signal CHG is performed in a time-sharing manner for each predetermined transport distance (for example, every predetermined number of pulses of the mechanical clock) according to the external clock 60. The light receiving outputs eo1 and eo2 of the LEDs 11 and 12 switched to are alternately output from the light projecting / light receiving switching means 20. The details of the configuration of the light projecting / light receiving switching means 20 will be described with reference to a specific example of the switching circuit in an embodiment described later..
[0015]
The storage means 41 and 42 are light receiving outputs e on the LED 11 side._o1And the light receiving output e on the LED 12 side_o2In the example of FIG. 1, the light receiving output e is composed of S / H circuits (sample and hold circuits) 1 and 2 and amplified by the signal amplifying means 30._o1, E_o2(Light reception outputs before and after switching) are stored in the S / H circuits 1 and 2, respectively. The comparison means 50 receives light (amplification) output e of the LEDs 11 and 12 before and after switching._o1, E_o2This is a means for comparing (the outputs of the S / H circuits 1 and 2) with a predetermined value, and is composed of, for example, an adding circuit 51 and a comparing circuit 52. In the comparison means 50, the light reception signal e from the S / H circuits 1 and 2_o1, E_o2The presence or absence of the medium, the presence or absence of overlap of two sheets, and the like are determined by comparing whether or not the sum exceeds the threshold value, and a signal indicating the determination result is output.
[0016]
A basic operation example of the configuration as described above will be described with reference to the timing chart of FIG. The light projecting / light receiving switching means 20 sends a switching signal CHG to the LED 11 and the LED 12, and alternately switches between mode 1 and mode 2 every predetermined number of pulses of the basic clock, as shown in (1) of FIG. . In mode 1, a forward current is applied to the LED 12 and a reverse voltage is applied to the LED 11. As shown in FIG. 4A, the LED 12 is on the light emitting side and the LED 11 is on the light receiving side. The transmitted light 1 is received by the LED 11. On the other hand, in mode 2, a reverse voltage is applied to the LED 12 and a forward current is passed to the LED 11. As shown in FIG. 4B, the LED 12 is the light receiving side and the LED 11 is the light emitting side. Light transmitted through the paper sheet 1 is received by the LED 12.
[0017]
From the LEDs 11 and 12 switched for light reception, the light reception signal e having an amplified waveform as shown in (2) of FIG._o1, E_o2Is output. Light reception signal e_o1, E_o2In mode 1, sampling is performed at the time point “S1” of the control signal of the S / H circuit 1 shown in (3) of FIG._o1Is held in the S / H circuit 1 as shown in (3A) of FIG. In mode 2, it is performed at the time of “S2” of the control signal of the S / H circuit 2 shown in (4) of FIG._o2Is held in the S / H circuit 2 as shown in (4A) of FIG. Light reception signal e held in S / H circuits 1 and 2_o2, E_o1Are input to the adder 51 and added at the time of “H1” and “H2” of the control signals of the S / H circuits 1 and 2 shown in (3) and (4) of FIG. 3, respectively. The output signal of the adder 51 has a waveform as shown in (5) of FIG. 3, and a preset threshold value is compared with the added value by the comparator (comparing circuit) 52 in the comparison means 50, and the output signal of (6) in FIG. A signal eo indicating the comparison result as shown in FIG. This can be determined by reading it at the timing of (7) in FIG. In the comparator output eo in FIG. 3, “H” indicates the presence of paper sheets (or overlap), and “L” indicates the absence of paper sheets (or no overlap).
[0018]
As described above, the output side due to the passing position of the paper sheet is absorbed by alternately switching between the light emitting side and the light receiving side and detecting the presence or absence of the paper sheet based on the light reception signals on both sides of the paper sheet. can do. That is, as shown in FIGS. 4A and 4B, when the distance between the LED 11 and the LED 12 is d, and the distance between the LED 12 and the paper sheet 1 is x, the passage position x of the paper sheet 1 is LED 11 and 12 detection output e_o1, E_o25 is expressed as shown in FIG. 5, and the detection outputs of the LEDs 11 and 12 at the passing position x = a are expressed as e._o1(A), e_o2If corrected by the following equation (2) as (da), the corrected detection output eo becomes a stable output that is not affected by the passage position of the paper sheet. When the distance d between the LEDs 11 and 12 is small, the characteristic of the detection output eo can be regarded as a straight line. Therefore, the coefficient α1 = α2 = 0.5 in the following equation 2, and the simple average may be used as the detection output eo. .
