JP5117907B2 - Master status detection device - Google Patents

Description

  The present invention relates to a master state detection device for detecting the presence / absence of a master to be conveyed and the presence / absence of an end mark provided on the master.

  The stencil printing apparatus winds a stencil sheet called a master made by stencil around a rotating drum, presses the printing paper against the master wound around the drum, and supplies ink to the master from the inside of the drum, thereby supplying the master. A printed image is formed by transferring the formed perforated portion onto a printing paper.

  In this type of stencil printing apparatus, a thermal head having a plurality of heat generating elements is selectively heated and perforated based on image information of the original to form a perforated portion in the master, which is a plate making process. The master used for the plate making process is set in the apparatus while being wound in a roll shape, and is conveyed to the thermal head while being drawn out by a platen roller or the like. Then, the master punched by heating with the thermal head is cut to a predetermined length, thereby completing the plate making for one plate.

As described above, since the master is wound in a roll shape, a mark portion called an end mark is provided at the end portion of the roll to notify that there is little remaining of one roll. A normal stencil printing apparatus is provided with a sheet state detection device having a reflection type sensor for detecting the presence or absence of a master and a transmission type sensor for detecting an end mark provided at the end of the master. It has been. When the end mark is detected during the conveyance of the master by the sheet state detection device, a message prompting the user to replace the master is displayed. As a conventional example of such a sheet state detection device, for example, a light detection sensor that outputs a level output capable of determining three states of a master-free state, a certain state, and an end mark passing state is provided, and a sensor mounting space is provided. There is known one sensor that does not bother the sensor mounting man-hours (see Patent Document 1).
JP 2000-327146 A

  The above-described conventional sheet state detection apparatus sets two threshold values A and B to discriminate three states, and there is no master if the light reception voltage value output from the light detection sensor is equal to or greater than the threshold value A. If the value is between the threshold values A and B, the master is determined. For this reason, when a disturbance occurs in the use environment, for example, when the light reception voltage value at the light detection sensor is actually between the threshold values A and B, but is greater than or equal to the threshold value A. Had the problem of misdetecting the state of the master.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in a configuration in which the master state is detected by one sensor, a master state detection device that can always detect the master state accurately without being affected by disturbance. The purpose is to provide.

  In order to achieve the above object, the invention according to claim 1 detects whether or not the long master is set at a predetermined position on the conveyance path, and includes an end mark provided at the end portion of the master. A master state detection device for detecting, a sensor having a light emitting unit and a light receiving unit disposed opposite to each other across the master at a predetermined position on the transport path, and a light receiving unit for light irradiation from the light emitting unit of the sensor A light emission current control means for controlling a light emission current to be supplied to the light emitting section so that a light reception voltage output from the sensor is equal to or higher than a preset reference value; and a predetermined period of the light reception voltage output from the light receiving section of the sensor A received light voltage calculating means for calculating an average value and a voltage fluctuation range for each, and the average value of the received light voltage calculated by the received light voltage calculating means is a reference value or more and the voltage fluctuation width is a specified value or less. If there is a master and there is no end mark, if the average value of the received light voltage calculated by the received light voltage calculation means is less than a reference value and the voltage fluctuation range is less than a specified value, there is a master. If the average value of the received light voltage calculated by the received light voltage calculation means is not less than a reference value and the voltage fluctuation range is less than a specified value, it is determined that there is no master. And a master state determination unit.

  In order to achieve the above object, the invention according to claim 2 detects whether or not the long master is set at a predetermined position on the conveyance path, and detects the end provided at the end portion of the master. A master state detection device for detecting a mark, wherein a sensor having a light emitting part and a light receiving part arranged opposite to each other with the master sandwiched at a predetermined position on the transport path, and light irradiation from the light emitting part of the sensor A light emission current control means for supplying a light emission current to the light emitting section so that a light reception voltage output from the light receiving section rises at a constant slope every predetermined period; and a predetermined period of the light reception voltage output from the light receiving section of the sensor A received light voltage calculation means for calculating an average change rate and a voltage fluctuation range for each, and the average change rate of the received light voltage calculated by the received light voltage calculation means is less than a preset slope regulation value. If the voltage fluctuation range is equal to or greater than a specified value, it is determined that there is a master and no end mark, and the average rate of change of the received light voltage calculated by the received light voltage calculating means is a preset slope specified value. If the voltage fluctuation range is less than the specified value, it is determined that the master is present and the end mark is present, and the average change rate of the received light voltage calculated by the received light voltage calculating means is a preset slope specified value. A master state determination unit for determining that there is no master if the voltage fluctuation range is less than a predetermined value as described above.

