JPH054368A - Thermal line head controller - Google Patents

Abstract

PURPOSE:To conduct printing in optimum printing density in response to the changes of various conditions. CONSTITUTION:Frequency is varied in response to the driving voltage of a power supply section in a V/F converter 19, a signal having low frequency is output when the number of energized heating elements 12 is increased and a voltage drop is large, and a signal having high frequency is output when the number of the energized heating elements 12 is decreased and the voltage drop is small. These frequency signals are changed into timing signals counting down a count-down counter 18, and correspond to a count-down time. Accordingly, a conduction time is lengthened and sufficient heat is obtained when the number of the energized heating elements 12 is increased and the voltage drop is large, and the conduction time is shortened and sufficient heat is not obtained when the number of the energized heating elements 12 is decreased and the voltage drop is small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal line head control device, and more particularly to a thermal line head control device in which the amount of heat generated by each heating element in a thermal line head changes according to the energization time.

[0002]

2. Description of the Related Art Conventionally, a thermal line head controller of this type is known as shown in FIG.

In the figure, a thermal line head 1 is constructed by arranging a plurality of heating elements 2-1 to 2-n in a row, and a drive circuit 3 is driven from a power supply section 5 based on an output of an AND circuit 4. The supplied current is supplied to the required heating element 2.

The AND circuit 4 performs a logical product operation of the print data of the bit image set in the data register 6 and the energization signal, and based on the operation result, each of the heating elements 2-1 to 2-2 by the drive circuit 3 described above. Control the energization to -n.

On the other hand, the print data is set in the data register 6 by the general control unit 7, and the general control unit 7 outputs the energization signal only for a preset time.

In such a configuration, the overall control section 7 sets the print data in the data register 6 and outputs the energization signal for a time corresponding to the heat generation amount so that the heat generation amount is set in advance. Then, AND circuit 4
Causes the drive circuit 3 to energize the predetermined heating element 2 in the thermal line head 1 based on the print data set in the data register 6 only while the energization signal is being output.

[0007]

In the above-described conventional thermal line head control device, the heating element in the thermal line head is energized for a preset time, so that the required heating value depends on the print data and the ambient temperature. However, there is a problem that the desired print density cannot be obtained when the value changes.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a thermal line head controller capable of performing printing at an optimum printing density according to changes in various conditions.

[0009]

In order to achieve the above object, the invention according to claim 1 provides a thermal line head in which a plurality of heating elements are arranged in a row, and a heat generation amount required for printing in the thermal line head. And a drive means for supplying a drive current to each of the heating elements in the thermal line head in accordance with predetermined print data for the energization time detected by the detection means. There is.

The invention according to claim 2 provides the invention according to claim 1.
In the thermal line head controller described in the above item (1), the detection means is provided with a voltage detection means for detecting the energization time based on the voltage drop of the power supply to the drive means.

Further, the invention according to claim 3 is the thermal line head controller according to claim 1, wherein the detecting means detects the energizing time based on the ambient temperature of the thermal line head. Is provided.

[0012]

In the invention according to claim 1 configured as described above, when the detection means detects the energization time corresponding to the required heat generation amount during printing in the thermal line head, the drive means is detected by this detection means. A drive current is supplied to each of the heating elements in the thermal line head in which a plurality of heating elements are arranged in a row according to predetermined print data for the energization time.

Further, in the invention according to claim 2 configured as described above, the voltage detection means in the detection means detects the energization time based on the voltage drop of the power supply to the drive means.

Further, in the invention according to claim 3 configured as described above, the temperature detecting means in the detecting means detects the energization time based on the ambient temperature of the thermal line head.

That is, the required heat generation amount at the time of printing is detected directly or indirectly, and the drive current is supplied to each heating element in the thermal line head for the energization time corresponding to the required heat generation amount.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a thermal line head controller according to an embodiment of the present invention.

In the figure, the thermal line head 11
Is formed by arranging a plurality of heating elements 12-1 to 12-n in a row, and the drive circuit 13 requires the current supplied from the power supply unit 15 based on the output of the AND circuit 14 Supply to.

The AND circuit 14 performs a logical product operation of the print data of the bit image set in the data register 16 and the energization signal, and based on the operation result, each of the heating elements 12-1 to 12- by the drive circuit 13 described above. Control the energization to n.

On the other hand, the data register 16 is the entire control unit 1
7, the print data is set, and the total control unit 17 counts down when the printing is started.
The count start signal is output to.

The count value X is set in advance in the countdown counter 18, and the AND circuit 4 is energized until the frequency signal output from the V / F converter 19 is counted down from the time the count signal is input to "0". Output a signal.

Here, the V / F converter 19 outputs a frequency signal corresponding to the drive voltage supplied to the drive circuit 13, and when the drive voltage is high, a high frequency signal (a signal having a short cycle) is generated. ) Is output, and a frequency signal with a low frequency (a signal with a long period) is output when the drive voltage is low.

The paper feed control mechanism 20 feeds the required amount of printing paper to be printed by the thermal line head 11.

