JP2005193555A - Printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printer having a principal feature that an energization information table is provided on a reference table in order to set on/off of heating elements. <P>SOLUTION: The printer comprises a thermal head having shift registers, latch circuits and drive circuits corresponding to the number of pixels in one line and a heating element, a line memory for recording the gray scale information of a plurality of bits per pixel for the number of pixels of the thermal head, an address counter for reading out the gray scale information sequentially by scanning the line memory, a gray scale counter cascaded with the counter and outputting gray scale data, and a reference table storing 1 bit data for controlling on/off of the heating elements using the gray scale information read out from the line memory and gray scale data of the gray scale counter as an address wherein the output from the reference table is delivered to the shift register of the thermal head. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thermal line head control circuit that controls the heat generation of a thermal line head by changing the time width of the thermal line head drive current. Images of a digital still camera, a digital video camera, a camera-equipped mobile phone, etc. The present invention relates to a printer apparatus capable of gradation control capable of multi-gradation recording, which can be widely applied to a printing apparatus or the like.

  In a thermal transfer printer with gradation, such as a video printer, the amount of heat generated in the thermal head heating element is controlled by controlling the pulse width of the driving current of the thermal head to obtain a desired print density.

  FIG. 6 is a block diagram showing the configuration of a conventional printer apparatus. FIG. 6 shows an example of the configuration of an image printer that performs gradation printing by controlling the time width of the energization pulse of the serial input thermal line head in accordance with the digital print data.

  In FIG. 6, 1 is a 2n dot line head, 2 is a 2n drive circuit corresponding to the line head 1, and 3 is a data transfer of the next line after 2n data serial-parallel converted by the shift register 4. Latch circuit for storing until completion, 4 is a shift register for converting data sent serially from the line memory 5 into parallel, 5 is for storing print data for one line, and an address given from the address counter 6 b is a line memory that outputs print data e corresponding to b, 6 is an address counter as a first counter, and 7 is an address counter 6 and a shift register 4 for transferring data from the line memory 5 to the shift register 4. Generates a common clock a to be applied, and loads the latch circuit 3 after transferring one line of data. A clock generation circuit for generating the pulse d, 8 is a gradation counter which is a second counter for counting the carry of the address counter 6, and 9 is for comparing the output f of the gradation counter 8 with the output e of the line memory 5. It is a comparator that sends a 1-bit output g to the shift register 4.

  The operation of the conventional printer configured as described above will be described below.

  When the thermal line head 1 is 2n elements and the printing is 2m gradation, the drive circuit 2, the latch circuit 3 and the shift register 4 are 2n elements, and the address inputs of the address counter 6 and the line memory 5 are n bits. The data output of the line memory 5 and the two inputs of the gradation counter 8 and the comparator 9 are each m bits, and the comparison output of the comparator 9 is 1 bit. In the line memory 5, m-bit data corresponding to the gradation to be printed is written, and an n-bit address b is given from the address counter 6. The address counter 6 and the shift register 4 are supplied with a clock a that determines the transfer rate of serial data from the clock generation circuit 7 to the thermal head, and read m-bit gradation print data from the line memory 5. When the address counter 6 makes a round, all the contents of the line memory 5 are read, the output of the gradation counter 8 increases by 1, and the contents of the line memory 5 are read again from the beginning. The output e of the line memory 5 and the output f of the gradation counter 8 are compared in magnitude by the comparator 9. From the output g, 1 is sent to the shift register 4 only when the line memory output e is larger than the gradation counter output f. It is done.

  That is, a cycle corresponding to T in FIG. 7 to be described later is repeated 2 m times as many as the number of output bits of the gradation counter 8, and printing is performed. At that time, the same data e is read from the line memory 5 every cycle. However, since the value of the gradation counter 8 increases every cycle, the output g of the comparator 9 is set to 0 because the output e of the line memory 5 becomes equal to or less than the value f of the gradation counter 8. It will change. Here, since the increase in the value f of the gradation counter 8 is a function of time, the output of each drive circuit 2 is proportional to the value of the corresponding data in the line memory 5 in 2n steps with the minimum resolution T. The energization pulse width can be controlled. FIG. 5 is a timing chart for explaining the operation of the conventional printer. FIG. 5 shows a case where m is 4 and n is 8. Since m is 4, the data e of the line memory 5 and the output f of the gradation counter 8 are 4 bits, and the pulse width of 16 gradations can be controlled. Since n is 8, the thermal line head 1, the drive circuit 2, the latch circuit 3 and the shift register 4 are all 256 elements, and the comparators 9 to 256 during the period T which is the minimum resolution of the energization pulse width. Data is transferred serially.

