JP2007331179A - Recorder and method for protecting the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recorder capable of eliminating unintentional supplying of power to a heating element caused by noise or the like, thereby preventing a recording head from being damaged. <P>SOLUTION: This recorder comprises a thermal head 21 having many heating elements 50 arranged in a line, a latch circuit 41 for storing one line of image data, a drive circuit 42 for selectively driving the heating elements 50 in response to the one line of image data, and an MCU 16 for initializing the latch circuit 41 when finishing the writing of the one line of image data stored in the latch circuit 41 to a recording material. As the image data stored in the latch circuit 41 is erased upon the finishing of the writing of the image data to the recording material, it is possible to eliminate the unintentional supplying of power to the heating elements caused by noise or the like, thereby preventing the thermal head 21 from being damaged. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording apparatus that records an image by a thermal (thermal transfer) method.

  In a thermal recording apparatus, a thermal head as an image forming unit and a platen roller as a rotating body are arranged to face each other and are brought into pressure contact with each other. An image is formed by feeding a thermal paper by rotating a platen roller while driving a thermal head based on the information.

  However, if the strobe signal that controls the time for which the heating element of the thermal head generates heat is active beyond a predetermined time determined in advance by noise or the like, the energization time to the heating element becomes too long and the heating element May overheat. In particular, when the recording apparatus finishes recording and enters a standby state, the written data is not deleted from the thermal head. For this reason, if a strobe signal due to noise is input to the thermal head during standby, energization of the heating element is started as soon as power supply to the thermal head is resumed, which may cause thermal loss of the thermal head.

  Therefore, in Patent Document 1, a conversion circuit that converts the time during which the strobe signal is active within a predetermined time and a reset signal that resets the conversion circuit according to the printing speed are generated at a timing according to the printing speed. A reset signal generation circuit is provided separately.

Japanese Utility Model Publication No. 5-53951

  However, in Patent Document 1, it is necessary to provide a special device such as a conversion circuit or a reset circuit, and there is a problem that the device configuration increases in size.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a recording apparatus and a protection method thereof that can prevent damage to the recording head with a simple configuration.

In order to achieve this object, a recording apparatus of the present invention includes a recording head having a large number of heating elements arranged in a line, a latch circuit for storing image data for one line, and image data for one line. And a control circuit that initializes the latch circuit when the writing of the image data for one line held in the latch circuit to the recording material is completed. It has composition which has.
As described above, according to the present invention, when the writing of the image data to the recording material is completed, the image data held in the latch circuit by the control unit is erased to prevent unnecessary power supply to the heating element. For this reason, it is possible to prevent the recording head from being damaged by the control means without providing a special device.

In the recording apparatus, the control unit may initialize the latch circuit by writing empty data for one line.
Therefore, the latch circuit can be easily initialized.

  In the recording apparatus, the control unit may initialize the latch circuit when transporting the recording material on which writing has been completed. Further, the control means may initialize the latch circuit when cutting the recording material that has been written into a predetermined size, or transports a recording material that has finished writing and that records the next image. At this time, the latch circuit may be initialized. Further, the latch circuit may be initialized at the time of waiting until the next image data is input.

  In the recording apparatus, the recording apparatus includes a head position detecting unit that detects a head-up state when the recording head is not recording and a head-down state during recording, and the control unit is configured to detect the head-up state by the head position detecting unit. When the state is detected, the latch circuit may be initialized. A recording material detecting unit configured to detect whether or not the recording material is conveyed at a recording position of the recording head; and the control unit detects the recording material at the recording position by the recording material detecting unit. When it is detected that the sheet is not conveyed, the latch circuit may be initialized. Furthermore, it has an abnormality detecting means for detecting an abnormality of the voltage supplied to the heating element, and the control means may initialize the latch circuit when the abnormality of the voltage is detected by the abnormality detecting means. .

  The recording apparatus protection method of the present invention includes a step of storing image data for one line in a storage unit, a step of selectively driving a heating element of the recording head in accordance with the image data for one line, A step of initializing the storage means when the writing of the image data for one line stored in the storage means to the recording material is completed.

  According to the present invention, it is possible to prevent inadvertent power supply to the heating element due to noise or the like, and to prevent damage to the recording head.

  The best embodiment of the present embodiment will be described with reference to the accompanying drawings.

