JPH0141509B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive for a thermal recording head in thermal printers and facsimile machines.

In general, thermal printers use thermal recording paper that develops color with heat, and a thermal recording head is brought into contact with the surface of the paper to develop and record a colored dot pattern. Pixel-shaped heating elements for one line are provided, and voltage application to each heating element is controlled according to input image information (digital signal), and images are recorded while moving the recording paper in the sub-scanning direction. That's what I do.

Conventionally, in such a thermal recording head, when controlling the drive of a large number of heating elements for one line (for example, 1728 heating elements are required to apply to A4 size recording paper), it is necessary to A diode is connected to each power supply line, and each n block is divided into m groups, and diodes are sequentially selected for each group using an n-bit shift register that transfers input image information. In this way, the drive circuit is simplified by driving the drive circuit while keeping the drive current.

However, in such a conventional thermal recording head driving method, n diodes are selected while sequentially shifting the input image information pixel by block, and this is repeated m times for one line. Since the thermal recording head is driven by executing the data, in order to increase the driving speed, due to the transfer time of the shift register that performs data transfer (particularly if it is placed near the heating element) There is a natural limit to the shift register provided (the clock time cannot be made very short). In addition, if such a drive method is adopted, from the viewpoint of the actual circuit configuration, it is necessary to connect the same number of diodes as the heating elements, and to perform multiple wiring to the shift register for each block group. In addition, since the number of wires is extremely large, contact between pads and bumps, which are the connection points between the board and lead wires, becomes a problem when converting the drive circuit to an IC, making it necessary to make high-density connections. is becoming difficult.

The present invention has been made in consideration of the above points, and
It is an object of the present invention to provide a driving device for a thermal recording head that can drive the thermal recording head at high speed and has a circuit configuration that is especially advantageous when integrated into an IC.

In the thermal recording head driving device according to the present invention, drive control of each heating element of a thermal recording head having a plurality of heating elements for one line is performed while sequentially transferring input image information pixel by pixel using a shift register. In order to increase the speed, the drive units corresponding to each heating element are divided into an even number group and an odd number group, and the drive control is performed while adjusting the data transfer timing for each group. There is.

Furthermore, when implementing the thermal recording head drive device according to the present invention into an IC, the even and odd groups of the drive units corresponding to each heating element are divided into small blocks and made into chips, so that the chip area is not increased. The above-mentioned problem during high-density processing is solved by incorporating the chip on the same substrate on which multiple heating elements are formed, using a special method that allows the terminal spacing to be widened without the need for That's what I do.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows the circuit configuration of a driving device for a thermal recording head according to the present invention, in which a plurality of heating elements H1, H2, ..., H8, ... (parts of which are shown in the figure) for one line are shown. _Switch elements Q1, Q2, . . . , Q8, .
SR2, ..., SR8, ... are respectively provided, and the odd-numbered shift registers and even-numbered shift registers are connected in cascade, respectively, and clock signals CLOCK1, CLOCK1, and CLOCK1 of different systems are respectively connected.
The input image information DATA sent from the outside according to CLOCK2 can be divided into two systems and sequentially stored and transferred.

In the thermal recording head drive device configured in this way, each shift register SR in an odd numbered column is
Input image information DATA to 1, SR3,…, SR7,…
A clock signal that causes data transfer to occur sequentially.
For CLOCK1, each shift register SR2, SR4, ..., in the corner sequence with the same frequency as CLOCK1
By delaying the phase of the clock signal CLOCK that sequentially transfers the input image information DATA to SR8, ... by half a cycle, the odd column shift register group and the even column shift register group transfer one pixel at a time alternately. The shifted data is extracted and transferred separately. At that time, odd-numbered switch elements Q1 and Q
3,..., Q7,... are controlled to open and close as appropriate,
Similarly, depending on the data transfer of the other side, even-numbered switch elements Q2, Q4, ..., Q8, ... are controlled to open and close as appropriate, and as a result, one line of heating elements H
1, H2,..., H8,... are clock signals CLOCK
It is sequentially driven at twice the input image information DATA reading speed by CLOCK 1 or CLOCK 2.

Therefore, in the drive device for a thermal recording head according to the present invention, the clock signals CLOCK1 and CLOCK2 are
It is possible to greatly adjust the driving speed of the thermal recording head by simply changing the frequency of the recording head. Especially when trying to speed up the clock signal CLOCK1,
Shift register SR using CLOCK2 frequency
By setting the value to the minimum allowable value, it becomes possible to drive the thermal recording head at high speed, which was not possible with the conventional drive method described above. Note that FIG. 2 is a flowchart of signals for each part in the drive device for the thermal recording head shown in FIG.
is the timing clock for reading the input image information DATA, FIG. There is.

