JP5937370B2 - Printer - Google Patents

Description

The present invention relates to a printer, and more particularly, to a printer including a control unit that compares an output voltage of a reflective sensor with a threshold value and detects an end in a conveyance direction of a print medium based on the comparison result.

  2. Description of the Related Art Conventionally, a printer that performs a printing process on a printing medium such as a plate or a sheet is known (see, for example, Patent Document 1). When printing is performed by this printer, printing is performed on the print medium by detecting the conveyance direction end of the print medium with a reflective sensor. A reflective sensor is composed of a light emitting element (for example, LED) and a light receiving element (for example, a phototransistor). Light from the light emitting element is reflected by a print medium being conveyed, and the reflected light is reflected by the light receiving element. The end of the print medium in the conveyance direction is detected.

  In order to exert such a function, a sensor control circuit as shown in FIG. 10 is generally used. In this sensor control circuit, the anode side of the LED is connected to a constant voltage power supply (for example, +5 V), and the cathode side is connected to the collector side of the transistor. The emitter side of the transistor is connected to the ground (GND) through a resistor. The base side of the transistor is connected to the microcomputer MC through an OP amplifier and a DA converter. For this reason, LED can be light-emitted by outputting a digital voltage from microcomputer MC. It is also possible to adjust the light emission amount (luminance) of the LED by adjusting the output of the digital voltage. On the other hand, the collector side of the phototransistor is connected to a constant voltage power source (for example, +3.3 V) via a resistor R (for example, resistance value: 47 kΩ), and the emitter side is connected to the ground. The output voltage of the collector of the phototransistor (see the voltage measurement point in FIG. 10) is taken into the microcomputer MC via the AD converter.

  When reflected light is input to the phototransistor, a current flows from the collector side to the emitter side, a voltage is generated at both ends of the resistor R connected to the constant voltage power source, and the voltage at the voltage measurement point is lowered. As shown in FIG. 3, the voltage at the voltage measurement point (output voltage of the reflection type sensor) is the saturation voltage (0 V) of the reflection type sensor from the non-detection voltage (+3.3 V) side of the print medium (see plate P) by the reflection type sensor. ) Side of the printing medium is detected when a preset threshold value (for example, 2.8 V) is exceeded, and the non-detected voltage of the printing medium by the reflective sensor is detected from the saturation voltage side of the reflective sensor. The trailing edge of the print medium in the transport direction can be detected when the threshold is exceeded again toward the side.

  In addition, when detecting the conveyance direction end of the print medium using such a sensor control circuit, since the reflectance varies depending on the type of the print medium, in order to eliminate variations in the detection position of the conveyance direction end, The threshold value was changed according to the type of medium (see, for example, Patent Document 2). When the color and material of the print medium are almost constant (for example, white paper, thin paper, plain paper, and thick paper), the above-described sensor control circuit (using one resistor R) is used for the print medium. By changing the threshold value accordingly, the position of the end of the print medium in the conveyance direction can be accurately detected.

  In the above description, a 3.3V phototransistor is shown as an example of the light receiving element of the reflective sensor. However, for example, 1.8V, 5V, and 12V phototransistors are also widely used.

JP 2002-137471 A JP 2007-003734 A

  Recently, there is a need for printers capable of printing with high accuracy on a wide variety of printing media (for example, glossy black plates, glossy black plates, white plates, roll paper, die-cut labels with labels on the mount at predetermined intervals). Increasingly. However, when the threshold value is changed according to the print medium using the sensor control circuit described above, it is difficult to accurately detect the conveyance direction ends of all the print media. This will be specifically described below.

  Normally, in this type of printer, a glossy plate with a low reflectance is used as a reference print medium, and the resistance value of the resistor R in FIG. 10 is set accordingly (a glossy or black plate with a low reflectance is used). By using the reference print medium, it is possible to detect the conveyance direction end of the print medium having a higher reflectance. However, as in the past, when the glossy black plate is used as the reference print medium, the detection at the end of the glossy black plate, which has a lower reflectance than the glossy black plate, in the transport direction is performed at the voltage measurement point. It becomes difficult to detect the end of the black plate in the conveyance direction as the voltage reaches the threshold (see FIG. 11B). Therefore, if the resistance value of the resistor R is increased in order to make the reference print medium a non-black plate (for example, if the resistance value of the resistor R in FIG. 10 is 82 kΩ), the voltage at the voltage measurement point exceeds the threshold value. Therefore, this problem can be solved (see FIG. 12A). However, there is a problem that the sensor output waveform is crushed for other print media. For example, in die-cut labels, the position of the label break (position where printing can be started and finished with respect to the label) is detected by using the difference in reflectance between the label and the backing sheet. The position of the break cannot be detected with high accuracy (see FIG. 12B).

  An object of the present invention is to provide a printer capable of printing on various types of print media with high accuracy.

In order to solve the above-described problems, the present invention provides a transport unit that transports a print medium, a print unit that performs a printing process on the print medium transported by the transport unit, an upstream side of the print unit, and a light emission A reflection type sensor having an element and a light receiving element, a resistance control value of a load resistance connected to the light receiving element, a sensor control circuit for controlling the reflection type sensor, and information on the type of the print medium. and type information acquisition means for acquiring, comparing the output voltage with the threshold of the reflective sensor, control means for detecting the conveying direction leading end and the trailing end of the print medium that will be conveyed by said conveying means on the basis of the comparison result If, with the previous SL control means, in accordance with the information on the type of the printing medium acquired by the type information acquiring unit, to control the sensor control circuit to set the resistance value of the load resistor Together, select the threshold from a plurality of predetermined threshold value, characterized in that.