FIG. 1 shows the configuration of a recording apparatus to which the present invention is applied. The recording apparatus 1 according to this embodiment includes a control unit 10, a mechanical unit 20, a power supply device 30, and a paper cutter device 31.
The control unit 10 is a unit that drives and controls the mechanical unit 20, and includes a power supply control circuit (corresponding to the abnormality detecting means of the present invention) 11, a communication interface unit 12, a ROM (Read Only Memory) 13, a RAM (Random Access). A memory) 14, an EEPROM (Electronically Erasable and Programmable Read Only Memory) 15, an MCU (Micro Controller Unit) 16, a thermal head drive circuit 17, and motor drive circuits 18 and 19. The mechanical unit 20 includes a thermal head 21, a paper feed motor 22, a paper detection sensor (corresponding to the recording material detection means of the present invention) 23, a head position detection sensor (corresponding to the head position detection means of the present invention) 24, A paper conveyance detection sensor 25 is provided.

  The power control circuit 11 is a circuit that controls power supply from the power supply device 30. When the recording apparatus 1 is activated, the power supply control circuit 11 supplies power to each unit in the control unit 10. The power supply control circuit 11 controls power supply to the thermal head 21 in accordance with an instruction from the MCU 16. Further, when the power supply control circuit 11 determines that an abnormality occurs in the power supply device 30 and the supply voltage is abnormal, the power supply control circuit 11 outputs an abnormality notification signal to the MCU 16.

  The communication interface unit 12 functions as an interface with a host device (not shown), and inputs print data and various print control data sent from the host device. Also, various response commands sent from the MCU 16 are transferred to the host device.

  The MCU 16 controls the entire recording apparatus 1 according to a program stored in the ROM 13. Specifically, image data and various print control data input from the communication interface unit 12 are received, and printing is executed while controlling the operation of the mechanical unit 20.

  The RAM 14 is configured by an SRAM or the like, and temporarily stores various data necessary for controlling the MCU 16 and data to be printed. The EEPROM 15 is a non-volatile memory and stores various data necessary for print control. The data stored in the EEPROM 15 does not disappear even when the power is turned off. When the power is turned on, the data is read by the MCU 16 and written in a predetermined area of the RAM 14.

  In addition to these, the control unit 10 includes a thermal head drive circuit 17 that drives and controls the thermal head 21 according to the control of the MCU 16, a motor drive circuit 18 that drives the paper feed motor 22, and a paper cut motor 32 of the paper cut device 31. And a motor drive circuit 19 for driving.

  FIG. 2 shows a detailed configuration of the thermal head 21 and the thermal head drive circuit 17. The thermal head drive circuit 17 has a shift register 40, a latch circuit 41, and a drive circuit 42 as shown in FIG. Further, the thermal head 21 has a configuration in which a large number of heating elements 50 are arranged in a line as shown in FIG.

  In the thermal head 21, a current flows through the heating element 50 by driving the drive circuit 42, and the heating element 50 is heated. By pressing the thermal head in this state against the thermal paper, a desired image can be formed on the thermal paper.

  The shift register 40 inputs data to be recorded (hereinafter referred to as recording data) (data input shown in FIG. 2) dot by dot in synchronization with a clock signal (clock input shown in FIG. 2) supplied from the MCU 16. . When recording data for one line is accumulated in the shift register 40 and the latch signal supplied from the MCU 16 is turned on, the latch circuit 41 captures and stores the recording data for one line. Recording data for one line is output from the shift register 40 to the latch circuit 41 in parallel.

  The drive circuit 42 is selectively driven by a strobe signal supplied from the MCU 16 to capture recording data in the latch circuit 41 and heat the heating element 50 according to the recording data. That is, when the recording data fetched from the latch circuit 41 is 1 (that is, there is data), a current flows through the corresponding heating element 50 to generate heat. Further, when the strobe signal is off or the recording data of the latch circuit 41 is 0 (that is, no data), no current flows and the heating element 50 does not generate heat.

Returning to FIG. 1, the paper feed motor 22 in the mechanical unit 20 is a motor for transporting the thermal paper to the printing position during the printing operation and transporting the thermal paper after printing to the discharge port.
The paper detection sensor 23 is a sensor that detects whether or not the thermal paper is being conveyed to the pressing position of the thermal head 21 that is the printing position.
The head position detection sensor 24 detects whether the thermal head 21 is in contact with or separated from the platen roller, and is configured by, for example, a micro switch.
The paper transport detection sensor 25 is provided on the transport path for transporting the thermal paper to the pressing position of the thermal head 21, and detects whether or not the thermal paper is transported on the transport path.

