JPH02137939A - Dot printing head driver - Google Patents

Abstract

PURPOSE:To suppress the quantity of generated heat due to iron loss and to improve the printing efficiency of an impact printer by detecting the temperature rise of a dot printing head, and altering a printing cycle and a power source voltage according to the level of the temperature rise. CONSTITUTION:A temperature detector 3 is provided to receive a signal from a temperature sensor 7 thereby to monitor the temperature of a printing head 6 and to drive a carriage motor 8 by a speed command circuit 4 upon reception of a signal from the detector 3. The circuit 4 outputs a signal to a print command circuit 2 to drive the head 6 and outputs a signal to a power source voltage circuit 5 to drive the head 6. When the detector 3 detects the high temperature of the head 6 to output a signal, the period of the signal output from the circuit 2 to the head 6 and the power source voltage output from the circuit 5 to the head 6 are varied.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention is a dot print head drive device in a serial printer, in particular, a dot print head drive device that detects a temperature rise in the dot print head, slows down the print cycle, and controls the power supply voltage. This invention relates to a drive device for a dot print head.

(Prior Art) Conventionally, impact printers often use dot print heads that perform printing by driving a print wire. Among these, the spring-charged type has an armature to which a printing wire is fixed, which is swingably supported by a bias leaf spring, and the armature is previously attached to a core by a permanent magnet against the elastic force of the bias leaf spring. When the magnet is attracted and printed, a coil wound around the core is excited to generate a magnetic flux in the opposite direction to the permanent magnet, and the armature is released.

In recent years, there has been a demand for faster printing, so this spring-charged dot print head, which has good high-speed response, has been widely adopted.

By the way, in the dot print head mentioned above, in order to protect the print head and obtain appropriate print quality, when the temperature of the dot print head rises to a certain level, this is detected and the impact operation is stopped or the print density is reduced and the heat generation is stopped. control measures such as lowering the

(Problem to be Solved by the Invention) However, in the conventional dot print head described above, the temperature rise is only controlled by detecting the temperature rise of the print head and stopping the printing operation or reducing the print dot density. Therefore, although it was possible to control the calorific value by copper loss, it was not possible to control the calorific value by iron loss <n.

Therefore, in the dot print head drive device described above, the present invention suppresses not only the amount of heat generated due to copper loss but also the amount of heat generated due to iron loss in the control after detecting the temperature of the print head. The purpose is to improve the printing efficiency (printing duty) of impact printers.

(Means for Solving the Problems) To this end, the dot print head drive device of the present invention includes a temperature sensor that detects the temperature of the print head, and receives a signal from the temperature sensor to monitor the temperature of the print head. At the same time, a temperature detection circuit sends a signal to the speed command circuit, a speed command circuit receives the signal from the temperature detection circuit, sends a signal to the print command circuit and the power supply voltage command circuit, and drives the carriage motor; It consists of a print command circuit that receives signals from the command circuit to drive the print head, and a power supply voltage command circuit that receives signals from the speed command circuit and drives the print head.

(Function) According to the present invention, a temperature detection circuit is provided to monitor the temperature of the print head in response to a signal from the temperature sensor, and a speed command circuit to monitor the temperature of the print head in response to a signal from the temperature detection circuit. Drive the motor. Further, the speed command circuit outputs a signal to the print command circuit to drive the print head, and also outputs a signal to the power supply voltage circuit to drive the gutter for printing.

When the temperature detection circuit detects the high temperature of the print head and outputs a signal, the period of the signal output from the print command circuit to the print head and the power supply voltage output from the power supply voltage circuit to the print head are changed. .

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a dot print head driving device showing an embodiment of the present invention.

In the figure, 1 is a control circuit of the impact printer, 2 is a print command circuit that issues printing commands to the print head 6, and 3 is a circuit that inputs a signal from a temperature sensor 7 provided in the print head 6 to control the temperature of the print head 6. 4 is a speed command circuit that sends a signal to the print head via the print command circuit and also sends a signal to the carriage motor 8 to command the print cycle and print speed; 5 is a speed command circuit that sends a signal to the carriage motor 8 to command the print cycle and printing speed; A power supply voltage command circuit is shown that obtains information from circuit 4 and sets the power supply voltage to a value corresponding to the printing speed. Note that 9 is a power source.

Next, the operation of the dot print head drive device having the above structure will be explained.

FIG. 2 is an operation time chart of the dot print head driving device of the present invention.

