JPS59196271A - Drive apparatus - Google Patents

Abstract

PURPOSE:To make it possible to suppress the rising in the temp. of a head, in the drive apparatus of a printer, by subjecting a light emitting body or a heat generating body to time sharing driving while controlling a driving time corresponding to driving frequency and the temps. of a drive element and the head. CONSTITUTION:Printing data of a first line and a second line are inputted to a shift register 1 and successively sent to latches 2a, 2b at every line to be converted to parallel data. On the other hand, a select signal group 9 controls the time sharing drivings of drivers 3a-3d and controls driving time pulse amplitude during passage through a select signal change-over circuit 14 on the basis of the output signal 15 of a data comparator so as to make the same narrow, for example, when the power consumption of a print head is large. Therefore, the driving currents of the drivers 3a-3d are reduced and the rising in the temp. of the head 4 is suppressed. By this mechanism, a thermal print head can be highly densified.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a driving device for a light emitting element or a heat generating element (for example, a print), which has a temperature and power consumption control function.

As shown in FIG. 1, the conventional print head writes data 6 to a shift register 1 using a shift clock 5, holds data 6 using a latch 2, and then writes data 6 to a drive element 3.
was used to drive the head resistor 4 to perform printing. In this method, the head resistor 4 and the drive element 3 consume a drive current equal to the number of drive heads (for example, 32 bits). This power consumption generates so-called Zeel heat,
Heat has accumulated on the mounting board. Therefore, in the case of continuous driving, even when the drive signal 8 is in the #OFF f state after driving, the heat capacity of the head and the head mounting board is large, so the temperature of the print head remains elevated without sufficient heat dissipation. It had become. As a result, in the case of a thermal print head using thermal paper, the printing contrast may be reduced, the printing may be unclear, or the entire thermal paper may become sensitive to heat (for example, 70"C) and the entire surface may change color, resulting in poor printing quality. Note that 7 is a latch enable.

The present invention suppresses the temperature rise of the drive element and print head, and also averages out the temperature rise due to the generation of Joule heat by using the drive part of the print head in a time-sharing manner in order to maintain print quality. In the case of continuous driving, the purpose is to reduce the driving pulse width, reduce the driving current, and suppress the temperature rise.

The embodiments of the present invention will be explained in detail using FIG. 2 below.

I will clarify. FIG. 2 shows a block diagram of the drive device of the present invention, which includes a shift register 1, a shift register 2α, and a latch 2b.
, driver 3a, ~3d, to print/sodo 4, day
The comparator includes a select signal switching circuit 14. Note that 5 digits are shift clocks, 6 is filled with data for printing, 7α and 7b are latch enable, and 20 is a comparison enable word. Also, latches 2α and 2b are
Data A and B are output from each. First, the data to be printed on the 1st line (or 1st column) and the data to be printed on the 2nd line (or 2nd column) are input to the shift register 1, and they are transferred to the first and second rows. Nochi 2α and 2b
will be sent sequentially. In other words, serial data data; parallel 1j
data. Therefore latch 2bVC is 1
The data for the line next to the line to be printed is always present in the latch 2α, such as the data for the second line in the line 2α.

The select signal group 9 controls the time-division drive of Drino (6α to sd) and also controls the I/C drive time when passing through the select signal switching circuit 14 by the K (for example, 4 bits) data comparator output signal 13. In other words, when the power consumption of the print head is large as shown in FIG. The drive current of a and ~3d is reduced to suppress the warm rise.

Note that the select signals SO to S are signals for selecting the three drivers 3α to 3d, respectively. Further, 21 is a group of drive input terminals.

FIG. 5 is a detailed circuit diagram of the driver 3a shown in FIG. 2. Drive elements 10α to 10 and drive control gates 11α to
11/L. The drive signal group 21 (for example, 32 bits) from the latch 2b is time-divided (for example, divided into four) as shown in FIG. However, as shown in FIG.
It consists of 15 hours. In comparison with the case of simultaneous driving in FIG. 3, the heat generation is averaged out in this case.

If the heat dissipation conditions are equalized, it is possible to avoid the sudden rise in temperature as described above, thereby improving reliability and completely avoiding the adverse effects of transient currents on the logic system by reducing the power supply current. be able to.

Furthermore, when continuous electric pulses are input to a print head that requires high-speed printing, a sudden increase in temperature is unavoidable. If the same bit is driven twice in a row, or if two successive bits of the same driver are driven, the temperature of the head will reach close to the thermal threshold of the thermal paper, so It must be possible to print using the same amount of power. By comparing data A and data B of latch 2a and latch 2b in advance, it is possible to determine whether the drive data of latch B2 is input immediately after the drive data of latch A to the drive signal input terminal (for example), and in other cases. Divided bits, for example, drive signal input terminal D+ -
DsK Check the case (2) in which the drive data is input without gaps.The select signal S has a pulse width reduced according to the number of signals VC of the drive data of the driver 6α so as not to increase the temperature of the head. -83 is the drive signal input terminal.

~D3 to control the drive consumption wealth to decrease.

In this case, there are six types of select signals with small pulse widths available, so you can select an appropriate pulse width from these. It goes without saying that it is possible to control the drive pulse width of the select signal depending on the data content even when driving simultaneously without dividing the drive.In order to make this function even more effective, we have changed the type of data alignment. It goes without saying that the same control method is used even when controlling by increasing the number of latch stages, increasing the depth of comparison data by increasing the number of latch stages, or increasing the depth of comparison data by increasing the number of latch stages. .

As is clear from the above description, the present invention makes it possible to equalize heat generation through time-division driving and suppress maximum power consumption through drive pulse width control through data comparison in a thermal print drive device. It compensates for the weakness of thermal print heads in terms of high density, and makes full use of its advantages.

[Brief explanation of drawings]

Figure 1 shows a typical print head drive device.
FIG. 2 is a diagram showing an embodiment of the present invention that takes into account the temperature rise of the print head. FIG. 3 is a detailed circuit diagram of the driver circuit shown in FIG. 2, and FIG. 4 is a diagram showing an example of a select signal of the drive circuit. 1...Shift register 2α, 2b...Latch 12...Data comparator 17)...Select signal switching circuit 3a, ~3d-
Fist...Koma Driver 4...Print head and above Applicant Daini Seikosha Co., Ltd. Agent Patent Attorney Tsutomu Mogami Figure 1 Figure 32 Figure 3I21 Figure 4

Claims (1)

[Claims] A drive device that performs time-division driving for driving a light emitting element or a heating element, and controls the driving time according to the driving frequency, driving element, and head temperature.