JP2616025B2 - Platen deformation protection mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to protection of an image forming apparatus such as a printer from deformation of a platen, in particular.

[Conventional technology]

FIG. 10 is a sectional view of a main part of an image forming apparatus disclosed in, for example, JP-A-61-11274.

In the figure, (1) is a cylindrical platen whose outer periphery is coated with hard rubber or the like made of a material having a large coefficient of friction with paper and whose surface is precisely finished, and is rotated by a driving device (not shown). The shafts (1a) at both ends are not coated. (2) is a pinch roller, which presses the outer periphery of the platen (1) and presses the platen (1).
And the printing paper (3) are brought into close contact with each other to prevent the printing paper (3) from slipping due to the rotation of the platen (1). (4) is a print head.

In the image forming apparatus of the platen (1) driven paper feed system as described above, especially in the color thermal image forming apparatus, the printing paper (3) is reciprocated several times by the rotation of the platen (1) to form the image color ink. Since the image is formed by thermal transfer by the print head (4), if there is a slip between the platen (1) and the printing paper (3), color shift occurs, so the pinch roller (2) is moved to the platen (1) with a strong force. It is pressed.

[Problems to be solved by the invention]

The conventional image forming apparatus is configured as described above, and the outer periphery of the platen (1) is constantly deformed by the pressing force of the pinch roller (2). Normally, when the image forming apparatus is used, the deformed portion by the pinch roller (2) moves by rotation of the platen (1), so that the deformed portion returns elastically and no deformation mark remains. However, when the image forming apparatus is not used for a long period of time, for example, during transportation and storage in a distribution process, the image forming apparatus is not used at all, so that the outer periphery of the platen (1) has the same position as the pinch roller (2). There is a problem that a deformed mark remains at a portion where the image forming apparatus is pressed due to being pressed and not resiliently restored, and when the image forming apparatus is reused, a print scar due to the deformed mark is generated, thereby deteriorating printing quality. Was.

Further, when the platen (1) is stored as a disassembly for assembling or repairing the image forming apparatus, the platen (1) is directly scratched on a floor surface or the like, and a contact portion with the floor surface is damaged. There has been a problem that print flaws occur and print quality is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and the invention has been described with reference to claims 1 and 2, wherein even if the image forming apparatus is not used for a long period of time, the pinch roller (2).
It is an object of the present invention to provide a platen deformation protection mechanism that can prevent deformation marks on the outer periphery of the platen (1) due to the pressure contact force.
Another object of the present invention is to provide a platen deformation protection mechanism which does not cause a contact flaw with the floor surface even when the platen (1) is placed on the floor surface or the like as it is.

[Means for solving the problem]

The platen deformation protection mechanism according to claim 1 of the present invention is:
A platen, a pinch roller pressed against the outer periphery of the platen, and a pinch roller inserted between the platen shaft and the pinch roller when the platen and the pinch roller are separated, and pressed against the platen outer periphery when the separation force between the platen and the pinch roller is lost. And a removable spacer for reducing the force.

The platen deformation protection mechanism according to claim 2 of the present invention is:
A platen, a pinch roller pressed against the outer periphery of the platen, and a pinch roller interposed between the platen shaft and the pinch roller when the platen and the pinch roller are separated at a predetermined rotation position rotatably provided on shafts on both sides of the platen. And a cam spacer for reducing the pressing force of the roller against the outer periphery of the platen.

The platen deformation protection mechanism according to claim 3 of the present invention is:
In addition to the configuration of the second aspect, a line connecting adjacent convex portions on the outer periphery of the camshade is outside the outer periphery of the platen.

[Action]

In the first aspect of the present invention, the spacer inserted between the platen shaft and the pinch roller alleviates the pressing force of the pinch roller against the outer periphery of the platen.

In the second aspect of the present invention, the cam spacer interposed between the platen shaft and the pinch roller reduces the pressing force of the pinch roller against the outer periphery of the platen.

According to the third aspect of the present invention, when the platen disassembled from the image forming apparatus is placed on a floor or the like, the convex portion of the cam spacer prevents contact between the outer periphery of the platen and the floor or the like.

〔Example〕

FIG. 1 is a perspective view of a platen deformation protection mechanism showing one embodiment of the present invention, and FIG. 2 is a first embodiment of the present invention.
FIGS. 3 to 5 are perspective views of a spacer used in one embodiment of the present invention, and FIGS. 3 to 5 are cross-sectional views of a main part of the first embodiment of the present invention. FIG. FIG. 5 is a view showing a state in which the platen and the pinch roller are separated, and FIG. 5 is a view showing a platen deformation protection state.

