JP2534608Y2 - Print head - Google Patents

Description

[Detailed description of the invention]

[Industrial applications]

The present invention relates to a print head such as a thermal print head that selectively drives a plurality of heating elements arranged in a line at a high density and prints on recording paper by heat.

[Prior art]

For example, a general structure of a thermal print head is as shown in FIG. On one side of the upper surface of the heat sink 1 having a rectangular shape in a plan view, a head substrate 4 having a fixed thickness and having the heating element 2 and its drive circuit 3 provided on the upper surface is fixed. Further, on one side of the upper surface of the head substrate 4, there is provided a comb-shaped terminal portion 5 which is electrically connected to the drive circuit 3. On the other hand, on the other side of the upper surface of the heat radiating plate 1, a flexible circuit board 7 having a thickness substantially equal to that of the head substrate 4 and having a reinforcing plate 6 serving as a spacer function applied to the back surface is arranged. It is fixed to the heat radiating plate 1 together with the protective cover 8 which is overlaid to protect the drive circuit 3 and the like. A comb-shaped terminal portion 5 corresponding to the comb-shaped terminal portion 5 of the head substrate 4 is provided on the back surface of one side of the flexible circuit board 7 extending from the end of the reinforcing plate 6. This portion is overlapped with the comb-shaped terminal portion 5 of the head substrate 4 and a flexible circuit in the overlapping portion of the terminal portions 5, 5 is held by a round bar-shaped elastic pressing body 9 held in a holding groove on the back surface of the protective cover 8. By pressing the upper surface of the substrate 7, both the comb-shaped terminal portions 5, 5 of the head substrate 4 and the flexible circuit substrate 7 are brought into contact with each other at an appropriate pressure, and the electrical connection between the head substrate 4 and the flexible circuit substrate 7 is made. The reliability of electrical conduction is assured.
The width of the reinforcing plate 6 is determined such that the end opposite to the comb-teeth-shaped terminal portion 5 extends a predetermined length from the end of the heat sink 1. This is because the reinforcing plate 6 serves as a mounting seat for the connector 10 for connecting the thermal print head to an external circuit. Note that, in the figure, in order to make the structure of the thermal print head easy to understand,
The 5,5 overlapped part is enlarged and drawn.

[Problems to be solved by the invention]

By the way, in the case of a general thermal print head configured as described above, the reinforcing plate 6 is an indispensable member because of the connection structure of the terminal portions 5, 5 between the head substrate 4 and the flexible circuit substrate 7. Become. A spacer member is required in order to match the height positions of the head substrate-side terminal portions 5 provided on the upper surface of the head substrate 4 having a constant thickness and the circuit board-side terminal portions 5 provided on the back surface of the flexible circuit board 7. Because it becomes. However, if there is no need to provide such a reinforcing plate 6, the operation of attaching the reinforcing plate 6 to the flexible circuit board 7 can be omitted, and the number of manufacturing steps can be reduced by one. Further, since the number of components is reduced by one, the production cost can be reduced. The present invention has been conceived under the circumstances described above, and provides a print head that does not require the reinforcing plate serving as a spacer function for adjusting the height position of the flexible circuit board. That is its purpose.

[Means to solve the problem]

In order to solve the above problems, the present invention takes the following technical measures. That is, in the present invention, the head substrate having a predetermined thickness, which is fixed on the heat sink, and on which the print medium and its driving circuit are provided on the upper surface, and the terminal portion provided on the back surface are provided on the upper surface of the head substrate. A flexible circuit board mounted on the heat radiating plate so as to overlap with and press against the terminal portion. While the circuit board supporting step located at substantially the same height as the upper surface of the head substrate is integrally formed and provided, the flexible circuit board mounted on the upper terminal section or the circuit board supporting step of the head substrate is: It has this bent portion which is bent at one side along the side surface of the heat sink. In the electrophotographic process, a print head for an optical printer configured to linearly irradiate light from a light-emitting body such as a light-emitting diode (LED) to a photosensitive drum and expose the photosensitive drum is provided on the head substrate. Although the present invention has a structure in which light emitting elements are arranged in a high-density line in place of the heating element as a printing medium, the present invention can be applied to such a print head for optical printing.

