Information
-
Patent Grant
-
6556232
-
Patent Number
6,556,232
-
Date Filed
Friday, March 30, 200123 years ago
-
Date Issued
Tuesday, April 29, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 347 242
- 347 245
- 347 252
- 347 263
- 347 257
- 400 82
- 310 32302
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International Classifications
-
Abstract
A platform for precisely moving a stage and holding the stage at a position to which the stage has been moved, using an eccentric cam. The platform uses plate springs to support the stage at which an exposure head is formed. An outer circumferential portion and a central axis portion of the eccentric cam rotate relative to one another, and the plate springs urge legs of the stage toward the outer circumference. As a stepping motor drives the eccentric cam to rotate, the legs are urged to abut the outer circumference. Due to the rotation of the eccentric cam, the stage is moved in the direction the plate springs and the rotating drum approach/separate from one another, and held at a position where the eccentric cam has stopped.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a base structure, a processing device, and an image forming device.
2. Description of the Related Art
In an image exposure device for exposing a light-sensitive material such as a light-sensitive planographic printing plate used for printing or the like (which is referred to as a “printing plate” hereinafter), a semiconductor laser, an LED (light emitting diode) or the like is used as a light source, and a light beam emitted from this light source scans and exposes a printing plate. At this time, the light beam is modulated on the basis of image data, and an image is formed on the printing plate.
A light source for exposure provided at such an image exposure device is mounted on a substantially plate-shaped stage integrated with an optical system to thereby form an exposure head. Thus, a light beam emitted from the light source is irradiated from the exposure head onto the printing plate, whereby the printing plate is exposed.
If a distance between the exposure head and the printing plate is not adjusted appropriately, focal displacement may occur in which a spot diameter of the light beam spreads. In order to prevent such focal displacement, sometimes a moving mechanism is provided at the stage at which the light source and the like are mounted to enable the exposure head to approach and move away from the recording medium. Accordingly, the printing plate and the exposure head can be held at an appropriate distance and focused.
An example of the moving mechanism which is applied to such a focusing includes: a moving mechanism in which a fine movement of the stage by about 1 μm, for example, can be performed by using an eccentric cam. In the moving mechanism using such an eccentric cam, a sliding member, a bearing, and the like are disposed at legs which protrude from the stage so as to face the eccentric cam. While the eccentric cam rotates eccentrically, the circumferential surface of the eccentric cam and the sliding member or the bearing abut against one another and press the legs, and the stage thereby moves.
However, when the sliding member is disposed at the eccentric cam, as the eccentric cam rotates, the sliding member is slid with the rotation of the eccentric cam so that abrasion or deformation may cause therebetween, thus leading to an error in a moving amount of the stage. Further, when the bearing is disposed so as to face the eccentric cam, as the eccentric cam rotates, a position at which the eccentric cam contacts the bearing changes, thus leading to a change in the moving amount of the stage.
The most important problem with the moving mechanism using the eccentric cam is that, since another fixing means is provided independently of the moving mechanism in order to fix the stage which has stopped moving, it becomes extremely difficult to move, position, and fix the stage by using the eccentric cam while maintaining the position to which the stage has moved. When the stage thus positioned is fixed by the fixing means, there arises a problem that the stage may be displaced slightly from a desired position at which the stage should be fixed.
SUMMARY OF THE INVENTION
In view of the aforementioned facts, it is an object of the present invention to provide a base structure, a processing device, and an image forming device capable of successfully overcoming and improving such drawbacks as described above.
In order to solve the aforementioned problems, a first aspect of the present invention is a base structure, the base structure comprising: (A) two bases between which a linear relative movement is enabled; (B) a cam element provided at one of said two bases and driven to rotate; and (C) an abutting portion provided at the other of said two bases and on which said cam element abuts, (D) wherein said cam element includes: a central axis portion rotatable around a rotational axis as a center; a rolling element movably provided at said central axis portion; and a cylindrical outer ring rotatably provided with respect to said central axis portion through said rolling element, the rotational axes of said outer ring and said central axis portion being substantially parallel to one another and spaced apart from one another at a predetermined distance.