  According to a third aspect of the present invention, in the first or second aspect, the light emission current control means supplies a light emission current to the light emitting section only during the conveyance of the master.

  According to the first aspect of the invention, when determining the presence or absence of the master and the end mark, the average value of the received light voltage in the predetermined period is compared with the threshold value, and the voltage fluctuation width in the predetermined period is compared with the specified value. Thus, even if the received light voltage value is affected by disturbance, accurate determination can be performed by comparing the voltage fluctuation range that is not easily affected by disturbance with a specified value. Therefore, it is possible to always detect the master state accurately without being affected by the disturbance even though it is configured to detect the master state with one sensor.

  According to the invention of claim 2, when determining the presence or absence of the master and the end mark, the average change rate of the received light voltage in the predetermined period is compared with the specified slope value, and the voltage fluctuation width and the specified value in the predetermined period are compared. To compare. Since both the average rate of change of the received light voltage and the electric fluctuation range are not easily affected by disturbance, accurate determination can be made. Therefore, it is possible to always detect the master state accurately without being affected by the disturbance even though it is configured to detect the master state with one sensor.

  In the second aspect of the invention, the amount of light emitted from the light emitting unit is increased with a constant slope so that the received light voltage output from the light receiving section increases with a constant slope. Since the inclination of the light reception voltage does not affect the accuracy even if the straight line indicating the inclination shifts up and down, the light reception voltage output from the light receiving unit becomes a predetermined voltage value (a constant value). There is no need to periodically correct variations in light emission luminance and light receiving sensitivity, and there is no problem of reduced accuracy even when used for a long time. In addition, it is excellent in maintainability.

  Furthermore, in the invention of claim 3, since the light emission current is supplied to the light emitting section only during the conveyance of the master, the light emission current supplied to the light emission section can be made zero during the period other than the master conveyance period. Therefore, the power consumption can be greatly reduced as compared with the case where light is always emitted from the light emitting unit while the stencil printing apparatus is turned on or from the reading of the document to the end of printing.

  Hereinafter, an embodiment in which the master state detection device according to the present invention is applied to a stencil printing apparatus will be described.

[Embodiment 1]
FIG. 1 is a block diagram showing an electrical configuration of the master state detection apparatus according to the first embodiment, FIG. 2 is an overall configuration diagram of the stencil printing apparatus according to the first embodiment (and 2), and FIG. 3 is an arrangement of the master detection sensor. FIG. 4 is an explanatory view showing the arrangement of the operation panel.

  First, the overall configuration of the stencil printing apparatus 1 will be described. As shown in FIG. 2, the stencil printing apparatus 1 of this embodiment is roughly composed of a document reading unit 10, a plate making / writing unit 20, a cutter unit 30, and a printing unit 40.

  The document reading unit 10 is a mechanism for performing a document reading process. The document reading unit 10 sets a document 7 that is a copy object, and a document sensor that detects the document 7 set on the document setting table 12. 17, a pair of document conveying rolls 14 that are rotationally driven by a detection signal from the document sensor 17, a contact image sensor 11 that optically reads an image of the conveyed document 7 and converts it into an analog electric signal, and an image A document discharge roll pair 15 for discharging the document 7 read by the sensor 11 to the document discharge tray 19 is configured.

  The document IN sensor 16 is a means for detecting the conveyed document 7 and determines the start of the plate making / writing unit 20 described later. Further, the document transport roll pair 14 and the document discharge roll pair 15 are rotationally driven by a stepping motor 18 as indicated by dotted lines in the drawing.

  In the document reading unit 10, when a detection signal from the document sensor 17 is received by a system control unit (not shown), the document transport roll pair 14 is rotated to transport the document 7 in a predetermined direction. The image of the document 7 is optically read. The original 7 from which the image has been read is discharged to the original discharge tray 19 by the original discharge roll pair 15. Further, an analog electrical signal for one plate read by the image sensor 11 is converted into 8-bit digital data by an A / D converter (not shown) and then sent to an image processor (not shown).

