JPH075745U - Thermal head holding mechanism - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a holding mechanism for a thermal head, which can easily hold the thermal head on the frame of the printer main body with one touch and does not require a special member for holding. With the goal. [Structure] Protrusions are provided at both ends of the heat sink of the thermal head, and when the thermal head is attached to the frame, the protrusions are inserted, and when the attached thermal head is tilted to the platen side, the protrusions fall off. Provide a locking hole to prevent

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of a thermal head holding mechanism when a thermal head is attached to a frame in a thermal printer that prints on paper by heat of the thermal head.

[0002]

[Prior art]

 As a conventional holding mechanism for the thermal head, there can be used, for example, Japanese Utility Model Laid-Open Nos. 62-139657, 62-45145, 62-116670 and 01-294081. Japanese Utility Model Laid-Open No. Sho 62-139657 holds a thermal head on a frame through a head support, and the head support has a shaft hole formed on both sides of the head support, which is rotatably held by a frame. It is retained by fitting it to.

In Japanese Utility Model Laid-Open No. 62-45145, a flat type thermal head is supported by a support shaft and pins attached to a support plate. In Japanese Patent Laid-Open No. 62-11670, a thermal head is supported by a head holder mounted on a ball bearing fixed to a hinge shaft that is stretched between both frames. In Japanese Patent Laid-Open No. 01-294081, the thermal head is fixed to the pressing lever by a threaded connecting member via an elastic body.

Among these, Japanese Patent Laid-Open No. 01-294081 requires a connecting member as a member for fixing, and the other members all have another holding metal fitting attached to the heat sink of the thermal head, and the through shaft is attached thereto. Is supported by the frame as a rotating shaft and is crimped to the platen.

[0005]

[Problems to be solved by the device]

 However, all of these require special members for fixing, and their structure is complicated, so that they have a drawback in that they are poor in assemblability and therefore the heads cannot be replaced easily.

The present invention has been made in view of the above conventional problems, and a protrusion is formed on the heat sink portion of the thermal head, and a locking hole into which the protrusion is fitted is formed on the frame. An object of the present invention is to provide a holding mechanism for a thermal head that does not require a holding member.

[0007]

[Means for Solving the Problems]

 To achieve the above object, the present invention comprises a protrusion formed on both ends of a heat sink portion of a thermal head, and a locking hole formed in the frame into which the protrusion is fitted when the thermal head is attached to the frame. The projections formed at both ends of the heat sink have a D-shaped cross section, the locking holes formed in the frame have a shape corresponding to the cross-sectional shape of the projections, and the thermal head is provided below the locking holes. The protrusions are inserted when mounting on the frame, and gaps are provided to prevent the protrusions from falling off when the mounted thermal head is tilted to the platen side. The protrusions are characterized in that the bushes are press-fitted into the protrusions formed at the both ends.

[0008]

[Action]

 When the protrusions formed on both ends of the heat sink of the thermal head are fitted into the locking holes formed on both ends of the frame and the thermal head is tilted to the platen side, the protrusion on the heat sink is prevented from falling off and the thermal head is attached to the frame. Hold securely.

[0009]

【Example】

 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view showing an embodiment of the present invention. FIG. 2 is a cross-sectional view of a main part showing a printing state in which the thermal head is attached to the printer body. FIG. 3 is a cross-sectional view of an essential part showing a state in which the pressing of the thermal head on the platen is released.

First, the configuration will be described. Reference numeral 1 is a frame of the printer body in which a rotatable platen 2 is pivotally supported in the front thereof. Reference numeral 3 is a thermal head having a heat sink portion 4. Reference numeral 5 is a head spring assembly for pressing the thermal head 3 held by the frame 1 toward the platen.

Projecting pieces 6, 6 are formed below both ends of the heat sink portion 4 of the thermal head 3 in the longitudinal direction, and bushes 7, 7 are fitted into the projecting pieces 6, 6. The bush 7 has a D-shaped cross section in which one side of the outer circumference is cut off, and the bush 7 is press-fitted and attached to the protrusion 6. Locking holes 8, 8 into which the bushes 7, 7 are fitted are formed below both ends of the frame 1. The locking hole 8 is composed of an insertion groove 8a below the locking hole 8 and a hole 8b above which has a diameter such that the D-shaped cross section of the bush 7 can rotate.

The width of the insertion groove 8a is such that the bush 7 slips when the thermal head 3 is attached to the frame 1 and the bush 7 does not fall off when the attached thermal head 3 is tilted toward the platen 2 side. It is smaller than the diameter of the D-shaped portion of the bush 7 so as to be blocked.

