JP5693285B2 - Printer - Google Patents

Description

  The present invention relates to a printer including an optical sensor that detects an object to be detected such as recording paper.

  In general, a printer often includes an optical sensor as a sensor for detecting the state of an object to be detected such as recording paper. For example, in a printer, an optical sensor is used to detect whether an object to be detected such as recording paper is present at a predetermined position.

  The optical sensor includes a light projecting unit that irradiates light to the position of the detected object and a light receiving unit that receives light from the light projecting unit, and the level of the detection signal of the light receiving unit is an indicator of the presence or absence of the detected object It becomes. Note that the position of the detected object means a position where the detected object is supposed to be arranged.

  For example, a transmissive optical sensor includes a light projecting unit and a light receiving unit that are arranged to face both sides of the position of the object to be detected. Then, when there is no object to be detected, the light receiving unit receives direct light directly reaching from the light projecting unit, and the level of the detection signal of the light receiving unit exceeds a predetermined threshold value.

  Further, the reflection type optical sensor includes a light projecting unit and a light receiving unit disposed within an angle range of less than 180 degrees when viewed from the position of the object to be detected. When the object to be detected exists, the light receiving unit receives the reflected light that is reflected by the light detected by the light projecting unit, and the level of the detection signal of the light receiving unit exceeds a predetermined threshold value.

  By the way, when the disturbance light other than the light (direct light or reflected light) from the light projecting unit reaches the light receiving unit, the optical sensor outputs an erroneous detection signal, which is a cause of erroneous detection of the detected object. It may become. In the printer, external light such as sunlight or indoor illumination light that enters the housing from the outside of the housing forming the exterior becomes disturbance light for the optical sensor.

  Conventionally, in a printer, a countermeasure for preventing malfunction of an optical sensor caused by external light has been proposed.

  For example, in the printer disclosed in Patent Document 1, the level of the detection signal of the light receiving unit when the light projecting unit is turned off, and the level of the detection signal of the light receiving unit when the light projecting unit is turned on, The presence or absence of recording paper is determined according to the difference. This determination method is based on the premise that the level of the detection signal of the light receiving unit corresponds to the added value of the intensity of outside light and the intensity of light from the light projecting unit.

  In addition, the printer disclosed in Patent Document 2 includes eaves that block external light at the opening of the recording paper conveyance path.

JP 2002-68529 A JP 2006-298532 A

  However, when the intensity of outside light entering the printer is strong, the SN ratio in the detection signal of the light receiving unit deteriorates, and the level of the detection signal of the light receiving unit does not easily change according to the presence or absence of light from the light projecting unit. Become. Therefore, the first prior art disclosed in Patent Document 1 has a problem that it is not sufficient as a measure for preventing malfunction of the optical sensor due to external light.

  That is, in order to prevent malfunction of the optical sensor due to external light, it is important to operate the optical sensor in a state where external light does not enter the printer housing as much as possible.

  Further, the second prior art disclosed in Patent Document 2 has a problem that when a large eaves capable of sufficiently blocking outside light is provided, the eaves easily cause the recording paper to be jammed. Furthermore, the second prior art has a problem that it is difficult to sufficiently block outside light by such a small eave when a relatively small eave is provided so as not to cause the recording paper to be jammed. doing.

  An object of the present invention is to prevent the optical sensor in the printer casing from malfunctioning due to external light without providing a shield that causes the recording paper to be jammed.

A printer according to the present invention is an apparatus for forming an image on recording paper, and includes the following components to achieve the above object.
(1) The first component is a transport unit that transports the recording paper along a transport path from a supply unit in the housing to a discharge port formed in the housing.
(2) The second component is an optical sensor including a light projecting unit that irradiates light to the position of the object to be detected in the housing and a light receiving unit that receives light from the light projecting unit.
(3) The third component is a first transport control unit that causes the transport unit to execute an operation of transporting the recording paper to a light shielding position where a part of the recording paper protrudes outward from the discharge port.
(4) The fourth component is a first optical sensor control unit that inputs a detection signal of the light receiving unit while performing light irradiation by the light projecting unit after the transport operation by the first transport control unit is performed. is there.
(5) The fifth component is a first determination unit that determines the state of the detected object according to the level of the detection signal of the light receiving unit obtained by the first optical sensor control unit.