  The plate-making writing unit 20 includes a thermal head 21 in which a plurality of heating elements 21a are arranged in a line in the main scanning direction, and a platen roll 24 that conveys the master 23 sent from the master roll 22 while pressing the master 23 against the thermal head 21. The master 23 made by the thermal head 21 is composed of a base paper transporting roll pair 26 that transports the master 23 toward a clamp part 32 of a drum 33 described later. Note that a writing motor 25 indicated by a dotted line in the figure is a stepping motor, and rotates the platen roll 24 and the base paper transporting roll pair 26.

  The plate making / writing unit 20 is provided with a master detection sensor 27. As shown in FIG. 3, the master detection sensor 27 includes a light emitting unit 28 and a light receiving unit 29 that are disposed to face each other with the master 23 interposed therebetween. As the light emission part 28, the light emitting element which can light-irradiate infrared light or visible light, such as LED, can be used, for example.

  The master detection sensor 27 includes three states of the master 23, that is, a state where the master 23 is present and the end mark 23a is not present, a state where the master 23 is present and the end mark 23a is present, and no master 23 (and no end mark 23a). It is for detecting the state. In the present embodiment, as the master detection sensor 27, a separate transmission type sensor in which the light emitting / receiving unit is separated is shown as an example, but a U-shaped transmission sensor in which the light emitting / receiving unit is integrated is used. Also good.

  On the other hand, the master 23 is a heat-sensitive base paper in which a thermoplastic resin film and a Japanese paper as a support are bonded together with an adhesive, and is a translucent member having a transmittance of about 50 to 60%. And the end mark 23a which notifies that there is little remaining of the roll is provided in the termination | terminus part of the master roll 22 which wound this master 23 in roll shape. The end mark 23a is a light shielding region having a transmittance of 5% or less. The master detection sensor 27 is disposed in the vicinity of the master roll 22 and at a position where the end mark 23a passes when the transported master 23 is viewed in plan.

  The cutter unit 30 is a mechanism for cutting the master 23. When the master 23 made by the thermal head 21 is wound around the drum 33 and has a predetermined length, the master 23 is cut at a predetermined position. A cutter 31 is provided.

  The printing unit 40 includes a drum 33 as a rotating part for image transfer, which includes an ink supply unit that supplies a predetermined amount of ink to the inner surface of the ink reservoir 58 formed between the doctor roll 56 and the squeegee roll 57, and a paper feed. The primary paper feed roll 46 that picks up and conveys the print paper 43 one by one from the print paper that is loaded on the table 44 and becomes a copy, and the print paper 43 that has been conveyed from the primary paper feed roll 46 at a predetermined timing. A pair of secondary paper feed rolls 42 to be sent out, a press roll 35 that presses the printing paper 43 fed from the secondary paper feeding roll 42 against the outer peripheral surface of the drum 33, and the printed printing paper 43 is peeled off from the drum 33. A separation claw 55 for removing the paper and a paper discharge stand 49 for discharging and stacking the print paper 43 peeled off from the drum 33 and discharged.

  A clamp 32 is provided on the outer peripheral surface of the drum 33 to clamp the leading end of the master 23 that has been made and conveyed by the thermal head 21. The master 23 having been subjected to the plate making clamped by the clamp portion 32 is wound around the outer peripheral surface by rotating the drum 33 (plate making).

  Note that the main motor 34 indicated by a dotted line in the drawing is a DC motor, and is for driving the drum 33 to rotate. Moreover, in FIG. 2, the code | symbol 41 is a conveyance path.

  Further, an operation panel 60 as shown in FIG. 4 is provided on the upper surface of the apparatus main body. The operation panel 60 includes a start key 62 for starting mode-making plate making and printing processing, a stop key 63 for stopping plate making and printing processing in operation, and a reset for resetting items set from the operation panel 60. A key 64, a numeric keypad 65 for inputting the number of prints, a top and bottom position movement amount, a mode selection key 66 for selecting a mode such as plate making and printing, a setting confirmation key 67 for confirming the selected mode setting, A trial printing key 68 for performing trial printing after the plate making process and a center key 69 for centering the printing position are arranged.

  A display / input panel 70 is disposed on the operation panel 60. The display / input panel 70 includes a pressure-sensitive or electrostatic transparent touch panel (not shown) disposed on the front surface, and a liquid crystal display panel (not illustrated) disposed on the back surface of the touch panel. Yes. The user can input various parameters by directly touching the surface of the touch panel with a finger while viewing the display screen of the liquid crystal display panel. For example, when plate making or printing processing is performed, setting of a sorter function, setting of continuous shooting / continuous printing function, and the like can be performed through a setting input screen displayed below the touch panel.

