JP2003034047A - Thermal head, driving method therefor, and head driving ic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal head capable of easily achieving high speed recording and improving the productivity, a driving method therefor, and a head driving IC. SOLUTION: In a thermal head comprising a large number of heat generating resistors R1-R256, and a shift resistor 1 for serial transfer of image data for controlling individually the energy supply to the heat generating resistors R1-R256 in the inside, the shift resistor 1 is divided into a plurality of groups G1-G4 comprising M pieces (M is a natural number of 2 or more) of shift resistor cells 2 as well as integrated to a head driving IC (D1-D4) per each group. Furthermore, the final stage of the shift register cells 2 belonging to the group in the inside of each head driving IC (D1-D4) is connected with selection circuits B1-B4 for controlling the input of the image data to the shift resistor 1 of the head driving IC of the next stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head used as a recording device such as a facsimile or a video printer, a driving method thereof, and a head driving IC used in the thermal head.

[0002]

2. Description of the Related Art Conventionally, thermal heads have been used as recording devices for facsimiles, video printers and the like.

Such a conventional thermal head has a large number of heating resistors arranged in a straight line and a plurality of driver ICs for controlling the heat generation of these heating resistors. , A shift register in which a large number of shift register cells are connected in series, a large number of switching elements corresponding to the heating resistors in a one-to-one relationship,
The driver ICs and the blocks corresponding to each other are integrated. In the shift register of such a driver IC, image data from the outside is supplied serially for each printing line in synchronization with a clock signal during a recording operation, and these image data are supplied to a switching element. By supplying power and switching on / off of the switching element based on the image data, the heating resistor is selectively energized, and the heat is transferred to the recording medium such as a thermal paper or the like so that the heat is generated on the recording medium. Print is formed.

[0004]

However, in the above-mentioned thermal head, all the shift register cells forming the shift register are connected in series,
In order to store image data in these shift register cells, one line of image data must be serially transferred bit by bit from the first data to the final data. Therefore, it takes a relatively long time to store all the image data for one line in the shift register, which makes it difficult to cope with high-speed recording.

Therefore, in order to solve the above-mentioned drawback, the number of data inputs is increased, that is, the shift register is divided into a plurality of blocks, and the image data corresponding to these blocks are simultaneously and simultaneously stored in the shift registers of the respective blocks. It is proposed to reduce the transfer time of image data by supplying them in parallel.

However, when there are a plurality of types of data input, it is necessary to prepare a thermal head pattern corresponding to the types, which complicates the manufacturing control and leads to an increase in cost and the thermal head. It causes a drawback that the productivity of is significantly reduced.

The present invention has been devised in view of the above drawbacks, and an object thereof is to provide a thermal head capable of easily supporting high-speed recording and improving productivity, a driving method thereof, and a head. It is to provide a driving IC.

[0008]

A thermal head according to the present invention comprises a large number of heating resistors and a shift register for internally serially transferring image data for individually controlling energization of these heating resistors. In the thermal head, the shift register is divided into a plurality of groups of M (M is a natural number of 2 or more) shift register cells, and each group is integrated in a head driving IC, and Inside each head drive IC,
At the last stage of the shift register cell belonging to that group,
A selection circuit for controlling input of image data to the shift register of the head-driving IC in the next stage is connected.

In the thermal head driving method of the present invention, a plurality of head driving ICs provided in the thermal head are divided into N (N is a natural number of 2 or more) blocks and one line is used. The image data for one minute is divided into N sections corresponding to the blocks, and these image data are supplied to the head drive ICs of the blocks in parallel for each section.

Further, the thermal head driving method of the present invention is characterized in that the number of blocks of the head driving IC is varied based on the select data input to the selecting circuit.

Furthermore, the head drive IC of the present invention is
Head driving I having M (M is a natural number of 2 or more) shift register cells for serially transferring image data for heating and driving a large number of heating resistors of the thermal head
C, at the last stage of the shift register cell, either the image data stored in the shift register cell or the image data input from the outside without passing through the shift register cell is used as a selection signal. It is characterized in that it is provided with a selection circuit for selecting based on the above and outputting to the outside.

Furthermore, the head drive IC of the present invention is
The waveform of the selection signal is determined based on the selection data stored in the last stage of the shift register cell and a control signal from the outside.

