JP2016030690A - Device and method for detecting paper existence - Google Patents

Abstract

To provide a paper sheet presence / absence detection device and a paper sheet presence / absence detection method capable of automatically setting an appropriate threshold value for the presence / absence of paper sheets even when light of a light emitting element becomes weak due to a change over time. An example of a paper sheet presence / absence detection device includes a light emitting element and a light receiving element that face each other across a paper sheet conveyance path, and a paper sheet presence / absence detection unit that detects the presence or absence of paper sheets in the conveyance path. And, at a predetermined timing, when the paper sheet presence / absence detecting unit determines that there is no paper sheet in the transport path, the light receiving element reduces the operating current to the light emitting element. A control unit that obtains an optimum output voltage of the light receiving element based on characteristics of an output voltage that is received and output, and resets the threshold as the presence or absence of paper sheets. [Selection] Figure 1

Description

  Embodiments described herein relate generally to a paper sheet presence / absence detection apparatus and a paper sheet presence / absence detection method for optically detecting the presence or absence of paper sheets.

  A printing apparatus that prints on a paper sheet includes a paper sheet sensor that optically detects the paper sheet in order to detect that the paper sheet has been set.

  This type of paper sheet sensor is composed of a light emitting element and a light receiving element that are opposed to each other with a conveyance path interposed therebetween, and whether or not the light emitted from the light emitting element passes through the paper and reaches the light receiving element. The presence or absence of paper sheets is detected by looking at the change in the output voltage of the light receiving element.

  While the paper sheet is between the light emitting element and the light receiving element, the operating current of the light emitting element is increased, and the output voltage of the light receiving element is examined, and the operating current of the light emitting element without the paper sheet A method for adjusting a paper sheet sensor is known in which a threshold value for detecting the presence or absence of a paper sheet is appropriately set based on characteristics obtained by examining the change in the output voltage of the light receiving element at that time.

JP 2010-215375 A

  Provided are a paper sheet presence / absence detection device and a paper sheet presence / absence detection method capable of automatically setting an appropriate threshold value for the presence / absence of paper sheets even when light of a light emitting element becomes weak due to a change with time.

  An example of the present invention includes a light emitting element and a light receiving element that face each other across a paper sheet conveyance path, a paper sheet presence / absence detection unit that detects the presence or absence of paper sheets in the conveyance path, and a predetermined timing, When the paper sheet presence / absence detecting unit determines that there is no paper sheet in the transport path, the output voltage received and output by the light receiving element when the operating current is reduced in the light emitting element A paper sheet presence / absence detection apparatus including a control unit that obtains an optimum output voltage of the light receiving element based on the characteristics of the light receiving element and resets the threshold as the paper sheet presence / absence threshold value.

It is a figure which shows the structure of the printer apparatus of one Embodiment. It is a figure which shows the structural example of the whole control circuit of one Embodiment. 3 is a diagram illustrating a configuration example of a sheet sensor. FIG. FIG. 10 is a characteristic curve diagram for explaining a process of setting a threshold value for the presence or absence of paper sheets of the paper sensor. In an embodiment, it is a figure for explaining that the characteristic of input current decrease output voltage increase changes by change with time. It is a figure which shows the structural example of the paper sheet presence or absence detection apparatus of one Embodiment. It is a figure which shows the structural example of the apparatus condition detection part of embodiment shown in FIG. It is a figure which shows the flowchart for demonstrating operation | movement of one Embodiment shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings. The mechanical configuration of the sheet presence / absence detection apparatus according to the embodiment of the present invention will be described with reference to FIG. 1 and the entire control circuit configuration with reference to FIG. A specific example of the sensor circuit will be described with reference to FIG. 3, and a paper sensor adjustment method will be described with reference to FIG. Prior to these descriptions, the concept of the embodiment of the present invention will be briefly described with reference to FIGS.

  FIG. 4 is a characteristic diagram of the paper sensor. The operation (input) current (mA) of a light emitting element (for example, a light emitting diode) facing each other across the paper conveyance path and the output voltage (V) of the light receiving element (for example, phototransistor). Indicates. This characteristic is usually measured before the device is shipped, and an optimum threshold value for detecting the presence or absence of paper is set.