In the present invention, the sensor control circuit has a plurality of switch resistor circuits each composed of a switch element and a load resistor in parallel, and may be connected in series with the light receiving element between the constant voltage power source and the ground. Good. At this time, a table defining the relationship between the information on the type of print medium, the on / off control information of each switch element constituting the plurality of switch resistance circuits, and the threshold value for the output voltage output from the reflective sensor Storage means stored in advance is further provided, and the control means sets the resistance value of the load resistance according to the information about the type of the print medium acquired by the type information acquisition means based on the table stored in the storage means. on the respective switch elements constituting the plurality of switch resistance circuit may by that control off Unishi. Further, the resistance values of the load resistors constituting the plurality of switch resistance circuits may be different from each other. Further, each of the plurality of switch resistor circuits has a switch element and a load resistor connected in series, one side of each switch element is connected to a constant voltage power source, and one end is connected to the other side of the switch element. The other end of the load resistor may be connected to the light receiving element, and the connection point between each other end of the load resistor and the light receiving element may be the output point of the output voltage of the reflective sensor.

  The sensor control circuit has a light emission control unit for controlling the light emitting element of the reflective sensor. The light emission control unit includes a DA converter connected to the output port of the control means, and a positive phase input terminal connected to the DA converter. An amplifier connected to the base, a transistor connected to the base from the output terminal of the OP amplifier via a resistor and a collector connected to one side of the light emitting element, an emitter of the transistor, and a negative phase input terminal of the OP amplifier The other end of the light emitting element may be connected to a constant voltage power source. Furthermore, display means for displaying the type of print medium that can be printed may be further provided.

According to the present invention, the control means, in response to information about the type of print medium acquired by the type information acquiring unit controls the sensor control circuit to set the resistance value of the load resistor, predetermined since selecting a threshold from a plurality of threshold values, to prevent the influence of noise due collapse of the waveform of the output voltage of the reflection type sensor, it can be accurately detected in the conveying direction end of the print medium regardless of the type of print media Therefore, it is possible to obtain an effect that printing can be performed with high accuracy on a print medium.

1 is a schematic front view of a printer according to an embodiment to which the present invention is applicable. It is an enlarged front view of the vicinity of the printing unit of the printer of the embodiment. It is an enlarged view of the operation panel of the printer of the embodiment. It is a circuit diagram of a sensor control circuit of the printer of the embodiment. It is a flowchart of a printing routine executed by the CPU of the microcomputer of the printer according to the embodiment. 6 is a flowchart showing details of a setting process of the printing routine shown in FIG. 5. 6 is a flowchart showing details of a printing process of the printing routine shown in FIG. 5. It is a partial front view which shows the operation state when detecting the thickness of a printing medium, (A) shows the case where a printing medium is a plate, (B) shows the case where a printing medium is a label sheet. The vertical axis represents the output voltage of the reflection type sensor, and the horizontal axis represents the relationship between the output voltage of the reflection type sensor of the printer of the embodiment, the threshold value, the label break, and the leading and trailing edge detection with respect to the die-cut label. is there. It is a circuit diagram of the conventional sensor control circuit which controls a reflection type sensor. It is explanatory drawing which shows the relationship between the output voltage of a reflection type sensor on a vertical axis | shaft, the output voltage of a reflection type sensor when time is taken on a horizontal axis, a threshold value, and the front-and-rear end detection, (A) is the reflection with respect to a glossy black plate The relationship between the output voltage of the mold sensor, the threshold value, and the front and rear end detection is shown, and FIG. Description of the relationship between the output voltage of the reflective sensor, the threshold value, and the detection of the leading and trailing edges when the vertical axis represents the output voltage of the reflective sensor and the horizontal axis represents time, and the resistance value of the resistance of the sensor control circuit shown in FIG. (A) shows the relationship between the output voltage, threshold value, and leading and trailing edge detection of the reflective sensor with respect to the glossless black plate, and (B) shows the relationship between the output voltage of the reflective sensor with respect to the die-cut label and the label break. Show.

(Constitution)
Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIGS. 1 to 3, the printer 1 according to the present embodiment is wound in a roll shape with a relatively thick printing medium such as a plate P having a thickness of about 0.5 mm to about 3 mm. It is a thermal printer that prints a relatively soft and thin print medium such as a label sheet S or a soft vinyl chloride sheet.

  The printer 1 has a cleaning roller 2 such as adhesive silicon rubber that cleans the printing surface of the plate P and the label sheet S before printing, and dust adhered to the surface of the cleaning roller 2 in order to maintain the adhesiveness of the cleaning roller 2. A cleaning unit 3 for periodic removal is provided. The cleaning unit 3 includes a storage cassette 4 that stores a cleaning sheet so that the cleaning sheet can be pulled out, and a cleaning sheet transport roller 5 that transports the cleaning sheet of the mounted storage cassette 4 to the cleaning roller 2.

  The cleaning roller 2 is rotatably provided on a swing rod 8 that is swingable with respect to the printer body. The swing rod 8 is a shaft 8a formed by a motor 9, a gear train (not shown), and a cam 10. The cleaning roller 2 is moved in the vertical direction. The position of the cleaning roller 2 shown in FIG. 2 is a state before the printing medium is transported under the plate feed condition described later, and moves toward the lower transporting roller 11 when the printing medium such as the plate P is transported. When cleaning the cleaning roller 2, it moves toward the upper cleaning sheet conveying roller 5.