FIG. 3 shows another embodiment of the thermal recording head driving device according to the present invention. In this case, as in the embodiment described above, each data transfer to each of the shift register groups in the even and even columns is performed. A series of shift registers SR1, SR2, ..., SR8, SR8, SR8, SR8, SR8, etc. are controlled by a single clock signal CLOCK instead of timing by two clock signals CLOCK1, CLOCK2.
Input image information DATA is sequentially sent to..., and latch circuits L1, L2,..., L8,... are provided on the drive output side of each shift register SR, and each latch is activated by a store signal STORE sent from the outside. The circuit L is appropriately controlled to input image signals corresponding to each heating element H.
Note that STROBE in the figure indicates a strobe signal for giving a heat generation standby time to the output of each latch circuit L.

FIG. 4 shows the configuration of the drive device for the thermal recording head according to the present invention described above when it is integrated into an IC.
An IC chip 5 incorporating the aforementioned drive circuit shown in FIG. 1 is placed on a ceramic substrate 4 on which a heating element portion 1 is formed in the center and bus wiring boards 2 and 3 are attached to both sides. It is made up of things. At this time, the drive units corresponding to the large number of heating elements H for one line are divided into blocks into n groups, and each odd-numbered drive unit and each even-numbered drive unit of each block is separately integrated into ICs.
Chips 51, in which odd-numbered driving parts are chipped, are arranged on one side of the central heating element section 1, and chips 52, in which even-numbered driving parts are chipped, are arranged on one side of the central heating element section 1. A pair of upper and lower IC chips 51 and 52 are arranged on the other side of 2.
Thus, one block of drive section is formed. Each of these IC chips 5 is arranged on a ceramic substrate 4 via a tape carrier (insulating sheet) 6.

FIG. 5 shows an enlarged structure of part A in FIG. 4. In this case, eight sets of drive sections are integrated into one block, and an IC chip 51 incorporating an odd-numbered drive section among them is A power supply _Vp line 7 printed on the ceramic board 4, a terminal 8 led out from it to each heating element H, and a clock signal CLOCK printed on the bus wiring board 2.
A ground wire provided on the tape carrier 6 covered over one line 9 and printed wiring from above the tape carrier 6 onto the bus wiring board 2.
It is appropriately connected to the GND line 10 and input image information DATA line 11 through terminals 12, respectively, and similarly connected to each heating element H through terminals 13 from above the tape carrier 6. In addition, at this time, the terminal 8 connected from the power supply V _p line 7 to the heating element H and the terminal 8 connected from the IC chip 5 to the heating element H
The terminals 13 connected to the terminals 13 are arranged alternately at a predetermined interval d. Further, the mounting and wiring methods of the IC chips 52 incorporating even-numbered drive sections are also carried out in the same manner. In the figure, 14 indicates the earth GND line printed on the bus wiring board 3, 15 indicates the input image information DATA line, 16 indicates the clock signal CLOCK2 line, and 17
is the power supply printed on the ceramic board 4
V _p line is shown.

As described above, in the thermal recording head drive device according to the present invention, when implementing the IC, it is necessary to distinguish between the odd numbered drive unit and the even number drive unit of each heat generating element H divided into n groups. are made into separate IC chips, arranged so as to correspond to both sides of the heating element section, and provided on various lines via tape carriers 6. Spacing 2 between terminals 13 each connected to heating element H
d can be made wider (double the spacing of the conventional one), and the terminal 13 can be easily pulled out without adjacent pads and pump parts coming into contact with each other. At the same time, the space factor improves, making it possible to achieve even higher density.

As described above, in the thermal recording head driving device according to the present invention, a switch element is provided in each drive power supply line of a plurality of heating elements for one line, and each switch element responds to input image information. 1-bit shift registers are provided to control the opening and closing of the shift registers, and the odd-numbered shift registers and the even-numbered shift registers are connected in cascade, each having the same frequency, and each having the same frequency. The shift register groups in each column are operated by two systems of clock signals whose phases differ by half a cycle.This allows the thermal recording head to be driven at high speed, and also allows the thermal recording head to be driven at high speed.
It has excellent advantages in terms of terminal connections and higher density when integrated circuits are integrated.

[Brief explanation of drawings]

FIG. 1 is an electrical wiring diagram showing an embodiment of a driving device for a thermal recording head according to the present invention, FIG. 2 is a flowchart showing the timing of operation of each part in the same embodiment, and FIG. FIG. 4 is an electrical wiring diagram showing an embodiment of the present invention, FIG. 4 is a diagram showing a driving device for a thermal recording head implemented as an IC, and FIG. 5 is an enlarged view of section A thereof. 1... Heat generating element part, 2, 3... Bus wiring board,
4... Ceramic substrate, 5, 51, 52... IC
Chip, 6...tape carrier, H...heating element, Q...switch element, SR...shift register, L...latch circuit.

Claims (1)

[Claims] 1. A switch element is provided in each drive power supply line of a plurality of heating elements, and a 1-bit shift register is provided for each of these switch elements to control opening and closing according to input image information, and The odd-numbered shift registers and the even-numbered shift registers are connected in cascade, respectively, and the odd-numbered and even-numbered shift registers are connected in series by two systems of clock signals, each having the same frequency and having a phase different from each other by half a cycle. A driving device for a thermal recording head configured to respectively operate each even numbered shift register group.