  First, a sheet is set on the conveyance path of the sheet presence / absence detection device. In this state, the output voltage of the light receiving element when the operating current of the light emitting element is almost zero is measured. At this time, the light receiving element (for example, phototransistor) is in an off state, and when the operating current of the light emitting element is gradually increased, the output voltage rapidly decreases when the predetermined current is reached, that is, the state of the light receiving element A characteristic curve 51 shown in FIG. 4 is obtained in which changes from OFF to ON. This characteristic curve is called an input current increase output voltage decrease characteristic curve 51.

  Next, there is no paper between the light receiving elements of the opposing light emitting elements (conveyance path). Then, the operating current of the light emitting element is gradually decreased from a large value. When the operating current of the light emitting element is large, sufficient light reaches the light receiving element, and the light receiving element is initially in the on state. However, when the operating current of the light emitting element is lowered, light cannot reach the light receiving element. Therefore, the light receiving element shifts to the off state from the middle, and the output voltage becomes higher as shown by the characteristic curve 52 in FIG. This characteristic is called an input current decrease output voltage increase characteristic curve 52.

  Therefore, if the two characteristic curves 51 and 52 detect the presence / absence of paper based on the threshold value at the position where the output voltage of the light receiving element is the central voltage value Vm with respect to the central operating current value Im of the light emitting element. The most appropriate paper detection becomes possible.

  By the way, when such a sheet presence / absence detection device is manufactured, shipped after setting a sheet presence / absence threshold, the light emission intensity of the light emitting element and the light receiving sensitivity of the light receiving element change little by little. Therefore, it is desirable to be able to set an appropriate threshold for the presence or absence of paper such as paper even when the characteristics have changed over time.

  In particular, the light intensity of the light emitting element is reduced, that is, the light intensity emitted with respect to the operating current of the light emitting element is deteriorated. However, after shipment from the factory, the sheet presence / absence detection device is under the control of the user, and it is usually difficult for the manufacturer / shipper to reset the threshold value and the like.

  Further, it is conceivable that the user is using the apparatus in a state where there is a sheet on the conveyance path, and measuring the characteristics during the use may impair the convenience of the user. On the other hand, when there is no paper in the transport path for a long time, the apparatus is not used, and it is relatively easy to detect this state.

  Therefore, in one embodiment of the present invention, the characteristic curve 52 of the input current decrease output voltage increase shown in FIG. 4 described above is automatically measured again in a state where there is no sheet in the conveyance path that is not used by the user, and this characteristic is obtained. The optimum operating current In and output voltage Vn are automatically set as thresholds using the curve 52 and the characteristic curve 51 of the input current increasing output voltage decreasing measured before shipment.

  First, the configuration of a printing apparatus to which an embodiment of the present invention is applied will be described with reference to FIG. The printing apparatus 1 shown in FIG. 1 has a fascia part 2 serving as an entrance / exit of the bankbook T and an exit of statement paper at the front part, and a paper setting part 3 at the rear part.

  Thermal paper wound in a roll shape is set on the paper setting unit 3. The set thermal paper 4 has its leading end pulled out by the first transport section 5 and guided to the transport path 6a. A thermal printing unit 7 and a cutting unit 8 are disposed on the transport path 6a.

  Further, a second transport unit 10 is provided following the first transport unit 5. The second transport unit 10 includes a transport path 6b connected to the transport path 6a, transport roller pairs 11a to 11e, an entrance / exit roller pair 12, and a feed roller pair 15 disposed along the transport path 6b. The passbook T inserted into the paper is transported, and the thermal paper 4 sent from the transport path 6 a is transported toward the fascia section 2.

  A dot printer section 9 having a 24-pin dot matrix head 9a is disposed between the transport roller pairs 11a and 11b in the transport path 6b. The pair of entrance / exit rollers 12 takes in the passbook T inserted into the fascia unit 2 and sends out the printed passbook T and statement paper out of the fascia unit 2.

  Furthermore, a paper sensor 28 is provided as a paper sheet sensor on the thermal paper introduction side of the second transport unit 10. The paper sensor 28 optically detects the thermal paper 4 that is the paper sheet to be printed.