[0019]
[Expression 2]
eo = α1 · e_o1(A) + α2 · e_o2(Da)
However, α1, α2 ≦ 1
FIG. 6 is a graph (broken line in FIG. 6) showing the detection output eo corrected by the above equation 2, and if the determination criterion So for a two-sheet ticket is set as the threshold value to be compared by the comparison means 50, It is possible to detect double feeding of paper sheets. That is, it is possible to realize a check for overlapping two sheets according to the amount of transmitted light. Further, in the paper sheet pattern detection based on the amount of transmitted light, the conventional normalization process is not necessary, and a more stable and high-speed process is possible.
[0020]
In the configuration example of the first embodiment described above, an example in which data collection and comparison processing is performed using a hardware circuit is shown. However, as shown in the block configuration diagram of FIG. 7, the storage unit in the configuration example of FIG. It is also possible to realize a configuration in which 41 and 42 are the RAM 73 and the processing by the comparing means 50 is performed by the CPU 71. In this case, after sending the sampling start control signal, the data obtained by reading the AD conversion values before and after the switching and storing them in the array areas D1 (i) and D2 (i) in the interrupt process at every constant transport distance. A collection process is performed so that the data in the array areas D1 (i) and D2 (i) is corrected by the equation 2 and a determination process such as overlapping of two sheets can be performed based on the corrected data D (i). That's fine.
[0021]
The received light data sampling control and correction calculation processing in the configuration example of FIG. 7 will be described below with reference to flowcharts. The correction calculation process may be performed every time the received light output before and after switching is sampled, but here, a case where the correction calculation process is performed after sampling all the data of one sheet of paper will be described as an example.
[0022]
First, an example of the light reception data sampling procedure will be described with reference to the flowchart of FIG. First, various registers, counters, flags, etc. are cleared and initialized. The counters of the light projection / light reception switching means 20 are initialized by the output of the sampling start signal or the reset signal of the CPU 71 (step S1). The CPU 71 first sets “0” to a counter i that counts the number of times of switching between mode 1 and mode 2. This count i is also used as a pointer for the array areas D1 (i) and D2 (i) in the RAM 73 (step S2). Subsequently, the light projection / light reception switching signal CHG = “0” is set to operate the LED 11 as the light receiving side and the LED 12 as the light projecting side (step S3).
[0023]
Upon receiving the mode 1 switching signal CHG, the light projecting / light receiving switching means 20 waits for a certain time until the light receiving output of the LED 11 becomes stable (step S4), and then the detection output e of the LED 11_o1Is output. In the CPU 71, the detection output e converted by the A / D converter 31_o1The AD conversion value AD1 is stored in the array area D1 (i) in the RAM 73 (steps S5 to S7). Subsequently, the light projection / light reception switching signal CHG = "1" is sent to the light projection / light reception switching means 20, and the LED 12 is switched to the light receiving side and the LED 11 is switched to the light projecting side (step S8). Upon receiving the mode 2 switching signal CHG, the light projection / light reception switching means 20 waits for a certain period of time until the light reception output of the LED 12 is stabilized (step S9), and then the detection output e of the LED 12_o2Is output. In the CPU 71, the detection output e of the LED 12_o2The A / D conversion value AD2 is stored in the array area D2 (i) in the RAM 73 (steps S10 to S12).
[0024]
Then, the counter i is incremented by “1” (step S13), and if i ≦ N−1, the process returns to step S3 (step S14), and the above-described process of sampling the received light data before and after switching is repeated. In the case of N-1, that is, if N pieces of received light data before and after switching are sampled, the sampling process is terminated.