[Action and effect]

The circuit board supporting step portion provided on the arrangement portion of the flexible circuit board on the upper surface of the heat sink has an upper surface at substantially the same height as the upper surface of the head substrate fixed on the heat sink. Therefore, if the flexible circuit board is placed on the circuit board supporting step, the height of the terminal provided on the upper surface of the head substrate and the height of the terminal provided on the back of the flexible circuit board superimposed on the flexible circuit board can be adjusted. Can be matched. That is, when arranging the flexible circuit board on the heat sink, it is necessary to interpose a reinforcing plate having a spacer function having a thickness substantially equal to that of the head board between the flexible circuit board and the heat sink as in a conventional print head. There is no. Further, in the present invention, since one side of the flexible circuit board mounted on the circuit board supporting step is bent and the bent portion is formed along the side surface of the heat radiating plate, the heat is radiated as in the related art. There is no need to extend the reinforcing plate as compared with the conventional structure in which the reinforcing plate is extended from one side of the plate and the connector connected to the flexible board is supported using the extending reinforcing plate. Accordingly, the size of the print head in the width direction can be reduced, and the size can be reduced. Further, since the connector is located at the position retracted to the back side of the head substrate, the connector does not interfere with the recording paper transport path, and the degree of freedom in setting the recording paper transport path is increased. Can be arranged at any position in the longitudinal direction of the print head. This means that restrictions on the transfer path of the recording paper and the positions of the wirings are reduced, and the degree of freedom in configuring the printer is increased. As described above, according to the present invention, it is not necessary to provide the above-mentioned reinforcing plate attached to the back surface of the flexible circuit board, which was indispensable in the conventional general print head. In addition, the number of parts can be reduced, and the production cost can be reduced. Further, since the flexible circuit board is bent and the bent portion is formed along the side surface of the heat sink, the size of the print head can be reduced, and a higher degree of freedom can be achieved when configuring a printer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. In this example, a case where the present invention is applied to a thermal printhead which is one of the printheads is shown. The thermal print head of this embodiment basically has substantially the same configuration as a conventional general thermal print head whose structure is described in detail in the section of [Prior Art]. That is, as shown in FIG. 1, the thermal print head of this example is fixed to one side of the upper surface of a heat sink 1 and has a fixed thickness head substrate 4 having a heating element 2 and a driving circuit 3 on the upper surface. The comb-shaped terminal portion 5 formed on the back surface is
And a film-shaped flexible circuit board 7 arranged on a heat sink so as to be overlapped with the comb-shaped terminal portion 5 formed on one side of the upper surface of the substrate. Also, the flexible circuit board 7
On the upper surface, covers the drive circuit 3 and the terminal portions
A protective cover 8 that presses the upper surface of the flexible circuit board 7 at the overlapping portion of 5, 5 via the elastic pressing body 9 is overlaid. It should be noted that, in the figure, in order to make the structure of the thermal print head easy to understand, the overlapping portion of the terminal portions 5, 5 is illustrated in an enlarged scale. Now, in this example, the circuit board supporting stage in which the upper surface of the radiator plate 1 is located at substantially the same height as the upper surface of the head substrate 4 placed on the radiator plate in the arrangement portion of the flexible circuit board 4 on the upper surface thereof A unit 11 is provided. This is the heat sink 1
The heat sink 1 is usually formed of a light metal material such as aluminum which can easily form a complicated and fine cross section by extrusion or die casting. Can also be easily formed. Strictly speaking, the height position of the upper surface of the circuit board supporting step portion 11 is determined so as to be higher than the upper surface of the head substrate 4 in consideration of the thickness of the comb-like terminal portions 5 and the like on the head substrate side. Can be Then, the flexible circuit board 7 is placed on the upper surface of the circuit board supporting step 11, so that the flexible circuit board 7 is disposed on the heat sink. In this case, as described above, since the upper surface of the circuit board supporting step 11 and the upper surface of the head substrate 4 are located at substantially the same height, if the flexible circuit board 7 is placed on the circuit board supporting step, The comb-shaped terminal portions 5 on the rear surface side of the flexible circuit board 7 are located at a height corresponding to the comb-shaped terminal portions 5 on the upper surface side of the head substrate 4, and the two terminal portions 5, 5 are in an overlapping state. That is, in the thermal print head of this example, a reinforcing plate, which is a spacer member for aligning the heights of both terminal portions of the head substrate and the flexible circuit board, as in the conventional thermal print head, is used as the flexible circuit board. There is no need to provide between the heatsink. Therefore, in this example, unlike the case of the conventional thermal print head, the work of attaching the reinforcing plate to the back surface of the flexible circuit board becomes unnecessary, and the number of components can be reduced. Cost can be reduced. In this example, as shown in FIG. 1, a stepped portion 12 is provided at the lower end of one side surface of the heat sink 1. Then, one side of the flexible circuit board 7 having flexibility is bent so that the bent portion is wrapped around the side surface of the heat sink 1, and the connector 10 attached to the end is connected to the step-down portion.