Next, the operation of this embodiment having the above-mentioned structure will be described, but before that, the voltage fluctuation due to the printing rate will be described. Heating element 12 in the thermal line head 11
-1 to 12-n are resistance loads, but the load value depends on the print data. That is, as the number of heating elements 12 that are energized corresponding to the print data increases, the resistance load increases (the combined resistance value decreases) and the current increases, so that a voltage drop occurs due to the internal impedance of the power supply unit 15. In particular, this fluctuation becomes large when the power supply unit 15 uses a battery or a storage battery.

On the contrary, if the number of heating elements 12 to be energized corresponding to the print data decreases, the resistance load is small and the voltage drop is unlikely to occur.

By the way, when the overall control unit 17 sets the print data in the data register 16 and outputs the count start signal, the countdown counter 18 starts the countdown with the frequency signal corresponding to the voltage output from the power supply unit 15 at the initial stage. . When the countdown counter 18 starts counting down, the countdown counter 18 outputs an energization signal to the AND circuit 14, so that the AND circuit 14 causes the drive circuit 13 to drive the thermal line head 11 based on the print data set in the data register 16. The predetermined heating element 12 in is energized.

At this time, a voltage drop occurs due to the number of energized heating elements 12, and the cycle of the frequency signal output from the V / F converter 19 changes. For example, the heating element 12 that is energized
Since the voltage drop is small when the number of V is small, the V / F converter 19
The cycle of the frequency signal output by is short, the countdown counter 18 counts down quickly, and the count value X becomes "0" in a short time. However, since a driving voltage with a small voltage drop is applied, the amount of heat generated by each heating element 12 is necessary and sufficient, and the print density is appropriate.

On the other hand, if the number of heating elements 12 to be energized is large, the voltage drop is large, so that the cycle of the frequency signal output from the V / F converter 19 becomes long and the countdown by the countdown counter 18 is delayed. That is, the count value X becomes “0” over a long time, and the heating element 12
The energization time to becomes longer. However, since the drive voltage with a large voltage drop is applied, the energization time is extended and the required amount of heat generation can be generated, so that a sufficient print density can be obtained.

Next, FIG. 2 is a block diagram of a thermal line head controller according to another embodiment of the present invention. In the figure, the temperature sensor 21 outputs a voltage signal corresponding to the ambient temperature to the V / F converter 19, outputs a high voltage signal when the ambient temperature is high, and outputs a high voltage signal when the ambient temperature is low. Outputs a low voltage signal.

2 is different from that shown in FIG. 1 in that the V / F converter 19 does not change the cycle of the frequency signal in accordance with the drive voltage of the power supply section 15, but the V / F is changed. The converter 19 is different in that the cycle of the frequency signal is changed according to the output voltage of the temperature sensor 21.

Generally, when the ambient temperature changes, the heating element 1
2 also changes the amount of heat that should be generated. For example, if the ambient temperature is low, the amount of heat radiated by the paper or the like increases, so that the heat generating element 12 cannot obtain a sufficient print density unless a large amount of heat is generated.

Further, when the ambient temperature is high, the amount of heat radiated by the paper or the like is small. Therefore, unless the amount of heat generated by the heating element 12 is reduced, the print density is too high.

With the above configuration, when the ambient temperature is high, the output voltage of the temperature sensor 21 becomes high, the cycle of the frequency signal output from the V / F converter 19 becomes high, and the countdown time by the countdown counter 18 becomes shorter. It gets shorter. Therefore, the energization time is shortened, and it is possible to prevent the print density from becoming too high.

On the other hand, when the ambient temperature is low, the output voltage of the temperature sensor 21 is low, so the cycle of the frequency signal output from the V / F converter 19 is low, and the countdown time by the countdown counter 18 is become longer. That is, when the temperature is low, electricity is supplied for a long time, and a sufficient print density can be obtained.

[0034]

As described above, according to the present invention, since the driving current is supplied to the heating element in the thermal line head so as to obtain the required heating value at the time of printing, it is possible to obtain a desired printing density. A line head controller can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a thermal line head controller according to an embodiment of the present invention.

FIG. 2 is a block diagram of a thermal line head controller according to another embodiment of the present invention.

FIG. 3 is a block diagram of a conventional thermal line head controller.

[Explanation of symbols]

11 ... Thermal line head 12-1 to 12-n ... Heating element 13 ... Drive circuit 14 ... AND circuit 15 ... Power supply 16 ... Data register 17 ... Overall control unit 18 ... Countdown counter 19 ... V / F converter 21 ... Temperature sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B41J 29/00 9113-2C B41J 3/20 115 B 8804-2C 29/00 U

Claims (3)

[Claims] 1. A thermal line head in which a plurality of heating elements are arranged in a row, a detection means for detecting an energization time corresponding to a required heat generation amount at the time of printing in the thermal line head, and the detection means. A thermal line head controller comprising: drive means for supplying a drive current to each of the heating elements in the thermal line head in accordance with predetermined print data for a power-on time. 2. The thermal line head control device according to claim 1, wherein the detection means has a voltage detection means for detecting the energization time based on a voltage drop of a power supply to the drive means. The thermal line head controller. 3. The thermal line head controller according to claim 1, wherein the detection means has a temperature detection means for detecting the energization time based on the ambient temperature of the thermal line head. Thermal line head controller.