[0025]
Next, an example of the operation in the correction calculation process will be described using the flowchart of FIG. In the correction calculation process, after the passage of one sheet of paper is detected, the correction calculation is performed by the following process. Note that the passage of paper sheets is detected by, for example, passage detection sensor means. First, the CPU 71 sets “0” to the counter i (step S21), and then reads the data before and after the i-th switching from the array areas D1 (i) and D2 (i). It is obtained and stored in the array area D (i) in the RAM 73 (step S22).
[0026]
[Equation 3]
D (i) = α1 · D1 (i) + α2 · D2 (i)
However, α1, α2 are correction coefficients, α1, α2 ≦ 1
Usually α1 = α2 = 0.5
[0027]
Then, the counter i is incremented by “1” (step S23). If i ≦ N−1, the process returns to step S22 and the above processing is repeated (step S24). If i ≦ N−1 in step S24, that is, switching is performed. If N preceding and following received light data have been corrected, the correction calculation process is terminated.
[0028]
Through the above processing, optical data for one sheet of transported paper is collected in the array area D (i). By reading the data stored in the array area D (i), It is possible to determine whether or not there are overlapping leaves. That is, the number of “i” that is equal to or less than the threshold value of the two-sheet ticket is counted. Further, the length of the paper sheet in the conveyance direction can be obtained from the count value of the number “i” equal to or less than the threshold value.
[0029]
Next, a second embodiment of the optical data collecting apparatus for paper sheets will be described. The optical data collection device according to the second embodiment is provided with array type sensors (hereinafter referred to as “LED arrays”) in which LED elements are arranged in a substantially linear manner so as to face each other, and the light projecting side and the light receiving side are alternately arranged. In this way, the optical data of the paper sheet is collected over the entire surface of the paper sheet. FIG. 10 shows a configuration example of the second embodiment. In the second embodiment, in order to distinguish from the configuration of the first embodiment, the sensor means for reading the optical data of the paper sheet is referred to as “light emitting / receiving sensor”. Means ”, the light emission / light reception switching means is called“ light emission / light reception switching means ”, and the optical data storage means before and after the switching is called“ first and second storage means ”. In the second embodiment, an example of a configuration in which the received light data correction calculation process is performed by software is taken as an example.
[0030]
In FIG. 10, a pair of LED arrays 111 and 112 are used as the light emitting / receiving sensor means 110, and these LED arrays 111 and 112 are installed facing the top and bottom of the paper sheet conveyance path. . The LED elements in the LED arrays 111 and 112 are arranged substantially linearly on almost the entire path width (for example, on both sides instead of the entire surface in the width detection device) in a direction transverse to the conveyance direction of the paper sheet 1. It is installed. 11A and 11B show an example of the arrangement configuration of the LED elements 11A in the LED arrays 111 and 112, and FIG. 11A shows the LEDs (1 to n) at a constant interval L (for example, 2 mm), FIG. 4 shows an example in which the arrangement interval L in FIG. 3 is set to (1/2) * L and LEDs (1 to n) are arranged in two rows in order to increase the resolution. It is. When one LED array operates as a light source, the light emission / light reception sensor unit 110 operates as a light reception sensor, and the light emission / light reception switching unit 120 switches so that the light projecting side and the light receiving side are switched alternately. Controlled by.
[0031]
In the first mode, the light emission / light reception switching means 120 causes a forward current to flow through one LED array to operate the LEDs (1 to n) as light emitting elements, and applies a reverse voltage to the other LED array. (1 to n) are operated as light receiving elements (photodiode arrays), and in the second mode, the reverse operation is performed. The switching between the first mode and the second mode is performed by inputting a light emission / light reception switching signal CTL from the reading AD conversion means 130.
