JPS59207273A - Serial dot printer - Google Patents

Abstract

PURPOSE:To enable the accurate control of a driving element of each printing element of a serial dot printer by a method wherein a current proportional to a current flowing through said driving element is made to flow through a resistor provided outside a printing head and the driving element is controlled by a signal from a temperature detecting means provided in proximity to the resistor. CONSTITUTION:Each of resistors (heaters) 41-49 is connected directly between each of coils 11-19 for driving each printing element (wire) of a dot printer and each of transistors 61-69 controlling the selective electrification of each of these coils 11-19 in accordance with a printing signal, and each of temperature detecting elements 51-59 is provided in close proximity to each resistor. Detection signals from these detecting elements 51-59 are inputted to a discrimination circuit and compared therein with threshold values determined beforehand. They are inputted further to a drive controlling unit 3 through an OR gate, and thereby the electrifications of the coils 11-19 are controlled respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a serial dot printer.

The present invention relates to a serial dot printer that can detect temperature rises and has good controllability against temperature rises.

[Background of the invention]

For example, when printing is performed continuously in a printer having a wire dot matrix print head, the coil that drives the wire generates heat, and if printing continues, the coil and print head components will burn out. For this reason, conventionally, a temperature detection means is provided inside the print head, and when the temperature rises and reaches a limit, control is performed such as stopping the printing operation or reducing the printing speed.

However, in recent years, with the spread of kanji printers, the number of wires has increased and the printing speed has also become much faster.On the other hand, the temperature detection means is approximately 1m per print head, which has caused the following problems. . That is, for example,
In a print head having 24 wires, there are 24 heat-generating parts (fills), and each of the coils is separated by a certain distance due to the arrangement, but there is only one humidity detection means as described above. Even if the coil is placed at an optimal position, the problem is that the heat generated by the coil is detected with a certain delay time due to the relationship between heat transfer and the heat capacity of the circumferential recessed member. Furthermore, when a specific wire in the print head intensively performs printing operations in a short period of time, the temperature of the coil that drives that wire locally increases, but the temperature detection means cannot properly detect this. There may be no. In order to prevent the coil from burning out even in such cases, conventionally the limit point or control point was set at a temperature much lower than the heat resistance temperature of the fill, and printing control was performed with respect to temperature with a sufficient margin. Therefore, there was a problem in that it was not possible to perform continuous high-density printing operations.

In order to solve the problem of using one temperature detection means as described above, when a plurality of temperature detection means are provided inside the print head, the outer dimensions of the print head become larger, the weight increases, and the printing There were problems such as a large number of cables coming out from the head, making it difficult to implement and increasing costs.

[Purpose of the invention]

The present invention was developed in view of the above circumstances, and its purpose is to solve the above-mentioned problems in conventional serial dot printers and to promptly and accurately detect the temperature rise of the print head. An object of the present invention is to provide a serial dot printer that is capable of controlling temperature rises and has good controllability over temperature rises.

[Summary of the invention]

The gist of the present invention is to provide a serial dot printer having a print head in which a plurality of print elements are arranged in a predetermined manner, and an element drive section that selectively drives the print elements, in which a current proportional to the current flowing through the element drive section is provided. The present invention is configured to include at least a heating element provided outside the print head and a temperature detecting means provided close to the heating element so that the temperature flows smoothly.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a wire dot matrix printer which is an embodiment of the present invention, and FIG. 2' is a circuit diagram of the main part thereof. In both figures, l represents a print head, 2 represents a connection cable, and 3 represents a print head drive control package.

As shown in FIG. 1, a print head 1 is connected to a print head drive control package 3 by a cable 2.
A heating element connected in series with the wire driving coil of the print head 1 is placed inside the drive control package 3;
A drive transistor 6 turns on and off the print head 1. In addition, a temperature detection element 5 is provided near the heating element 4.
is located.