According to the present invention, the plurality of head driving ICs provided in the thermal head are divided into N (N is a natural number of 2 or more) blocks, and one line of image data is stored in the block. Since the image data is divided into N sections corresponding to the blocks and these image data are supplied to the shift register of each block simultaneously and in parallel, the transfer time of the image data is significantly shortened. A thermal head compatible with high-speed recording can be realized.

Further, according to the present invention, a head driving IC
Since the selection circuit for controlling the input of the image data to the shift register of the head driving IC in the next stage is provided therein, the number of data inputs can be changed based on the selection data input to this selection circuit. . Therefore, a single thermal head pattern can handle multiple types of data input, simplifying manufacturing control and
The cost can be reduced and the productivity of the thermal head can be improved.

Further, according to the present invention, since the select data is input to the selection circuit via the shift register cell forming the shift register, a wiring for supplying the select data to the selection circuit. Need not be newly provided on the head driving IC and the substrate on which the head driving IC is mounted, and it is possible to effectively prevent the circuit patterns from becoming complicated.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a circuit diagram showing one form of the thermal head of the present invention, and FIG. 2 is a circuit diagram of a head driving IC used in the thermal head of FIG. 1. The thermal head shown in FIG. Heating resistors R1 and R2
56 and a plurality of (four in this embodiment) head drive ICs (D1) for controlling heat generation of the heat generating resistors R1 to R256.
To D4) are included in each of the head driving ICs (D1 to D4), the shift register internally serially transferring image data for controlling energization to the heating resistors R1 to R256. 1 are integrated in a form divided into a plurality of groups G1 to G4 each including M (M is a natural number of 2 or more, M is 64 in this embodiment) shift register cells 2.

The heating resistors R1 to R256 are provided on the upper surface of an insulating substrate made of, for example, alumina ceramics.
Since they are deposited / arranged linearly at a density of 0 to 600 dpi (dot per inch) and each is formed of an electric resistance material such as tantalum nitride, the switching element 4 and the like in the head driving IC described later, etc. When an electric power is applied from an external power source through the printer, heat is generated at a temperature necessary to form a print on the recording medium, for example, a temperature of 150 ° C to 400 ° C.

On the other hand, the plurality of head driving ICs (D1
To D4) are arranged in a row on the above-mentioned insulating substrate, and inside each of the head driving ICs (D1 to D4), the shift register cell 2, the latch 3 and the switching element 4 which constitute the shift register 1 are formed. M and the like are integrated, and selection circuits B1 to B4 are further provided.

The shift register cell 2 is serially connected to the heating resistors R1 to R256 in a one-to-one correspondence, and the shift register cell 2 synchronizes image data with a clock signal in units of one bit. Each image data is stored in a predetermined shift register cell 2 by sequentially inputting the image data and serially transferring the image data between the shift register cells 2.

The latch 3 is for temporarily holding the image data stored in the shift register cell 2. When the latch signal from the printer main body is supplied to the latch 3, the latch 3 shifts. The image data stored in the register cell 2 is taken in simultaneously and in parallel.

The switching element 4 is composed of an AND gate, a switching transistor and the like. When a strobe signal is supplied from the printer main body, the switching transistor is turned on / off based on the image data held in the latch 3. By switching off, the heating resistors R1 to R256 are energized.

Each group G of the shift register 1
In the last stage of the shift register cells 2 belonging to 1 to G4,
Selection circuits B1 to B4 for controlling the input of image data to the shift register cell 2 in the head driving IC in the next stage are connected.

The selection circuits B1 to B4 are connected to the last stage of the shift register cell 2 and a logic circuit connected to the D flip-flop circuit and configured by combining AND gates, OR gates and the like. When a control signal from the outside is input to the D flip-flop circuit, the D flip-flop circuit determines the waveform of the selection signal based on the select data stored in the shift register cell 2 at the last stage. Together with outputting the waveform of the selection signal to the logic circuit, after that,
The image data input to the shift register cell 2 based on the selection signal in the logic circuit, or the selection circuits B1 to B3 from outside without passing through the shift register cell 2
Select either one of the image data supplied to the. Then, when the selected image data is input to the head driving IC, it is input to the head driving IC in the next stage.

Specifically, when the selection circuit B2 determines a low-level selection signal based on the selection data, it selects the image data stored in the shift register cell 2 of the group G2 and outputs the high-level selection signal. If you decide,
Image data supplied from outside without passing through the shift register cell 2 of the group G2 is selected. Then, when the selected image data is input to the head drive IC (D2), the image data is input to the head drive IC (D3).