  In the printer, when a part of the recording paper is conveyed to a position (a light shielding position) that protrudes outward from the discharge port, the discharge port is almost blocked. The printer according to the present invention operates the optical sensor in a state where the recording paper is present at the light shielding position, that is, in a state where external light does not substantially enter the housing, and the detection signal of the light receiving unit obtained by the operation is Used to determine the state of the object to be detected. As a result, it is possible to prevent malfunction of the optical sensor due to external light. In addition, it is not necessary to provide a shielding object in the discharge port or the recording paper conveyance path that causes the recording paper itself to block outside light and cause the recording paper to be jammed.

It is the schematic in the 1st state of the printer 1 which concerns on embodiment of this invention. FIG. 3 is a schematic diagram of the printer 1 in a second state. 2 is a block diagram of a system controller provided in the printer 1. FIG. 3 is a flowchart showing a procedure of optical sensing processing according to the first embodiment executed by the printer 1; 6 is a flowchart illustrating a procedure of light sensing processing according to a second embodiment executed by the printer 1; 2 is a circuit diagram of an optical sensor provided in the printer 1. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following embodiment is an example embodying the present invention, and is not an example of limiting the technical scope of the present invention.

  A printer 1 according to an embodiment of the present invention is a frame sequential thermal transfer printer including a thermal head.

<Device configuration>
First, the configuration of the printer 1 according to the embodiment of the present invention will be described with reference to FIGS. 1, 2, 3, and 6. As shown in FIGS. 1 and 2, the image forming unit of the printer 1 includes a thermal head 21, a head displacement device 210, a platen roller 22, a platen roller drive motor 220, a pinch roller mechanism 24, a pinch roller drive motor 240, and ink. A sheet unit 30 and a cutting device 23 are provided. The printer 1 further includes a system controller 10, a paper roll 40, and an optical sensor 50.

  Each component of the printer 1 described above is housed inside a housing 60 that forms the exterior of the printer 1.

  Further, as shown in FIG. 3, the system controller 10 includes a communication interface 11, a microcomputer 12, an operation unit 13, a display unit 14, an actuator drive circuit 15, a memory 16, an image processing circuit 17, and a thermal head controller 18. . The communication interface 11, the microcomputer 12, the operation unit 13, the display unit 14, the image processing circuit 17, and the thermal head controller 18 can exchange data with each other via, for example, a bus.

<Basic configuration of image forming unit>
The ink sheet unit 30 includes a feeding portion 31 that is a portion in which the belt-shaped ink sheet 3 is wound in a roll shape, and a winding portion 32 that is a portion in which the ink sheet 3 fed from the feeding portion 31 is wound. Prepare. Further, the ink sheet 3 includes an ink forming portion which is a portion in which a sublimable dye ink layer of a plurality of colors is formed on the surface of a base material layer made of a belt-like film, and a transparent protection on the surface of the base material layer. And a protective material forming portion which is a portion where the material layer is formed. Each of the ink forming portions and the protective material forming portion is repeatedly arranged in a predetermined order in the longitudinal direction of the strip-shaped ink sheet 3.

  The ink forming portion of the ink sheet includes, for example, a yellow ink layer portion, a magenta ink layer portion, and a cyan ink layer portion. The ink forming unit may include a black ink layer portion.

  The paper roll 40 is a roll-like recording paper 4 that is rolled up and collected into a roll. The recording paper 4 for a sublimation thermal transfer printer has a structure in which a receiving layer is formed on the surface of a sheet-like base material layer. The receiving layer is a resin layer having high affinity with the dye ink, and the ink of the ink sheet 3 is transferred to the receiving layer of the recording paper 4.

  The pinch roller mechanism 24 is a mechanism for transporting the recording paper 4 in the first direction and the second direction opposite thereto, and includes a pinch roller 241 and a grip roller 242 that rotate while sandwiching the recording paper 4. The pinch roller drive motor 240 is a motor that rotates the pinch roller 241 forward and backward.

