JPS58197955A - Heat sensible type printer - Google Patents

Abstract

PURPOSE:To simplify the signal processing and to simplify the circuit configuration, by providing a storage device having capacity of the number of heating elements multiplied by the gradation number bit, writing successively a gradation data by the number of heating elements in said storage device, and reading out the written data by the number of heating elements each. CONSTITUTION:A controlling circuit of a heating element is provided in a head housing of a heat sensible printer, and a two bit data converted to PWM, having pulse width corresponding to density of each picture element from an input terminal 26 is inputted to an RAM25 of its controlling circuit, and is written under the control of address counters 14, 18. Capacity of this RAM25 consists of the number of heating elements X gradation number bit, and the data written in this RAM25 is read out to a head drive 20 by the number of heating elements each. In this way, by using the RAM25, a data from an ROM of the pre-stage of an input terminal 26 is converted to a parallel data and provided to a heating element 6 through the driver 20, and the process for processing a signal is simplified, and the circuit configuration is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal printer that simplifies the process of signal processing.

A thermal printer uses a single rotating drum (1
) thermal ink paper (3) wrapped around recording paper (2)
The ink on the ink paper (3) is transferred to the recording paper (2) by heating the ink paper (3) locally with the heating head (4) from above.
It is designed to be attached to. When drawing images with shading using this thermal printer, the screen is subdivided into, for example, 1024 x 512 pixels (as shown in Figure 2).
5) with a heating head (6) having 512 heating elements (6).
This is performed by scanning T in the direction of arrow H in step 4). In this case, scanning is performed by moving the head (4) intermittently 1024 times, and during this scanning, each heating element (6) is heated by energizing each pixel for a time corresponding to the density of the image. I do. In addition, in the case of the printer shown in Figure 111, the head (4)
is fixed, and the above scanning is performed by intermittently rotating the drum (1).
Ink paper of four colors, such as magenta, yellow, cyan, and black, is used, and the above scanning is performed for each color.

Figure jI6 schematically shows an example of a circuit configuration for carrying out the above method.

In this example, the energization time of each heating element (6) is controlled according to the density of the image, but this control signal is a PWM signal (pulse width modulation signal) having a pulse width depending on the density of each pixel.
or used. In this case, it is assumed that the density of the 1iIi element is expressed in 32 gradations. Therefore, each element of the video signal has 3
It is converted into a PWM signal with two stages of pulse width. The 512 heating elements (6) are divided into odd-numbered blocks (hereinafter referred to as odd-numbered blocks) and even-numbered blocks (hereinafter referred to as even-numbered blocks), and the two blocks are interlaced. ing.

In Fig. 3, switch Q7) is first closed to contact W, and analog video signal 8m for 1 screen is applied to input terminal (IQ). It may be a signal, for example, reproduced from a magnetic sheet, etc. After this signal S is sampled and held in a sampling and holding circuit, it is converted into, for example, a 5-bit digital video signal sD by an A/D converter a3. In the case of Fig. 2, the sampling is performed for each vertical line indicated by arrow V (hereinafter referred to as V line).

The A/D converted signal SD specifies the address of itoM (read only memory) Ql. This R.U.
M (1:l is preloaded with T data that indicates the gradation for the 328i type data of the 5-bit signal 8D. This gradation data is expressed in 32 bits, and the density Codes of [1] are consecutive for the length corresponding to
1", the lowest density is expressed as "OoO・number of turns 000", and the intermediate density is, for example, "1111100...
・・・・・・・・・It is operated at 0OOJ.

When the address of OM (I) is determined by one data of one word SD, 12 pulses are generated from the generator a.By counting these pulses with the address counter α, ROMQ3 ) is read out.

The extracted gradation data is added to RAM (Random Access Memory) (II) and stored in J Address Callan 1.
．． .

It is sent to the address specified by αhiro. Kottoki V
In order to indicate the pixel data of the line, addresses 1 to 256 indicated by the address counter (c) are written together with the above data. The address counter (to) counts the horizontal synchronizing signal HD applied to the terminal. Furthermore, belief 9. HD is used separated from the signal SM.

