JPH05254187A - Printing device - Google Patents

Abstract

PURPOSE:To eliminate static electricity to be generated on a surface of a thermal head so as to protect the thermal head. CONSTITUTION:A platen roller 42 is constituted of a conductive roller axis 43 and a conductive roller body 44 to be fitted to the periphery of the roller axis 43. An earth plate for conductively connecting the roller axis 43 and end plates 3 of a frame 5 is provided. Accordingly, static electricity generated on a surface of a thermal head 32 can be earthed to the frame 5 through the roller body 44 and the roller axis 43 of the thermal head 32 and the earth plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer using a thermal head.

[0002]

2. Description of the Related Art As a printing apparatus such as a facsimile or a word processor, a thermal head called a line thermal head, which is long in the width direction of a sheet to be printed, is used to eliminate movement of the thermal head in the sheet width direction. ..

In this printing apparatus, a paper such as thermal paper is sandwiched between the printing surface of the thermal head and the platen roller,
The platen roller rotates to feed the paper in the lengthwise direction while printing, and an opening / closing mechanism is provided to open the thermal head and platen roller for attaching and detaching the paper. A spring for closing is also provided. The platen roller has a structure in which an insulating platen rubber is fitted around the roller shaft.

[0004]

By the way, during printing, static electricity is generated on the surface of the thermal head due to paper feeding and the like.

However, since the conventional printing apparatus is not provided with a grounding means for removing static electricity generated on the surface of the thermal head during printing, static electricity is charged on the surface of the thermal head and damages the thermal head. Sometimes.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a printing apparatus capable of removing static electricity generated on the surface of the thermal head during printing and protecting the thermal head. It is what

[0007]

According to the present invention, a frame having end plates at both ends, a thermal head provided between the end plates at both ends of the frame, and a frame facing a printing surface of the thermal head. In a printing apparatus provided with a platen roller rotatably provided between end plates of the platen roller, the platen roller having a conductive roller shaft, and a conductive roller fitted around the roller shaft. And a ground plate for conductively connecting the roller shaft and the end plate of the frame.

[0008]

In the present invention, during printing, static electricity generated on the surface of the thermal head due to paper feeding is grounded to the frame through the roller body and roller shaft of the platen roller and the ground plate.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the printing apparatus of the present invention will be described below with reference to the drawings.

In the figure, reference numeral 1 is a frame unit, which is an elongated plate-like substrate 2 made of a conductive metal and end plates 3 made of a conductive metal provided at both ends of the substrate 2.
And a frame 5 composed of a conductive metal guide rod 4 connecting the both end plates 3.

The substrate 2 is a frame member formed by extrusion molding of aluminum or the like and cut into a predetermined length.
Mounting grooves 6 are formed in the rear side edge portion of the upper surface and in an intermediate portion near the front side edge, respectively, and support pins 7 are vertically planted on the front side portions of the left and right ends thereof, respectively. The lower ends of the coiled springs 8 are fitted to the outer sides of the support pins 7, respectively.

The end plates 3 are formed by press molding and are fixed to the end portions of the substrate 2 by screws 9 that are screwed into the mounting grooves 6. Circular holes 10 and 11 having narrow insertion openings are formed in the upper edge portion and the front edge portion of the end plate 3. A mounting hole 12 is formed on the rear side of the circular hole 10 of the one end plate 3.

Further, in the vicinity of the rear edge of the inner surface of both end plates 3,
A shaft body 14 having an annular groove 13 is projectingly provided. On the outer surface of the other end plate 3, a rod 15 having a screw hole is projected.

A drive unit 21 has a motor 23 attached to the outer surface of the support plate 22 and a motor 23 on the inner surface of the support plate 22.
A gear 24 attached to the drive shaft of the is protruded, and a gear 25 having a large diameter gear portion 25a and a small diameter gear portion 25b meshing with the gear 24 is rotatably supported.

The drive unit 21 is attached to the rod 15 of the other end plate 3 by screwing a screw 26 inserted through the support plate 22.