  In the vicinity of the entrance / exit roller pair 12 in the second transport unit 10, a passbook sensor 29 is provided as a paper sheet sensor. The passbook sensor 29 optically detects the passbook T, which is a paper sheet to be printed.

  The thermal printing unit 7 includes a thermal head 17 for back side printing and a thermal head 18 for front side printing at positions at predetermined intervals along the conveyance direction of the thermal paper 4. Platen rollers 20 and 21 are pressed against these thermal heads 17 and 18 so as to be rotatable.

  Information is printed on both sides of the thermal paper 4 by the thermal heads 17 and 18 while being sandwiched between the thermal heads 17 and 18 and the platen rollers 20 and 21. The cutting unit 8 has a rotary cutter 23 and cuts the thermal paper by rotating the rotary cutter 23. This cut piece becomes a statement sheet. The statement sheet is sent to the second transport unit 10 by the feed roller pair 14.

  A motor 25 is provided for driving the platen rollers 20 and 21, the rotary cutter 23, and the feed roller pair 14. A motor 26 is provided for driving the transport roller pairs 11 a to 11 e, the entrance / exit roller pair 12, and the feed roller pair 15.

  In such a printing apparatus 1, a statement printer ST that performs printing on the thermal paper while conveying the thermal paper 4 by the paper setting unit 3, the first conveyance unit 5, and its peripheral part is configured.

  A passbook printer PB is configured that performs printing on the passbook T while carrying the passbook T by the feed roller pair 15, the second transport unit 10, and its peripheral part, and also transporting thermal paper when the statement printer ST prints. The

  A configuration example of the control circuit of the printing apparatus 1 is shown in FIG. A control unit 30 is provided for controlling the statement printer ST and for controlling the passbook printer PB. The control unit 30 is connected to the component parts of the statement printer ST and the component parts of the passbook printer PB. Furthermore, a host device 31 is connected to the control unit 30.

  The control unit 30 includes, for example, a sensor circuit shown in FIG. 3 for driving control of the paper sensor 28. In this sensor circuit, the CPU 40 operates a ROM 41 for storing a control program, a RAM 42 for storing data, a D / A (digital / analog) converter 43 for outputting a driving signal to the paper sensor 28, and a driving signal for the paper sensor 28. An operation unit 44s is connected.

  The D / A converter 43 outputs a DC voltage for setting an operating current for the paper sensor 28 in accordance with a command from the CPU 40 and outputs a reference voltage Vs for paper determination in response to a command from the CPU 40. The DC voltage for setting the operating current is amplified by the operational amplifier 44 and applied between the base and emitter of the NPN transistor 46 via the resistor 45.

  The paper sensor 28 includes a light emitting element, for example, a light emitting diode 28a and a light receiving element, for example, a phototransistor 28b, which face each other across the conveyance path 6b through which the thermal paper 4 is conveyed. The anode of the light emitting diode 28 a is connected to the positive terminal of the DC voltage 5 V, and the cathode of the light emitting diode 28 a is grounded between the collector and emitter of the transistor 46 and the resistor 47.

  The collector of the phototransistor 28b is connected to the positive terminal of the DC voltage 5V through the resistor 48, and the emitter of the phototransistor 28b is grounded. The voltage generated at the collector of the phototransistor 28b is input to the negative input terminal of the comparator 49 as the output voltage V of the phototransistor 28b and supplied to the CPU 40.

  The reference voltage Vs output from the CPU 40 is input to the positive side input terminal of the comparator 49. The output terminal of the comparator 49 is connected to the positive terminal of the DC voltage 3.5V through the resistor 50, and the interconnection point between the output terminal and the resistor 50 is connected to the CPU 40. The comparator 49 compares the output voltage V of the phototransistor 28b with the reference voltage Vs, and outputs a low level voltage signal indicating that the thermal paper 4 is present when the output voltage V drops below the reference voltage Vs.

  Next, a method for adjusting the paper sensor 28 will be described. In the above description, the example in which the input current of the light emitting element and the output voltage of the light receiving element are sampled at a predetermined interval has been described, but here, a specific description will be given based on the circuit configuration shown in FIG.