In this way, for example, the odd-numbered pixel 2 of the V line
When each gradation data is determined for 56 pieces of data,
The switch aη is switched to the contact R side, and RAMQ~ is read out. Address counter has gradations from 1 to 62 +
Every time the mth visit is made, the address counter (to) starts the oscillator (2
) is counted, and 256 pieces of data corresponding to the gray level are read out. RAM
The serial data read from aI is held at the corresponding address of shift store register a9 and converted into parallel data, and then sent to the corresponding heating element (6) of the head (4) via the head drive circuit. Added. Then, only the heating element (6) to which data "1" has been added is energized, and printing of the corresponding pixel is performed. In this way, only 256 wI fists are performed for each of the 62 gradations, and as a result, each heating element (6) is energized only during the period during which the gradation data "1" continues. That is, each heating element (6 days ciii
This means that a PWM signal having a pulse width corresponding to the degree of immersion is added.

In FIG. 3), the shift store register a9 for converting serial data read from the tAM into parallel data and applying it to the head drive circuit (2) is a shift store register a9 for converting serial data into parallel data. It consists of a register and a latch circuit that latches the output of this register. Generally, this register Ql, head drive circuit MQI, and head (4) are housed in one housing. Further, the RAMQ8 and the circuits in the preceding stage are arranged on a common circuit board, and are connected to this circuit board by the head casing, a flat cable, or the like. Conventionally, since such a head casing is used, there is no RA between this head casing and kLOMQ3.
I used M Qll to convert data.

In the present invention, the above-mentioned shift store register Q1 is omitted and the RAMQI is improved to perform signal processing in a simpler manner.Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 shows a circuit housed in the head logic body, and shows the part surrounded by dotted lines or the head housing.

Note that the same parts as in Figure W46 are given the same reference numerals.

PWM converted 32-bit data from ROMQ3 in FIG. 6 is applied to the input terminal (c). This data is R
AMc! In addition to 51, address counter o41@
They are imprisoned according to the following. This ordinary man MG! 5+ is 256×
It has a capacity of 32 bits and input/output of 256 bits.
It is configured to have that. Data is written to this RAM (to) as shown in FIG. 5, for example. In this case, the 62-bit data is sequentially written 256 times. Furthermore, the written data is extracted 32 times, each with 256 pieces. RAM like this
By using ROMQ;1, serial data obtained from ROMQ;1 can be converted to parallel data without using the register a field in FIG. 813. Also, the head (
RAMP i iw for one heating element (6) in 4)
Since it is sufficient to output 256 outputs in parallel at one time for each of the gradations of the output terminals 1 to 52, the gradation can be switched in a short time.

As described above, the present invention provides a thermal printer with:
A storage device having a capacity equal to the number of heating elements x the number of gradation bits is provided, and the gradation data is sequentially written in the storage device by the number of heating elements.

A thermal printer characterized in that the written data is sequentially read out by the number of gradation levels for each of the heating elements, and each piece of data read out at one time is applied to each heating element. This is related to.

Therefore, according to the present invention, the data processing process is simplified and reliability is improved.

It is possible to shorten printing time.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle of a thermal printer, Fig. 2 is a diagram showing the relationship between a thermal head and a screen, Fig. 6 is a circuit block diagram of a conventional thermal printer, and Fig. 4 is an implementation of the present invention. FIG. 5, a circuit block diagram showing an example, is a diagram showing an example of data stored in the RAM. In addition, in the symbols used in the drawings, (4)・・・・・・・・・・・・Head (6)・
・・・・・・・・・・・・Heating element 0・・・・・・−・
・・・・・・・・・ROMall・・・・・・・・・・・・
・・・Bonmu Kaede 4・・・・・・・・・・・・Head drive times. Agent Satj1ml) l Yoshio Tsuneko l Toshiki Sugiura

Claims (1)

[Claims] A head having a plurality of heating elements is moved relative to the screen to scan the screen, and during the scanning, a PWM signal having a pulse width corresponding to the gradation of image density is applied to each of the plurality of heating elements. In the thermal printer, a storage device having a capacity equal to the number of heating elements x the number of gradation bits is provided, and the gradation data is sequentially written in the storage device by the number of heating elements. The thermal printer is characterized in that the data is sequentially read out by the number of gradations for each of the heating elements, and each readout at a time applies one evening to each heating element. .