JPH11291571A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To position an axial center of a roller and an element of a device by projecting a protrusion formed connectibly with a U-shaped groove at the device, thereby merely engaging the protrusion at the device side with the groove of the roller side. SOLUTION: A positioning member 7 is provided at a roller unit for arranging a platen roller 2. A U-shaped groove 7a formed substantially in a U-like state is formed on the member 7. A protrusion 5a formed connectibly with the groove 7a is projected from a thermal head 1. The member 7 is disposed so that an axial center O of the roller 2 is positioned on a centerline of the groove 7a as seen from a side face. The member 7 is formed integrally with a support member 6 rotatably supporting the roller 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a facsimile apparatus, which comprises a device such as a recording device and a reading device, and a roller having a fixed positional relationship with the device. Related to the device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a facsimile apparatus, devices such as a thermal head as a recording apparatus and an image sensor as a reading apparatus include:
A plurality of elements arranged in a line are provided, and a sheet is passed between the element and a roller in a fixed positional relationship with the device, and recording is performed on the sheet,
Some of them read the contents of the paper. In order to perform recording and reading in this manner, it is necessary to align the positions of the elements arranged in a line with the axis of the roller, and the positioning mechanism includes a support movably attached to the device. In some cases, a U-shaped groove is formed in a member or the like, and positioning is performed by fitting the U-shaped groove to a roller shaft.

[0003]

However, as described above, if the U-shaped groove formed on the device side is used to position the element of the device and the axis of the roller, the position of the device relative to the rotation direction of the roller shaft can be improved. It is necessary to separately position the device, and there has been a problem that the positioning accuracy between the device and the roller is reduced as a whole, and the number of parts is increased. Furthermore, when the rotation direction of the roller is reversed, there is a serious problem that the positioning is incorrect.

[0004]

According to the present invention, the following means are used to solve the above-mentioned problems in the paper conveying apparatus. That is, according to claim 1, an image forming apparatus including a device and a roller having a fixed positional relationship with respect to the device, wherein a positioning member is provided in a roller unit provided with the roller, A U-shaped groove formed in a U-shape is formed in the positioning member, and the U-shaped groove is formed.
A protrusion formed to be fittable with the groove is projected from the device.

In the present invention, the positioning member is arranged such that the axis of the roller is located on the center line of the U-shaped groove in a side view.

According to a third aspect of the present invention, the positioning member is formed integrally with a supporting member that rotatably supports the roller.

[0007]

Embodiments of the present invention will be described with reference to the accompanying drawings. 1 is a side view showing a recording unit of the facsimile apparatus, FIG. 2 is a front view showing a state in which the thermal head and the platen roller are in pressure contact with each other, and FIG. FIG. 4 is a perspective view showing a recording unit in a state where the recording unit is not fitted in the groove, and FIG.
FIG. 5 is a perspective view showing a state fitted in the U-shaped groove. FIG. 5 is a front-rear positional relationship between the axis of the roller shaft and the center line of the U-shaped groove, and a front-rear position between the center line of the heating resistor and the center of the protrusion. FIG. 6 is a side view showing the relationship, and FIG. 6 is a side view showing another embodiment.

A facsimile apparatus as an image forming apparatus according to the present invention will be described. 1 and 2, for example, a recording unit of a facsimile apparatus is provided with a thermal head 1 as a recording device and a platen roller 2 as a roller pressed against the thermal head 1. A roller shaft 2a of the platen roller 2 is provided horizontally on the left and right, and a heating resistor 1a, which is a recording element constituting the thermal head 1, is disposed on a lower surface of the thermal head 1; A plurality are arranged in a line in the direction.

A support member 5 is fixed to the thermal head 1, and the thermal head 1 is vertically movably attached to a front portion of the swing frame 3 via the support member 5. A coil spring 4 is provided on the swing frame 3 above the thermal head 1. The swing frame 3 is configured to be vertically rotatable about a rotation center 3a.

A platen roller 2 is disposed below the thermal head 1, and a roller shaft 2a of the platen roller 2 is provided.
Are rotatably supported at both ends thereof by bearings 6 as support members. A positioning member 7 is disposed at an outer end of the bearing 6, and the positioning member 7 and the bearing 6 are formed integrally. The positioning member 7 is fixed to, for example, a frame of the main body of the facsimile apparatus, and the bearing 6 may be rotatably attached to the positioning member 7.

