JPH06986A - Driving circuit of thermosensitive recording head - Google Patents

Abstract

PURPOSE:To reduce the power consumption by dividing the drive pulse of a thermosensitive recording head and holding down a peak value using an LC filter. CONSTITUTION:A driving pulsed current which is divided from a power supply circuit 105 is applied to the thermal element 114 of a thermosensitive recording head by entering print data and a print pulse to an AND circuit 116 from a control part and then activating a transistor 115. In addition, this divided driving pulse is allowed to run at a low peak current value by an LC filter 1 consisting of a capacitor 10 and a coil 20. Next, the thermal element is thermally driven by this driving current against print data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for a thermal recording head used in a facsimile or the like.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of a conventional thermal recording apparatus. The control unit 101 executes the control of the entire apparatus by the control program recorded in the ROM 103 and the CPU 102. The thermal recording head 104 receives R from the control unit 101.
The print data, which is the content of AM, is input from the signal line 112, and the print pulse is input from the signal line 111.

According to the print data latched by the print pulse, the thermal recording head 104 is energized through the power supply circuit 105 and driven to generate heat. FIG. 5 is a circuit diagram of a conventional thermal recording head drive circuit. Referring to FIG. 5 for the above operation, the thermal recording head 104 is switched by the print data input to the AND circuit 116 and the output by the print pulse. The transistor 115 operates, a current flows from the power supply circuit 105 to the heat generating element 114, and heat generation is performed.

The waveform at point A in this case is the drive pulse and drive current waveform of the thermal recording head 104 shown in the waveform diagram of FIG.

[0005]

However, in the prior art shown in FIG. 5, the thermal recording head continues to pass the peak value current as the drive current during the printing drive period as shown in the waveform chart of FIG. Therefore, there is a problem that the power supply capacity is larger than necessary.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a driving circuit for a thermal recording head which can reduce the peak value of the driving current and downsize the power supply.

[0007]

In order to achieve the above object, a thermal recording head having a plurality of heating elements is provided, and a recording current by a driving pulse is applied to the thermal recording head according to print data for recording. In a heat-sensitive recording apparatus such as a facsimile that heats and records by heating, an LC filter that divides and inputs the drive pulse of the heat-sensitive recording head, suppresses the fluctuation of the drive current due to the drive pulse, and reduces the peak current value is used as a power supply circuit. It is provided between the thermal recording heads.

[0008]

With the above configuration, the LC pulse provided between the thermal recording head and the power supply circuit is divided by dividing the drive pulse that latches the print data and defines the drive energization period of the thermal recording head. The peak current value is reduced by filtering the drive pulse with the drive pulse, and the recording peak power of the thermal recording head is reduced because the thermal recording head is driven to generate heat corresponding to the print data by the drive current having the reduced peak value. You can

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a drive circuit for a thermal recording head according to an embodiment of the present invention. FIG. 2 is a block diagram of a thermal recording apparatus using the drive circuit shown in FIG. FIG. 3 is a diagram showing drive waveforms of the thermal recording head shown in FIG.

In these figures, 1 is a power supply circuit 105.
This is an LC filter composed of a capacitor 10 and a coil 20 connected between the thermal recording head 104 and the thermal recording head 104.

Next, the operation will be described. A control program and a CPU stored in the ROM 103 as shown in FIG.
The control unit 10 that controls the entire apparatus by the process of 102.
The print data for recording from 1 to the contents of the RAM 117 and the print pulse for latching the print data and separately setting the drive pulse during the drive period are input to the thermal recording head 104.

The print data and the print pulse are input to the thermal recording head circuit shown in FIG. 1, and the drive transistor 115 is switched by the output pulse ANDed by the AND circuit 116, and is recorded on the heating element 114 from the power supply circuit 105. Apply current.

In this case, the power supply circuit 10 is connected to the heating element 114.
The waveform applied from No. 5 is a drive pulse divided and defined by the print pulse shown in FIG. 3, and the drive current is a drive pulse current having a peak value ih of 24V, for example.

Since the LC filter including the condenser 10 and the coil 20 is inserted in the circuit of the thermal recording head 104, the power supply circuit 105 is provided at the point a.
The drive current from is filtered and the current value i in FIG.
_The waveform shown by the dotted line for _L results in an average drive current lower than the peak current value ih, and the thermal recording head 104
Is applied to drive the heating element 114 to generate heat in accordance with the print data. The circuit of FIG. 1 is shown as a circuit for one dot, but there are a plurality of heating elements 114.

In this way, the heat-sensitive recording head 104 is driven to generate heat, and after printing and recording on heat-sensitive paper or the like, the control unit 101.
Based on a drive signal from the recording paper conveyance motor 107, the recording paper conveyance motor 107 is driven via the driver circuit 106, and the platen 108, the paper feed, the paper ejection roller 109, etc. are rotationally driven to convey the recording paper, Print the next record. The sensor 11
Reference numeral 0 denotes a sensor for detecting the heat generation temperature of the thermal recording head 104 and a recording sheet position or the like.

In this embodiment as described above, the thermal recording head 104 is pulse-driven and the driving peak current value is further reduced by the LC filter 1. Therefore, the peak power consumption is increased as compared with the conventional example. And the power supply can be downsized.

[0017]

As described above, according to the present invention, a thermal recording head having a plurality of heat generating elements is provided, and a recording current by a drive pulse is applied to the thermal recording head according to print data for recording. In a thermal recording device such as a facsimile that heats and records by heating, an LC filter that divides the drive pulse of the thermal recording head and inputs it and suppresses the fluctuation of the drive current due to the drive pulse to reduce the peak current value and the thermal recording Since it is provided between the heads, there is an effect that the peak value of the drive current becomes small and the capacity of the power supply can be made small.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a drive circuit of a thermal recording head according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a thermal recording apparatus according to the embodiment shown in FIG.

FIG. 3 is a diagram showing drive waveforms of the embodiment shown in FIG.

FIG. 4 is a configuration diagram of a conventional thermal recording device.

FIG. 5 is a circuit diagram of a drive circuit of a conventional thermal recording head.

6 is a diagram showing drive waveforms of the drive circuit shown in FIG.

[Explanation of symbols]

 1 LC Filter 10 Capacitor 20 Coil 101 Control Unit 102 CPU 103 ROM 104 Thermal Recording Head 105 Power Supply Circuit 114 Heating Element 115 Transistor 116 AND Circuit

Claims (1)

[Claims] 1. A heat-sensitive recording apparatus such as a facsimile apparatus which comprises a heat-sensitive recording head having a plurality of heat-generating elements, and which records heat by applying a recording current by a driving pulse to the heat-sensitive recording head in accordance with print data for recording. In the apparatus, an LC filter for dividing and inputting a drive pulse of the thermal recording head and suppressing a fluctuation of a drive current due to the drive pulse to reduce a peak current value is provided between a power supply circuit and the thermal recording head. A drive circuit for a thermal recording head, characterized by.