JPH06286191A - Controlling method for thermal head - Google Patents

Abstract

PURPOSE:To eliminate a diode and to obviate a deviation, unevenness of recording by applying a voltage to a specific heat generating element by a value of exclusive OR operation with data for indicating presence/absence of a drive of the element. CONSTITUTION:When heat generating resistors R1, R2, R5 generate heats and the other heat generating elements generate heats, data corresponding to the respective elements are transmitted at each one line to a shift register 15 in synchronization with a cock signal CLK from a controller 16. The controller 16 outputs a latch signal LTH to latching circuit group 13. In this case, record data are outputted from the register 15 in parallel to EXOR gate group 14. In this case, since one input terminal of the EXOR gate E1 is grounded, its logical value is '0', and record data of a logical value '1' from the register 15 to the resistor R1 is inputted to the other input terminal. Drive data of the value '1' is outputted from the gate E1 to latch the latching circuit L1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a thermal head used in a thermal recording apparatus, a thermal transfer recording apparatus, etc., for recording on a recording paper by selectively driving a plurality of heating resistance elements to generate heat. Regarding

[0002]

2. Description of the Related Art FIG. 3 is a diagram schematically showing the structure of a conventional alternating read type thermal head. In this thermal head, in order to enable each of the heating resistance elements R1 to R11 to generate heat, the common electrode is divided into the common electrode 1A and the common electrode 1B in the A phase and the B phase, and the common electrode side lead conductor is used. 2 is arranged every other heating element. Then, when recording one line of data on the recording paper, the select signal SEL from the control circuit (not shown) for these common electrodes of A phase and B phase
The data for energizing each heating resistance element while switching at a predetermined timing is given by the opening / closing control of the switches S1 to S6.

That is, when the heating resistor element R1 is to generate heat, the switch S1 is closed and the switch SW is switched to the contact A side. Then, the current from the power source E flows through the common electrode 1A, the lead conductor 2, and the diode D1 to the heating resistor element R1, and the heating resistor element R1 generates heat. When the switch S2 is closed, the current from the power source E becomes
The heating resistance element R2 flows through the same path as described above, and the heating resistance element R2 generates heat. Further, the heating resistor element R3
In the case of generating heat, the switch S2 is closed and the switch SW is switched to the contact B side, and the current from the power source E is applied to the heating resistor element R3 through the common electrode 1B, the lead conductor 2, and the diode D2. To do so.

[0004]

Such a thermal head needs a diode in order to prevent a current flowing through a certain heating resistance element from sneaking into another heating resistance element, and the thermal head itself is small in size. However, there is a drawback that it is difficult to reduce the price and price. Further, since each heating resistance element connected to the B-phase common electrode is energized later than each heating resistance element connected to the A-phase common electrode, when the recording paper feed speed is high, However, there is a drawback that the recording position of each heating resistor element is displaced. In addition, since each heating resistance element connected to the B-phase common electrode that is energized with a delay is heated to a higher temperature by the residual heat of each heating resistance element that is connected to the A-phase common electrode that has generated heat earlier, heat is generated. There is also a drawback that the dot diameter becomes large and uneven recording occurs. Further, as shown in FIG. 3, when the switch S2 is closed and the switch SW is switched to the A contact side, and the current iA is supplied only to the heating resistor element R2 to perform dot recording, the diode D3 is turned on. The current iB is also applied to the heat generating resistance elements R5, R4, R3 via the heat generating elements R5, R4, R3, and there is a possibility that other dots may be recorded in addition to the desired dot.

Therefore, it is an object of the present invention to provide a control method which eliminates the need for a diode and causes no deviation or unevenness in recording when heat-sensitive recording is performed by causing each heating resistance element of a thermal head to generate heat. .

[0006]

In order to solve such a problem, the present invention relates to each heating resistor element constituting a heating resistor, 1, 2, 3, ..., J-1, j, ... When arranged in the order of n, when the j-th heating resistance element is driven, the electrode potential between the j-th heating resistance element is different from the electrode potential between the j-1th heating resistance element. When the j-th heating resistance element is not driven, the electrode potential between the j-th heating resistance element is controlled to be the same as the electrode potential between the (j-1) th heating resistance element. is there. In addition, the potential applied to the j-th heating resistance element is j−
This is a control method that is given by the result of the exclusive OR operation of the data indicating the electrode potential between the first heating resistance element and the data indicating whether or not the j-th heating resistance element is driven.

[0007]

Therefore, the diode for preventing the sneak of the energizing current to each heating resistance element becomes unnecessary, and the common electrode is divided into two phases of A phase and B phase to drive each heating resistance element separately. Such an alternate read method is unnecessary, and as a result, the recording does not deviate or become uneven.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an apparatus to which a method of controlling a thermal head according to the present invention is applied. In this apparatus, heat-generating resistors R1, R2, ... It is composed of a resistor body 11, an AND circuit group 12, a latch circuit group 13, an exclusive OR circuit (hereinafter, EXOR circuit) group 14 for performing an exclusive OR operation, a shift register 15, and a control circuit 16.