  The platen roller 22 is a roller that rotates while sandwiching the recording sheet 4 as a transfer target and the ink sheet 3 as a developer between the thermal head 21. The platen roller drive motor 220 is a motor that rotates the platen roller 22 forward and backward.

  A discharge port 61 for the recording paper 4 is formed in the housing 60 of the printer 1. The discharge port 61 is a through hole that communicates with the inside and the outside of the housing 60.

  The pinch roller mechanism 24, the pinch roller drive motor 240, the platen roller 22, and the platen roller drive motor 220 convey the recording paper 4 along the conveyance path from the paper roll 40 in the housing 60 to the discharge port 61. It is an example. Hereinafter, the whole of the pinch roller driving motor 240, the platen roller 22, and the platen roller driving motor 220 is collectively referred to as a conveying device (24, 240, 22, 220). The paper roll 40 is an example of a supply unit for the recording paper 4 in the housing 60.

  The thermal head 21 is a device that sequentially heats each ink forming portion and the protective material forming portion in the ink sheet 3. A heater 211 is provided at a contact portion of the thermal head 21 with the ink sheet 3. The thermal head 21 can adjust the heating energy of the ink sheet 3 in pixel units of the image.

  The head displacement device 210 is an actuator that movably supports the thermal head 21. The thermal head 21 is supported by the head displacement device 210 so as to be movable between a recording position where the ink sheet 3 is sandwiched between the platen roller 22 and a retracted position away from the platen roller 22. Has been. The head displacement device 210 is, for example, a solenoid. 1 and 2 show a state in which the thermal head 21 exists at the retracted position.

  The cutting device 23 is a device that is arranged near the discharge port 61 in the housing 60 and cuts the recording paper 4 discharged from the discharge port 61 one page at a time while being connected to the paper roll 40 side.

  When the printing process is executed, first, in a state where the thermal head 21 is in the retracted position, the recording paper 4 is being fed out from the paper roll 40 by the pinch roller mechanism 24 and the platen roller 22 that rotate in the first direction. Then, the sheet is conveyed in the forward direction toward the discharge port 61 through between the platen roller 22 and the ink sheet 3. FIG. 1 shows a state in which the recording paper 4 is conveyed in the forward direction. At that time, the ink sheet 3 is stopped in a state of being separated from the recording paper 4 as shown in FIG.

  Next, in a state where the thermal head 21 exists at the recording position, the recording paper 4 is conveyed in the reverse direction from the discharge port 61 to the paper roll 40 by the pinch roller mechanism 24 and the platen roller 22 that rotate in the second direction. The At that time, the ink sheet 3 moves from the feeding unit 31 to the winding unit 32 in a state of being in close contact with the recording paper 4.

  Further, the thermal head 21 heats the moving ink sheet 3 to transfer the image or the overcoat layer from the ink sheet 3 to the recording paper 4. At that time, the thermal head 21 heats the ink forming portion of the ink sheet 3 with heating energy corresponding to the density of each pixel in the image data.

  The recording paper 4 on which the image is formed is again conveyed in the forward direction by the pinch roller mechanism 24 and the platen roller 22 and is discharged from the discharge port 61. Finally, the cutting device 23 cuts the recording paper 4.

  As described above, in the printing process, the printer 1 moves the thermal head 21 to the retracted position and conveys the recording paper 4 in the forward direction by one page, and moves the thermal head 21 to the recording position. The operation of transferring the image by conveying the recording paper 4 in the reverse direction while heating the ink sheet 3 is sequentially repeated.

  By the printing process, the ink images of the respective colors are sequentially transferred from the ink sheet 3 to the recording paper 4 and transferred. Further, the overcoat layer is transferred from the ink sheet 3 to the recording paper 4 so as to cover the color image on the recording paper 4. Each device that executes the printing process is controlled by the microcomputer 12.

  Further, as shown in FIG. 2, the printer 1 can also transport the recording paper 4 in the reverse direction with the thermal head 21 in the retracted position. In this case, image formation on the recording paper 4 is not executed.