  Further, on the liquid crystal display panel, a message prompting replacement of the master roll 22 is displayed in addition to the end of plate making and the start of printing. Such various data and setting input means are not limited to the example of the operation panel 60 of the present embodiment, and may be in other forms and forms as long as they function in the same manner.

  Next, the electrical configuration of the master state determination apparatus according to the first embodiment will be described with reference to FIG.

  In FIG. 1, a control unit 81 is a part that controls the operation as the master state detection device, and executes various arithmetic processes and processes such as data input / output. The control unit 81 stores various commands and data input from the operation panel 60, a RAM (Random Access Memory) 82 for storing a received light voltage value, a status flag, a current instruction value, a control program, and the like. A ROM (read only memory) 83, a constant current circuit 84 and the like are connected (illustration and description of other connected devices are omitted).

  In the control unit 81, as processing related to the main part of the present invention, the light emitting unit 28 is configured so that the light reception voltage output from the light receiving unit 29 of the master detection sensor 27 is equal to or higher than a preset threshold value (reference value). Processing as light emission current control means for controlling the light emission current to be supplied is executed. In the processing as the light emission current control means, the control unit 81 converts a predetermined current instruction value (fixed value) into an analog signal by a D / A conversion circuit (not shown), and then outputs the analog signal to the constant current circuit 84. In the circuit 84, a light emission current corresponding to the current instruction value is supplied to the light emitting unit 28. Thereby, in the light emission part 28, infrared light is irradiated with the light quantity according to the light emission current, for example.

  The threshold value is determined by the light receiving voltage output when the master 23 having a transmittance of about 50 to 60% is detected by the master detection sensor 27 and the end mark 23a having a transmittance of about 5% provided on the master 23. It is set to a value approximately in the middle of the received light voltage output when detected by the master detection sensor 27. Accordingly, if the average value of the received light voltage described later is equal to or greater than the threshold value, at least 50 to 60% of the light emitted from the light emitting unit 28 is transmitted. It can be determined that the state is either “no” or “no master (of course, no end mark)”. If the average value of the received light voltage is less than the threshold value, approximately 95% of the light emitted from the light emitting unit 28 is shielded, so that it can be determined that there is an end mark.

  Further, in the transmission type sensor used as the master detection sensor 27, output variation occurs due to sensor mounting accuracy, master transmittance, sensitivity adjustment, deterioration with time, paper dust and the like. For this reason, after setting the light emission current to be supplied to the light emitting unit 28, it is possible to periodically correct variations in light emission luminance and light receiving sensitivity so that the light reception voltage output from the light receiving unit 29 becomes a predetermined voltage value. desirable.

  Furthermore, the magnitude of the light receiving voltage output from the light receiving unit 29 may be set by adjusting the light emission amount electrically or mechanically in the light emitting unit 28.

  In the control unit 81, as a process related to the main part of the present invention, a light reception voltage for calculating an average value and a voltage fluctuation width (ripple width) for each predetermined period of the light reception voltage output from the light reception unit 29 of the master detection sensor 27, respectively. Processing as voltage calculation means is executed. In the processing as the light reception voltage calculation means, the control unit 81 converts the analog light reception voltage output from the light reception unit 29 into a digital signal by an A / D conversion circuit (not shown), and has a predetermined measurement period t (several ms). Each time, the average value of received light voltage and the voltage fluctuation range are calculated.

  Here, the average value of the received light voltage is obtained by sequentially adding the received light voltage values detected in a predetermined sampling period (several tens of ms) within the measurement period t in a predetermined storage area of the RAM 82, and after the measurement period t has elapsed. It can be calculated by a technique such as dividing the sum of values by the number of samplings.

  In addition, the voltage fluctuation width is obtained by sequentially storing light reception voltage values detected at a predetermined sampling period in the measurement period t in a predetermined storage area of the RAM 82, and storing the received light reception voltage after the measurement period t has elapsed. It can be calculated by a technique such as extracting the maximum value and the minimum value from the values and calculating the difference.

  The voltage fluctuation range is caused by variations in the transmittance of the thermoplastic resin film and the Japanese paper constituting the master 23. When the master 23 is being transported (detected), it is usually not the end mark 23a. Will cause a voltage fluctuation range exceeding the specified value. Therefore, if the voltage fluctuation range is equal to or less than the specified value, it can be determined that the state is the end mark 23a portion of the master 23 or the master 23 does not exist.