  First, the thermal paper 4 is set between the light emitting diode 28a and the phototransistor 28b, and the adjustment mode is set by operating the operation unit 44s. Then, in response to a command from the CPU 40 to the D / A converter 43, a DC voltage for setting an operating current is output from the D / A converter 43, and the voltage level gradually increases. This DC voltage is amplified by the operational amplifier 44 and applied between the base and emitter of the transistor 46. The conductivity of the transistor 46 increases as the applied base-emitter voltage increases. As the conductivity of the transistor 46 increases, the operating current I flowing through the light emitting diode 28a gradually increases from zero. A change in the output voltage V of the phototransistor 28b with the increase in the operating current I at this time is shown in a characteristic curve 51 in FIG.

  That is, as the operating current I (mA) flowing through the light emitting diode 28a gradually increases from zero, the light emission amount of the light emitting diode 28a increases. As the amount of emitted light increases, the light eventually passes through the thermal paper 4, and the transmitted light reaches the phototransistor 28b.

  While the light does not pass through the thermal paper 4, the phototransistor 28b is in an off state without receiving light, and the output voltage V of the phototransistor 28b maintains a high level. This output voltage V is higher than the reference voltage Vm, so that the output of the comparator 49 is at a low level.

  When the light transmitted through the thermal paper 4 reaches the phototransistor 28b, the phototransistor 28b is turned on, and the output voltage V of the phototransistor 28b decreases. When the output voltage V becomes equal to or lower than the reference voltage Vm, the output of the comparator 49 becomes high level.

  The CPU 40 monitors the output voltage V of the comparator 49, and when the output voltage V starts to decrease and falls below a predetermined light receiving level Vx, the operating current I at that time is converted to the DC voltage for setting the operating current. The operating current I obtained from the output control is stored in the RAM 42 as I1 (not shown) (first procedure). Further, the CPU 40 stores the output voltage V immediately before the output voltage V becomes equal to or lower than the light reception level Vx in the RAM 42 as V1 (second procedure).

  Subsequently, the thermal paper 4 is removed from between the light emitting diode 28a and the phototransistor 28b, and in this state, the continuation of the adjustment mode is set by operating the operation unit 44s. Then, in response to a command sent from the CPU 40 to the D / A converter 43, the operating current setting DC voltage output from the D / A converter 43 gradually decreases. As a result, the conductivity of the transistor 46 decreases, and the operating current I flowing through the light emitting diode 28a gradually decreases. A change in the output voltage V of the phototransistor 28b accompanying the decrease in the operating current I at this time (input current decrease-output voltage increase curve) is shown in the characteristic curve 52 of FIG.

  That is, as the operating current I flowing through the light emitting diode 28a gradually decreases, the light emission amount of the light emitting diode 28a decreases. As the amount of light emission decreases, the light eventually reaches the phototransistor 28b.

  While the light reaches the phototransistor 28b, the phototransistor 28b is turned on, and the output voltage of the phototransistor 28b maintains a low level.

  When the light does not reach the phototransistor 28b, the phototransistor 28b is turned off, and the output voltage of the phototransistor 28b becomes a high level.

  The CPU 40 monitors the output voltage V, and stores the relationship between the operating current I of the light emitting diode and the output voltage V at that time in the RAM 42.

  Further, when the output voltage V becomes equal to or higher than a predetermined non-light receiving level Vy, the operating current I at that time is grasped from the output control of the direct current voltage for setting the operating current, and the grasped operating current I is set as I2 in the RAM 42. Remember. Further, the CPU 40 stores the output voltage V immediately before the output voltage V becomes equal to or higher than the non-light receiving level Vy in the RAM 42 as V2.

  When I1, V1, I2, and V2 are stored in this way, the CPU 40 sets the operating current I during the normal operation of the light emitting diode 28a within the range of I1 and I2, and for paper determination with respect to the output voltage V of the phototransistor 28b. Is set within the range of V1 and V2. Specifically, the operating current I during normal operation of the light emitting diode 28a is set to (I1 + I2) / 2, which is an intermediate value between I1 and I2, and the reference voltage Vs for paper determination with respect to the output voltage V of the phototransistor 28b. Is set to (V1 + V2) / 2, which is an intermediate value between V1 and V2.