A U-shaped groove 7a is formed in the upper portion of the positioning member 7, and the U-shaped groove 7a is a substantially U-shaped groove when viewed from the side, and is open upward. Then, the platen roller 2, the roller shaft 2a, the bearing 6, and
A roller unit is constituted by the positioning member 7 and the like. In addition, a protrusion 5a protruding outward is formed on the outer surface of the support member 5, and the protrusion 5a is configured to be able to fit with the U-shaped groove 7a of the positioning member 7.

When the front portion of the swing frame 3 is rotated downward, the thermal head 1 moves downward from the state shown in FIG. 3, and as shown in FIG. The protrusion 5a of the member 5 is
When the heat generating resistor 1a on the lower surface of the thermal head 1 comes into contact with the outer peripheral surface of the platen roller 2, the downward movement of the thermal head 1 is stopped. Thereafter, when the swing frame 3 is further rotated downward, the coil spring 4 attached to the swing frame 3 comes into contact with the upper surface of the thermal head 1 and is compressed.

As a result, the thermal head 1 is urged downward, and moves downward within a range until the projection 5a reaches the lower end of the U-shaped groove 7a, and the heating resistor 1a of the thermal head 1 and the platen are moved. The roller 2 comes into pressure contact with the roller 2.
In this state, the swing frame 3 is configured so that its upper and lower positions are fixed and recording is performed on paper.

The outer diameter of the projection 5a of the support member 5 is formed to be equal to or slightly smaller than the inner diameter of the U-shaped groove 7a of the positioning member 7, and the projection 5a is fitted into the U-shaped groove 7a. The thermal head 1 and the platen roller 2
Is configured to be able to maintain a constant relative position with respect to. That is, the heating resistor 1a of the thermal head 1
And the relative position of the platen roller 2 with respect to the axis of the roller shaft 2a can be kept constant for positioning.

In FIG. 5, the positioning member 7 has a shaft center O of a roller shaft 2a supported by a bearing 6 formed integrally with the positioning member 7 in a side view. It is arranged so as to be located on the center line X of the groove 7a. Further, the center P of the protrusion 5a of the support member 5 is disposed so as to be located on the center line Y of the heating resistor 1a of the thermal head 1. When the protrusion 5a is fitted into the U-shaped groove 7a. The center P of the projection 5a and the U-shaped groove 7
Since the center line X of a coincides with the front-back position thereof, the front-rear position of the center line Y of the heating resistor 1a and the axis O of the roller shaft 2a also coincides. In this manner, by fitting the protrusion 5a on the thermal head 1 side into the U-shaped groove 7a on the platen roller 2 side, the axis O of the roller shaft 2a and the center line Y of the heating resistor 1a of the thermal head 1 are And the front and rear positions are matched.

The positioning between the axis O of the roller shaft 2a and the heating resistor 1a of the thermal head 1 may be performed as follows. For example, as shown in FIG. 6, the center line Y of the heating resistor 1 a of the thermal head 1 is displaced from the center P of the protrusion 5 a of the support member 5 by a dimension D in the front-rear direction, and The center O of the shaft 2a is moved in the same direction as the center P with respect to the center line Y, and the positioning member 7
Are shifted from the center line X of the U-shaped groove 7a by a dimension D. Even when the projection 5a is fitted in the U-shaped groove 7a with this configuration, the heating resistor 1a
Of the roller shaft 2a and the center line Y of the roller shaft 2a can be matched.

Further, the axis O of the roller shaft 2a is
a, and the center line Y of the heating resistor 1a and the center P of the protrusion 5a can be arranged so as to be displaced by the dimension D in the front-rear direction. In this case, when the projection 5a is fitted into the U-shaped groove 7a, the center line Y of the heating resistor 1a and the axis O of the roller shaft 2a are formed.
Is shifted by the dimension D. When the thermal head 1 is mounted on the image forming apparatus, when the mounting position is to be finely adjusted by actual physical alignment, the center line Y of the heating resistor 1a and the axis O of the roller shaft 2a are positioned in this manner. The position can be shifted by a certain dimension.