Next, the case of printing with the above-mentioned thermal head will be described with reference to the timing chart of FIG. In this embodiment, a head drive IC
Will be described as a case in which is divided into two blocks and the number of data inputs is “2”.

First, the head driving ICs (D1 to D3)
By inputting a reset signal from the outside to the D flip-flop circuit in the selection circuits B1 to B3 configuring the shift circuits 1, the selection circuits B1 to B3 are initialized.
All the shift register cells 2 constituting the above are set to be connected in series.

Then, select data consisting of "0" and "1" having the same number of bits (256 bits) as that of the cell 2 is sequentially shifted to all shift register cells 2 bit by bit in synchronization with the clock signal. By inputting to the register cell 2 and serially transferring the input select data between the shift register cells 2, the selection of '0' is made to the last shift register cell 2 in the head driving IC (D1, D3). Data is head drive IC
The select data of "1" is stored in the shift register cell 2 at the final stage in (D2), and at the same time, the select data is input to the D flip-flop circuit connected to the shift register cell 2 at the final stage. Will be.

As described above, since the select data is input to the select circuits B1 to B3 via the shift register cell 2, the select data is sent to the select circuit B1.
To the wiring for supplying to B3 to the head driving IC (D1
D4) and the thermal head do not need to be newly provided, and it is possible to effectively prevent the circuit patterns from becoming complicated.

Based on the select data, the D flip-flop circuits in the selection circuits B1 and B3 select signals having a low level waveform, and the D flip-flop circuits in the selection circuit B2 select signals having a high level waveform. The signal is determined, and the determined selection signal is output to the logic circuit, and the selection circuit B1,
The image data stored in the shift register cell 2 at B3 is selected by the selection circuit B2 from the printer body without being passed through the shift register cell 2 to the head driving IC (D3). As a result, the head drive I
The image data is transferred between C (D1, D2) and (D3, D4), and the transfer of image data is interrupted between the head driving ICs (D2, D3). D1 to D4) are divided into two blocks.

Since the selection circuits B1 to B3 make selections based on the select data stored in the shift register cell 2 at the last stage, the data stored in the shift register cells 2 other than the last stage are '. It may be either 0'or '1'.

If select data of "1" is stored in the shift register cell 2 at the last stage in the head drive IC (D2), the head drive ICs (D1 to D) are stored.
4) is divided into 4 blocks, and the number of data inputs is "4".

Next, the head driving ICs (D1 to D)
4) The image data for one line is divided into two sections on the printer side corresponding to the block number “2”, and these image data are synchronized with the clock signal to drive the head driving IC ( D1 to D4) are simultaneously input in parallel and the input image data is serially transferred between the shift register cells 2 in the block, so that all the image data of the first line constitutes the shift register 1. Stored in the shift register cell 2 of

As described above, a plurality of head driving ICs (D
1 to D4) are divided into two blocks, and the image data is supplied in parallel to the head driving ICs (D1 to D4) of these blocks.
Since two pieces of image data are simultaneously input to the printer, the shortening of the transfer time of the image data is significantly shortened, and a thermal head compatible with high-speed printing can be realized.

Moreover, in this case, the head drive IC (D1
.. to D3), selection circuits (B1 to B) for controlling input of image data to the shift register 1 of the head driving IC in the next stage.
Since 3) is provided, the number of data inputs can be changed based on the select data input to the selection circuits (B1 to B3). Therefore, a single thermal head pattern can handle a plurality of types of data input, which simplifies manufacturing control and also reduces costs and improves the productivity of thermal heads. It will be possible.

Subsequently, a latch signal is supplied from the printer body to the latch 3 and the image data in the shift register cell 2 is taken into the latch 3, and then the output from the latch 3 and the strobe signal from the printer body are input to the switching element 4. When the strobe signal is supplied by the operation of the switching element 4, the heating resistors R1 to R1 are supplied.
R256 is individually and selectively exothermicized, which causes the first
The line is printed.

Thereafter, the image data of the second line divided into two sections are simultaneously input in parallel to the shift register 1 in the head driving ICs (D1 to D4) of each block in synchronization with the clock signal. Hereinafter, by repeating the same operation as the case of printing based on the image data of the first line, the printing up to the final line is formed.

The waveform of the selection signal is the selection circuit B1.
~ Output from the D flip-flop circuit in B3 to the logic circuit is stored as it is in the logic circuit. Therefore, once the head driving ICs (D1 to D4) are divided into blocks, the number of data inputs is changed. Unless otherwise, it is not necessary to input select data and control signals to the selection circuits B1 to B3.