[0032]
The read AD conversion means 130 sends a switching signal CTL to the light emission / light reception switching means 120 to perform switching control between the first and second modes, and outputs light reception from n LEDs in the light receiving side LED array. Read one by one and perform A / D conversion. At that time, the light reception output from the LED array 111 is written by designating the address of the first storage means 141. The light reception output from the LED array 112 is written by designating the address of the second storage means 142. When the writing of the received light data is completed, an interrupt signal is output to notify the CPU 101 of the end of sampling. This interrupt signal is output at the end of sampling of light reception data for one LED, light reception data for one line, or light reception data for all lines.
[0033]
The first and second storage means 140 are constituted by a dual port RAM, and the read AD conversion means 130 writes the received light data for one bill. Light reception data of the LED array 111 is written in the first storage unit 141, and light reception data of the LED array 112 is written in the second storage unit 142. These readings are performed by the CPU 101.
[0034]
The average value calculation means 100 comprises a CPU 101, a ROM 102 and a RAM 103, reads the A / D conversion value of each LED light receiving output written at the same address of the first and second storage means 140, and faces the LED. An average value of the received light output of (1 to n) with the A / D conversion value is obtained for each LED (1 to n), and an average value for one bill is obtained. The passage detection sensor unit 150 is a unit that detects arrival and passage of the paper sheet 1 to the light emission / light reception sensor unit, and sends a detection signal to the average value calculation unit 100. The average value calculation means 100 sends a sampling start signal CTL to the read AD conversion means 130 in response to the input of the detection signal, and starts the sampling operation of the received light data.
[0035]
FIG. 12 shows an example of the configuration of the read AD conversion means 130 of FIG. 10. The read AD conversion means 130 includes an OSC (oscilloscope) 131, a timing control circuit 132, a selector (multiplexer) 133, an amplifier 134, and an A / D converter. 135 and a binary counter 136, which are operated by a control command (H: start of operation, L: reset) of the CPU 101.
[0036]
The OSC 131 generates an operation clock (carrier clock) MLCK. The timing control circuit 132 is a circuit for performing control of the A / D converter 135, writing control of the dual port RAM 140, and switching control of the first and second modes, and outputs a control signal to timing each operation. Take control. The timing control circuit 132 starts a sampling operation in response to a control command from the CPU 101, and sends a light emission / light reception switching signal CTL to the light emission / light reception switching means 20 to switch between the light emission side and the light reception side of the LED arrays 111, 112. At the same time, the control signal is output to switch the High / Low address of the dual port RAM 140. Further, after a reset signal is output to the binary counter 136 to reset the counter, a pulse is output to control reading of received light data.
[0037]
The selector 133 is a circuit that selects and outputs the light reception output of each LED (n → 1) in the LED array one by one in response to the selection signal input from the binary counter 136. The n input lines emit / receive light. It is connected to the output line of the light receiving side LED array via the switching means 120. The output line of the selector 133 is connected to the A / D converter 135 via the amplifier 134, and the light reception output of the LEDs (1 to n) corresponding to the count values (1 to n) of the binary counter is amplified to obtain the A / D It is output to the D converter 135.
[0038]
The A / D converter 135 performs A / D conversion of the received light output amplification signal according to the conversion start control signal from the timing control circuit 132. The A / D conversion values of the received light data of the LED array 111 and the LED array 112 are written in the high address and low address storage areas of the dual port RAM 140 switched by the timing control circuit 132, respectively. The binary counter 136 is a counter that outputs a selection signal of the selector 133 and an address (location) signal of the dual port RAM 140 and operates in response to a pulse from the timing control circuit 132.
[0039]
An overall operation example of the optical data collection device according to the second embodiment having the above-described configuration will be described. When the average value calculation means 100 receives the arrival detection signal of the paper sheet 1 from the passage detection sensor means 150, it sends a start signal (control command; H) to the reading AD conversion means 130 to start the sampling operation. At this time, if the interrupt mode is specified for all lines, an interrupt signal is input at the end of sampling for all lines. Here, description will be made assuming that the interrupt mode is designated as for all lines. Upon receipt of the start signal, the read AD conversion means 130 performs initialization processing (such as resetting the binary counter 136), and then sends a switching signal CTL to the light emission / light reception switching means 20 so that the light emission side of the LED arrays 111 and 112 is connected. While switching the light receiving side, a control signal (H / L address) is sent to the storage means 140 to switch to the storage means 141, 142 corresponding to the LED arrays 111, 112.