  The motor drive circuit 19 is a circuit that drives and controls the paper cutting motor 32 of the paper cutting device 31. The paper cutting device 31 includes a fixed blade and a movable blade, and cuts the thermal paper after printing into a predetermined size by moving the movable blade by driving the paper cutting motor 32.

Next, a series of processing procedures of the recording apparatus 1 will be described with reference to the flowchart shown in FIG.
When the recording apparatus 1 is turned on (step S1), the MCU 16 initializes the thermal head drive circuit 17 (step S2). For example, empty data (NULL data) is transmitted to the thermal head drive circuit 17, and the shift register 40 and the latch circuit 41 are initialized.

  Next, when image data is received from a host device (not shown) (step S3), the MCU 16 temporarily stores the received data in the RAM. When the MCU 16 determines the state of the thermal head driving circuit 17 and determines that the data can be transferred, the MCU 16 outputs the recording data to the shift register 40 one dot at a time in synchronization with the clock signal. When recording data for one line is stored in the shift register 40 and the latch signal is turned on by the MCU 16, the latch circuit 40 captures and stores the recording data of the shift register 40. The drive circuit 42 is selectively driven by a strobe signal supplied from the MCU 16 to capture recording data in the latch circuit 41 and heat the heating element 50 according to the recording data. As a result, a desired image is printed on the thermal paper conveyed to the nip portion between the thermal head 21 and the platen roller (step S4). When the recording data is printed on the thermal paper, the MCU 16 initializes the latch circuit 41 (step S5). Details of steps S3, S4, and S5 will be described later.

  The thermal paper that has been printed is conveyed to the cutting position of the paper cutting device 31 by driving the paper feed motor 22 (step S6), and the thermal paper that has been cut to a desired size (step S7) is discharged from the discharge port. Further, the MCU 16 controls the motor drive circuit 18 so that the next thermal paper is conveyed to the nip portion between the thermal head 21 and the platen roller (step S8).

  In this embodiment, the latch circuit 41 is initialized every time printing of the recording data for one line stored in the latch circuit 41 is completed. By erasing the image data held in the latch circuit 41, it is possible to prevent inadvertent power supply to the heating element due to noise or the like, and to prevent the thermal head 21 from being damaged.

  The initialization method of the latch circuit is performed by the MCU 16 writing NULL data for one line in the latch circuit 41. Since the latch circuit 41 is initialized by writing NULL data, it can be easily initialized without providing a special device.

The details of steps S3, S4, S4, and S5 described above will be described with reference to the flowchart shown in FIG.
First, the MCU 16 initializes the value of a counter that counts the number of recording data output to the thermal head drive circuit 17 (step S11). Next, when the MCU 16 determines the state of the thermal head driving circuit 17 and determines that the recording data can be transferred to the thermal head driving circuit 17 (step S12 / YES), it starts transferring the recording data (step S13). ).
The MCU 16 refers to the count value of the counter and determines the completion of transfer of the recording data for one line of the shift register 40. When it is determined that the transfer of the recording data for one line has been completed (step S14), NULL data for one line is output to the thermal head drive circuit 17 following the recording data (step S15). Thereafter, by turning on the latch signal supplied to the latch circuit 41, NULL data is taken into the latch circuit 41 from the shift register 40, and the latch circuit 41 is initialized.

In the flowchart shown in FIG. 4, when recording data for one line is sent to the thermal head drive circuit 17, the latch circuit 41 is initialized subsequently. As other initialization timings, the latch circuit 41 is initialized after completion of any of the paper feed (step S3), cut (step S4), and paper transport (step S5) steps in the flowchart shown in FIG. May be.
In the paper feeding step of Step S3, the latch circuit 41 is initialized after the motor driving circuit 18 drives the paper feeding motor 22 for a predetermined step.
In the paper cutting step of step S4, the latch circuit 41 is initialized after the motor driving circuit 19 drives the paper cutting motor for a predetermined step.
In the paper transport step of step S5, the latch circuit 41 is initialized after the paper feed motor 22 is driven for a predetermined step.