  Note that the voltage fluctuation range is only the displacement of the entire voltage value within the measurement period even when a disturbance occurs, and the individual voltage values do not vary within the measurement period. Not affected by disturbance. However, if there is a large or small value in the detected light-receiving voltage value, it is assumed that a disturbance or the like has occurred, and an arithmetic method such as extracting the maximum or minimum value after excluding these values is used. May be.

  Further, in the control unit 81, as a process related to the main part of the present invention, the average value of the received light voltage calculated in the process as the received light voltage calculating means is not less than a preset threshold value and the voltage fluctuation range is not less than a specified value. If so, it is determined that there is a master and no end mark, and the average value of the received light voltage calculated in the process as the received light voltage calculation means is less than a preset threshold value and the voltage fluctuation range is a specified value. If it is less than that, it is determined that there is a master and an end mark, and the average value of the received light voltage calculated in the processing as the received light voltage calculation means is equal to or greater than a preset threshold value and the voltage fluctuation range is specified. If it is less than the value, processing as master state determination means for determining that there is no master is executed.

  The control unit 81 stores the determination result in the RAM 82 as a status flag. The status flag is a flag corresponding to the above three states, specifically, a flag with a master and without an end mark, a flag with a master and with an end mark, and a flag without a master.

  In FIG. 1, the master detection sensor 27, the light emission current control means, the light reception voltage calculation means, and the master state determination means of the control unit 81 constitute the master state detection apparatus according to the first embodiment. Among these, the control means excluding the master detection sensor 27 is constituted by a microcomputer having a CPU (Central Processing Unit), a RAM, a ROM, and an input / output interface. However, the control means may be constituted by a plurality of microcomputers. In that case, in addition to the function as the master state detection device, the functions of a plurality of control systems may be executed. Further, the operation of the control unit 81 may be executed as one function of a system control unit (not shown) that controls the overall operation of the stencil printing apparatus 1.

  Next, a processing procedure of master state detection by the master state detection device of the first embodiment will be described with reference to a flowchart of FIG. 5 and a timing chart of FIG.

  First, in the processing as the light emission current control means, the control unit 81 converts a predetermined current instruction value into an analog signal, then outputs the analog signal to the constant current circuit 84 and supplies the light emission unit 28 with the light emission current corresponding to the current instruction value. (Step S101). Subsequently, the control unit 81 detects the received light voltage output from the light receiving unit 29 at a predetermined sampling period in the process as the received light voltage calculation means, converts it to a digital signal, and sequentially stores it in the RAM 82 (step S102). ). Then, it is determined whether or not a predetermined measurement period t has passed (step S103). If "NO" here, the process returns to the step S102. If YES in step S103, the average value of the received light voltage within the measurement period t is calculated (step S104), and the voltage fluctuation width of the received light voltage within the measurement period t is calculated (step S105). Next, in the process as the master state determination unit, the control unit 81 determines whether or not the average value of the received light voltage calculated in step S104 is equal to or greater than a threshold value (step S106). If “YES” is determined here, it is determined whether or not the voltage fluctuation range of the received light voltage calculated in the step S105 is equal to or larger than a specified value (step S107). If YES here, a flag indicating that there is a master and no end mark is set as the status flag of the RAM 82 (step S108). In this case, as shown in FIG. 6A, the average value of the received light voltage is equal to or greater than the threshold value (dotted line), and the voltage fluctuation range of the received light voltage is equal to or greater than the specified value. 23 is conveyed, but the end mark 23a is not detected.

  On the other hand, if “NO” in the step S106, it is determined whether or not the voltage fluctuation range of the received light voltage calculated in the step S105 is less than a specified value (step S109). If YES here, a flag indicating that there is a master and that there is an end mark is set as a status flag in the RAM 82 (step S110). In this case, as shown in FIG. 6B, since the average value of the received light voltage is less than the threshold value and the voltage fluctuation range of the received light voltage is less than the specified value, the master 23 is transported. In this state, the end mark 23a is detected. As described above, when the flag indicating the presence of the master and the presence of the end mark is set, the control unit 81 displays a message prompting the replacement of the master roll 22 on the display / input panel 70 of FIG.

  If NO in step S109, it is determined that a disturbance or the like has occurred, and the process returns to step S102. On the other hand, if NO in step S107, a flag indicating no master is set as the status flag of the RAM 82 (step S111). In this case, as shown in FIG. 6C, the average value of the received light voltage is equal to or greater than the threshold value, and the voltage fluctuation range of the received light voltage is less than the specified value, so that the master 23 does not exist ( It is detected that the sheet is not conveyed.