[0040]
Subsequently, the light reception output from the LEDs in the LED array on the light reception side is sequentially read out, the light reception output is amplified and A / D conversion is performed, and the write signal is output to the corresponding storage means 141 or 142 as a digital value. Write. When writing is completed for n LEDs, the first and second modes are switched, and the mode switching signal CTL is sent to the light emission / light reception switching means 20 to repeat the above operation. When the reception of the received light data for one sheet is completed, an interrupt signal is sent to the average value calculation means 100 and the operation in the read AD conversion means 130 is ended. The reception of the received light data ends when the preset data for K lines is acquired or when the passage detection signal of the passage detection sensor means 150 is input.
[0041]
The average value calculation means 100 that has received the interrupt signal reads the light reception data of the LED arrays 111 and 112 from the first and second storage means 141 and 142, and the A / D of the light reception output of the opposing LEDs (1 to n). The average value of the conversion values is obtained for all the lines for each LED (1 to n). Then, the obtained average value for one banknote is stored in the RAM 103 as collected data, and the data sampling process for one banknote is completed. In the configuration example of FIG. 10, the CPU 101 may directly read and process the output of the read AD conversion unit 130 without providing the first and second storage units 141 and 142.
[0042]
Hereinafter, the light projection / light reception switching method in the first and second embodiments will be described with reference to a specific example of the switching circuit.
[0043]
【Example】
FIG. 13 is a conceptual diagram illustrating a configuration example of the light projection / light reception switching unit 20 in the first embodiment, where R1 is a current-voltage conversion resistor, and R2 is a current control resistor (R1> R2). When the LED (11 or 12) is set to the light receiving mode, the contact 1 and the contact 2 in FIG. 13 are connected, and the LED and the current-voltage conversion resistor R1 are connected in series as shown in the equivalent circuit of FIG. Connect to. As a result, a reverse voltage (−Vcc) is applied to the LED, the LED operates as a light receiving element (photodiode), and light is received through the amplifier AMP connected to the node between the LED and the current-voltage conversion resistor R1. The output is amplified and output. When the LED is set to the light projection mode, the contact 3 and the contact 2 in FIG. 13 are connected, and the LED and the current control resistor R2 are connected in series as shown in the equivalent circuit of FIG. Thereby, a forward current flows through the LED 11, and the LED 11 operates as a light emitting element.
[0044]
FIG. 15 shows an example of a specific circuit configuration of the light projecting / light receiving switching means 20 in the first embodiment. This light projection / light reception switching circuit is an example in which the switch part of the switching circuits 21, 22 is configured by PNP type and NPN type transistors, and the light projection / light reception operation of the LEDs 11, 12 is performed by the input of the switching signal CHG. The light receiving output of the LEDs 11 and 12 switched to the light receiving side is output by switching by the transistor and switching the output from the LEDs 11 and 12 by the analog switch ASW. The PNP type and NPN type transistors in FIG. 15 may use P-channel type and N-channel type FETs (field effect transistors), respectively, and can also be realized by using an analog switch ASW.
[0045]
FIG. 16 shows an example of a specific circuit configuration of the light emission / light reception switching means 120 in the second embodiment, and shows the configuration on the LED array 111 side. The configuration on the LED array 112 side is that the inverter INV for inverting the control signal CTL is not inserted, and the configuration of the light projecting / light receiving switching circuit is the same. This light projection / light reception switching circuit is configured to control the light projection / light reception operations of the LED elements 1 to n in the LED array by inputting a control signal CTL (H level = light projection mode, L level = light reception mode). It is configured to be switched by a transistor. In FIG. 16, there is a resistor R between the transistor Tr1 and LEDn (n = 1 to 8)._DnAnd a diode Dn are connected in series, and a resistor R is connected between the node between the diode Dn and the LEDn and the ground._LnIs connected. The switch unit may use a P-channel FET instead of the PNP transistor Tr1.