A second aspect of the present invention is a processing device for applying a predetermined processing to an object, the processing device comprising: (I) a processing element for applying a predetermined processing to an object; and (II) a base device capable of changing a position of said processing element with respect to said object, the base device including: (a) a first base and a second base between which a linear relative movement is enabled; (b) a cam element provided at said first base and driven to rotate; and (c) an abutting portion provided at said second base and on which said cam element abuts, wherein said cam element includes: a central axis portion rotatable around a rotational axis as a center; a rolling element movably provided at said central axis portion; and a cylindrical outer ring rotatably provided with respect to said central axis portion through said rolling element, the rotational axes of said outer ring and said central axis portion being substantially parallel to one another and spaced apart from one another at a predetermined distance.
A third aspect of the present invention is an image forming device for forming an image on a printing plate, the image forming device comprising: (I) a rotatably mounted drum having a periphery around which a printing plate can be releasably wound and fixed; (II) a mount for rotatably supporting said drum; (III) a recording head for recording an image on a printing plate; (IV) a base device for changing a position of said recording head with respect to said rotating drum, said base device including: (a) a first base and a second base, one of the bases being fixed at said mount side and the other being fixed at said recording head side, between which a linear relative movement is enabled; (b) a cam element provided at said first base and driven to rotate; and (c) an abutting portion provided at said second base and on which said cam element abuts; (d) wherein said cam element includes: a central axis portion rotatable around a rotational axis as a center; a rolling element movably provided at said central axis portion; and a cylindrical outer ring rotatably provided with respect to said central axis portion through said rolling element; the rotational axes of said outer ring and said central axis portion being substantially parallel to one another and spaced apart from one another at a predetermined distance.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic structural view of an image exposure device to which an embodiment of the present invention is applied.
FIG. 2
is a schematic structural view illustrating a recording section of the image exposure device.
FIG. 3
is a schematic structural view illustrating a main portion of a scanning and exposing device provided at the recording section.
FIG. 4
is a schematic perspective view illustrating a main portion of a position adjustment mechanism provided at the scanning and exposing device.
FIG. 5
is a schematic structural view illustrating a movement of a leg in accordance with a rotation of an eccentric cam.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to drawings, an embodiment of the present invention will be explained hereinafter.
FIG. 1
shows a schematic structure of an image exposure device
10
to which the embodiment of the present invention is applied. Using a light-sensitive planographic plate (hereinafter referred to as a “printing plate
12
”), in which a light-sensitive layer is formed on a thin (e.g., having a thickness of about 0.3 mm), rectangular plate support formed of, for example, aluminum, the image exposure device
10
irradiates onto the printing plate
12
a light beam modified on the basis of image data, whereby the printing plate
12
is scanned and exposed. The printing plate
12
for which an image exposure has been completed by the image exposure device
10
is subjected to development processing or the like by an unillustrated automatic processor or the like.
As shown in
FIG. 1
, at the image exposure device
10
, there are provided a cassette loading section
18
, a plate feeding and conveyance section
20
, a recording section
22
, a discharge buffer section
24
, and the like inside a machine casing
14
. The cassette loading section
18
is disposed at the right lower side of the machine casing
14
in
FIG. 1. A
plurality of cassettes
16
, that each accommodate a plurality of printing plates
12
, is loaded at a predetermined angle in a state in which the cassettes
16
are slanted in the cassette loading section
18
.
It is possible to process in the image exposure device
10
numerous-sized printing plates
12
having different vertical and horizontal dimensions. Printing plates
12
of whatever size are accommodated in the cassettes
16
such that the light-sensitive layers of the printing plates
12
face upward and an end thereof is positioned to correspond to a predetermined position. Further, the cassettes
16
which accommodate therein different sizes of the printing plates
12
are loaded at the cassette loading section
18
at predetermined intervals such that an end of the printing plates
12
accommodated in each cassette
16
reaches a substantially constant height.