  As described above, in the master state detection device according to the first embodiment, when determining the presence or absence of the master and the end mark, the average value of the received light voltage in the predetermined measurement period is compared with the threshold value, and the predetermined measurement is performed. Since the voltage fluctuation range in the period is compared with the specified value, even if the received light voltage value is affected by the disturbance, accurate determination is made by comparing the voltage fluctuation range that is less affected by the disturbance and the specified value. It can be carried out. Therefore, it is possible to always detect the master state accurately without being affected by the disturbance even though it is configured to detect the master state with one sensor.

[Embodiment 2]
Next, Embodiment 2 of the present invention will be described. Since the electrical configuration of the master state detection apparatus according to the second embodiment is the same as that in FIG. 1, the illustration is omitted, and only the differences will be described.

  In the control unit 81 of the second embodiment, as a process related to the main part of the present invention, the light emitting unit 28 is configured so that the light reception voltage output from the light receiving unit 29 of the master detection sensor 27 rises at a constant slope every predetermined period. The process as the light emission current control means for controlling the light emission current to be supplied to is executed.

  In the processing as the light emission current control means, the control unit 81 continuously increases the current instruction value at a constant time period and at a constant rate until it reaches a predetermined maximum value, so that the light emission amount at the light emission unit 28 is constant. The light reception voltage output from the light receiving unit 29 is increased at a constant inclination. The current instruction value is output to the constant current circuit 84, and the light emission current corresponding to the current instruction value is supplied to the light emitting unit 28 from here. The current instruction value is assumed to increase from an initial value 0 (zero) to a maximum value (predetermined value). In this embodiment, the time required to increase the current instruction value from 0 to the maximum value is set as the measurement period t (several ms), and the measurement period t elapses when the current instruction value reaches the maximum value. The current instruction value is cleared to 0 every time.

  Further, the control unit 81 calculates an average change rate and a voltage fluctuation range (ripple width) for each predetermined period of the received light voltage output from the light receiving unit 29 of the master detection sensor 27 as processing related to the main part of the present invention. Processing as a received light voltage calculation means is executed. In the processing as the light reception voltage calculation means, the control unit 81 converts the analog light reception voltage output from the light reception unit 29 into a digital signal by an A / D conversion circuit (not shown) and receives light in the measurement period t (unit time Δt). The average change rate of the received light voltage for each measurement period t is calculated by obtaining the increment (ΔV) of the voltage value from ΔV / Δt.

  Note that, even when a disturbance occurs, the received light voltage value is merely displaced as a whole within the period, and the individual voltage values do not vary within the period. For this reason, the average rate of change is hardly affected by disturbance. On the other hand, the calculation method of the voltage fluctuation range is the same as that of the first embodiment.

  Further, in the control unit 81, as a process related to the main part of the present invention, the average change rate of the received light voltage calculated in the process as the received light voltage calculating means is equal to or greater than a preset slope specified value and the voltage fluctuation range is specified. If it is equal to or greater than the value, it is determined that there is a master and no end mark. Similarly, the average rate of change of the received light voltage calculated in the process as the received light voltage calculation means is less than a preset slope regulation value and the voltage fluctuation range is If it is less than the specified value, it is determined that the master is present and the end mark is present, and the average rate of change of the received light voltage calculated in the process of the received light voltage calculation means is equal to or greater than the preset specified slope value and voltage fluctuation If the width is less than the specified value, processing as a master state determination unit that determines that there is no master is executed. The control unit 81 stores the determination result in the RAM 82 as a status flag.

  Note that the specified slope value is the slope of the light reception voltage actually output from the light receiving unit 29 when light is emitted from the light emitting unit 28 so that the light reception voltage output from the light receiving unit 29 rises with a constant inclination. In the process as the light emission current control means of the control unit 81, a slope that is substantially the same as the slope when the current instruction value is continuously increased at a constant time period and at a constant rate is set. Is done. Therefore, if the calculated average change rate of the received light voltage is equal to or greater than the specified slope value, the master 23 is transported (detected) and is not part of the end mark 23a or the master 23 does not exist (transmittance). Therefore, it can be determined that the inclination is 100%. If the calculated average change rate of the received light voltage is less than the specified slope value, it is determined that the master 23 is transported (detected) and the end mark 23a portion (because the transmittance is less than 5%, the slope is small). can do.