In the figure, (1) to (3) are the same as those described in the above conventional example.

(5) is a backup roller for reinforcing the pinch roller (2), (6) is two sets of arms pivotally supporting the pinch roller (2) and the backup roller (5), and (7) is to the frame (8). A fixed bearing pin rotatably supports one end of each arm (6). Reference numeral (9) denotes a tension spring that is stretched between the other ends of the opposing arms (6), and applies a pressing force to the outer periphery of the platen (1) of the pinch roller (2) via the arm (6). I have. Reference numeral (10) denotes a cam provided between the opposed arms (6). The cam (10) is rotated by a lever (not shown) extended to the cam (10) to increase the interval between the arms (6) and to increase the platen (1). And the pinch roller (2) are separated. (11) is a support pin fixed to the frame (8), (12) is a U-shaped spacer made of a material having some elasticity (for example, hard rubber, polyacetal resin, etc.), and the space between the U-shaped sides is The width (L) of the U-shaped side (12a) is slightly wider than the axis (1a) diameter of the platen (1)
Is slightly thicker than the gap between the shaft (1a) and the core metal (2a) of the pinch roller (2) in a state where the platen (1) and the pinch roller (2) are in contact with each other, and the width of the tip (12b) is larger than the above gap. It is formed thin. The spacer (12) is provided with a Dharma hole (12c) which engages with the support pin (11) on the outer side of the U-shaped bottom. When the support pin (11) engages with the inner hole, the side (12a) is formed. ) Is on the center line of the platen (1) and the pinch roller (2), and when the support pin (11) is engaged with the outer hole, the tip () is located on the center line of the platen (1) and the pinch roller (2). 12b) is configured to come.

The platen deformation protection mechanism configured as described above will be described. In FIG. 3, a pinch roller (2) is pressed against a platen (1) via a printing paper (3).
The support pin (11) engages with the hole inside the Dharma hole (12c) of the spacer (12), and the side (12a) is in contact with the shaft (1a) and the core metal (2a) of the pinch roller (2). No, platen (1)
The photographic paper (3) is fed without any trouble by the pinch roller (2) being driven by the rotation of. Then, the cam (10) is turned in the direction of the arrow (A) to expand the space between the arms (6) against the tension spring (9). As a result, the space between the platen (1) and the pinch roller (2) is separated, and the separating force between the platen (1) and the pinch roller (2) disappears. Therefore, the spacer (12) is inserted in the direction of the arrow (B). This state is shown in FIG.
When the cam (10) is returned to the original position, the state shown in FIG. In the state shown in FIG. 5, the side (12) is located between the shaft (1a) and the metal core (2a).
a) is sandwiched, and the side portion (12a) supports the pressing force of the extension spring (9).

Therefore, when the apparatus is not used for a long period of time, the outer periphery of the platen (1) is released from the pressing force of the pinch roller (2) by setting the state of FIG. 5 and the surface is protected from deformation. Returning the device to normal use
Turn the cam (10), expand the arm (6), and place the spacer (1
If 2) is pulled out in the direction of arrow (C), the state returns to the state shown in FIG.

In a normal use state, the spacer (12) may be removed from the device, and the spacer (12) may be used only during the transportation and storage of the device. FIG. 6 is a sectional view of an essential part showing an embodiment of claim 2 of the present invention.
6 is a view showing a normal printing state, and FIG. 7 is a view showing a platen deformation protection state. FIG. 8 is a perspective view of a platen portion according to an embodiment of the present invention. In the figure, (1) to (3), (5)
Steps (10) to (10) are the same as those described in the first embodiment.

(13) is a pair of cam spacers rotatably disposed on the shafts (1a) on both sides of the platen (1), and (14) is a gear fixed to the cam spacer (13). The cam spacer (13) is rotated around (1a). The cam spacer (13) has a concave portion (13
b), the projection (13a) is provided, and the axis (1) of the projection (13a) is provided.
The height H from the center of (a) is larger than the radius D of the platen (1), and the height of the recess (13b) from the axis (1a) is smaller than the radius D of the platen (1). When the radius of the pinch roller (2) is R and the radius of the cored bar (2a) is r, the dimensional relationship is such that HD> R-r.