They are arranged along 12 sides. In the thermal print head of this embodiment to which the connector 10 is attached in this manner, the pressing force when the socket is inserted into the connector 10 can be received by the heat radiating plate 1, so that the connector 10 can be prevented from wobbling when the socket is inserted. At the same time, the mounting stability of the connector 10 is improved. Further, in this example, since the reinforcing plate does not need to be provided as described above, the flexible circuit board 7 can be directly pinched and held by the protective cover 8 and the heat radiating plate 1. 7 can be firmly fixed. In addition, in the case of this example, a sheet holding portion that sandwiches the side portion of the flexible circuit board 7 wrapped around the side surface of the radiator plate 1 together with the radiator plate 1 on the side portion of the protective cover 8.
Since the cover 13 is formed integrally with the protective cover 8, the fixing of the flexible circuit board 7 can be further strengthened. Further, by providing the sheet pressing plate portion 13, there is an advantage that the fluttering of the connector supporting portion of the flexible circuit board 7 can be prevented, and the supporting stability for the connector 10 can be improved. The protective cover 8
Is usually formed by extruding aluminum or the like in the same manner as the heat radiating plate 1.
The formation of 13 can be easily performed. Further, the sheet holding portion 13 and the flexible circuit board 7 together with the heat sink 1
If it is screwed to the flexible circuit board 7
And the support stability of the connector 10 can be further improved. The connector 10 is for electrically connecting the thermal print head to an external circuit, and must be electrically connected to the flexible circuit board 7 at the time of attachment. Therefore, in the conventional thermal printhead in which the reinforcing plate must be provided on the back surface of the flexible circuit board, in order to enable connection between the flexible circuit board 7 and the connector, the reinforcing plate must be used as a mounting seat for the connector. did not become. Therefore, in the conventional thermal print head, as shown in FIG. 3, the end of the reinforcing plate is further extended from the end of the heat radiating plate, and the connector is connected to the protruding portion 6a.
10 had been installed. However, the protruding portion protruding from the heat radiating plate over the entire longitudinal direction of the thermal print head restricts the miniaturization of the thermal print head, and the thermal print head becomes bulky. was there. On the other hand, in the case of the thermal print head of the present embodiment, since the reinforcing plate is not required, the connector 10 can be linearly attached to the flexible circuit board 7, and thus, the protrusion is not required. Therefore, the size of the thermal print head can be reduced. Further, in this example, the connector 10 is accommodated in the stepped portion 12 as described above, so that the thermal printhead can be further reduced in size. Also, as shown in FIG.
The connector 10 may be attached to the side surface without providing the connector 12. Also in this case, the size of the thermal print head can be reduced as compared with the related art. This is because the length of the connector 10 is usually overwhelmingly smaller than that of the protruding portion extending in the entire longitudinal direction of the thermal print head. Further, since the side surface of the connector 10 extends along the side surface of the heat radiating plate 1 via the flexible circuit board 7, the pressing force at the time of inserting the socket is reduced as in the above-described embodiment.
You can catch it. By the way, the scope of the present invention is not limited to the above-described embodiment. For example, the present invention can be applied to an LED print head used in an optical printer. this is,
The heating element 2 of the conventional thermal print head shown in FIG.
It has a structure in which a large number of LED elements are replaced by LED rows arranged linearly, and a reinforcing plate serving as a spacer is interposed between the flexible circuit board and the heat sink.
Therefore, structurally, it has the same problem as the conventional thermal print head. In addition, the shape of the circuit board supporting step is not particularly limited.

[Brief description of the drawings]

1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view of another embodiment, and FIG. 3 is a sectional view of a conventional example. 1 ... heat sink, 2 ... heating element, 3 ... drive circuit, 4 ...
Head board, 5 ... Terminal section, 7 ... Flexible circuit board, 11 ... Circuit board supporting step.

Claims (1)

(57) [Scope of request for utility model registration] A head substrate having a predetermined thickness fixed on a heat sink and having a print medium and a drive circuit provided on an upper surface thereof; and a terminal having a terminal portion provided on a rear surface provided on an upper surface of the head substrate. And a flexible circuit board disposed on the radiator plate so as to overlap with and press against the portion. An upper surface of the flexible circuit board on an upper surface of the radiator plate has an upper surface of the head substrate. A circuit board supporting step positioned at substantially the same height as that of the flexible printed circuit board mounted on the upper terminal section of the head substrate or the circuit board supporting step is provided on one side. A print head having a bent portion bent along a side surface of the heat sink.