In FIG. 7, C0 to C3 are bits of the output f of the gradation counter 8, and H0 to H255 are illustrated by extracting data corresponding to each head from the serial data g. Therefore, when H0 to H255 of each period T is viewed vertically, it becomes serial data g. When the density printed on the head 0 (H0) is 6 (e = 6), H0 is a period 1 corresponding to 6 cycles from cycle 0 to 5, and printing is performed on the head 0 with a pulse width of 6. Similarly, the case where the data e to be printed on the head 1 (H1) is 11 (e = 11), the head 2 (H2) is 0 (e = 0), and the head 255 (H2) is 13 (e = 13) is illustrated. ing.
JP 2000-280514 A (page 5, FIG. 3)

  The problem to be solved is that the configuration using the comparator as in the example cannot be divided even if the pulse width of a single pulse can be varied. Therefore, a preheating pulse or the like cannot be added.

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a printer device whose main feature is to have an energization information table on a reference table in order to set heating elements on / off for each gradation level. And

The present invention solves the above-described problems. A thermal head having a shift register, a latch circuit, a drive circuit, and a heating element corresponding to the number of pixels of one line, and gradation information of a plurality of bits per pixel for the number of pixels of the thermal head. A line memory to be recorded, an address counter that scans the line memory and sequentially reads gradation information, a gradation counter that is cascade-connected to the counter and outputs gradation data, and gradation information read from the line memory And a reference table for storing 1-bit data for controlling on / off of the heating element, using the gradation data of the gradation counter as an address, and outputting the output of the reference table to the shift register of the thermal head Energization information table on reference table to set heating element on / off for each gradation level The main feature is to have

  The printer apparatus of the present invention can divide pulses applied to the thermal head with a simple configuration and can control the pulse width, so that it can easily cope with preheating pulses. Further, since the pulse width control data can be rewritten in the memory, there is an advantage that even if the thermal head or the medium is changed, it can be easily changed to the optimum pulse width only by changing the firmware.

  According to a first aspect of the present invention, there is provided a thermal head having a shift register, a latch circuit, a drive circuit, and a heating element corresponding to the number of pixels in one line, and gradation information of a plurality of bits per pixel. A line memory that records the number of pixels, an address counter that scans the line memory and sequentially reads gradation information, a gradation counter that is cascade-connected to the counter and outputs gradation data, and is read from the line memory A reference table for storing 1-bit data for controlling on / off of the heating element, using the gradation information and gradation data of the gradation counter as addresses, and outputting the output of the reference table to the shift register of the thermal head This makes it possible to divide the pulse applied to the thermal head with a simple configuration and It can be controlled, and it is also easily adapted to preheat pulse. In addition, since the pulse width control data can be rewritten in the memory, even if the thermal head or the medium is changed, it can be easily changed to the optimum pulse width only by changing the firmware.

(Embodiment 1)
FIG. 1 is a block diagram of a configuration for realizing the purpose of performing gradation control with a minimum number of parts while adding a preheating pulse to the head of energization pulses of each heating element in a printer apparatus according to an embodiment of the present invention. Indicates.

  In FIG. 1, 1 is a 2n dot line head, 2 is a 2n drive circuit corresponding to the line head 1, and 3 is a data transfer of the next line after 2n data serial-parallel converted by a shift register 4. Latch circuit for storing until completion, 4 is a shift register for converting data sent serially from the line memory 5 into parallel, 5 is for storing print data for one line, and an address given from the address counter 6 b is a line memory that outputs print data e corresponding to b, 6 is an address counter as a first counter, and 7 is an address counter 6 and a shift register 4 for transferring data from the line memory 5 to the shift register 4. Generates a common clock a to be applied, and loads the latch circuit 3 after transferring one line of data. Clock generating circuit for generating a pulse d, the gradation counter 8 is a second counter for counting the carry of the address counter 6, 19 is a reference table. FIG. 2 shows the contents of the reference table. A table of 8-bit input address and 1-bit output is prepared for the number of gradations (256).

  f = 0, 1 indicates the gradation data f given by the gradation counter 8 and is given as an upper address of the reference table. The horizontal axis represents the input address e, and the vertical axis represents on (1) off (0) data g of the heating element.

