JPS63207663A - Printing controller in thermal printer - Google Patents

Abstract

PURPOSE:To transfer data serialy to enable a high-speed printing, by a method wherein, a printing controller stores data for a plurality of heating elements, shift registers are connected in series and divided by N-pieces into register groups, the register groups are used as data storage circuits for the heating elements, and a conduction time to an arbitrary heating element is determined by a gate circuit. CONSTITUTION:New data is transferred from an S-IN terminal to be stored in a first register group. If the data at the present time exists in a register 5a, the data transferred one time before is retained in a register 5b, and the data transferred two times before is in a register 5c; thus, the shift registers retain the data from the past to the present. Gate circuit units 9 connected to data storage circuits determine conduction times on the basis of the stored data for a heating element of its own and the stored data for the adjacent heating element. A CPU 4 writes the present data and imparts a conduction interval signal to a head control circuit 1. Then, the conduction time to a heating element is automatically selected by the gate circuit units 9. A stable printing density is ensured by putting the temperature information of a thermal head in the conduction interval signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is applicable to thermal printers, and particularly to a control circuit for controlling heat generation of a heat generating element thereof.

[Conventional technology]

Conventionally, in thermal printers, in order to prevent low printing quality due to zero drop during continuous use of the thermal head,
Various methods are used. As an example of this, a head drive IC with a latch circuit shown in FIG. 4 is mounted on a thermal hept, and it has been common practice to determine the energization time to the heat generating element by changing the data based on the past driving history.

FIG. 4 is a schematic diagram of a conventional thermal printer according to an embodiment of the present invention, and 51 is a head drive IC;
53 indicates a thermal head, and 53 indicates a C)U, respectively. The head drive IC includes a shift register 54, a latch circuit 55, an AND gate 56, and a drive transistor 57. 52 a is a heating element, 52
b Shows the power supply terminal: Data is sent from the data input terminal to the input terminal P53a from P U 53 in synchronization. This is taken into the latch circuit 55 using the latch input terminal f'53c, and is passed to the heat generating type m52a of the thermal head by the enable terminal 53d.
Determine the time.

In the thermal printer of this conventional embodiment, in order to control the energization time for each heat generating element, it is necessary to send data from the data input terminal several times to update the data.

[Problem that the invention seeks to solve]

In these conventional examples, data is transferred serially, so the data update time cannot be ignored, and especially in thermal heads that require high resolution, the number of dots is 248 or more in serial heads, which must be operated at high speed. If an attempt is made to do so, the number of times data is updated due to the history will increase in order to suppress heat accumulation. For this reason, C
I'U requires data processing and data transfer, and cannot be completed in a short period of time, which has its limits and is an obstacle to achieving higher speeds. An object of the present invention is to provide a print control device for a thermal head that can perform high-speed printing while serially transferring data.

[Bottom section for solving problems]

The print control Halt of the thermal printer according to the present invention is as follows:
At least NX3 or more shift registers that store and transfer data for a plurality of N heat generating elements to be controlled are connected in a straight line, and these are divided into N shift registers.
. . . The nth register group is set, and the register 1IT- is used as the data transfer input terminal. From this direction, the current, the past one time, the past two times ... the data storage circuit of the heating element of the nth past past. This is a printing control device for a thermal printer which has a head control circuit characterized in that the energization time of an arbitrary heat generating element is determined by a gate circuit connected to the eight data recording circuits.

〔Example〕

FIG. 1 is a schematic diagram of an embodiment of a print control device for a thermal printer according to the present invention.

1 is a head control circuit which is generally implemented as an IC such as a gate array. A thermal head 2 has a heat generating type M2a and is connected to the head driver 3. - The number of heating elements to be controlled by way of example is shown as N=24.

Reference numeral 4 indicates a C l) U that centrally controls the thermal printer.

The head control circuit L connects at least 2-' circuits of N shift registers 5 connected in 11' columns. And it has more than knits. In this embodiment, the number of shift registers is NX3. The first register J! H), m2 rugister group 7, in the 7th (
This is register group 8. When converting the head 1ilJ control circuit into an IC, in order to enable expansion, N pieces are cut in advance and placed outside the IC as shown in Figure 1 (17-18).
(it)-20). 11 is a clock input terminal of the SIT register 5, and l! to which serial data is sequentially sent. It inputs the 111 signal of I.

When the latest data is transferred from the 5-IN terminal, it is recorded in the first register group tα. This is the current data. The previous data is moved to the second register group,
The data from two previous times remains in the third register group. In the connection method shown in FIG. 1, when the current data is in the register 5a, the data one time before is stored in the register 5b, and the data two times before is stored in the register 5c. In this way, the shift register uses the data record as a gold circuit to store data from the present to the past.