That is, the strobe signal STB from the control circuit 16 is applied to one input terminal of each AND circuit in the AND circuit group 12 for driving the heating resistor 11, and the latch circuit group 13 is applied to the other input terminal. The output signals of the respective latch circuits are input. The latch signal LTH from the control circuit 16 and the output signal from the EXOR circuit group 12 are input to the input terminals of each latch circuit in the latch circuit group 13. On the other hand, each EXO in the EXOR circuit group 12
In the R circuit, one input terminal is connected to the EX of the preceding stage (j-1 stage).
The output signal of the OR circuit and the output signal from the shift register 15 are input to the other input terminal. The heating resistor element R1 that constitutes the heating resistor 11
And one terminal of the EXOR circuit E1 are grounded.

Next, a method of controlling the thermal head having the above-described structure and its operation will be described in detail with reference to the timing charts of FIGS. 1 and 2. When recording is performed with this thermal head, as an example, the heating resistance elements R1, R2. Consider a case where recording is performed in a pattern that causes R5 to generate heat and does not cause the other heating resistance elements to generate heat. Normally, when heating each heating resistor element, the control circuit 16 outputs data corresponding to each heating resistor element for one line in synchronization with the clock signal CLK as shown in FIGS. Are transmitted to the shift register 15 one by one. Here, in the case of the heat generation pattern as described above, the control circuit 16 outputs (1, 1, 1,
0, 0, 1, ...) are sequentially transmitted to the shift register 15 (actually, assuming that the number of heating resistance elements is n, each heating resistance element Rn, Rn-1, ..., R5, R4). , R
3, R2, R1 array order, that is, as data ...
1,0,0,1,1 are transmitted in this order). When the shift register 15 receives one line of serial data,
This is converted into parallel data and each data output port D
Data 1, 1, 0, 0, 1 are set in T1 to DT5, respectively.

When the data for one line is transmitted, the control circuit 16 outputs a latch signal LTH as shown in FIG. 2C to the latch circuit group 13. At this time, the recording data is the shift register 15 To EXOR circuit group 14
Are output in parallel. Here, since one input terminal of the EXOR circuit E1 is grounded, its logical value is "0", and the other input terminal has recording data of the logical value "1" from the shift register 15 to the heating resistor element R1. Is input, the drive data having the logical value "1" is output from the EXOR circuit E1 and latched by the latch circuit L1. Further, the output data "1" of the EXOR circuit E1 is input to one input terminal of the EXOR circuit E2, and the recording data of the logical value "1" for the heating resistance element R2 is input from the shift register 15 to the other input terminal. As a result, the EXOR circuit E2 outputs drive data having a logical value of "0" and is latched by the latch circuit L2. Similarly, the driving data for the heating resistance elements R3 to R5 are determined by the calculation of the output value of the EXOR circuit at the previous stage and the recording data from the shift register 15, and are latched by the corresponding latch circuits.

Next, the control circuit 16 is operated for a predetermined period as shown in FIG.
The strobe signal STB of “H” level (logical value “1”) as shown in (d) is output to the AND circuit group 12. Here, one input terminal of the AND circuit G1 has a logical value "1".
Of the strobe signal STB and the output data of the logical value "1" of the latch circuit L1 is input to the other input terminal, the output logical value of the AND circuit G1 becomes "1". Therefore, the electrode at one end of the heating resistor element R1 connected to this is at "H" level, and the electrode at the other end is at "L" level because it is grounded, and a potential difference V is generated at both ends thereof, resulting in heat generation. The resistance element R1 is energized and generates heat. Further, one input terminal of the AND circuit G2 is
Since the strobe signal STB having the logical value "1" and the output data having the logical value "0" of the latch circuit L2 are respectively input to the other input terminals, the output logical value of the AND circuit G2 is "0". Become. Therefore, the electrode at one end of the heating resistance element R2 connected to this is at the "L" level, and the electrode at the other end is at the "H" level because it is the output value of the AND circuit G1, and a potential difference V is generated at both ends thereof. As a result, the heating resistor element R2 is energized and generates heat.