As shown in FIG. 2, inside the print head 1 there are wire drive coils 11-19, each of which is connected to the print head drive side package 3 by a connecting cable 21-29. Common positive line 20
are connected by a cable 30. The connection cables 21 to 29 are each connected in series with the heating elements 41 to 49 in the drive control package δ, and the drive transistors 61 to 69 control the wire drive coils 11 to 19 of the print head 1 to ON and OFF, respectively. do. 0 again
Temperature detection elements 51 to 59 are respectively disposed close to the heating elements 41 to 49 in the drive control package 3, and are configured to simulate and detect the temperatures of the wire drive coils 11 to 19, respectively. has been done.

The outputs of the temperature detection elements 51 to 59 are guided to a determination circuit (not shown) provided corresponding to the temperature detection element, and compared there with a predetermined threshold value. The result of the above comparison is the OR for each temperature detection element 51 to 59.
As an output, it is sent to the printing speed control section in the drive control package δ.

The operation of this embodiment configured as described above will be explained below.

When the printing operation is performed, electric current is also applied to the heating elements 41 to 49 (hereinafter simply referred to as "heating elements J corresponding to the wires") connected in series to the wire driving coils 11 to 19 corresponding to the wires to be driven. As a result, the temperature of the heating element corresponding to the driven wire increases.This temperature rise is detected by the flooding detection elements 51-59 provided corresponding to the heating elements 21-29. As mentioned above, the outputs of the temperature detection confectionery 51 to 59 are led to the judgment circuit, where they are compared with a predetermined threshold value.The outputs of the judgment circuits corresponding to each temperature detection element are led to the OR gate. The output of the OR gate is guided to a printing speed control section within the drive control circuit 5.

The above-mentioned printing speed control section is, for example, a special i! l1986-1987
As disclosed in Japanese Patent No. 289, it is possible to use a type in which the rotation angle of the printing element drive period setting motor is varied according to the output of the above-mentioned OR gate.

FIG. 3 is a schematic configuration diagram showing another embodiment of the present invention.

The difference from the embodiment shown in FIGS. 1 and 2 is that the heating element 4
And, instead of providing the temperature detection convex inside the drive control package 3, it is provided outside the print head 1 by using the joint with the connection cable 2. For example, by creating a very close-contact structure like a collective resistor and placing temperature detection elements in close contact with it, it is possible to significantly reduce the number of temperature detection elements and obtain the same effect. It is.

Furthermore, in the above embodiment, the heating element 4 is connected in series with the coil of the print head l, but a current proportional to the current flowing through the coil of the print head may be passed through the heating element 4-. , the heald method is not limited to the above embodiments.

As the temperature detection element, in addition to thermistors and thermocouples with various characteristics, it is also possible to use bimetals.

When bimetal is used, there is an advantage that the determination circuit described above is not required.

Although the above embodiment has been explained using a 1' dot type printer as an example, it goes without saying that the present invention is effective for all other serial dot printers in which the temperature of the printing element drive section increases. stomach.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a heating element provided at least outside the print head such that a current proportional to the current flowing through the element driving section flows, and a temperature detection element provided close to the heating element. Since the structure is configured to have a means, it is possible to quickly and accurately detect the temperature rise of the print head. It is what Qin Dynasty did.

[Brief explanation of the drawing]

1 and 3 are schematic configuration diagrams showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing details of FIG. 1. 1: Print head, ]1-]9: Wire cutting coil, 2
, 21 to 29: Connection cable, 32 drive control gauge, cow, 41 to 49 two heating elements, 5°51 to 59: temperature detection element, 61 to 69: drive transistor.゛・,,−1:′ 1st Fig. 3 Fig. 3

Claims (1)

[Claims] In a serial dot printer having a print head in which a plurality of printing elements are arranged in a predetermined manner, and an element driving section that selectively drives the printing elements, at least the printing is performed so that a current proportional to the current flowing through the element driving section flows. A serial dot printer characterized by having a heating element provided outside the head and a temperature detection means provided close to the heating element.