<Configuration of optical sensor>
The optical sensor 50 is a non-contact sensor that detects the presence or absence of an object to be detected in the housing 60. In the present embodiment, the printer 1 includes two optical sensors 50. Hereinafter, one optical sensor 50 is referred to as a first optical sensor 50A, and the other optical sensor 50 is referred to as a second optical sensor 50B.

  The first optical sensor 50A is a sensor that detects whether or not the paper roll 40 is mounted at an appropriate position. The first optical sensor 50 </ b> A also functions as a sensor that detects whether or not a predetermined amount or more of the recording paper 4 remains on the paper roll 40.

  On the other hand, the second optical sensor 50 </ b> B is a sensor that detects whether or not the recording paper 4 exists at a predetermined position between the image forming position and the discharge port 61 in the conveyance path of the recording paper 4.

  The optical sensor 50 includes a light projecting unit 51 that irradiates light to the position of an object to be detected, and a light receiving unit 52 that receives light from the light projecting unit 51.

  FIG. 6 is an example of a circuit diagram of the optical sensor 50. In the example shown in FIG. 6, the circuit constituting the light projecting unit 51 of the optical sensor 50 includes a light emitting diode 511, a transistor 512, and a resistance element 513 connected in series between the potential supply unit and the ground. The transistor 512 is a switch element that switches on and off of the light emitting diode 511 in accordance with a control signal input to the control input terminal 514. The light of the light emitting diode 511 is irradiated to the position of the object to be detected.

  The circuit constituting the light receiving unit 52 of the optical sensor 50 includes a phototransistor 521 and a resistance element 522 connected in series between the potential supply unit and the ground. The phototransistor 521 is an example of a light receiving element that receives light from the light emitting diode 511, and outputs a detection signal whose level changes according to the intensity of the received light through the signal output terminal 523.

  The light receiving portions 52 of the two optical sensors 50 included in the printer 1 are disposed at a position lower than the discharge port 61 in the housing 60. The two optical sensors 50 shown in FIGS. 1 and 2 are both transmissive optical sensors, but reflective optical sensors may be employed.

  In addition, since the transmissive optical sensor easily transmits the light from the light projecting unit 51 to the light receiving unit 52, the light receiving unit 52 can obtain a detection signal with a high S / N ratio and has high detection accuracy. Furthermore, the transmissive optical sensor is low in cost and easy to install.

  On the other hand, in the reflection type optical sensor, both the light projecting unit 51 and the light receiving unit 52 can be arranged on one side with respect to the object to be detected. Therefore, the reflection type optical sensor is suitable when the space for arranging the reflection type optical sensor is large or when the object to be detected is large.

<Configuration of control-related equipment>
The operation unit 13 is a device that inputs information according to an operation by a user, such as an operation button or a touch panel.

  The display unit 14 is a device that displays the status of the printer 1 or information on an operation guide for the user, such as an LED lamp or a liquid crystal display panel.

  The communication interface 11 is a device that relays data communication between the microcomputer 12 and the external host device 5.

  The microcomputer 12 is a processor that performs data communication with the host device 5 through the communication interface 11 and controls the image processing circuit 17, the thermal head controller 18, the actuator driving circuit 15, and the optical sensor 50.

  The microcomputer 12 functions as a control unit that controls each device provided in the printer 1 by executing a program module stored in the memory 16 in advance.

  For example, the microcomputer 12 functions as an event detection unit 121, a conveyance control unit 122, a light projection control unit 123, a light reception control unit 124, and a level determination unit 125 by executing a program module related to optical sensing processing. The optical sensing process is a process of inputting the detection signal of the light receiving unit 52 while controlling the lighting and extinguishing of the light projecting unit 51 of each optical sensor 50 and determining the state according to the level of the detection signal.

  Details of processing executed by the event detection unit 121, the conveyance control unit 122, the light projection control unit 123, the light reception control unit 124, and the level determination unit 125 will be described later. Note that the event detection unit 121, the conveyance control unit 122, the light projection control unit 123, the light reception control unit 124, and the level determination unit 125 may be configured as circuits that perform the respective functions.

  The memory 16 is a nonvolatile memory that stores program modules executed by the microcomputer 12 and various parameters referred to by the microcomputer 12.