  With this setting, whether or not the thermal paper 4 is present between the light emitting diode 28a and the phototransistor 28b can be properly detected according to the thickness of the thermal paper 4.

  The CPU 40 associates the set data of the operating current I during normal operation and the reference voltage Vs for paper determination with the type, name, model number, etc. of the thermal paper 4 set when setting the adjustment mode. Register in the paper database. With this registration, the adjustment mode ends.

  In the paper database, a set of operating current I and reference voltage Vs can be registered according to a plurality of paper sheets including various thermal papers 4.

  On the other hand, when a specific paper sheet is designated from the host device 31 in a normal state, the CPU 40 reads out the operating current I and the reference voltage Vs corresponding to the designated paper sheet from the paper database, and reads them from the paper sensor. 28 is set.

  Next, a change in characteristics after the sheet presence / absence detecting device is shipped will be described. In FIG. 5, characteristic curves 51 and 52 are characteristic curves of the input current increase output voltage decrease and the input current decrease output voltage increase shown in FIG.

  At the time of shipment, the characteristic curve 52 is obtained when there is no paper in the conveyance path. In the circuit example shown in FIG. 3, characteristic curves 51 and 52 are obtained according to the characteristics of the light emitting diode 28a as a light emitting element and the phototransistor 28b as a light receiving element.

  However, when the light emitting diode 28a is used for a long period of time, the light intensity deteriorates. Therefore, the emitted light with respect to the input current becomes weak, that is, the incident current at which the phototransistor 28b changes from on to off moves to the higher side. In terms of the input current decrease-output voltage increase characteristic, the changed portion moves to the right. Specifically, the characteristic curve 52 changes from the characteristic curve 52 to the characteristic curve 53, the characteristic curve 54, and the characteristic curve 55 due to a change with time. Accordingly, the operating current Im as the optimum threshold value moves to In (to the right side).

  A block configuration example of the sheet presence / absence detection apparatus according to the embodiment is shown in FIG. A light emitting element 61a and a light receiving element 61p are provided facing each other across the conveyance path of the thermal paper 4.

  This paper presence / absence detection device detects a light-emitting element 61a and a light-receiving element 61p that are provided to face each other across a conveyance path through which the thermal paper 4 is conveyed, and a paper presence / absence detection that detects whether or not the thermal paper 4 is present in this conveyance path. Unit 59, a central control unit (CPU) 60 that controls the overall operation such as receiving a sheet presence / absence detection control signal from sheet presence / absence detection unit 59, and an operating current that is controlled by CPU 60 and changes the operating current of light emitting element 61a. The change unit 62, the output voltage detection unit 63 for detecting the output voltage of the light receiving element 61p, and the relationship between the operating current (input current) of the light emitting element 61a and the output voltage of the light receiving element detected by the output voltage detection unit 63 are characterized. And a characteristic threshold value storage unit 64 for storing an appropriate input current and output voltage threshold value obtained from this characteristic, and an appropriate input current threshold value after installation of the device. Current threshold value calculation unit 65, appropriate initial input current threshold value before shipment stored in characteristic threshold value storage unit 64 (or prior input current threshold value after that), and current input current value calculated by current threshold value calculation unit 65 A current threshold comparing unit 66 that compares the threshold values and sends a control signal for requesting a threshold change to the CPU 60 if the difference between the two threshold values exceeds a predetermined value; and an operation unit 67 for initial setting and operation of the user by the user; A device status detection unit 68 for detecting the status of the device for characteristic remeasurement.

  Here, the CPU 60, the operating current change unit 62, the output voltage detection unit 63, the characteristic threshold value storage unit 64, the current threshold value calculation unit 65, the current threshold value comparison unit 66, and the device status detection unit 68 constitute a control unit.

  A configuration example of the apparatus status detection unit 68 is shown in FIG. The device status detection unit 68 detects a non-operation time measuring unit 71 that measures a continuous time during which the sheet presence / absence detection device is not operating, a clock 72 that detects the current time, and whether or not there is a person around the printing device. And a human sensor 73. The non-operation time measuring unit 71 is a timer that starts time measurement every time the printing apparatus stops operating.