Since the hole 8b closely contacts the print surface of the thermal head 3 to the outer periphery of the platen 2, it is desirable that the hole 8b be slightly larger than the bush 7 so as to have some backlash to avoid excessive restraint. The head spring assembly 5 has a spring 9 attached to the front thereof for pressing the thermal head 3 attached to the frame 1, a stopper portion 10 at both ends, and a square hole into which a positioning protrusion 12 of the frame 1 is fitted to a holder 11 at the rear. 13 is formed. Reference numeral 14 is a head up lever that releases the pressing of the thermal head 3 toward the printing side, and 15 is a receiving window into which the stopper portion 10 of the head spring assembly 5 is inserted.

The actual use of the thermal head holding mechanism of the present invention having the above structure will be described. Insert the heat sink part 4 from the lower side of the frame 1, insert the bushes 7, 7 into the insertion grooves 8a, 8a of the respective locking holes 8, 8 and slide the bushes 7, 7 into the holes 8b, 8b. The thermal head 3 is tilted to the platen 2 side in the state in which the thermal head 3 enters. As a result, the thermal head 3 is held by the frame 1 without the bush 7 falling off from the locking hole 8. Next, the holder 11 at the rear of the head spring assembly 5 is placed on the positioning protrusions 12, 12 of the frame 1, and the stopper portions 10, 10 are put into the receiving windows 15, 15 of the frame 1 and pushed down to form the square hole 13, The head spring assembly 5 is attached to the frame by shifting the head spring assembly 5 so that 13 is inserted in the positioning protrusions 12, 12.

As described above, the printer main body in which the thermal head 3 and the head spring assembly 5 are incorporated in the frame 1 is in the lower side or the rear side as shown by an arrow in FIG. 3 with the head up lever 14 pulled forward. After feeding the paper from the side, the head up lever 14 is tilted to the platen 2 side as shown in FIG. 2 to start printing. Note that the head-up lever 14 is pulled forward as shown in FIG. 3 not only when the paper is supplied. By pulling it toward you when you are not printing, you can prevent distortion due to distortion without imposing an unnecessary burden on the heat sink of the thermal head.

The removal of the thermal head 3 from the frame 1 is performed in the reverse order of the above. That is, when the square holes 13 and 13 of the head spring assembly 5 are removed from the positioning protrusions 12 and 12 and the stopper portions 10 and 10 are displaced so as to be removed from the receiving windows 15 and 15 of the frame 1, the head spring assembly 5 is removed. Further, when the heat sink portion 4 is pulled toward you and the straight line portions of the D-cuts of the bushes 7, 7 and the straight line surface of the insertion groove 8a are aligned with each other, the heat sink 4 falls downward and the thermal head 3 comes off the frame 1.

In the above embodiment, the protrusions 6 are formed by press-fitting the bushes 7 on the both ends of the heat sink portion 4. Can also be formed. However, the method of fitting the bush as in the present embodiment has an advantage that the heat sink can be easily manufactured.

[0018]

[Effect of device]

 As described above, since the thermal head holding mechanism according to the present invention is provided with the projections at both ends of the heat sink and only has the corresponding locking holes at both ends of the frame, a special member for holding is required. In addition, no special technique is required because the bush and the locking hole need only be aligned when mounting. Therefore, it can be attached / detached with one touch, and the number of parts can be significantly reduced. Therefore, the maintainability is improved, and further, the cost can be reduced, which is a great effect.

[Brief description of drawings]

FIG. 1 is an overall exploded perspective view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part showing a printing state in which a thermal head is attached to a printer body.

FIG. 3 is a cross-sectional view of essential parts showing a state in which the pressing of the thermal head against the platen is released.

[Explanation of symbols]

 1 frame 2 platen 3 thermal head 4 heat sink 5 head spring assembly 6 projecting piece 7 bush 8 locking hole

Claims (3)

[Scope of utility model registration request] 1. A thermal printer comprising a thermal head mounted on a frame and a platen, wherein printing is performed on the paper by the heat of the thermal head, when protrusions formed on both ends of a heat sink of the thermal head and the thermal head are mounted on the frame. A thermal head holding mechanism comprising: a locking hole formed in a frame into which the projection is fitted. 2. The projections formed at both ends of the heat sink portion have different cross-sectional shapes, the locking holes formed in the frame have shapes corresponding to the cross-sectional shapes of the projections, and the thermal holes are provided below the locking holes. The holding mechanism for the thermal head according to claim 1, wherein the projection is inserted when the head is attached to the frame, and a gap is provided to prevent the projection from falling off when the attached thermal head is tilted to the platen side. . 3. The thermal head holding mechanism according to claim 2, wherein the protrusions formed at both ends of the heat sink portion of the thermal head are formed by pressing bushes into the protrusions formed at the both ends.