The present invention is not limited to the above-mentioned embodiments, and various modifications and improvements can be made without departing from the gist of the present invention.

For example, in the above-described embodiment, the latch 3 is integrated in the head driving IC (D1 to D4), and the image data stored in the shift register cell 2 is temporarily held by the latch 3. I tried to hold it,
The latch 3 is not always necessary, and the output of the shift register cell 2 may be directly supplied to the switching element 4 without integrating the latch.

In the above embodiment, the select data is input to the select circuits B1 to B3 via the shift register cell 2, but instead of this,
Even if the select data is directly input to the selection circuits B1 to B3 without passing through the shift register cell 2, the image data can be supplied to the shift register 1 of each block simultaneously and in parallel, and the data input can be performed. Since the number can be changed, it is possible to realize a thermal head that can easily support high-speed recording and can improve productivity.

Further, in the above-described embodiment, the blocks of the head driving ICs (D1 to D4) may be divided in correspondence with the heat generating area used for printing, for example, the effective printing width ( The maximum width that can be printed is divided into heating area and non-heating area into blocks, and image data is supplied only to the heating area, as when printing on B5 size paper using an A3 size thermal head. You may choose to do this.

[0042]

According to the present invention, a plurality of head driving ICs provided in the thermal head are divided into N blocks (N is a natural number of 2 or more) and image data for one line is divided. , The image data is divided into N sections corresponding to the blocks and these image data are supplied to the shift register of each block simultaneously and in parallel, so that the transfer time of the image data is significantly reduced. This means that a thermal head compatible with high speed recording can be realized.

Further, according to the present invention, a head driving IC
Since the selection circuit for controlling the input of the image data to the shift register of the head driving IC in the next stage is provided therein, the number of data inputs can be changed based on the selection data input to this selection circuit. . Therefore, a single thermal head pattern can handle multiple types of data input, simplifying manufacturing control and
The cost can be reduced and the productivity of the thermal head can be improved.

Further, according to the present invention, since the select data is inputted to the selection circuit via the shift register cell which constitutes the shift register, the wiring for supplying the select data to the selection circuit. Need not be newly provided on the head driving IC and the substrate on which the head driving IC is mounted, and it is possible to effectively prevent the circuit patterns from becoming complicated.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a thermal head of the present invention.

FIG. 2 is a circuit diagram of a head drive IC that constitutes the thermal head of FIG.

FIG. 3 is a timing chart when a printing operation is performed using the thermal head of the present invention.

[Explanation of Codes] R1 to R256 ... Heating resistors, D1 to D4 ... Head driving IC, B1 to B4 ... Selection circuit, 1 ...
Shift register, 2 ... shift register cell, 3 ...
.Latches, 4 ... switching elements

Claims (5)

[Claims] 1. A thermal head comprising a large number of heating resistors and a shift register for serially internally transferring image data for individually controlling energization of the heating resistors, wherein the shift register is M The head drive ICs are divided into a plurality of groups each consisting of a number (M is a natural number of 2 or more) of shift register cells, and each group is integrated in the head drive IC. A thermal head characterized in that a selection circuit for controlling input of image data to a shift register of a head driving IC at the next stage is connected to the last stage of the shift register cells belonging to the group. 2. A plurality of head driving ICs provided in the thermal head according to claim 1 are divided into N (N is a natural number of 2 or more) blocks, and image data for one line is recorded. A method of driving a thermal head, characterized in that the image data is divided into N sections corresponding to the blocks and these image data are supplied in parallel to the head driving ICs of the blocks for each section. 3. The thermal head according to claim 2, wherein the number of blocks of the head driving IC is variable based on select data input to a select circuit of the thermal head according to claim 1. How to drive the head. 4. A number M of serially transferring image data for heating and driving a large number of heating resistors of a thermal head.
A head driving IC provided with (M is a natural number of 2 or more) shift register cells, wherein image data stored in the shift register cells or the shift register cells is passed to the last stage of the shift register cells. An IC for driving a head, comprising a selection circuit for selecting either one of image data input from the outside without any selection based on a selection signal and outputting the selected image data to the outside. 5. The waveform of the select signal is determined based on select data stored in the last stage of the shift register cell and a control signal from the outside.
An IC for driving a head according to item 1.