  The image processing circuit 17, when receiving a processing start instruction from the microcomputer 12, executes a calculation for performing various image correction processes such as sharpness calculation and gamma conversion on the image data received from the host device 5. It is.

  The thermal head controller 18 is a circuit that adjusts the heating energy of the thermal head 21 for each pixel based on the image data corrected by the image processing circuit 17.

  The actuator drive circuit 15 is a circuit that outputs a drive signal and a stop signal to an actuator including the head displacement device 210, the platen roller drive motor 220, and the pinch roller drive motor 240 in accordance with a control command from the microcomputer 12. The microcomputer 12 controls the operations of the head displacement device 210, the platen roller drive motor 220, and the pinch roller drive motor 240 through the actuator drive circuit 15.

<Optical sensing processing according to the first embodiment>
Next, a first embodiment of the optical sensing process executed by the system controller 10 of the printer 1 will be described with reference to the flowchart shown in FIG.

  The process shown in FIG. 4 is started when, for example, power is supplied to the system controller 10 of the printer 1 and the system controller 10 is activated.

  In the first embodiment, first, the event detection unit 121 uses the optical sensor 50 to execute a process for detecting the occurrence of an event for starting the optical sensing process (S1). The start event of the optical sensing process is, for example, a predetermined start operation for the operation unit 13 or a start signal from the host device 5 through the communication interface 11 in a state where the prohibition condition for the conveyance operation of the recording paper 4 is not satisfied. Entered, and so on.

  In addition, the prohibition condition for the conveyance operation of the recording paper 4 is, for example, that a door provided in the housing 60 is opened.

  When the start event of the optical sensing process is detected, the transport control unit 122 blocks the recording paper 4 from the discharge port 61 to the outside with respect to the transport device (24, 240, 22, 220). The operation of transporting to the position is executed. For example, the conveyance control unit 122 rotates the pinch roller driving motor 240 and the platen roller driving motor 220 in the forward direction only for a predetermined time necessary for the recording paper 4 to reach the light shielding position.

  FIG. 1 shows a state in which the recording paper 4 is conveyed to the light shielding position. As shown in FIG. 1, when a part of the recording paper 4 is conveyed to a position (a light shielding position) that protrudes outward from the discharge port, the discharge port 61 is almost blocked. For this reason, most of the external light 8 such as sunlight or light from room lighting is reflected by the portion of the recording paper 4 that protrudes from the discharge port 61, and hardly enters the housing 60.

  Next, the light projecting control unit 123 outputs a control signal to the light projecting unit 51, thereby turning on the light emitting diode 511 which is a light emitting unit (S3).

  Further, in a state where the recording paper 4 exists at the light shielding position and the light emitting diode 511 is lit, the light reception control unit 124 performs a process of inputting a detection signal of the light receiving unit 52, that is, a light reception level input process. Execute (S4).

  As described above, in steps S3 and S4, the light projection control unit 123 and the light reception control unit 124 execute the light irradiation by the light projection unit 51 after the operation of transporting the recording paper 4 to the light shielding position is performed. The detection signal of the light receiving unit 52 is input. The light projection control unit 123 and the light reception control unit 124 are an example of a first light sensor control unit.

  Furthermore, the light projection control unit 123 stops the output of the control signal to the light projection unit 51, thereby turning off the light emitting unit (light emitting diode 511) (S5).

  And the level determination part 125 performs the process which determines the state of a to-be-detected object according to the light reception level obtained by step S4 (S6-S8). The level determination unit 125 that executes the processes of steps S6 to S8 is an example of a first determination unit.

  More specifically, the level determination unit 125 determines whether or not the light reception level obtained in step S4 is less than a preset threshold value (S6). If the level determination unit 125 determines that the light reception level is less than the threshold value, the level determination unit 125 sets a detection flag, which is data indicating the state of the detected object, to ON (S7). If the level determination unit 125 determines that the received light level is equal to or higher than the threshold value, the level determination unit 125 sets the detection flag to OFF (S8).

  In the printer 1 employing the transmissive optical sensor 50, the detection flag indicates that the detected object is present at the light irradiation position when the value is ON, and when the value is OFF. This means that the object to be detected does not exist at the light irradiation position.