Incidentally, as in the above-described embodiment, the heat generation of the thermal head 1 is performed by fitting the protrusion 5a formed on the thermal head 1 into the U-shaped groove 7a of the positioning member 7 provided on the roller unit. The mechanism for positioning the resistor 1a and the axis O of the platen roller 2 can be applied to other devices, for example, a mechanism for positioning the reading element of the image sensor and the roller.

As described above, the positioning member 7 having the U-shaped groove 7a is provided on the roller unit, and the protrusion 5a formed so as to be able to be fitted to the U-shaped groove 7a is connected to the thermal head 1 via the supporting member 5. The protrusion 5a on the thermal head 1 side in the U-shaped groove 7a on the platen roller 2 side.
, It is possible to position the axis O of the roller shaft 2a and the heating resistor 1a of the thermal head 1 and at the same time to position the thermal head 1 in the rotation direction of the platen roller 2. Can be done. Therefore, the positioning can be performed accurately, and even if the rotation direction of the platen roller 2 is reversed, the position of the thermal head 1 can be prevented from being out of order.

Further, the axis O of the platen roller 2 is positioned on the center line X of the U-shaped groove 7a in a side view.
By disposing the positioning member 7, the heating resistor 1a
The positional relationship between the heating resistor 1a and the axis O of the roller shaft 2a in the front-rear direction can be the same as the front-rear positional relationship between the heating element 1a and the center P of the protrusion 5a. Can be.

Further, by forming the positioning member 7 integrally with the bearing 6, the number of parts can be reduced, so that the positioning accuracy can be further improved and the cost can be reduced.

[0022]

According to the present invention, the following effects can be obtained by employing the above-described configuration in the image forming apparatus.
First, a positioning member is provided in a roller unit in which a roller is provided, and a U-shaped groove formed in a substantially U-shape is formed in the positioning member so that the U-shaped groove can be fitted. Since the formed protrusion is provided on the device, the device-side protrusion is simply fitted into the roller-side U-shaped groove.
As a result, the device can be positioned with respect to the rotation direction of the roller at the same time that the axis of the roller and the device element can be positioned. As a result, the positioning can be performed accurately, and the position of the device can be prevented from being out of order even when the rotation direction of the roller is reversed.

Furthermore, the positioning member is arranged such that the axis of the roller is located on the center line of the U-shaped groove in a side view. Can be used as it is as the positional relationship between the element and the axis of the roller.
The positioning accuracy could be further improved.

Further, since the positioning member is formed integrally with the supporting member that rotatably supports the roller, the number of parts can be reduced, and the positioning accuracy is further improved. And reduced costs.

[Brief description of the drawings]

FIG. 1 is a side view showing a recording unit of a facsimile apparatus.

FIG. 2 is a front view showing a state in which the thermal head and a platen roller are in pressure contact with each other.

FIG. 3 is a perspective view showing the recording unit in a state where a protrusion of a support member of the thermal head is not fitted into a U-shaped groove of a positioning member.

FIG. 4 is a perspective view showing a state in which a protrusion of a support member of the thermal head is fitted in a U-shaped groove of a positioning member.

FIG. 5 is a side view showing a front-rear positional relationship between a shaft center of a roller shaft and a center line of a U-shaped groove and a front-rear positional relationship between a center line of a heating resistor and a center of a protrusion.

FIG. 6 is a side view showing another embodiment.

[Explanation of symbols]

 O Center of axis (of roller shaft) P Center of (projection) X Center line of U-shaped groove Y Center line of heating resistor 1 Thermal head (device) 1a Heating resistor (element) 2 Platen roller ( Roller) 2a Roller shaft 5 Support member 5a Projection 6 Bearing (support member supporting roller shaft) 7 Positioning member 7a U-shaped groove

Claims (3)

[Claims] 1. An image forming apparatus comprising: a device; and a roller having a predetermined positional relationship with the device, wherein a positioning member is provided on a roller unit on which the roller is disposed, and a substantially U-shaped member is provided. A U-shaped groove formed in the positioning member is formed on the positioning member.
An image forming apparatus protruding from the device. 2. The image forming apparatus according to claim 1, wherein the positioning member is arranged such that an axis of the roller is located on a center line of the U-shaped groove in a side view. 3. The image forming apparatus according to claim 1, wherein the positioning member is formed integrally with a support member that rotatably supports the roller.