[0046]
FIG. 17 (A) shows an equivalent circuit at the time of light projection._ledLEDn operates as a light emitting element. Resistance value is R_Ln>> R_Dn(Resistance R_LnCurrent I flowing through_RLIs approximately 0) and the resistance R_LnIs equivalent to that shown in FIG. 17B, and the current I flowing in LEDn when the voltage Vcc is applied is shown._ledIs expressed by the following equation (4).
[Expression 4]
I_led= (Vcc- (V_{F (LED)}+ VF_(D))) / R_Dn
However, V_{F (LED)}: LED forward voltage drop,
VF_(D): Diode forward voltage drop
[0047]
On the other hand, the equivalent circuit of FIG. 16 in the light receiving mode is shown in FIG._LnCurrent I in the reverse direction toward_PnLEDn operates as a light receiving element. The diode Dn has a leakage current I_enFlows, but I_en<< I_PnTherefore, this leakage current I_enIs ignored, ie resistance R_DnIf the diode Dn is ignored, the equivalent circuit is shown in FIG._nIs expressed by the following equation (5).
[Equation 5]
e_n= -I_Pn・ R_Ln
[0048]
As described above, the conventional transmission sensor using the LED and the Ph-D (photodiode) or the Ph-Tr (phototransistor) has a drawback that the output fluctuates depending on the passage position of the medium. By changing the direction in which the light strikes and the position where the light is received and averaging (or adding) the detected data, it is possible to eliminate the influence of the output fluctuation depending on the passage position of the medium. Further, Ph-D or Ph-Tr has a wide spectral characteristic, and the conventional transmission type sensor is affected by disturbance. However, in the present invention, the same light emitting side and light receiving side are used. The spectral sensitivity characteristics of the received light are equal, and the band can be narrow, so that it is not affected by fluorescence or the like. In addition, when detecting the bill width, even if 5000 yen passing through the passage passes through the light source side, the sensor output when light is projected from the other side can be taken into account, so the banknote is broken even though there is a bill. It is possible to eliminate false detection as if the occurrence of
[0049]
In the first and second embodiments and examples described above, the transmissive sensor has been described as an example. However, as shown in the configuration example of the reflective sensor in FIG. 19, two LEDs 11, 12 (or LEDs) (Array) may be arranged in parallel, and the projection / reception of the LEDs 11 and 12 may be switched to collect the optical data of the reflected light before and after switching.
[0050]
【The invention's effect】
As described above, according to the first and second aspects of the present invention, the detected value does not change even if the passage position of the banknote transporting the passage changes, so the detection of the two-layered banknote is stable. Yes. Further, according to the invention of claim 2, if the banknote passes through the vicinity of the projector side and the oil stain is generated, it is erroneously recognized that a hole is opened in the conventional detection method. Since the determination can be made based on both the detected value and the other detected value by switching the light emission / light reception, erroneous recognition can be prevented. Furthermore, since the same LED is used as a projector and a light receiver, a steep spectral sensitivity characteristic can be obtained and the influence of disturbance light is small. In addition, since an inexpensive LED is used for the light receiver, the production cost of the apparatus can be kept low.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration example of a first embodiment of an optical data collection apparatus for paper sheets according to the present invention.
2 is a block diagram showing a configuration example of a light projecting / light receiving switching unit 20 in FIG. 1. FIG.
FIG. 3 is a timing chart for explaining a basic operation example in the first embodiment;
FIG. 4 is a diagram for explaining a light projecting / receiving operation of a sensor unit in the first embodiment.
FIG. 5 is a diagram illustrating a relationship between a passage position of a medium and output characteristics of an LED.
FIG. 6 is a diagram for explaining a method for detecting a double feed of paper sheets.
FIG. 7 is a block diagram showing another configuration example of the first embodiment.
FIG. 8 is a flowchart for explaining an example of a sampling procedure of received light data in the first embodiment.