  In addition, after the input of the light reception level by the light reception control unit 124 is completed in step S4, the conveyance control unit 122 reversely conveys the recording paper 4 to the retreat position where the recording paper 4 is entirely contained in the housing 60. Is executed (S9). The conveyance control unit 122 that performs the process of step S9 is an example of a second conveyance control unit.

  In the present embodiment, the object to be detected is the recording paper 4 or a paper roll 40 that is a supply unit of the recording paper 4. Therefore, when the recording paper 4 that is the object to be detected does not exist at the light irradiation position, it is not necessary to reversely transport the recording paper 4 to the retracted position. Therefore, in the example shown in FIG. 4, the process of transporting the recording paper 4 back to the retracted position is executed only when the detection flag is set to ON (S9).

  The microcomputer 12 periodically repeats the processing after step S1 shown above. The processes in steps S3 to S8 are executed for each of the plurality of optical sensors 50 provided in the printer 1. The detection flag whose value is set for each optical sensor 50 is referred to in other processing.

  For example, when the value of the detection flag corresponding to the first optical sensor 50A is OFF, the microcomputer 12 prohibits the printing process and displays an error display indicating that the paper roll 40 is not attached through the display unit 14. Output.

  When the value of the detection flag corresponding to the second optical sensor 50B is OFF, the microcomputer 12 prohibits the printing process and outputs an error display indicating that no recording paper 4 remains through the display unit 14. To do.

<Effect>
As described above, the system controller 10 sets the optical sensor 50 in a state where the recording paper 4 exists in a light shielding position that blocks the discharge port 61, that is, in a state where the external light 8 does not substantially enter the housing 60. The detection signal of the light receiving unit 52 obtained by the operation is used for determining the state of the detected object. As a result, it is possible to prevent malfunction of the optical sensor 50 due to the external light 8. In addition, it is not necessary to provide a shielding object in the discharge port 61 or the conveyance path of the recording paper 4 that the recording paper 4 itself blocks the external light 8 and causes the recording paper 4 to be clogged.

  Incidentally, external light 8 such as sunlight or illumination light normally enters the printer 1 from above. On the other hand, in the printer 1, the light receiving unit 52 of the optical sensor 50 is disposed at a position lower than the discharge port 61 in the housing 60. That is, in the printer 1, even when a small part of the external light 8 enters the housing 60 through the gap between the discharge port 61 and the recording paper 4 located at the light shielding position, the light is received by the light receiving unit 52. The direct external light 8 is always blocked by the recording paper 4. Therefore, erroneous detection of the detection object is more reliably prevented.

  Further, after the detection signal of the light receiving unit 52 is input, the conveyance control unit 122 causes the conveyance devices (24, 240, 22, 220) to perform an operation of conveying the recording paper 4 back to the retracted position (S9). ). Therefore, it is possible to prevent the printer 1 from leaving a part of the recording paper 4 protruding from the discharge port 61 in an unsightly state.

<Optical sensing processing according to the second embodiment>
Next, a second embodiment of the optical sensing process executed by the system controller 10 of the printer 1 will be described with reference to the flowchart shown in FIG. Compared with the first embodiment shown in FIG. 4, the second embodiment has an additional process of inputting the light reception level of the optical sensor 50 and two determinations of the state of the detected object. Only the two points that are performed using the received light level are different. In FIG. 5, steps having the same contents as those shown in FIG. 4 are given the same reference numerals. Hereinafter, only different points in the second embodiment from the first embodiment will be described.

  If the recording paper 4 is not present in the printer 1, the external light 8 cannot be prevented from entering the housing 60 even if the operation of transporting the recording paper 4 to the light shielding position is executed in step S <b> 2. Therefore, it is considered that the state in which the light receiving level detected in a state where the light irradiation by the light projecting unit 51 is not performed after the carrying operation in step S2 is high is a state in which the recording paper 4 does not exist.

Therefore, in the optical sensing process according to the second embodiment, after the operation of transporting the recording paper 4 to the light shielding position is executed in step S2, before the light projecting unit 51 is turned on, the following steps S10, S10, S1 1 processing is executed.