  The output of the device status detection unit 68 is input to the CPU 60. Therefore, the CPU 60 detects the continuous non-operation time of the paper presence / absence detection device, the current time, and the absence of a person around the device. The CPU 60 detects whether or not the input current decrease output voltage increase characteristic is measured from the situation at that time and the output of the sheet presence / absence detection unit 59, and changes the operating current (decrease) to the operating current change unit 62 for characteristic measurement. I will tell you.

  First, the operation of the paper presence / absence detection device when characteristics are measured before shipment will be described. The presence / absence detection unit 59 detects the presence of the thermal paper 4 in the conveyance path. The presence of the thermal paper 4 is sent to the CPU 60 as a paper detection control signal.

  With the thermal paper 4 interposed, the operating current of the operating current changing unit 62 is controlled by the CPU 60. The current supplied to the light emitting element 61a is controlled by the operating current changing unit 62.

  With the thermal paper 4 set on the conveyance path, the operating current of the light emitting element 61a is gradually increased. In practice, a digital value of 0 to 255 is sent to the light emitting element 61a to flow a corresponding current. Then, this digital value is added every 8 levels to increase the operating current.

  When the operating current of the light emitting element 61a is sequentially sent to the light emitting element 61a in a direction of increasing at predetermined sampling intervals, the characteristic curve 51 of input current increase-output voltage decrease shown in FIG. 4 is obtained.

  The output voltage detection unit 63 detects a voltage corresponding to the light received by the light receiving element 61p and sends it to the characteristic threshold value storage unit 64. The operating current of the light emitting element 61 a is also input to the characteristic threshold storage unit 64, and the operating current I of the light emitting element 61 a and the output voltage V of the light receiving element 61 p are stored in the characteristic storage unit 67.

  Next, the thermal paper 4 is removed from the conveyance path between the light emitting element 61a and the light receiving element 61p. The absence or presence of the thermal paper 4 is detected by the paper presence / absence detection unit 59. The CPU 60 is controlled by the operation unit 67.

  Under the control of the CPU 65, the operating current changing unit 62 decreases the operating current of the light emitting element 61a at a predetermined sampling interval, and the output voltage detecting unit 63 detects the output voltage of the light receiving element 61p. The characteristics of the output voltages of the light emitting element 61a and the light receiving element 61p at this time are stored in the characteristic threshold value storage unit 64. This characteristic is stored in the characteristic threshold value storage unit 64 as sampling data of the input current decrease output voltage increase characteristic curve 52 shown in FIG. The input current increase-output voltage decrease curve (first characteristic curve) 51 and the input current decrease output voltage increase curve (second characteristic curve) 52 are referred to as basic characteristic curves.

  From the characteristic curve 51 and the characteristic curve 52, the input current threshold value Im and the output voltage threshold value Vm are obtained. These threshold values are stored in the characteristic threshold value storage unit 64.

  Next, a case where the characteristics of the increase in the input current decrease and the output voltage are automatically measured under the user after shipment will be described with reference to the flowchart shown in FIG.

  As will be described later, the remeasurement of characteristics may change depending on the detection state by the clock 72 or the human sensor 73 as described later, but here, only by the output measurement result of the non-operation time measuring unit 71 of the apparatus, A basic embodiment for performing characteristic remeasurement will be described.

  In FIG. 8, first in A801, the CPU 60 detects whether or not the apparatus has started operation. If the device has not started operation, wait until the start is detected. When the CPU 60 detects the start of operation of the apparatus, in A802, the CPU 60 detects whether the apparatus has stopped operating. When the apparatus stops operating, the paper presence / absence detection unit 59 detects whether the thermal paper 4 is not in the transport path by the paper presence / absence detection unit 59 in A803. When it is detected from the sheet presence / absence detection unit 59 that the thermal paper 4 is not in the transport path, the CPU 60 sends a measurement start control signal to the inactivity time measurement unit 71 of the apparatus status detection unit 68 to start measurement of the inactivity time. (A804).

  In A805, the CPU 60 detects whether the apparatus has started operation. If the device starts operating during the inactive time measurement (Y in A805), the process returns to A802 and the CPU 60 detects whether the device has stopped operating.