FIG. 9 is a flowchart for explaining an operation example in received light data correction calculation processing in the first embodiment;
FIG. 10 is a block diagram illustrating a configuration example of a second embodiment of the optical data collection apparatus for paper sheets of the present invention.
11 is a diagram showing an example of an arrangement configuration of LED elements in the LED arrays 111 and 112 in FIG.
12 is a block diagram showing a configuration example of read AD conversion means 130 in FIG.
FIG. 13 is a conceptual diagram showing a configuration example of a light projection / light reception switching unit in the first embodiment.
14 is a diagram showing an equivalent circuit in a light reception mode and a light projection mode of the light projection / light reception switching circuit of FIG.
FIG. 15 shows an example of a specific circuit configuration of light projection / light reception switching means in the first embodiment.
FIG. 16 is a diagram showing an example of a specific circuit configuration of light emission / light reception switching means in the second embodiment.
17 is a diagram showing an equivalent circuit during light projection of the light emission / light reception switching circuit of FIG. 16. FIG.
18 is a diagram showing an equivalent circuit during light reception of the light emission / light reception switching circuit of FIG. 16;
FIG. 19 is a block diagram showing an embodiment when the present invention is applied to a reflective sensor.
FIG. 20 is a diagram for explaining an example of a conventional apparatus in which an LED is used as both a light emitting element and a light receiving element.
FIG. 21 is a diagram illustrating a passage position of a medium between sensors.
FIG. 22 is a diagram showing the relationship between the passage position of a medium and the output characteristics of Ph-D or Ph-Tr.
FIG. 23 is a diagram showing a difference in detection output depending on a passing position of two tickets.
[Explanation of symbols]
1 Paper sheets
10 Sensor part
11,12 LED
20 Light projection / light reception switching means
21, 22 switching circuit
30 Signal amplification means
31 A / D converter
41, 42 storage means
50 comparison means
60 External clock
100 Mean value calculation means
101 CPU
102 ROM
103 RAM
110 Light emitting / receiving sensor means
111, 112 LED array
120 Light emission / light reception switching means
130 Reading AD conversion means
140 Storage means
141 First storage means
142 Second storage means

Claims (2)

In the optical data collection device of the paper sheet detection apparatus for collecting the optical data of the conveyed paper sheets and detecting the presence / absence and / or double feeding of the paper sheets, two LEDs are provided facing each other, 1 A light-emitting current is passed through one for light projection, and the other is connected with a current-voltage conversion resistor in series for light reception. When one LED operates as a light source , the other LED operates as a light-receiving sensor. When the other LED operates as a light source, a switching means for switching between the light projecting and the light receiving so that the one LED operates as a light receiving sensor, and the light receiving before and after the switching by the switching means. Storage means for storing the light reception signal values from the LEDs, and comparison means for performing addition or averaging of the light reception signal values before and after switching stored in the storage means and comparing with a predetermined value. Optical data collection device of the sheet, characterized in that. In an optical data collection device of a paper sheet discriminating apparatus that collects optical data of conveyed paper sheets and discriminates the type of the paper sheets, a path in a direction transverse to the transport direction of the paper sheets A light emitting / receiving sensor means having LEDs arranged substantially linearly on both sides of the passage surface in a substantially straight line and spaced apart by a predetermined interval; time-divisionally, in the first mode, on the other hand when the side of the LED operates as a light emitting source side LED the opposing to the light receiving side sensors to operate in the second mode of the one side is in the opposite LED operates as a light emitting source side Light emission / light reception switching means for switching between the light emission source side and the light reception side sensor so that the LED operates as a light reception side sensor; sequentially reading out the output of the light reception side sensor in the first and second modes AD Read to convert D conversion means; first and second storage means for storing a digital value from the read AD conversion means in association with the first and second modes together with address information for specifying the read LED; Optical data collection of a paper sheet discriminating apparatus, comprising: an average value calculating means for calculating an average value of stored values at the same address stored in the first storage means and the second storage means apparatus.

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