  A conveying roller 11 facing the cleaning roller 2, a platen roller 12 located on the downstream side (left side in FIG. 2), and the other conveying roller 13 convey a printing medium such as a plate P leftward in FIG. 2. Thus, it is driven to rotate in the forward and reverse directions by a driving unit (not shown) including a stepping motor and a gear train. The upstream conveying roller 11 is paired with the cleaning roller 2, and the downstream conveying roller 13 is paired with a pinch roller 14 to press and hold the print medium.

  The pinch roller 14 is rotatably provided on a swing rod 15 that is swingable about a shaft 15a with respect to the printer main body. The swing rod 15 includes an intermediate cam portion 16 and a slide plate 17. And the pinch roller 14 is moved in the vertical direction in conjunction with the swing rod 8. The relationship between the swing rod 8, the swing rod 15, the intermediate cam portion 16, and the slide plate 17 is configured such that the cleaning roller 2 and the pinch roller 14 are moved at equal intervals with respect to the transport roller 11 and the transport roller 13, respectively. Has been.

  Therefore, when the cleaning roller 2 moves up and down, the pinch roller 14 moves up and down in the same manner. When the cam 10 is further rotated by driving the motor 9, the cleaning roller 2 and the pinch roller 14 move up and down in conjunction with each other. . The springs 8b and 15b provided at one end portions of the swing rod 8 and the swing rod 15, respectively, bias the cleaning roller 2 and the pinch roller 14 toward the transport roller 11 and the transport roller 13, respectively.

  The above-described transport roller 11, platen roller 12, transport roller 13 and pinch roller 14 are obtained by increasing the transport force by winding a rubber material such as CR (chloroprene) rubber or EPDM (ethylene propylene) around the surface of the metal shaft portion. It is.

  The thermal printing head 20 is configured to face the platen roller 12 and move in the contact / separation direction with respect to the platen roller 12. That is, a cam (not shown) is in contact with the upper end (opposite side opposite end of the head) plane (see FIG. 2) of the print head 20, and this cam is rotated by a driving force of a motor (not shown). As a result, the print head 20 moves between a retracted position separated from the platen roller 12 and a pressure contact position where the print head 20 is pressed against the platen roller 12. During printing, print data transferred from a higher-level device such as a personal computer (hereinafter abbreviated as a personal computer) (not shown) is printed onto the print medium via the ink ribbon 21 while being pressed against the platen roller 12. The ink ribbon 21 is accommodated in a ribbon cassette 22, and the ribbon cassette 22 is detachably mounted in the printer body.

  As shown in FIGS. 1 and 3, the printer 1 includes an operation panel 23. As shown in FIG. 3, the operation panel 23 includes menu switching buttons 24 and 25, a menu selection (enter) button 26, a menu cancel / discharge button 27, and the status and operation menu of the printer 1 to the operator (operator). And a display unit 28 such as an LCD for displaying and an online / offline switch key 29 for a personal computer as a host device.

  As shown in FIG. 1, the printer 1 has a cutting device 30 for cutting the label sheet S and the like. The cutting device 30 includes a cutter 31 including a fixed blade and a moving blade, a motor for driving the cutter 31 and a gear train (both not shown), and the operation thereof is controlled by a control unit 50 described later.

  A medium detection sensor 40 (reflection type sensor) that detects that a print medium has been set in the printer 1 by an operator mainly on the lower side of the conveyance path on the upstream side (right direction in the drawing) of the conveyance roller 11 and the cleaning roller 2. ) Is arranged. Further, the leading end position and the trailing end position of the printing medium to be conveyed are detected on the upstream side of the printing section (printing section 20, platen roller 12) and on the upstream side of the conveying path on the downstream side of the conveying roller 11 and the cleaning roller 2. A reflective sensor 41 is disposed. The medium detection sensor 40 and the reflection type sensor 41 are respectively disposed at substantially the center in the width direction of the conveyance path. Further, a slide volume type linear sensor 42 is engaged with the protrusion 17 a at the substantially central portion of the slide plate 17, and the linear sensor 42 detects the movement amount of the slide plate 17 as an interval between the cleaning roller 2 and the conveying roller 11. To do.

  Further, the printer 1 is provided with a control unit 50 and a power supply unit (not shown). The control unit 50 includes a microcomputer MC (hereinafter simply referred to as a microcomputer MC) having a CPU, a ROM, a RAM, a nonvolatile memory such as an EEPROM, a reference voltage unit that generates a reference power source such as a timer IC, an AD converter, In addition, the above-described motors, sensors, operation panel 23, print head 20, and USB terminal 33 (see FIG. 1) are included. The USB terminal 33 is for connecting to a USB memory or a USB cable, and functions as an interface with a personal computer connected via the USB memory or the USB cable. The power supply unit generates drive power such as motors from commercial power, and + 3.3V power source and + 5V power source described later are also generated by this power source unit.

(Sensor control circuit)
As shown in FIG. 4, the printer 1 of this embodiment includes a sensor control circuit 60 that controls the reflective sensor 41, and the sensor control circuit 60 is disposed in the control unit 50. The sensor control circuit includes a light emission control unit 62 that controls the light emission amount of the light emitting element (LED) of the reflective sensor 41, and a light reception control unit 61 that controls the output voltage of the light receiving element (phototransistor) of the reflective sensor 41. Have.