  In FIG. 1, the master detection sensor 27, the light emission current control means, the light reception voltage calculation means, and the master state determination means of the control unit 81 constitute the master state detection device in the second embodiment.

  Next, a processing procedure of master state detection by the master state detection device of the second embodiment will be described with reference to a flowchart of FIG. 7 and a timing chart of FIG.

  First, in the processing as the light emission current control means, the control unit 81 converts the initial value (0) of the current instruction value into an analog signal, and then outputs the analog signal to the constant current circuit 84 to correspond to the current instruction value to the light emitting unit 28. A light emission current is supplied (step S201). Subsequently, in the process as the received light voltage calculation means, the control unit 81 detects the received light voltage output from the light receiving unit 29 at the timing of a predetermined sampling period, converts it to a digital signal, and sequentially stores it in the RAM 82 ( Step S202). Then, at the detection timing of each sampling period, it is determined whether or not the current instruction value is the maximum value (step S203). Here, if NO, the current instruction value is incremented, and the light emission current corresponding to this current instruction value is supplied to the light emitting unit 28 (step 204). Then, the process returns to step S202. By rotating through the loop of steps S202 to S204, the current instruction value continuously increases at a constant time period (sampling period) and at a constant rate within the measurement period t. The output light reception voltage also rises with a certain slope.

  On the other hand, if “YES” in the step S203, the current instruction value is cleared to 0 (step S205), the average rate of change of the received light voltage in the measurement period t is calculated (step S206), and the light reception in the measurement period t is also performed. A voltage fluctuation range of the voltage is calculated (step S207). Next, the control unit 81 determines whether or not the average change rate of the received light voltage calculated in step S206 is equal to or greater than the specified slope value in the process as the master state determination unit (step S208). If “YES” is determined here, it is determined whether or not the voltage fluctuation range of the received light voltage calculated in the step S207 is equal to or larger than a specified value (step S209). If YES here, a flag indicating that there is a master and no end mark is set as a status flag of the RAM 82 (step S210). In this case, as shown in FIG. 8A, since the average rate of change of the received light voltage is equal to or greater than the specified slope value, and the voltage fluctuation range of the received light voltage is equal to or greater than the specified value, the master 23 is transported. However, the end mark 23a is not detected.

  On the other hand, if “NO” in the step S208, it is determined whether or not the voltage fluctuation range of the received light voltage calculated in the step S207 is less than a specified value (step S211). If YES here, a flag indicating that there is a master and that there is an end mark is set as a status flag in the RAM 82 (step S212). In this case, as shown in FIG. 8B, since the average rate of change of the received light voltage is less than the specified slope value and the voltage fluctuation range of the received light voltage is less than the specified value, the master 23 is transported. In this state, the end mark 23a is detected. As described above, when the flag indicating the presence of the master and the presence of the end mark is set, the control unit 81 displays a message prompting the replacement of the master roll 22 on the display / input panel 70 of FIG.

  If NO in step S211, it is determined that a disturbance or the like has occurred, and the process returns to step S201. On the other hand, if NO in step S209, a flag indicating no master is set as the status flag of the RAM 82 (step S213). In this case, as shown in FIG. 8C, the average rate of change of the received light voltage is equal to or greater than the specified slope value, and the voltage fluctuation width of the received light voltage is less than the specified value (almost zero). It is detected that 23 is not present (not transported).

  As described above, in the master state detection device according to the second embodiment, when determining the presence or absence of the master and the end mark, the average change rate of the received light voltage in the predetermined measurement period is compared with the specified slope value, The voltage fluctuation range in the measurement period is compared with the specified value. Since both of the average change rate and the electric fluctuation range of the received light voltage are not easily affected by disturbance, more accurate determination can be made than in the first embodiment. Therefore, even in the master state detection device according to the second embodiment, it is possible to always detect the master state accurately without being affected by the disturbance even though the master state is detected by one sensor.

  Further, in the second embodiment, the light reception voltage output from the light receiving unit 29 is increased with a constant slope by increasing the light emission amount at the light emitting section 28 with a constant slope. Since the inclination of the light reception voltage does not affect the accuracy even if the straight line indicating the inclination shifts up and down, the light reception voltage output from the light receiving unit 29 as in the first embodiment has a predetermined voltage value ( There is no need to periodically correct the variation in light emission luminance and light receiving sensitivity so that it becomes a constant value), and there will be no inconvenience of a decrease in accuracy even when used for a long time. In addition, it is excellent in maintainability.

