JPH0617546Y2 - Wire dot print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding the structure of a print head of a wire dot printer, a plurality of print magnets are provided for the purpose of preventing burnout of a drive coil of the print head and controlling an appropriate print duty against temperature rise of the drive coil. In a wire dot print head that arranges in a loop shape and selectively excites the print magnet to perform printing with a print wire, a heat transfer member wound in a loop shape that is inscribed in the drive coil of the print magnet. , A heat sensitive element that is enclosed in the heat transfer member and detects heat of the drive coil.

[Industrial application field]

The present invention relates to the structure of a print head of a wire dot printer.

2. Description of the Related Art Recently, serial printers that print characters or the like by using dots are widely used in input / output terminals of data processing devices and word processors.

High speed printing is required for these printers, and therefore the drive frequency of the print head is increased.

As a result, the temperature rising rate of the drive coil of the print magnet is increased, and there is a demand for a temperature detection mechanism capable of following this.

[Conventional technology]

For example, as shown in the side sectional view of FIG. 3 (a), the release type print head 1 has a plurality of print wires 3 which are centrally aligned by being guided by a wire guide 4 projecting from the center thereof. This is configured to be driven by the print magnet 2 for printing.

The print magnet 2 is formed by winding a drive coil 6 around a core 5, and an armature 7 is arranged so as to abut on an end surface of the core 5.

The armature 7 is made of a magnetic material and is elastically fixed to the tip of the leaf spring 8 so as to face the core 5, and the printing wire 3 is fixed to the tip of the armature 7 via a holding portion 9.

The magnet base 10a and the magnetic path portion 10b are provided with a permanent magnet 11 between them, and a magnetic path portion 10d is arranged with a spacer 10c made of a magnetic material sandwiched between the core 5 and the armature 7.
When the print magnet 2 is not operating, it forms a loop-shaped magnetic path with the armature 7 by the magnetic force of the permanent magnet 11.
Are adsorbed on the core 5.

Here, the permanent magnet 11 is added to the drive coil 6 of the print magnet 2.
When a current is passed through the drive coil 6 such that the NS pole and the magnetic pole of the core 5 are opposite to each other, the core 5 acts so as to cancel the attractive force of the permanent magnet 11.

Then, the armature 7 jumps upward in the drawing due to the reaction force stored in the leaf spring 8, and the printing wire 3 simultaneously projects from the wire guide 4 to perform printing.

In this way, printing is performed by selectively driving the plurality of print magnets 2 in the print head 1.

In the print head having such a structure, there is a problem that the temperature of the drive coil 6 rises, and the temperature is detected in order to prevent the burnout and to control an appropriate print duty corresponding thereto. .

The method is to provide a cylindrical heat transfer ring 12 made of, for example, a copper plate or a copper pipe, which is inscribed in the drive coil 6, as shown in the enlarged perspective view of the portion A of FIG. Heat transfer ring
As shown in the enlarged perspective view of the main part of FIG. 1 (b), the outer peripheral portion of 12 is provided with a notch 12a, in which one or a plurality of thermosensitive elements (hereinafter referred to as thermistors) 13 such as thermistors are embedded. The heat transfer ring 12 is used for detection.

[Problems to be solved by the device]

When the temperature rise rate of the drive coil increases as the printing speed of the printer increases, the thermal capacity of the heat transfer ring is large and the followability of the thermistor temperature detection is poor. A gap occurs.

For this reason, there is a problem in that the print duty cannot be controlled appropriately with respect to the temperature rise, and the drive coil may be burned out.

The present invention is intended to prevent burnout of a drive coil and control an appropriate print duty with respect to a temperature rise of the drive coil.

[Means for Solving the Problems]

The above problem is caused by the heat transfer member 14 wound around the drive coil 6 in a loop shape as shown in the side sectional view of the main part of FIG. 1 (a).
And the thermistor 13, which is wrapped in the heat transfer member 14 and detects the heat of the drive coil 6, is solved.

[Action]

The thermistor is wrapped by the heat transfer member that is wound in a loop, so that the heat of the drive coil can be quickly detected.

〔Example〕

 1 and 2 show an embodiment of the present invention.

The same portions are denoted by the same reference numerals throughout the drawings.

In the present invention, a side sectional view of the main part of FIG.
As shown in the enlarged view of the portion B in FIG. 2 (a) shown in FIG. 2 (b), the heat transfer member 14 is wound around the drive coil 6 in a loop shape, and the heat transfer member 14 is wrapped around the heat transfer member 14 to drive it. The thermistor 13 for detecting the heat of the coil 6 is provided.

That is, the heat transfer member 14 is formed, for example, by winding a thin copper wire in a spiral shape so as to be inscribed in the drive coil 6 as shown in the drawing, or a side sectional view of the main part of FIG. ), A net-like member 14 'in which fine wires are braided is formed into a tubular shape by winding, as shown in the enlarged view of the C portion in FIG.

The thermistor 13 is wound into a thin wire as shown in FIG. 1 (b),
It is sealed to a thin thickness with good thermal conductivity, for example, silicon resin 15, or as shown in FIG. 2 (b), a copper wire mesh member 1
It is wrapped in 4 '.

By forming as described above, the temperature of the drive coil 6 is rapidly detected by the thermistor 13 via the heat transfer member 14 or 14 'having a small heat capacity.

Therefore, it becomes possible to prevent the drive coil 6 from being burnt out and appropriately control the print duty with respect to the temperature rise of the drive coil 6, and it is possible to obtain a print head with high throughput.

Although the above description has been made with the release type wire dot print head, the same effect can be obtained by applying it to the suction type wire dot print head that performs printing by sucking the armature to the core.

[Effect of device]

According to the present invention, it is possible to accurately detect the heat generation of the print head, prevent burnout of the drive coil, and accurately control the print duty corresponding to the temperature of the drive coil to obtain a print head with high throughput. It has a great effect on economy and industry.

[Brief description of drawings]

FIG. 1 (a) is a side sectional view of a main part of a wire dot print head according to the present invention, FIG. 1 (b) is an enlarged arrow view of part B of FIG. 1 (a), and FIG. FIG. 2 (b) is an enlarged arrow view of a portion C of FIG. 2 (a), and FIG. 3 (a) is a side sectional view of a conventional wire dot print head. FIG. 3 (b) is an enlarged perspective view of a portion A of FIG. 3 (a). In the figure, 2 is a print magnet, 5 is a core, 6 is a drive coil, 12 is a heat transfer ring, 13 is a heat sensitive element (thermistor), 14 and 14 'are heat transfer members, and 15 is a silicone resin.

Claims (1)

[Scope of utility model registration request] 1. A wire dot print head for arranging a plurality of print magnets (2) in a loop and selectively exciting the print magnets (2) to print with a print wire, wherein the print magnets A heat transfer member (14) wound around the drive coil (6) of (2) and wound in a loop, and a heat sensitive member that is wrapped in the heat transfer member (14) and detects heat of the drive coil (6) A wire dot print head characterized in that an element (13) is provided.