  That is, in step S10, the light reception control unit 124 inputs the detection signal of the light receiving unit 52 without executing the light irradiation by the light projecting unit 51, that is, in a state where the light emitting diode 511 is not lit. That is, the light receiving level input process is executed (S10). Hereinafter, the light reception level obtained in step S10 is referred to as a first light reception level, and the light reception level obtained in step S4 described above is referred to as a second light reception level. The light reception control unit 124 that executes the process of step S10 is an example of a second optical sensor control unit.

  Furthermore, in step S11, the level determination unit 125 performs the processing of steps S3 to S5 by the light projection control unit 123 and the light reception control unit 124 and the processing of steps S12 and S7 by the level determination unit 125 according to the first light reception level. Control whether to execute.

  Note that the processing in step S12 corresponds to the processing in step S6 in the first embodiment, and the contents will be described later. The level determination unit 125 that executes the process of step S11 is an example of a second determination unit.

  More specifically, in step S11, the level determination unit 125 determines whether or not the first light reception level is less than a predetermined first threshold value. The first threshold value is the maximum value that the detection level of the light receiving unit 52 can take when the external light 8 is blocked by the recording paper 4 and light irradiation by the light projecting unit 51 is not performed.

The level determining unit 125, when the first light receiving level is judged to be the first threshold value or more, the process of step S 3 ~S7 from being executed. In this case, the level determination unit 125 sets the detection flag to OFF (S8).

  Further, the level determination unit 125 executes the processes of steps S3 to S5, S12, and S7 only when it is determined that the first light reception level is less than the first threshold value.

  Furthermore, in step S12 corresponding to 6 in the first embodiment, the level determination unit 125 determines the state of the detected object according to the difference between the first light reception level and the second light reception level. For example, the level determination unit 125 determines whether there is an object to be detected by determining whether the difference between the first light reception level and the second light reception level is less than a predetermined second threshold value. (S12). In addition, it is also conceivable that the level determination unit 125 determines the presence or absence of an object to be detected by comparing the ratio of the second light reception level to the first light reception level and a threshold value.

  And the level determination part 125 sets a detection flag to ON, when the difference of the 2nd light reception level with respect to a 1st light reception level is less than a 2nd threshold value (S7). The level determination unit 125 sets the detection flag to OFF in other cases (S8).

<Effect>
When the optical sensing process according to the second embodiment is employed, the same effect as that obtained when the optical sensing process according to the first embodiment is employed can be obtained.

  In the second embodiment, the level determination unit 125 responds to the level of the detection signal of the light receiving unit 52 obtained without light irradiation by the light projecting unit 51 after the operation of transporting the recording paper 4 to the light shielding position. Then, it is controlled whether or not the processes of steps S3 to S5 are executed (S11). Therefore, even when the recording paper 4 is not present, malfunction of the optical sensor 50 due to the external light 8 is prevented.

  In the second embodiment, the first light receiving level obtained without the light irradiation of the light projecting unit 51 and the light irradiation of the light projecting unit 51 after the operation of transporting the recording paper 4 to the light shielding position is performed. The state of the object to be detected is determined according to the difference in the second light reception level obtained under (S12). Therefore, even when a part of the external light 8 enters the housing 60 through the gap between the discharge port 61 and the recording paper 4 located at the light shielding position, erroneous detection of the detection object is more reliable. To be prevented.

<Others>
In the embodiment described above, the processes of steps S3 to S8 and S12 are executed for each of the plurality of optical sensors 50 provided in the printer 1. However, it is also conceivable that a part of the optical sensor 50 in the housing 60 is present at a position that is not easily affected by the external light 8, such as being located far from the discharge port 61. For this reason, it is also conceivable that only the remaining processes except steps S2 and S9 in the first embodiment are executed for some sensors 50 that are not easily affected by the external light 8.

  The optical sensor 50 in the printer 1 is a sensor that detects the presence or absence of the recording paper 4 or the supply source of the recording paper 4. Therefore, in step S11 of the second embodiment, when it is determined that the first light reception level is equal to or higher than the first threshold value, processing for setting the detection flag indicating the state of the detected object to OFF is performed.