  The light emission control unit 62 is the same as the conventional circuit shown in FIG. That is, the light emission control unit 62 has a resistance from the DA converter whose one side is connected to the DA output port of the microcomputer MC, the OP amplifier whose positive phase input terminal is connected to the other side of the DA converter, and the output terminal of the OP amplifier. And an NPN transistor whose collector is connected to the cathode of the LED, and a resistor whose one end is connected to the emitter of the transistor and the negative phase input terminal of the OP amplifier and the other end is connected to the ground. It is configured. The anode of the LED is connected to a constant voltage power supply (+ 5V).

  On the other hand, the light reception controller 61 is inserted between the PNP transistors TR1 to TR3, the resistors R1 to R3 connected to the collectors of the transistors TR1 to TR3, and the microcomputer MC and the bases of the transistors TR1 to TR3. It consists of resistors. The reason why the resistor is inserted between the microcomputer MC and the bases of the transistors TR1 to TR3 is to prevent destruction of the microcomputer MC.

  Specifically, the base of the transistor TR1 is connected to the output port P1 of the microcomputer MC via a resistor, and the emitter is connected to a constant voltage power source. The collector of the transistor TR1 is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to the collector of the phototransistor. The transistors TR2 and TR3 have the same circuit configuration, the base of the transistor TR2 is connected to the output port P2 of the microcomputer MC via a resistor, and the emitter is connected to a constant voltage power source. The collector of the transistor TR2 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the collector of the phototransistor. The base of the transistor TR3 is connected to the output port P3 of the microcomputer MC via a resistor, and the emitter is connected to a constant voltage power source. The collector of the transistor TR3 is connected to one end of the resistor R3, and the other end of the resistor R3 is connected to the collector of the phototransistor. The emitter of the phototransistor is connected to the ground.

  That is, the light reception control unit 61 has three switch resistance circuits configured in parallel by connecting a switch element (transistor) and a resistor in series, and a phototransistor is connected between the constant voltage power source and the ground. Connected in series. The connection point between the other end of each of the resistors R1 to R3 and the collector of the phototransistor is the output point of the output voltage of the reflective sensor 41, and is connected to the AD input port of the microcomputer MC. In this embodiment, the resistance values of the resistors R1 to R3 are different, the resistance value of the resistor R1 is set to 47 kΩ, the resistance value of the resistor R2 is set to 82 kΩ, and the resistance value of the resistor R3 is set to 150 kΩ.

  When a low level signal is output from the output port P1 of the microcomputer MC, the transistor TR1 of the switch element is turned on, and the phototransistor of the reflective sensor 41 is connected to the constant voltage power supply via the resistor R1. Similarly, when a low level signal is output from the output port P2 of the microcomputer MC, the transistor TR2 of the switch element is turned on, and the phototransistor of the reflective sensor 41 is connected to the constant voltage power source via the resistor R2, and the microcomputer MC When a low level signal is output from the output port P3, the transistor TR3 of the switch element is turned on, and the phototransistor of the reflective sensor 41 is connected to the constant voltage power supply via the resistor R3. If a low level signal is simultaneously output from the output ports P1 and P2, the phototransistor of the reflective sensor 41 is connected to a constant voltage power source via a resistor R1 and a resistor R2 connected in parallel. Similarly, if a low level signal is simultaneously output from the output ports P1 and P3, the phototransistor of the reflective sensor 41 is connected to a constant voltage power source via a resistor R1 and a resistor R3 connected in parallel, and the output port P2 , P3 simultaneously outputs a low level signal, the phototransistor of the reflective sensor 41 is connected to a constant voltage power source via a resistor R2 and a resistor R3 connected in parallel. Furthermore, if a low level signal is output simultaneously from the output ports P1, P2, and P3, the phototransistor of the reflective sensor 41 is connected to a constant voltage power source via resistors R1, R2, and R3 connected in parallel. .

  Therefore, the sensor control circuit 60 (light reception control unit 61) of the present embodiment outputs a low level signal from the output ports P1 to P3, and controls each of the transistor TR1 to TR3 of the switch element to turn on and off, thereby reflecting the reflection type. The resistance value of the resistor connected to the phototransistor of the sensor 41 can be selected from seven values (R1, R2, R3, R1 and R2 are in parallel, R1 and R3 are in parallel, R2 and R3 are in parallel, R1 and R2 and R3 are in parallel). The reason why a plurality of resistance values can be selected in this way is to accurately detect the conveyance direction ends of various types of print media having different reflectances.

  While the sensor control circuit 60 of the reflective sensor 41 is configured as described above, the sensor control circuit of the medium detection sensor 40 uses the sensor control circuit having one resistor shown in FIG. The AD converter is built in the microcomputer MC similarly to the sensor control circuit 60 of the reflective sensor 41.

(Operation)
Next, the operation of the printer 1 will be described with reference to a flowchart. In the following, for the sake of simplicity of explanation, the case where the printing process is applied to the glossy black acrylic plate will be mainly illustrated, and the case where the printing process is applied to the die-cut label having a gap between the labels will also be referred to.