  On the other hand, when the apparatus does not operate during the measurement of the inactive time, in A806, the inactive time measuring unit 71 compares the continuous inactive time up to the present time with a predetermined time (characteristic re-measurement time). It is detected whether or not the non-operation continues for a predetermined time. The non-operation time measuring unit 71 continues measuring the time unless the predetermined time is exceeded.

  When the non-operation exceeds the predetermined time (Y in A806), the CPU 60 determines that the user does not use the device for a while, and in A807, the characteristic of the input current decrease output voltage increase (corresponding to the characteristic curve 52 in FIG. 4). Measurement). The CPU 60 causes the operating current changing unit 62 to change the operating current of the light emitting element 61a in a direction to decrease from the predetermined current. In a state where the presence / absence detection unit 59 detects that there is no thermal paper 4 in the conveyance path, light is emitted from the light emitting element 61a and light is received by the light receiving element 61p.

  The characteristics of the operating current of the light emitting element 61a and the output voltage output from the light receiving element 61p at this time are stored in the characteristic threshold value storage unit 64. This characteristic is, for example, as shown by a characteristic curve 53 in FIG. If the output light amount of the light emitting element when changing from on to off is the same, the necessary input current increases due to secular change. Therefore, the re-measured characteristic curve 53 is changed to the right side from the first characteristic curve 52. It becomes a coming characteristic curve.

  When the characteristic curve 53 is obtained in this way, appropriate input current threshold and output voltage threshold are obtained from the characteristic curve 53 and the characteristic curve 51 (FIG. 4) of the input current increasing output voltage decreasing measured at the time of shipment. .

  The input current threshold value at this time is calculated by the current threshold value calculation unit 65 (A808). The appropriate threshold value at this time is compared with the previous input current threshold value in the current threshold value comparison unit 66 (A809).

  When the threshold difference exceeds the predetermined value, in A811, the current input current threshold is newly set as the input current threshold under the control of the CPU, and stored in the characteristic threshold storage unit 64. When this is completed, the process returns to A801 again.

  On the other hand, when the difference between the two thresholds is compared with a predetermined value in A810 and detected that the difference is small (N in A810), the process returns to the original and the apparatus returns to A801. Detects the start of operation. As described above, the threshold is reset when the threshold difference exceeds the predetermined value because the effect is small even if the threshold is changed so frequently when the threshold difference is small. Of course, the threshold value may be reset every time the characteristic curve is measured.

  Note that when the light emission amount with respect to the input current of the light emitting element decreases due to secular change, the characteristic curve changes as shown by characteristic curves 53, 54, and 55 in FIG. Since these threshold values gradually increase, the threshold values can be updated when the threshold value increases, for example, as shown by the characteristic curve 55.

  Further, a characteristic curve when it is detected that there is no paper is obtained, a threshold value (voltage value) is obtained and stored, this threshold value is stored a predetermined number of times, an average is obtained, and an average value is calculated. When the average value is more than a certain value from the current threshold value, the threshold value is calculated based on the voltage value calculated when there is no paper, and is used to determine the presence of paper thereafter. Then, it is possible to store the averaged voltage value without a sheet for which the threshold value is calculated for the next comparison.

  According to the present embodiment, it is possible to automatically reset an appropriate threshold value of the input current even when the apparatus is used under the user and causes a secular change. It is possible to maintain accuracy compared to the above.

  In the above embodiment, the case has been described in which the characteristics are measured and reset only by the time during which the apparatus is not operating by the non-operation time measuring section 71 in the apparatus status detecting section 68 shown in FIG.

  However, the present invention is not limited to this, and the characteristic curve can be obtained as described above when the current time is night, for example, in combination with the current time, and the non-operation time continues for a predetermined time at that time. The current time can be detected by the clock 72, and the CPU 60 determines that the device has passed a predetermined time in the inactive time measuring unit 71 and that the current time range is, for example, after 23:00 and before 5:00 in the morning. In addition, the current sheet presence / absence detection unit 59 detects that there is no sheet in the conveyance path, and measures the characteristics of the increase in the input current decrease and the output voltage. Then, a current appropriate input current threshold value is obtained.