A head unit 31 has an elongated thermal head 32 called a line thermal head.
In this thermal head 32, a heat sink 35 made of metal such as aluminum is attached to the lower surface of a circuit board 34 having a printed surface 33 formed on the upper surface, and a metal cover 36 is attached to the upper surface of the circuit board 34. ing.

Mounting brackets 37 are attached to the lower surfaces of both ends of the heat dissipation plate 35 of the thermal head 32 by screws or the like, and bearing pieces 38 are formed at the rear ends of both ends of the thermal head 32 on each mounting bracket 37. This bearing piece 38 has a notched bearing portion 39
Are formed.

The head unit 31 is inserted from above between the both end plates 3 of the frame 5, and the bearing portion of the bearing piece 38 is inserted.
By fitting 39 into the annular groove 13 of the shaft body 14 protruding from the inner surface of the end plate 3, the shaft body 14 is supported rotatably in the up-down direction. In addition, the head unit 31 has a mounting bracket 37
Is urged upward by a spring 8 that contacts the lower surface of the front part of

Reference numeral 41 is a roller unit, which is a platen roller 42.
have. In this platen roller 42, a roller body 44 made of conductive rubber is formed around a roller shaft 43 made of metal having conductivity. Guide levers 45 made of synthetic resin are attached to both ends of the platen roller 42. The guide lever 45 has a base end formed with a bearing hole 46 into which the roller shaft 43 is rotatably fitted. A fitting protrusion 47 is provided on the outer end surface of the base end portion around the bearing hole 46, and an arc-shaped engaging portion 48 is formed at the tip end portion. A gear 49 is attached to one end of the roller shaft 43.

Then, both guide levers 45 of the roller unit 41 are vertically inserted, and the notches formed in the fitting projections 47 are vertically inserted into the circular holes 10 of the end plates 3 of the frame 5. After that, the guide lever 45 is rotated in the direction of the guide rod 4 and the engaging portion 48 at the tip of the guide lever 45 is fitted into the guide rod 4, whereby the guide lever 45 is held at that position. The fitting protrusion 47 is held in the circular hole 10.

In this state, the platen roller 42
Roller body 44 contacts the printing surface 33 of the thermal head 32 and pushes down the head unit 31 against the spring 8, and the roller body 44 of the platen roller 42 and the printing surface 33 of the thermal head 32 come into close contact with each other. It becomes a state.

The gear 49 of the roller unit 41 meshes with the small-diameter gear portion 25b of the gear 25 of the drive unit 21. Therefore, when the motor 23 of the drive unit 21 is driven in this state, the gear 24 shifts to the gear 25 large diameter gear parts 25
a, from the small diameter gear part 25b of this gear 25 to the roller unit
The rotation is transmitted to the gear 49 of 41, and the platen roller 42 is rotated.

Reference numeral 51 is a rod unit having a metal opening / closing rod 52, and rivets are provided near both ends of the opening / closing rod 52.
53 have been planted. Attaching / detaching levers 54 are attached to both ends of the opening / closing rod 52, and although not shown, a bearing hole for rotatably supporting the end portion of the opening / closing rod 52 is formed in the attaching / detaching lever 54, A fitting protrusion similar to the fitting protrusion 47 is provided on the outer end surface. Open / close rod
An opening / closing lever 55 is fixed to the other end of 52, and an engaging groove 56 is formed in the base portion of the opening / closing lever 55.

Like the roller unit 41, the rod unit 51 has both the attachment / detachment levers 54 in a horizontal position, and the cutout portions of the fitting protrusions of the attachment / detachment lever 54 in a horizontal position. After inserting into the circular hole 11 of each end plate 3, the attaching / detaching lever 54 is rotated in the direction of the platen roller 42, and the locking projection 54a on the outer end of the attaching / detaching lever 54 is attached to the end plate 3.
The fitting lever is held in that position and the fitting projection is held in the circular hole 11 by fitting the fitting protrusion into the circular hole 11.