  When the printer 1 is turned on, first, the program and program data stored in the ROM are expanded into the RAM, moved to the home position of each mechanism, and the initial printing condition values are read from the nonvolatile memory such as the EEPROM. Initial setting processing for reading is performed. As a condition to be read at this time, a feeding condition for the plates or sheets set on the operation panel 23 and stored in the nonvolatile memory is read. After such an initial setting process, the print routine shown in FIG. 5 is executed by the CPU of the microcomputer.

  In the printing routine, a determination is made as to whether the plate type or the sheet type based on the read feeding condition (S102). If the plate is set here, the cam 10 is rotated by the driving of the motor 9 to perform cleaning. The distance between the roller 2 and the conveying roller 11 is set to a predetermined interval (for example, 4 mm) (S104) (state shown in FIG. 2). If the sheets are set, the cleaning roller 2 is moved to a position in contact with the conveying roller 11 (S106). By this movement, plates that are relatively hard and easy to set and sheets that are soft and difficult to set because of curling are easily set to positions where the reflective sensor 41 detects them. This condition can be easily changed by operating the operation panel 23.

  Next, confirmation of print data acquisition (S108) and confirmation of presence / absence of a print medium from the medium detection sensor 40 (S110) are continuously performed. Since the printer 1 includes the USB terminal 33 and the operation panel 23, when acquiring print data, the USB connected to the USB terminal 33 is received even if it is received from a host computer via the USB cable. Print data may be acquired by the memory and the operation panel 23. In preparation for using the operation panel 23 as described above, the operator operates the buttons 24 to 26 to display information such as the type of print medium that can be processed by the printer 1 on the display unit 28 and acquire print data. It is also possible to do. If a negative determination is made in step 108, if the print medium is already set, that is, if the medium detection sensor 40 detects the presence of the medium, it is determined in step 110 that the medium is present, and the menu cancel / eject button 27 is pressed. A determination is made as to whether or not (S112). If the menu cancel / discharge button 27 is pressed in the case of an affirmative determination in step 110, a stepping motor (not shown) is driven to discharge the print medium from the printer 1 (S114).

  On the other hand, if the determination in step 108 is affirmative, the print data relating to the type of print medium such as acrylic plate, PVC (PVC) plate, die cut label, print density, number of prints, and print color is stored in the RAM. (S116) In the next step 118, the type of the printing medium developed from the ROM to the RAM in the initial setting process and the switching elements (TR1 to TR3) constituting the switch resistance circuit shown in FIG. 4 are turned on. , Referring to a table that defines the relationship between the off control information and the threshold value for the output voltage output from the reflective sensor 41, and the resistance connected to the light receiving element of the reflective sensor 41 according to the type of print medium. Outputs output from the reflective sensor 41 as well as determining ON / OFF of the TR1 to TR3 so as to set the resistance value. Determining a threshold for pressure. For example, a default value (information on the type of print medium) may be used as the type of print medium.

  The table below is an example of the table, and the resistance values and threshold values in the case where the print medium is a glossy black acrylic plate and the case of a die-cut label will be specifically described below. In the present embodiment, the transistor is in the on state when the output port of the microcomputer is at a low level. This is because the present embodiment employs a PNP transistor. Therefore, in the case of an NPN type transistor, the transistor is turned on when the output port of the microcomputer is at a high level.

  As shown in Table 1, when the printing medium is a glossy black acrylic plate, the output port P1 of the microcomputer MC is high level (H), the output port P2 is low level (L), and the output port P3 is high level. (H) and the threshold is set to 2.8V. With this setting, in the sensor control circuit 60 (light reception control unit 61) shown in FIG. 4, a low level signal is output from the microcomputer MC to the base of the transistor TR2 of the switch element, the transistor TR2 is turned on, and the reflection sensor 41 The light receiving element is connected to a constant voltage power supply (+3.3 V) via a resistor R2 (resistance value: 82 kΩ). On the other hand, when the print medium is a die-cut label, the output port P1 of the microcomputer MC is set to the low level (L), the output port P2 is set to the low level (L), the output port P3 is set to the high level (H), and the threshold is set to 2. Set to 8V and 1.2V. With this setting, in the sensor control circuit 60 (light receiving control unit 61) shown in FIG. 4, a low level signal is output from the microcomputer MC to the bases of the transistors TR1 and TR2 of the switch elements, and the transistors TR1 and TR2 are turned on. The light receiving element of the reflective sensor 41 is connected to a constant voltage power supply (+3.3 V) via a resistor R1 (resistance value: 47 kΩ) and a resistor R2 (resistance value: 82 kΩ) connected in parallel.

  Next, the presence / absence of the print medium is determined again (S120). If the print medium is not set, the process waits until the print medium is set (S122). Proceed to the set process 124.

  In the setting process (S124), as shown in FIG. 6, first, the conveyance roller 11 is rotated by forward rotation of a stepping motor (not shown), and the printing medium is conveyed (S202). At the same time, counting by the timer IC is started in the control unit 50 (S204), and conveyance processing is performed until the reflective sensor 41 detects the leading edge of the print medium within a predetermined time (S206, S208). When the reflective sensor 41 detects the leading edge of the print medium (S206, see also the description of S312 to be described later in detail), the print medium is transported to a predetermined position (S210), and the setting process ends normally. In step 210, the conveyance of the printing medium is temporarily stopped by stopping the (forward rotation) drive of the stepping motor (not shown), and the stepping motor (not shown) is reversely driven to reversely feed the predetermined number of steps. The print medium is positioned at the set position by stopping the driving. The reason why such reverse conveyance is performed is to perform cueing (detecting the leading edge of the print medium, see S312 in FIG. 7) in the printing process.