  However, it is also conceivable that the optical sensor 50 is a sensor that detects an object to be detected that is not related to the recording paper 4. In that case, it is also conceivable to skip the detection process using the optical sensor 50 when it is determined in step S11 of the second embodiment that the first light receiving level is equal to or higher than the first threshold value.

  In the second embodiment, it may be possible to employ an optical sensing process in which the process of step S11 is omitted.

  Further, in the present invention, the recording paper 4 conveyed to block the external light 8 may be a recording paper cut in advance for each page size in addition to the recording paper fed out from the paper roll 40. It is done. In this case, a paper feed cassette or a paper feed tray serves as a supply unit for the recording paper 4. The present invention can also be applied to various printers such as a thermal printer, a sublimation thermal transfer printer, a melt thermal transfer printer, an ink jet printer, and a laser printer.

  DESCRIPTION OF SYMBOLS 1 Printer, 3 Ink sheet, 4 Recording paper, 5 Host apparatus, 8 External light, 10 System controller, 11 Communication interface, 12 Microcomputer, 13 Operation part, 14 Display part, 15 Actuator drive circuit, 16 Memory, 17 Image processing Circuit, 18 Thermal head controller, 21 Thermal head, 22 Platen roller, 23 Cutting device, 24 Pinch roller mechanism, 30 Ink sheet unit, 31 Feeding unit, 32 Winding unit, 40 Paper roll, 50 Optical sensor, 50A First light Sensor, 50B second light sensor, 51 light projecting unit, 52 light receiving unit, 60 housing, 61 discharge port, 121 event detection unit, 122 transport control unit, 123 light projecting control unit, 124 light receiving control unit, 125 level determination unit 210 Head displacement equipment , 211 heater, 220 platen roller drive motor, 240 pinch roller drive motor, 241 pinch roller, 242 grip roller, 511 light emitting diode, 512 transistor, 513 resistance element, 514 control input terminal, 521 phototransistor, 522 resistance element, 523 Signal output terminal.

Claims (7)

A printer for forming an image on recording paper,
A transport unit that transports the recording paper along a transport path from a supply unit in the housing to a discharge port formed in the housing;
An optical sensor including a light projecting unit that irradiates light to the position of an object to be detected in the housing and a light receiving unit that receives light from the light projecting unit;
A first conveyance control unit that causes the conveyance unit to perform an operation of conveying the recording paper to a light shielding position where a part of the recording sheet protrudes outward from the discharge port;
A first optical sensor control unit that inputs a detection signal of the light receiving unit while performing light irradiation by the light projecting unit after the transport operation by the first transport control unit is performed;
A printer comprising: a first determination unit that determines a state of the detected object according to a level of a detection signal of the light receiving unit obtained by the first light sensor control unit.   The printer according to claim 1, wherein the light receiving unit of the optical sensor is disposed at a position lower than the discharge port in the housing.   After the detection signal of the light receiving unit is input by the first photosensor control unit, the transport unit performs a second operation of transporting the recording paper back to a retracted position where the recording paper is entirely contained in the housing. The printer according to claim 1, further comprising a conveyance control unit. A second optical sensor control unit that inputs a detection signal of the light receiving unit without performing light irradiation by the light projecting unit after the transport operation by the first transport control unit is performed;
A second determination unit that controls whether or not the processes of the first light sensor control unit and the first determination unit are executed according to the level of the detection signal of the light receiving unit obtained by the second photosensor control unit. The printer according to any one of claims 1 to 3, further comprising: A second optical sensor control unit that inputs a detection signal of the light receiving unit without performing light irradiation by the light projecting unit after the transport operation by the first transport control unit is performed;
The first determination unit determines the state of the detected object according to a difference in detection signal level of the light receiving unit obtained by the first light sensor control unit and the second light sensor control unit. The printer according to any one of claims 1 to 3.   The printer according to claim 1, wherein the optical sensor is a transmissive optical sensor in which the light receiving unit receives direct light from the light projecting unit.   The printer according to claim 1, wherein the light sensor is a reflection-type light sensor in which the light receiving unit receives reflected light obtained by reflecting light from the light projecting unit on the object to be detected. .

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