As shown in FIG. 6, in a normal printing state, a concave portion (13b) is arranged at an angle of contact with the platen (1) and the pinch roller (2) so that the pinch roller (2) is rotated by the rotation of the platen (1). And the printing paper (3) is fed without any trouble. Also, as shown in FIG. 7, in the platen deformation protection state, the cam spacer (13) is turned and the projection (13a) is arranged at the position where the platen (1) and the pinch roller (2) are in contact with each other. (2) core metal (2
The outer periphery of the platen (1) is released from the pressing force of the pinch roller (2), and the surface thereof is protected from deformation.

The transition from the state of FIG. 6 to the state of FIG.
Turn the arm (6), expand the gear (1)
The cam spacer (13) is rotated to a predetermined position via 4) to return the cam (10) to its original position. Returning from the state of FIG. 7 to the sixth state is performed in the same manner.

FIG. 9 is a view showing the relationship between the platen and the cam spacer for explaining one embodiment of the third aspect of the present invention. In the drawing, (1), (13), and (14) are the same as those described in the first embodiment, and the adjacent protrusions (13) sandwiching the recess (13b) of the cam spacer (13). 13a) is configured so that the line connecting them is outside the outer periphery of the platen (1). Therefore, even if the platen (1) is detached from the image forming apparatus and placed on a floor or the like as it is, the floor or the like and the outer periphery of the platen (1) do not come into contact with each other, so that the outer periphery of the platen (1) can be protected from being damaged.

[Effect of the invention]

As described above, according to the first aspect of the present invention, when the platen and the pinch roller are separated, they are inserted between the platen shaft and the pinch roller, and when the separation force between the platen and the pinch roller disappears, the pinch roller is moved to the outer periphery of the platen. A platen deformation protection mechanism that can prevent deformation marks on the outer periphery of the platen due to the pressing force of the pinch roller even when the image forming apparatus is not used for a long time by providing the insertable / removable spacer that reduces the pressing force of the platen. can do.

In the second aspect of the present invention, the platen is rotatably provided on the shafts on both sides of the platen and is interposed between the platen shaft and the pinch roller when the platen and the pinch roller are separated at a predetermined rotation position, and extends to the outer periphery of the platen of the pinch roller. By providing the cam spacer for reducing the pressing force of the platen, it is possible to provide a platen deformation protection mechanism capable of preventing deformation marks on the outer periphery of the platen due to the pressing force of the pinch roller even when the image forming apparatus is not used for a long time. .

According to the third aspect of the present invention, the line connecting the adjacent convex portions on the outer periphery of the cam spacer of the second aspect is outside the outer periphery of the platen. It is possible to provide a platen deformation protection mechanism that does not stick.

[Brief description of the drawings]

1 to 5 are views showing an embodiment of the first aspect of the present invention. FIG. 1 is a perspective view of a platen deformation protection mechanism, and FIG. 2 is a perspective view of a spacer used in the embodiment. FIG. 3 is a cross-sectional view of a main part in a normal printing state, FIG. 4 is a cross-sectional view of a main part in a state where a platen and a pinch roller are separated, FIG. 6 to 8 are views showing an embodiment of the second aspect of the present invention. FIG. 6 is a cross-sectional view of a main part in a normal printing state, and FIG. 7 is a cross-sectional view of a main part in a platen deformation protection state. FIG. 8, FIG. 8 is a perspective view of a platen portion, FIG. 9 is a diagram showing a relationship between a platen and a cam spacer for explaining one embodiment of the present invention, and FIG. 10 is a main part of a conventional image forming apparatus. It is sectional drawing. In the figure, (1) is a platen, (2) is a pinch roller, (6) is an arm, (7) is a bearing pin, (9) is a tension spring, (10) is a cam, (11) is a support pin, and (11). 12) is a spacer, and (13) is a cam spacer. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (3)

(57) [Claims] 1. A platen, a pinch roller which presses against the outer periphery of the platen, and inserted between the platen shaft and the pinch roller when the platen and the pinch roller are separated to eliminate the separating force between the platen and the pinch roller. A platen deformation protection mechanism, characterized in that the platen deformation protection mechanism comprises an insertable / removable spacer for reducing a pressing force of the pinch roller against the outer periphery of the platen. 2. A platen, a pinch roller pressed against the outer periphery of the platen, and rotatably provided on shafts on both sides of the platen. The platen shaft and the pinch are separated from each other at a predetermined rotation position when the platen and the pinch roller are separated. A platen deformation protection mechanism, comprising a cam spacer interposed between rollers to reduce a pressing force of the pinch roller against the outer periphery of the platen. 3. A line connecting adjacent protrusions on the outer periphery of the cam spacer is outside the outer periphery of the platen.
The platen deformation protection mechanism described in the above.