  On the other hand, the CPU notified of the elapse of the predetermined time from the timer IC executes error processing. That is, the conveyance of the printing medium is stopped (S212), and it is determined whether or not the printing medium is a plate (S214). If the printing medium is a plate, the cam 10 is rotated by driving the motor 9 and the cleaning roller 2 is moved upward. (S216) An error is displayed on the display unit 28 (S218), and the setting process is completed. If it is not a plate (for example, in the case of a label sheet), a stepping motor (not shown) is driven in reverse to rewind the printing medium onto the roll. In the same manner as in steps 216 and 218, the cleaning roller 2 is moved upward (S222), an error is displayed on the display unit 28 (S224), and the setting process is terminated abnormally.

  Next, in step 126 in FIG. 5, the cam 10 is rotated by driving the motor 9 to detect the thickness of the print medium, and the cleaning roller 2 is moved toward the transport roller 11. Here, the position of the cleaning roller 2 moves downward from the position of 4 mm because the feeding conditions are plates. If the feeding conditions are sheets, the cleaning roller 2 is once moved upward to a position of 4 mm and moved toward the conveying roller 11. When the cleaning roller 2 moves until it contacts the plate P, the movement stops. FIG. 8A shows this state. The CPU reads the position of the slide plate 17 that has moved with the movement of the cleaning roller 2 from the sensor 42, and replaces it with the distance between the cleaning roller 2 and the transport roller 11 for printing. It is calculated as the thickness of the medium (S126). This distance takes into account the elastic deformation of the surface rubber material of the cleaning roller 2 and the conveying roller 11. FIG. 8B shows a state in which the thickness of the label sheet S including the die cut label is detected.

  Subsequently, the CPU controls the motor 9 to control the position of the cleaning roller 2 based on the calculated thickness (for example, 2 mm) of the print medium so that the distance between the rollers is optimum for conveying the plate P having this thickness. Then, the thickness data is stored in the RAM (S130), and the process returns to step 120. In step 120, since the print medium set has already been confirmed, the printing process is executed (S132).

  In the printing process (S132), as shown in FIG. 7, it is determined whether the print medium type of the previously stored print data is read from the RAM and is a sheet (S302). If the print data information received here is a sheet, the thickness of the print medium stored in the RAM (2 mm in this case) is read in step 130 in FIG. The determined print medium is determined as the plate P (S304), the cutting process by the cutting device 30 is invalidated (S308), and then the printing medium is conveyed and printed.

  If a print medium of 0.6 mm or less such as the label sheet S is set, it is determined in step 306 that the print medium is 0.6 mm or less. Here, the 0.6 mm print medium is mostly sheets, but even if it is the plate P, the cutter 31 of the cutting device 30 may be a relatively large cutter if the plastic is thin like this. Does not occur.

  Next, a stepping motor (not shown) is driven to rotate forward to start transporting the print medium positioned at the set position in the set process (S310), and it is determined whether or not the front end in the transport direction of the print medium has been detected (S312). ). That is, the CPU takes in the output voltage of the reflection type sensor 41 via the AD converter built in the microcomputer MC every predetermined time, and determines whether or not the taken-in voltage value exceeds a preset threshold value. When the threshold value is exceeded, the leading edge of the print medium in the conveyance direction is detected.

  As described above, when the type of print medium is an acrylic plate, the threshold value is set to 2.8V as described above (see FIG. 12), and the captured voltage value is set to the threshold value 2.8V. It is determined whether or not the leading edge of the print medium in the conveyance direction has been detected. On the other hand, when the type of print medium is a die-cut label, the threshold values are set to 2.8 V (first threshold value) and 1.2 V (second threshold value) (see FIG. 9), and the captured voltage value is By determining whether or not the first threshold value of 2.8 V has been exceeded, it is determined whether or not the leading edge of the print medium in the transport direction has been detected. In the case of a die-cut label, since there is a break between the labels and the mount is exposed at the cut portion, the output voltage from the reflective sensor 41 is 1.2 V or less at the cut portion. After detecting the leading edge in the conveyance direction of the medium, the label edge can be detected when the taken-in voltage value exceeds the second threshold value 1.2 V, and even during one printing, the label edge can be detected. Printing (position) accuracy can be increased by printing each label.

  Next, the CPU drives a motor (not shown) and rotates a cam (not shown) that is in contact with the upper end plane of the print head 20 to move the print head 20 from the retracted position to the press-contact position. Printing by the head 20 is started (S314). The print head 20 executes a printing process on a print medium conveyed according to the print data. Note that at the start of printing, the print head 20 (the head portion thereof) is in contact with the leading end of the print medium in the transport direction via the ink ribbon 21, the lowering speed of the print head 20, the position of the reflective sensor 41, and the transport medium. The transport speed is set.

  Subsequently, it is determined whether or not the rear end in the transport direction of the print medium has been detected (S316). That is, the CPU determines whether the voltage value acquired from the reflective sensor 41 via the AD converter exceeds a threshold value (change threshold value: 2.8 V), thereby conveying the print medium when the threshold value is exceeded. The rear end of the direction is detected. As shown in FIG. 12 (acrylic plate) and FIG. 9 (die cut label), the output voltage of the reflective sensor 41 is generally less than 2.0 V after detecting the leading edge of the print medium in the conveyance direction. For this reason, when the threshold value of 2.8 V is exceeded, the trailing edge of the print medium in the conveyance direction can be detected. The reason why the rear end is detected in this manner is to enable printing processing on a long (elongated) print medium in addition to a standard print medium having a fixed length.