Then, in this state, the engaging groove 56 of the opening / closing lever 55 engages with the engaging pin 57 provided on the outer end surface of the end plate 3 to set the turning range of the opening / closing lever 55. Open / close lever
When 55 is rotated rearward, the rivet 53 of the opening / closing rod 52 is positioned above the mounting bracket 37 of the head unit 41, which causes the rivet 53 of the opening / closing rod 52 to move to the pair of mounting brackets 37.
Away from the head unit 31, the head unit 31 is lifted by the spring 8,
The printing surface 33 of the thermal head 32 of the head unit 31 is in close contact with the roller body 44 of the platen roller 42 of the roller unit 41. When the open / close lever 55 is rotated forward, the rivet 53 of the open / close rod 52 abuts the mounting bracket 37,
This rivet 53 pushes down the head unit 31 against the spring 8, and the print surface of the thermal head 32 of the head unit 31 is pressed.
33 is a roller unit 44 of the platen roller 42 of the roller unit 41
It is descending from and leaving.

Reference numeral 61 denotes a ground plate, which is made of, for example, stainless steel having conductivity and has a through hole 62 at the rear end and a contact piece 63 bent at the front end in a substantially U shape. Has been. Then, the ground plate 61 is attached to the attachment hole 12 of the one end plate 3 by screwing a screw 64 inserted through the through hole 62. In this mounted state, the contact piece portion 63 elastically comes into pressure contact with the end surface of the roller shaft 43 of the platen roller 42, so that the roller body 44 and the roller shaft 43 are electrically connected to the frame 5.

Next, the operation of this embodiment will be described.

In the printing apparatus having the above-described structure, the opening / closing lever 55 is pivotally operated to lower the thermal head 32 and separate it from the platen roller 42, whereby a paper such as thermal paper is printed on the printing surface of the thermal head 32. It can be inserted between 33 and the roller body 44 of the platen roller 42. In this state, the opening / closing lever 55 is rotated to raise the thermal head 32 by the spring 8 and urge the sheet toward the platen roller 42, so that the paper is printed on the printing surface 33 of the thermal head 32.
And the roller body 44 of the platen roller 42.

In this state, when the platen roller 42 is rotated by the motor 23, the paper can be moved, and the thermal head 32 is driven in conjunction with the movement of the paper to print on the paper. be able to. The paper is introduced between the thermal head 32 and the platen roller 42 through the guide rod 4, and then discharged through the open / close rod 52.

It should be noted that during printing, static electricity is generated on the surface of the thermal head 32 due to paper feeding and the like, and the static electricity can escape to the frame 5 through the roller body 44, the roller shaft 43, and the ground plate 61. it can. Therefore, the surface of the thermal head 32 can be prevented from being charged with static electricity,
The thermal head 32 can be protected.

When assembling the printing apparatus, the components are assembled to the head unit 31, the roller unit 41 and the rod unit 51 to some extent, and then the spring 8 and the like are attached to the separately assembled frame unit 1. Together with each unit in order to complete easily.

In the above-described embodiment, as shown by the chain double-dashed line in FIG. 2, the rear edge of the end plate 3 of the frame 5 is extended to integrally form a support piece 71. The roll-shaped paper P can be rotatably supported, and the roll-shaped paper P can be pulled out and introduced over the guide rod 4 between the thermal head 32 and the platen roller 42.

[0033]

According to the present invention, during printing, static electricity generated on the surface of the thermal head due to the feeding of the paper is conducted through the roller body and roller shaft of the platen roller, and the ground plate. The frame can be grounded and the thermal head can be protected. Therefore, the life of the thermal head can be extended and a good printing state can be maintained.

[Brief description of drawings]

FIG. 1 is a perspective view of a printer according to an embodiment of the present invention, which is exploded for each unit.

FIG. 2 is a plan view of the assembled state.

FIG. 3 is a plan view of a part thereof.

[Explanation of symbols]

 3 End plate 5 Frame 32 Thermal head 33 Printing surface 42 Platen roller 43 Roller shaft 44 Roller body 61 Ground plate

Claims (1)

[Claims] 1. A frame having end plates at both ends, a thermal head provided between the end plates at both ends of the frame, and a thermal head provided between the end plates at both ends of the frame facing a print surface of the thermal head. A platen roller provided so that the platen roller includes an electrically conductive roller shaft and an electrically conductive roller body fitted around the roller shaft; And a ground plate for conductively connecting the frame and the end plate of the frame.