0 is a gate circuit unit connected to these data 2118 circuits, which determines the energization time based on the own stored data of any heat generating element and the stored data of adjacent heat generating elements. 13 is an energized section (It number rgr), which is connected to each of the gate circuit units 9.The gate circuit unit 9 usually has N gate circuits, and there are gates connected to the heat generating elements at both ends. The circuit unit 0 has an extension input terminal 14 (r
However, an additional output terminal is provided from the shift register, so that the influence of adjacent heat generating elements can be incorporated into the energization time of the heat generating elements at both ends when the shift register is expanded. 16 is a serial data out terminal (S-OUT terminal).

A register 5a stores current data, and a register 5b stores the previous past data.

The current energization time is determined by the register 5c1 which stores the data of two previous past data (Il, ~H14) and transmitted to the head driver 3. 3a is a head drive terminal.

Figure m2 is an explanatory diagram showing the output waveform of the energized section signal output from CI) U/l, and 21 is the output terminal 13b.
22 shows the output waveform of the output terminal 13c, 23 shows the output terminal 13d, and 24 shows the output terminal r of the output terminal 13a, and the pulse widths are ts, tm, Ll, L.
T indicates the energization period.

FIG. 3 is an explanatory diagram showing head drive signals generated by the gate circuit unit 9.

41, 42, and 43 indicate data in the shift register, where 1 is on data and 0 is off data. 41 shows the current data, 42 shows the data from the previous one, and 43 shows the data from the past two times. The data is 11 from the top. , II, ...1 irises, and 31.32.33 are Il, respectively.
, If, , Il, output waveforms are shown.

When the power generation element is turned on twice in a row, the energization time is reduced, and when it is turned on three times in a row, it becomes ts+L.
*Time is reduced. (As shown in output waveform 31 in FIG. 3) When the previous data is off data and the previous data is on data, only 18 hours are reduced (as shown in output waveform 32), and the adjacent top - When two dots are on data at the same time, the t1 interval is reduced.

(Indicated by output waveform 33) In this way, the current energization time is selected from the gate circuit unit 9 based on the combination of past drive data and is output.

The CPU 4 only writes the current data and supplies the energization period signal to the head control circuit 1, and there is no need to update the data many times during one print cycle. The time for energizing the heat generating element is automatically selected by the gate circuit unit 9, and a time 111 suitable for the temperature condition of the heat generating element is generated.

The head control circuit 1 can be integrated into an IC and connected to the thermal head.

By including the temperature tff information of the thermal head in the energization period signal, printing t51I? is stable at 7K against temperature changes? It is possible to ensure that

〔Effect of the invention〕

According to the present invention, high-speed control of thermal printers is possible to extremely NIF-, and printing quality is improved because heat 1inWP, v4 control, which was conventionally limited by updating data, is handled by hardware. And 1! ′! i
This made it possible to improve speed and performance all at once.

Furthermore, since it is possible to increase the number of stages according to the number of heating elements, it is possible to apply it to high-speed facsimiles using line heads, and the range of its application and effects are remarkable.

Note that the number of shift registers is not limited to 1 in NX, and by increasing the number, it can be made more fine-grained (
Achieving heat generation control becomes an illumination function.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of a print control device for a thermal printer according to the present invention. FIG. 2 is an explanatory diagram showing the output waveform of the energization interval signal manually input to the head control circuit. FIG. 3 shows print control 5A of the thermal printer 7 according to the present invention.
An explanatory diagram of head drive signals output from the printer. Figure 4 is a schematic diagram of a conventional thermal printer. i... Head control circuit 2... Thermal head 4... CI) U 5... Shift register 9... Gate circuit unit and above Applicant Seiko Epson Corporation Figure 2 Figure 3

Claims (1)

[Claims] A thermal printer that uses a thermal head having a plurality of heat generating elements to print directly on thermal paper or on plain paper via a thermal transfer ribbon, the drive history of the heat generating elements being stored at least twice in the past; In a thermal printer that controls the energization time of each heat generating element based on the storage result, at least N x 2 shift registers are provided to store and transfer data of a plurality of N heat generating elements to be controlled. The above are installed so that they can be connected in series, and are divided into N register groups to form the first, second, ... nth register group. The previous past, the past two times ago,...n
Printing control of a thermal printer having a head control circuit characterized in that it is a data storage circuit for the heating element in the past, and the energization time of any heating element is determined by a gate circuit connected to the data storage circuit. Device.