  When the rear end of the print medium in the transport direction is detected, the printing process on the print medium by the print head 20 is still continued according to the print data, but the rear end of the print medium in the transport direction reaches the print head 20 (the head portion thereof). When the CPU drives the motor (not shown) and rotates the cam (not shown) that is in contact with the upper end plane of the print head 20, the CPU moves the print head 20 from the press contact position to the retracted position, Printing by the print head 20 is terminated (S318).

  Next, referring to the RAM, it is determined whether or not cutting is set to the valid state (S320). If the determination is affirmative, the print medium is disconnected (S322). If the determination is negative, the process proceeds to step 324. . In step 324, a stepping motor (not shown) is driven to rotate forward a predetermined number of steps in order to eject the print medium from the printer 1, and then the printing process is terminated by stopping.

  As described above, the printing of the first color by the printing routine is completed. However, when the operator desires the printing process of the second color, the mounted ribbon cassette 22 is replaced with a ribbon cassette 22 having ink ribbons of other colors. In order to perform the second color printing, the menu switching buttons 24 and 25 and the menu selection (enter) button 26 on the operation panel 23 are operated, or the second color printing is performed from the personal computer of the host device. Enter something. As a result, the CPU executes steps after step 108 of the printing routine shown in FIG.

(Effects etc.)
Next, functions and effects of the printer 1 of the present embodiment will be described.

  In the printer 1 of the present embodiment, the sensor control circuit 60 (light reception control unit 61) has three switch resistance circuits composed of transistors TR1 to TR3 and resistors R1 to R3 in parallel. The light receiving element (phototransistor) of the reflective sensor 41 is connected in series between +3.3 V) and the ground (FIG. 4). Further, the CPU of the microcomputer MC controls on and off of the transistors TR1 to TR3 constituting the three switch resistance circuits according to the type (information regarding the print medium) (Table 1). For this reason, the resistance value of the resistor connected in series to the light receiving element can be set to an appropriate value, and the collapse of the waveform of the output voltage can be prevented. Therefore, according to the printer 1 of the present embodiment, even when there are various types of print media, the end in the transport direction of each print medium can be accurately grasped, and printing on the print medium can be performed with high accuracy.

  Further, in the printer 1 of the present embodiment, on / off of each of the TR1 to TR3 constituting the plurality of switch resistance circuits is controlled according to the type (information regarding the print medium), and a plurality of predetermined numbers are set. A threshold value is selected from the threshold values (Table 1). For this reason, the resistance value of the resistor connected in series to the light receiving element is set to an appropriate value, and the relationship between the threshold value and the output voltage of the reflection type sensor can be appropriately ensured. Since the conveyance direction end can be grasped more accurately, higher-precision printing can be ensured on the print medium.

  Further, in the printer 1 of the present embodiment, the relationship between the type (information regarding the print medium), the on / off control information of the transistors TR1 to TR3, and the threshold for the output voltage output from the reflective sensor 41 is defined. A table is stored in the ROM, and based on this table, TR1 is set so that the resistance value of the resistor connected to the light receiving element of the reflective sensor 41 is set according to the type (information relating to) of the acquired print medium. Since the on / off of TR3 is controlled and the threshold value is determined, the resistance value of the resistor connected to the light receiving element (output voltage of the reflective sensor 41) and the output voltage of the reflective sensor 41 are simply and appropriately determined. A threshold can be set.

  In the printer 1 of the present embodiment, the thickness of the print medium is detected (S126), and the print head 20 is moved to the pressure contact position with the platen roller 12 by a cam in consideration of the thickness in the printing process. Since this is possible (S314), the pressure of the print head 20 on the print medium supported by the platen roller 12 can be made substantially constant regardless of the thickness of the print medium. For this reason, printing quality can be improved.

  In the present embodiment, the thermal print head 20 is exemplified as the printing unit. However, the present invention is not limited to this, and can be applied to, for example, an ink jet printing unit. Further, although the flat plate P is exemplified as the print medium, the present invention is not limited to this, and can be applied to, for example, a medium in which a plurality of small chips are combined into one plate shape. Furthermore, in the present embodiment, as exemplified by the die-cut label, the threshold (first and second thresholds) for distinguishing the mount and the label can be set using the difference in reflectance, so that the present invention Similarly, the present invention can be applied to a printer of a type that conveys a print medium using, for example, a carrier or a feeder that conveys the print medium by utilizing the difference in reflectance. At that time, the threshold value is not limited to two, and three or more threshold values may be set.

  Further, in the present embodiment, in order to perform the cueing of the print medium (FIG. 7, S312), an example is shown in which the print medium is reversely conveyed in the setting process (FIG. 6, S210), but such reverse conveyance is set. It may be performed before the print medium is conveyed in step 310 of FIG. Further, in the present embodiment, an example in which the presence or absence of the print medium is detected by the medium detection sensor 40 has been described. However, the print medium is temporarily conveyed and printed by detecting the print medium (reflected light from the reflection medium) by the reflective sensor 41. The medium detection sensor 40 may be eliminated by detecting the presence or absence of the medium. Further, the medium detection sensor 40 is not limited to a reflective sensor, and may be a transmissive sensor, for example.