  The operation of the printer apparatus of the present embodiment configured as described above will be described below.

  When the thermal line head 1 is 2n elements and the printing is 2m gradation, the drive circuit 2, the latch circuit 3 and the shift register 4 are 2n elements, and the address inputs of the address counter 6 and the line memory 5 are n bits. Further, the data output of the line memory 5, the two inputs of the gradation counter 8 and the reference table 19 are each m bits, and the comparison output of the reference table 19 is 1 bit.

  In the line memory 5, m-bit data corresponding to the gradation to be printed is written, and an n-bit address b is given from the address counter 6. The address counter 6 and the shift register 4 are supplied with a clock a that determines the transfer rate of serial data from the clock generation circuit 7 to the thermal head 1, and read m-bit gradation print data from the line memory 5. When the address counter 6 makes a round, all the contents of the line memory 5 are read, the output of the gradation counter 8 increases by 1, and the contents of the line memory 5 are read again from the beginning. The print data e read from the line memory 5 is input as the address of the reference table 9.

  From the contents of the reference table in FIG. 2, the output of the table corresponding to f = 0, 1 is “1”, so that all the heating elements are turned on and preheated regardless of the print data. Since the table corresponding to f = 2 outputs ‘0’ when the input value is from 0 to 254 and ‘1’ when the input value is 255, only the heating element having the print data e of 255 is energized.

  Similarly, the table corresponding to f = N outputs ‘0’ when the input value is from 0 to 256−N, and ‘1’ when the input value is 256−N + 1 or more. Therefore, the energization pulse of the heating element with the print data of 249 and 255 is as shown in FIG. 3, and it can be seen that the preheating pulse is added.

(Embodiment 2)
As another form, the energization waveform is turned off and on in small increments from a point beyond a certain gradation so that the temperature of the heating element does not rise too much, thereby reducing the peak temperature of the heating element and An example of performing a gradation control method having an effect of preventing sticking or the like will be described.

  FIG. 4 shows the contents of the reference table.

  In this case, the output f of the gradation counter 8 is 9 bits. From f = 0 to f = 503, the odd gradation table is the same as the even gradation table. Since f = 505, the odd gradation table outputs “0”, so that the energization is stopped. The energization waveform in this case is as shown in FIG. 7, and it can be seen that the peak temperature of the heating element can be suppressed.

  Since the printer device according to the present invention has a power supply information table on the reference table, it can generate a discontinuous power supply pulse, so that a preheating pulse is added, a heating element peak temperature is controlled, and an ink or head Even if the characteristics change, it can be easily handled by rewriting the table data.

1 is a block diagram illustrating a method for implementing a printer device according to a first embodiment of the present invention. Schematic diagram showing the contents of a reference table of the printer device in the first embodiment of the present invention FIG. 2 is a waveform diagram showing energization waveforms of the printer device in the first embodiment of the present invention Schematic diagram showing the contents of the reference table of the printer device in the second embodiment of the present invention Waveform diagram showing the energization waveform of the printer device in Embodiment 7 of the present invention Block diagram showing the configuration of a conventional printer device Timing chart for explaining the operation of a conventional printer

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal head 2 Drive circuit 3 Latch circuit 4 Shift register 5 Line memory 6 Address counter 7 Clock generation circuit 8 Gradation counter 9 Reference table

Claims (1)

A thermal head having a shift register, a latch circuit, a drive circuit, and a heating element corresponding to the number of pixels in one line, a line memory for recording gradation information of a plurality of bits per pixel for the number of pixels of the thermal head, and the line An address counter that scans a memory and sequentially reads gradation information, a gradation counter that is cascade-connected to the counter and outputs gradation data, gradation information read from the line memory, and gradation data of the gradation counter And a reference table for storing 1-bit data for controlling on / off of the heating element, and outputting the output of the reference table to the shift register of the thermal head.

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