  In the master state detection of the first and second embodiments, the output of the current instruction value from the control unit 81 to the constant current circuit 84 is limited only during the plate making process in which the master 23 is transported on the transport path 41. It may be. In that case, the light emission current supplied from the constant current circuit 84 to the light emitting unit 28 during the period other than the conveyance period of the master 23 can be made zero. Therefore, the power consumption can be greatly reduced as compared with the case where the light emitting unit 28 always emits light while the stencil printing apparatus is turned on or from the time of reading a document to the end of printing.

FIG. 2 is a block diagram showing an electrical configuration of the master state detection apparatus according to the first embodiment. 1 is an overall configuration diagram of a stencil printing apparatus according to Embodiment 1 (and 2). FIG. The perspective view which shows arrangement | positioning of a master detection sensor. Explanatory drawing which shows arrangement | positioning of an operation panel. 5 is a flowchart showing a processing procedure of master state detection by the master state detection device according to the first embodiment. 5 is a timing chart of master state detection by the master state detection device according to the first embodiment. 9 is a flowchart showing a processing procedure for master state detection by the master state detection apparatus according to the second embodiment. The timing chart of the master state detection by the master state detection apparatus of Embodiment 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Stencil printing apparatus 10 ... Document reading part 20 ... Plate-making writing part 22 ... Master roll 23 ... Master (stencil paper)
23a ... End mark 27 ... Master detection sensor 28 ... Light emitting unit 29 ... Light receiving unit 33 ... Drum 40 ... Printing unit 43 ... Printing paper 60 ... Operation panel 70 ... Display / input panel 81 ... Control unit 82 ... RAM
83 ... ROM
84 ... Constant current circuit

Claims (3)

A master state detection device that detects whether or not a long master is set at a predetermined position on a conveyance path and detects an end mark provided at a terminal end portion of the master,
A sensor having a light emitting unit and a light receiving unit disposed opposite to each other across the master at a predetermined position on the conveyance path;
A light emission current control means for controlling a light emission current to be supplied to the light emitting unit so that a light reception voltage output from the light receiving unit with respect to light irradiation from the light emitting unit of the sensor is equal to or higher than a preset reference value;
A received light voltage calculating means for calculating an average value and a voltage fluctuation range for each predetermined period of the received light voltage output from the light receiving unit of the sensor;
If the average value of the received light voltage calculated by the received light voltage calculating means is not less than a reference value and the voltage fluctuation range is not less than a specified value, it is determined that there is a master and no end mark, and the received light voltage calculating means If the average value of the received light voltage calculated in step 2 is less than a reference value and the voltage fluctuation range is less than a specified value, it is determined that there is a master and an end mark, and the received light voltage calculated by the received light voltage calculation unit Master state determination means for determining that there is no master if the average value of the voltage is equal to or greater than a reference value and the voltage fluctuation range is less than a specified value;
A master state detection device comprising: A master state detection device that detects whether or not a long master is set at a predetermined position on a conveyance path and detects an end mark provided at a terminal end portion of the master,
A sensor having a light emitting unit and a light receiving unit disposed opposite to each other across the master at a predetermined position on the conveyance path;
A light-emitting current control means for supplying a light-emitting current to the light-emitting unit so that a light-receiving voltage output from the light-receiving unit rises with a certain slope every predetermined period in response to light irradiation from the light-emitting unit of the sensor;
A received light voltage calculating means for calculating an average rate of change and a voltage fluctuation range for each predetermined period of the received light voltage output from the light receiving unit of the sensor;
If the average rate of change of the received light voltage calculated by the received light voltage calculating means is greater than or equal to a preset slope specified value and the voltage fluctuation range is greater than or equal to a specified value, it is determined that there is a master and no end mark. If the average change rate of the received light voltage calculated by the received light voltage calculating means is less than a preset slope regulation value and the voltage fluctuation range is less than a prescribed value, it is determined that there is a master and an end mark. Master state determining means for determining that there is no master if the average rate of change of the received light voltage calculated by the received light voltage calculating means is equal to or greater than a preset slope specified value and the voltage fluctuation range is less than a specified value. When,
A master state detection device comprising:   3. The master state detection device according to claim 1, wherein the light emission current control unit supplies a light emission current to the light emitting unit only while the master is being transported.

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