On the other hand, the strobe signal STB having the logical value "1" is input to one input terminal of the AND circuit G3, and the output data having the logical value "0" of the latch circuit L3 is input to the other input terminal. Therefore, the output logical value of the AND circuit G3 becomes "0". Therefore, the electrode at one end of the heating resistance element R3 connected to this is at the "L" level, and the electrode at the other end is the output value of the AND circuit G2, so that it becomes the "L" level and both ends thereof have the same potential. As a result, the heating resistor element R3 is not energized. Further, one input terminal of the AND circuit G4 has a strobe signal STB of logical value "1".
However, since the output data of the logical value "0" of the latch circuit L4 is input to the other input terminal, the output logical value of the AND circuit G4 becomes "0". Therefore, the electrode at one end of the heating resistance element R4 connected to this is at the "L" level, and the electrode at the other end is the output value of the AND circuit G3, so that the electrode potential at both ends becomes the same potential. As a result, the heating resistor element R4 is not energized.

As described above, each heating resistance element is connected in series, and the heating resistance elements are connected to 1, 2, 3, ..., J-1, j ,.
When arranged in this order, the driving data for the j-th heating resistor element is determined by the corresponding recording data and the driving data for the preceding (j-1) th heating resistor element. That is, j
When the th heating resistance element is driven, the electrode potential between the jth heating resistance element is set to a potential different from the electrode potential between the j−1th heating resistance element, and when the jth heating resistance element is not driven, , The electrode potential between the jth heating resistance element is j
-It is set to the same potential as the electrode potential between the first heating resistance element.
As a result of the above configuration, the diode for preventing the sneak of the energization current to each heating resistance element as in the conventional case is not necessary, and the common electrode is divided into two phases of A phase and B phase to generate heat. There is no need for a driving method (alternate reading method) in which the resistance elements are individually controlled, and therefore, deviation or unevenness in recording does not occur.

In the present embodiment, the drive data for each heating resistance element is mechanically calculated by the EXOR circuit, but the control circuit 16 may be calculated based on the recording data. good. With this configuration,
The EXOR circuit group 14 becomes unnecessary, and drive ICs such as a shift register, a latch circuit, and an AND circuit can be arranged on both sides of the heating resistor. That is, the drive IC
By mounting on both sides of the heating resistor instead of the unnecessary diode array, the conductor pattern of the conventional alternating lead type thermal head can be used as it is.

[0016]

As described above, according to the present invention, the heat generating resistor elements of the thermal head, which are connected in series, are arranged as 1, 2, 3, ..., J-1. ，
When arranging in the order of j, ..., N, when driving the j-th heating resistance element, the electrode potential between the j-th heating resistance elements is set as the electrode potential between the j-1th heating resistance elements. The potentials are controlled so that they are different from each other, and when the j-th heating resistance element is not driven, the electrode potential between the j-th heating resistance element is set to the same potential as the electrode potential between the j-1th heating resistance element. Since it is controlled so that the diode for preventing the sneak of the energizing current to each heating resistance element is unnecessary, the common electrode is divided into two phases of A phase and B phase, and each heating resistance element is separated. The alternate reading method such as driving in the same manner is not necessary, and as a result, there is no deviation or unevenness in recording. Further, the electrode potential between the j-th heating resistance elements is subjected to an exclusive OR operation with data indicating the electrode potential between the j-1th heating resistance elements and data indicating whether or not the j-th heating resistance element is driven. As a result, the heat generation control of each heat generation resistance element of the thermal head can be realized with a simple configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an apparatus to which a method of controlling a thermal head according to the present invention is applied.

FIG. 2 is a timing chart showing the operation of each unit of the above apparatus.

FIG. 3 is a diagram schematically showing a configuration of a conventional thermal head.

[Explanation of symbols]

11 Heating resistor 12 AND circuit group 13 Latch circuit group 14 Exclusive OR circuit group (EXO
R circuit group) 15 shift register 16 control circuit R1 to R5 heating resistance element G1 to G5 AND circuit L1 to L5 latch circuit E1 to E5 exclusive OR circuit (EXOR
Circuit) LTH Latch signal STB Strobe signal DATA Data signal CLK Clock signal

Claims (2)

[Claims] 1. A thermal head comprising a heating resistor having a plurality of heating resistors connected in series and an electrode connected to each heating resistor, wherein each heating resistor constituting the heating resistor is 1, 2,
, ..., j-1, j, ..., N, when the j-th heating resistance element is driven, the electrode potential between the j-th heating resistance elements is j-1. It is controlled so that it is different from the electrode potential between the th heating resistance elements, and when the jth heating resistance element is not driven, the electrode potential between the jth heating resistance elements is the electrode between the j-1th heating resistance elements. A method of controlling a thermal head, characterized in that the thermal head is controlled to have the same potential as the potential. 2. The method of controlling a thermal head according to claim 1, wherein the potential applied to the j-th heating resistance element is the j-1
The data indicating the electrode potential between the th heating resistance element and the above j
A method of controlling a thermal head, characterized in that it is given by a result of an exclusive OR operation with data indicating whether or not the second heating resistance element is driven.