A flow for determining the timing at which the MCU 16 performs initialization will be described with reference to the flowchart shown in FIG.
The MCU 16 first checks the state of the thermal head drive circuit 17. When recording data is transferred from the MCU 16 to the thermal head driving circuit 17 and processing is performed by the thermal head driving circuit 17 (step S21 / YES), and when the thermal head 21 is driven to print recording data (Step S22) The latch circuit 41 is not initialized. The MCU 16 also receives the initial data of the latch circuit 41 when image data received from the host device (for example, PC) of the recording apparatus 1 and not transferred to the thermal head drive circuit 17 is stored in the RAM 14 (step S23). No conversion is performed. If the recording data transferred by the thermal head driving circuit 17 is not being processed (step S21 / NO), or if printing is not being performed (step S22 / NO), the image data not transferred to the thermal head driving circuit 17 is transferred. Is not stored in the RAM 14 (step S23 / NO), the MCU 16 determines that it is an initialization timing, sends one line of NULL data to the thermal head drive circuit 17, and initializes the latch circuit 41. Is performed (step S24).

  In addition to the timing described above, when waiting until the next image data is input, when the head position detection sensor 24 detects the head up of the thermal head 21, the sheet detection sensor 23 conveys the sheet to the image forming position. The MCU 16 can also initialize the latch circuit 41 when it is detected that the power supply control circuit 11 detects an abnormality in the power supply device 30.

  The processing procedure of the MCU 16 will be described with reference to the flowchart shown in FIG. When the head position detection sensor 24 detects the head up of the thermal head 21 (step S41 / YES), the MCU 16 initializes the latch circuit 41 (step S44). When the paper detection signal indicating that there is no paper at the printing position is output from the paper detection sensor 23 (step S42 / YES), the latch circuit 41 is initialized (step S44). Further, when a notification signal for notifying that the supply voltage of the power supply device 30 is abnormal is input from the power supply control circuit 11 (step S43 / YES), the latch circuit 41 is initialized (step S44).

  The embodiment described above is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

It is a block diagram which shows the structure of a recording device. It is a figure which shows the structure of a thermal head and a thermal head drive circuit. It is a flowchart which shows the recording procedure of a recording device. It is a flowchart which shows the procedure which initializes recording data. It is a flowchart which shows the timing which initializes recording data. It is a flowchart which shows the timing which initializes recording data.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording device 10 Control unit 11 Power supply control circuit 12 Communication interface part 13 ROM
14 RAM
15 EEPROM
16 MCU
DESCRIPTION OF SYMBOLS 17 Thermal head drive circuit 18, 19 Motor drive circuit 20 Mechanical unit 21 Thermal head 22 Paper feed motor 23 Paper detection sensor 24 Head position detection sensor 25 Paper conveyance detection sensor 30 Power supply device 31 Paper cutter device 32 Paper cut motor

Claims (10)

A recording head having a large number of heating elements arranged in a line;
A latch circuit for storing image data for one line;
A drive circuit that selectively drives the heat generating element according to the image data for one line;
Control means for initializing the latch circuit when the writing of the image data for one line held in the latch circuit to the recording material is completed;
A recording apparatus comprising:   2. A recording apparatus according to claim 1, wherein said control means initializes the latch circuit by writing empty data for one line.   3. The recording apparatus according to claim 1, wherein the control unit initializes the latch circuit when transporting the recording material on which writing has been completed.   3. The recording apparatus according to claim 1, wherein the control unit initializes the latch circuit when the recording material that has been written is cut into a predetermined size.   3. The recording apparatus according to claim 1, wherein the control unit initializes the latch circuit when the recording is completed and a recording material for recording a next image is conveyed.   3. The recording apparatus according to claim 1, wherein the control unit initializes the latch circuit during standby until the next image data is input. A head position detecting means for detecting a head-up state at the time of non-recording of the recording head and a head-down state at the time of recording;
3. The recording apparatus according to claim 1, wherein the control unit initializes the latch circuit when the head position detection unit detects the head-up state. A recording material detecting means for detecting whether or not the recording material is conveyed at a recording position of the recording head;
3. A recording apparatus according to claim 1, wherein said control means initializes said latch circuit when said recording material detecting means detects that said recording material is not conveyed to said recording position. . Having an abnormality detecting means for detecting an abnormality of the voltage supplied to the heating element;
3. A recording apparatus according to claim 1, wherein said control means initializes said latch circuit when said abnormality of said voltage is detected by said abnormality detecting means. Storing image data for one line in a storage means;
Selectively driving the heating elements of the recording head according to the image data for one line;
When the writing of the image data for one line stored in the storage unit to the recording material is completed, the step of initializing the storage unit;
A method for protecting a recording apparatus, comprising:

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