First, when the temperature detection state detected by the temperature sensor 7 is normal when the print head is not at a high temperature, the temperature detection signal SI of the temperature detection circuit 3 is output as shown in the range a shown in FIG. It will be done. The temperature detection signal S is sent to the speed command circuit 4, and the speed command signal S is sent to the speed command circuit 4.
2 is output. Then, the speed command signal S! is sent to the print command circuit 2, and the print command circuit 2 outputs a print command signal S.

Also, the speed command signal S output from the speed command circuit 4 is
t is sent to the power supply voltage command circuit 5, and the power supply voltage command signal S
Outputs 4. The power supply voltage command signal S, as a speed function, is f(x)-α·Hz-V.

Vo: Initial value of power supply voltage α　;Coefficient Hz: Print cycle It is given as follows.

At this time, the supply voltage of the print head is ■It becomes 1-α・7・vo.

Next, when the temperature of the print head rises and the temperature detection signal S1 of the temperature detection circuit 3 is output as shown in the range b shown in FIG. The speed command signal S is sent to the speed command circuit 4.
! is output. The speed command signal S is sent to the print command circuit 2, and the print command signal S3 is output from the print command circuit 2 and sent to the print head.

Here, the period of the printing command signal S is T in the range a.
, but when it reaches the range b, it becomes T1 and the printing speed is reduced.

Further, when the speed command signal S2 output from the speed command circuit 4 is sent to the source voltage command circuit 5, the power supply voltage command signal S4 generates a pulse as shown in the figure when it falls within the range b. do. As a result, the power supply voltage (2) supplied to the print head is changed from V1 to (2).

When the print head is further heated and the temperature sensor 7 detects a high temperature, the same process as above is performed to generate a print command signal S that instructs the print speed of the print head.

The P1 period of is changed from T1 to T2, the printing speed is reduced, and the power supply voltage supplied to the print head is changed to ■.
It can be changed from 2 to V.

Note that the present invention is not limited to the above embodiments (
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, the temperature rise of the dot print head is detected and the print cycle and power supply voltage of the print head are made variable, so that the temperature rise of the print head can be controlled. By changing the print cycle and power supply voltage of the print head depending on the level, the following effects can be brought about.

That is, by lowering the power supply voltage, the heat generated by iron can be reduced. Expressing the amount of iron loss in the formula, W=Bm ”(σm f + tta f”t”)
(w/kg) B, : Maximum value of magnetic flux density σ7. σ: Coefficient [: Frequency. σI%f is hysteresis loss, and σf2tt is eddy current I shell. Further, ( is a function proportional to the drive voltage of the print head, and therefore, by lowering the drive voltage, it is possible to reduce iron loss.

Figure 3 shows the relationship between power supply voltage and iron loss.

That is, during high-speed printing, approximately 5++ J of heat is generated, whereas during low-speed printing, the amount of heat generated is approximately 3.1 J, which is a reduction of approximately 40% in terms of the amount of heat generated due to iron loss. (The amount of heat generated due to iron loss shown here is the amount per dot.) In the dot print head of the example, the ratio of heat generation copper loss to iron loss is about 6:4, and the dot print head The overall calorific value is reduced by approximately 16%.

In this way, in the control after detecting the temperature of the print head, not only the amount of heat generated by Numakawa is suppressed, but also the amount of heat generated by iron loss is suppressed, improving the printing efficiency (printing duty) of the impact printer. Therefore, it is possible to minimize the number of times the printer stops printing due to heat generation.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the dot printing nozzle drive device of the present invention, Fig. 2 is an operation time chart of the dot print head of the present invention, and Fig. 3 is a diagram showing the relationship between power supply voltage and iron loss. . l... Control circuit, 2... Print command circuit, 3... Temperature detection circuit, 4... Speed command circuit, 5... Power supply voltage command circuit, 6... Print head, 7...・Temperature sensor,
8... Carriage motor, 9... Power supply. Patent Applicant: Oki Electric Industry Co., Ltd. Agent, Patent Attorney: Makoto Kawai (and 1 other person) General specifications of the dot print head of the present invention, Figure 1. General specifications of the dot print head of the present invention. Second
figure

Claims (1)

[Claims] (a) A temperature sensor that detects the temperature of the print head; (b)
) A temperature detection circuit that receives a signal from the temperature sensor, monitors the temperature of the print head, and sends a signal to the speed command circuit; (e) a speed command circuit that sends signals to the voltage command circuit and drives the carriage motor; a print command circuit that receives signals from the speed command circuit and drives the print head; (e) a signal from the speed command circuit; What is claimed is: 1. A dot print head drive device comprising: a power supply voltage command circuit that receives the power voltage and drives the print head;