JPH01125251A - Thermal head drive device - Google Patents

Abstract

PURPOSE:To obtain a satisfactory recording image which is free from unevenness and can be well reproduced by providing a storage means to store representative values from a monitor drive temporarily and a correction means to correct image input data in accordance with each IC output. CONSTITUTION:Data is output from each IC chip monitor driver 4 on a line head substrate 20 against the same input data. A monitor output terminal 5 is connected by a common monitor terminal 21. The measurement of IC chip output is repeated by the number of times corresponding to the number of pieces of chip, and thereby the data is converted by an A/D converter. This converted data is stored in an IC data memory. IC output data is controlled for addressing, and an appropriate table corresponding to an unevenness in the output of each IC chip is selected from a correction table 18. After being input, image data stored in a buffer memory 19 is corrected by the selected correction table. The corrected data is output to a thermal head through a data conversion circuit 16 to perform recording.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal printer, and particularly to the configuration of a driving device for a thermal head.

[Summary of the invention]

The present invention provides a thermal head drive device that is equipped with a monitor driver that reads variations in output between a plurality of driver edges, and corrects human input data in advance using the read data to reduce uneven printing. It is something.

[Conventional technology]

A conventional line-type thermal head drive device has a plurality of driver IC chips mounted on a substrate, and has a configuration in which the line head is driven while controlling the driver IC chips through a control line.

[Problem that the invention seeks to solve]

However, if multiple driver IC chips are simply connected and driven using control lines, the output of each ICV chip will vary by ±20 to 30% due to IC manufacturing. Even with monochromatic samples, density unevenness appears, leading to a decline in print quality.

Therefore, in order to solve the above-mentioned problems, the present invention aims to realize a configuration in which printing unevenness does not occur even if there are variations in the output of a plurality of driver IC chips, and good recorded image reproducibility can be obtained. There is.

[Means for solving problems]

The thermal head driving device of the present invention includes α) a thermal head driving device using a plurality of driver ICs, b) a monitor driver that outputs a representative value of the output voltage of each chip on the driver chip; and C) [Function] The above aspect of the present invention is characterized by comprising: a storage means for temporarily storing the representative value from the monitor driver; and d) a correction means for correcting the image input data according to the output of each device. According to this configuration, the representative value of the output voltage of each driver chip can be measured by the monitor driver, and the image input data can be corrected according to the representative value.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a simple structure of a driver IC chip constituting the present invention. In the figure, 1 is a driver element, and 2 is a driver output terminal. Reference numeral 3 designates terminals such as a control wJ signal input, a data input, a mode switching signal input, and an m source. 4 is a monitor driver, and 5 is a monitor output terminal. The monitor driver 4 is formed by the same process as the driver element 1, but its size and capacity are 20 to 20 times larger than that of the driver element 1.
It is about 50%.

FIG. 2 is a block diagram of the electronic circuit of the driver air O constituting the thermal head driving device of the present invention. On the ICV chip used in the present invention, there are a driver circuit 6 connected to the heat generating electrode, a shift register 7 for replacing image input data, and a latch circuit 8 for temporarily storing image signals output from the shift register. It is set up.

The image input data input to the shift register 7 from the serial data input terminal 9 is sequentially shifted to the right according to the clock signal 10, and is transferred from the serial data output terminal 11 to the next adjacent chip.

In this way, the image data for one line that has been stored is
The process moves to the latch circuit 8 at the timing of the latch signal 12. Here, an AND gate is provided at the output section of the latch circuit 8, and the latched data is output only when the mode switching signal 13 or print mode is input to the gate terminal. When the image data output from the latch circuit 8 is given to the driver circuit 6, the electrodes are selectively energized according to the pulse width of the image data. In this manner, until one line of recording is completed, the next one line of image data is input from the serial data input terminal 9 and is ready for output. When the mode switching signal 13 is input to the gate terminal as a monitor mode, AND gates G1 to G are all closed, and data is transmitted only to the first stage latch output and the lower monitor 4D forming the AND gate GrIL. Output.

Next, a system block diagram and a monitor sequence diagram of a thermal head driving device of the present invention using an ICV chip having such a configuration are shown in FIGS. 3 and 4, respectively.

First, the mode switching signal 13 is sent from the system control circuit 14 to the head 15, and the 0
Next, one pulse signal is input from the system control circuit 14 to the head 15 via the data conversion circuit 16 at the same period as the latch signal 12 for the same number of clock signals 10 as the drivers of the driver IC pre-chip. In response to the input data, the line head board 20 as shown in FIG.
Monitor driver 4 of 10 O chips mounted on top
Data is output for each digit. These monitor drivers 4 have their monitor output terminals 5 connected to a common monitor, 1I21, as shown in FIG. Such ICV chip output measurement is repeated a number of times corresponding to the number of chips, that is, 10 times, and the data is A/D converted and stored in the ICV data memory 17. The ICV output data is address-controlled by a system control circuit 14,
Among the 16 ranks of correction tables 18, an appropriate table is selected according to the variation in output of each IO chip. The image data stored in the buffer memory 19 after input is
Corrected for each selected table. The correction data is stored in the data conversion port w1 in the print mode.
16 to the head for recording. K-5
- By doing so, a stable output that does not depend on variations between driver chips appears in the head.

In the embodiments described above, the correction table is not limited to 16 ranks, but by increasing the number of ranks, it becomes possible to perform more faithful corrections adapted to output variations between driver IC chips.

The present invention is effective for all printers that use a plurality of driver ICs, and can be applied to embodiments other than those described here.For example, image contrast in an electro-optical display device such as a liquid crystal using a plurality of driver ICs. It is also effective in reducing unevenness.

〔Effect of the invention〕

As described above, according to the present invention, by providing a monitor driver on the driver IC chip that outputs the representative value of the output voltage of each IC chip, image input data can be corrected in advance according to variations in this output. Therefore, even if there are variations in output between driver IC chips, a stable output appears in the head. Therefore, printing unevenness does not occur and good recorded image reproducibility can be obtained.

-4-8- #Power 1 H Kidney Surplus ,−°　　　　　Ka

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a simple structure of the Dryno chip according to the present invention. FIG. 2 is a block diagram of the n-child circuit of the Dry ICV according to the present invention. A system block diagram of a thermal head driving device according to an embodiment. Fig. 4 is a monitor sequence diagram showing the operating procedure in monitor mode. Fig. 5 is a system block diagram of a thermal head driving device according to an embodiment of the present invention. A simplified plan view of the substrate. Fig. 6 is a diagram showing the density distribution in the X-axis direction of a monochromatic sample recorded using a conventional thermal head driving device. 4...Monitor driver 17... ...IC data memory 18...Correction table and above Applicant Seiko Epson Corporation Figure 7 Figure 2 Figure e

Claims (1)

[Claims] (1) a) A thermal head drive device using a plurality of driver ICs, b) a monitor driver that outputs a representative value of the output voltage of each ICV chip onto the driver IC chip, and c) a representative value of the output voltage from the monitor driver. 1. A thermal head driving device comprising: storage means for temporarily storing values; and d) correction means for correcting image input data according to respective IC outputs.