  In the present embodiment, as shown in FIG. 4, the PNP transistors TR1 to TR3 are exemplified as the switch elements. However, the present invention is not limited to this, and for example, an NPN transistor or FET is used as the switch element. You may make it use. The reason why the PNP transistor is used in this embodiment is that when the Vce of the PNP transistor is about 0.1 V, there is almost no voltage drop and a stable output voltage is obtained. Furthermore, in the present embodiment, an example is shown in which the time is measured by the timer IC (FIG. 6, S204, S208), but the timer IC may be eliminated and the CPU may measure the time.

  Further, in the present embodiment, as shown in FIG. 4, an example in which the collector side of the phototransistor is used as the output voltage of the reflection type sensor is shown. However, the present invention is not limited to this, for example, the emitter side of the phototransistor May be the output voltage of the reflective sensor. In this case, the waveform of the reflection type output voltage is reversed in the vertical direction. When the emitter side of the phototransistor is used as the output voltage of the reflection type sensor, the three switch resistance circuits inserted between the constant voltage power supply (+3.3 V) and the collector side of the phototransistor are replaced with the phototransistor. Is inserted between the emitter side of the transistor and the ground (GND) (the emitter side of the transistors TR1 to TR3 is connected to the emitter side of the phototransistor and the other ends of the resistors R1 to R3 are connected to the ground), and the constant voltage power supply is directly You may make it connect to the collector side of a transistor.

  Furthermore, the phototransistor of the reflective sensor is not limited to the above-described 3.3V system, and for example, a 1.8V, 5V, or 12V system may be used. Further, the light emitting element and the light receiving element of the reflective sensor are not limited to LEDs and phototransistors.

  In this embodiment, the USB terminal is exemplified as a part of the type information acquisition unit. However, the present invention is not limited to this, and for example, a known serial or parallel interface that can be connected to a personal computer is used. May be.

  In the present embodiment, the form of each component and the materials, dimensions, or numerical values used should be changed according to cost, mutual relations, and the like, and should not be limited to the present embodiment. Further, it can be changed by combining known techniques without departing from the above. In particular, the change threshold may be set to a value that does not exceed the output voltage of the reflective sensor after detecting the leading edge of the print medium and before detecting the trailing edge.

  As described above, the present invention provides a printer capable of printing with high accuracy on a variety of print media, and thus contributes to the manufacture and sale of the printer, and thus has industrial applicability.

1 Printer 9 Motor (part of transport means)
11, 13 Conveying roller (part of conveying means)
20 Print head (part of printing means)
33 USB terminal (part of type information acquisition means)
41 reflective sensor 50 control unit (control means, part of type information acquisition means)
60 sensor control circuit 61 light reception control unit 62 light emission control unit P plate (print medium)
S Label sheet (printing medium)

Claims (7)

Conveying means for conveying the print medium;
Printing means for performing a printing process on a print medium conveyed by the conveying means;
A reflective sensor disposed upstream of the printing means and having a light emitting element and a light receiving element;
A resistance value of a load resistor connected to the light receiving element is variably configured, and a sensor control circuit for controlling the reflective sensor;
Type information acquisition means for acquiring information about the type of the print medium;
And control means for detecting the conveying direction leading end and the trailing end of the reflection type sensor compares the output voltage with a threshold, the printing medium that will be conveyed by said conveying means based on the comparison result,
With
Multiple pre-SL control means, in accordance with the information on the type of the printing medium acquired by the type information acquiring unit, and controls the sensor control circuit to set the resistance value of the load resistor, predetermined Select a threshold from among the thresholds of
A printer characterized by that. The sensor control circuit includes a plurality of switch resistor circuits each including a switch element and a load resistor, and is connected in series with the light receiving element between a constant voltage power source and a ground. The printer according to claim 1. A table defining a relationship between information on the type of the print medium, on / off control information of each switch element constituting the plurality of switch resistance circuits, and a threshold for an output voltage output from the reflective sensor; A storage means stored in advance is further provided, and the control means determines the resistance of the load resistance according to information on the type of the print medium acquired by the type information acquisition means based on a table stored in the storage means. the printer of claim 2, on the respective switching elements constituting the plurality of switch resistance circuit to set the value, wherein the benzalkonium control the off. 4. The printer according to claim 2 , wherein resistance values of load resistors constituting the plurality of switch resistance circuits are different from each other. In each of the plurality of switch resistance circuits, the switch element and the load resistor are connected in series, one side of each of the switch elements is connected to the constant voltage power source, and one end is the other side of the switch element The other end of the load resistor connected to each other is connected to the light receiving element, and the connection point between each other end of the load resistor and the light receiving element is an output point of the output voltage of the reflective sensor. The printer according to claim 4.   The sensor control circuit includes a light emission control unit that controls a light emitting element of the reflective sensor. The light emission control unit includes a DA converter connected to an output port of the control means, and a positive phase input terminal that is connected to the positive phase input terminal. An OP amplifier connected to the DA converter; a transistor connected to a base from the output terminal of the OP amplifier via a resistor; and a collector connected to one side of the light emitting element; an emitter of the transistor; and the OP 2. The amplifier has a resistor having one end connected to a negative phase input terminal and the other end connected to a ground, and the other side of the light emitting element is connected to a constant voltage power source. The printer according to claim 5.   7. The printer according to claim 1, further comprising display means for displaying a type of print medium that can be printed.

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