  It is also possible to detect the presence of a person around the device by the human sensor 73 and perform the characteristic measurement again only when a predetermined time has elapsed in the device in that state.

  In this embodiment, the presence sensor 73 detects that there is no person (moving thing) around the device, and the non-operation time measuring unit 71 detects that the device has not been operated for a predetermined time. Such device status information is sent from the device status detection unit 68 to the CPU 60. On the other hand, the absence of paper in the transport path is detected by the paper presence / absence detection unit 59, and this information is also sent to the CPU 60.

  The CPU 60 can measure the characteristics by instructing the operation current changing unit 62 or the like to perform an operation for obtaining the characteristics of the input current decrease output voltage increase based on the information.

  In the above embodiment, the change in the input current threshold value due to the secular change in the input current decrease output voltage increase characteristic has been described. However, not only this, but also the appropriate threshold of the output voltage may change.At this time, it is possible not only to reset the input current threshold, but also to reset the output voltage. For example, there is an advantage that paper sheet presence / absence can be detected more accurately. In this case as well, not only the continuous non-operation time but also the condition that the current time is within a predetermined time range or that there is no person around the device can be used.

  Although only the adjustment of the paper sensor has been described in the above embodiment, the adjustment of the passbook sensor can be similarly performed.

  Further, an example in which printing is performed on thermal paper by a printing apparatus including the statement printer ST and the passbook printer PB has been described. However, it is not limited to thermal paper, but can be applied to other devices and devices as long as it has a paper sheet sensor that optically detects paper sheets, such as copying machines and facsimile machines. It is.

  According to the embodiment, there is obtained a paper sheet presence / absence detection device and a paper sheet presence / absence detection method capable of automatically setting an appropriate threshold value for the presence / absence of paper sheets even when light of a light emitting element becomes weak due to secular change. .

  Although several embodiments of the present invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

61a... Light emitting element 61p... Light receiving element 63... Output voltage detection unit 62... Operation current changing unit 64. CPU
65... Current threshold calculation unit 66... Current threshold comparison unit 67 .. Operation unit 68... Device status detection unit 71.

Claims (5)

A light-emitting element and a light-receiving element that face each other across the conveyance path of the paper,
A paper sheet presence / absence detection unit for detecting the presence or absence of paper sheets in the conveyance path;
When the paper sheet presence / absence detection unit determines that there is no paper sheet in the transport path at a predetermined timing, the light receiving element receives light when the operating current is reduced in the light emitting element. A control unit that obtains the optimum output voltage of the light receiving element based on the characteristics of the output voltage that is output, and resets it as a threshold for the presence or absence of paper sheets;
Paper sheet presence / absence detection device.   The paper sheet presence / absence detection device according to claim 1, wherein the control unit performs the resetting when a threshold difference between the optimum output voltage and the threshold before resetting exceeds a predetermined value. A light-emitting element and a light-receiving element that face each other across the conveyance path of the paper,
A paper sheet presence / absence detection unit for detecting the presence or absence of paper sheets in the conveyance path;
When the paper sheet presence / absence detection unit determines that there is no paper sheet in the transport path at a predetermined timing, the light receiving element receives light when the operating current of the light emitting element is reduced. A control unit for obtaining an optimum input current of the light emitting element based on the characteristics of the output voltage output
Paper sheet presence / absence detection device   The paper sheet presence / absence detection device further includes a non-operation time measurement unit that measures a continuous time during which the paper sheet presence / absence detection device is not operating, and the predetermined timing is a predetermined time during which the non-operation time is measured by the non-operation time measurement unit. The paper sheet presence / absence detection device according to any one of claims 1 to 3, wherein the timing of the paper sheet is exceeded. The paper sheet presence / absence detection unit detects the presence or absence of paper sheets in the paper sheet conveyance path provided between the opposing light emitting element and light receiving element,
When the paper sheet presence / absence detection unit determines that there is no paper sheet in the transport path at a predetermined timing, the light receiving element receives light when the operating current is reduced in the light emitting element. The optimal output voltage of the light receiving element is obtained by the control unit based on the characteristics of the output voltage that is output, and is reset as a threshold for the presence or absence of paper sheets,
Paper sheet presence / absence detection method.

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