The plate feeding and conveyance section
20
is disposed above the cassette mounting portion
18
. The recording section
22
is disposed at a lower, central area within the image exposure device
10
, adjacent to the cassette loading section
18
. A pair of side plates
26
(one of them is shown in
FIG. 1
) is provided at the plate feeding and conveyance section
20
, and an reversal unit
28
and a sheet unit
30
are mounted to each of the side plates
26
.
The reversal unit
28
is provided with an reversal roller
32
having an outside diameter of a predetermined dimension. A plurality of small rollers
34
(for example, four small rollers
34
A,
34
B,
34
C and
34
D in the present embodiment) are provided around the reversal roller
32
. The small rollers
34
A to
34
D are disposed so a to straddle the inverting roller
32
from the cassette loading section
18
to the recording section
22
, and an endless conveyor belt
36
is entrained around these small rollers
34
A to
34
D. Accordingly, the conveyor belt
36
is entrained over the reverse roller
32
so that the conveyor belt
36
stretches to roughly half the circumference of the reverse roller
32
between the small roller
34
A and the small roller
34
D.
The sheet unit
30
is provided with a plurality of suction cups
38
which suck an upper end of the printing plate
12
in the cassettes
16
. The sheet unit
30
lowers the suction cups
38
so as to face the upper end of the printing plates
12
in the cassette
16
loaded at the cassette loading section
18
, whereby the printing plate
12
is sucked by the suction cups
38
. The sheet unit
30
then substantially raises the suction cups
38
which have adsorbed the printing plate
12
so as to pull the leading edge of the printing plate
12
from the cassette
16
, and the leading edge of the printing plate
12
is then inserted between the reverse roller
32
and the conveyor belt
36
. In
FIG. 1
, a position at which the suction cups
38
move is schematically illustrated by a double-dashed line.
At the reversal unit
28
, the reversal roller
32
and the conveyor belt
36
are rotated in a direction in which the printing plate
12
is pulled out from the cassette
16
(in the direction of arrow A in FIG.
1
). When the leading edge of the printing plate
12
is nipped between the reversal roller
32
and the conveyor belt
36
, the printing plate
12
is wound around the circumferential surface of the reversal roller
32
while being pulled out from the cassette
16
. Accordingly, the printing plate
12
is conveyed and inverted while being curved, and a direction in which the printing plate
12
is conveyed is thereby deflected. The radius of the reverse roller
32
is of a dimension (e.g., 100 mm or more) such that kinks or bends are not generated in the printing plate
12
at the time the printing plates
12
have been curved.
As shown by the solid line and the double-dashed line in
FIG. 1
, the side plates
26
move horizontally in accordance with the position of the cassette
16
from which the printing plate
12
is to be pulled out. Accordingly, the sheet unit
30
can move integrally with the reversal unit
28
so that the suction cups
38
face the printing plate
12
in the desired cassette
16
.
At the side plates
26
, a guide
40
is provided below the small roller
34
D. The printing plate
12
which has been inverted by the reversal roller
32
is passed between the reversal roller
32
at the small roller
34
D side and the conveyor belt
36
, and fed to this guide
40
.
A conveyer
42
is disposed above the recording section
22
, and the printing plate
12
which has been fed out from the reversal unit
28
is guided to the conveyer
42
by the guide
40
. Further, the guide
40
swings in accordance with the movement of the side plate
26
such that the direction in which the printing plate
12
is guided is always directed to the conveyer
42
. Moreover, the small roller
34
D near the recording section
22
moves in accompaniment with the movement of the side plate
26
to alter the direction in which the printing plate
12
is fed out from the reversal unit
28
. When the small roller
34
D moves, the small roller
34
C moves to provide a substantially fixed tension to the conveyor belt
36
, and the printing plate
12
fed out from the reversal unit
28
is thereby gently curved by the guide
40
.
At the conveyor
42
, a conveyor belt
48
is entrained between a roller
44
adjacent to an area beneath lower portion of the plate feeding and conveyance section
20
and a roller
46
adjacent to an area above the recording section
22
. The conveyor
42
is slanted such that the roller
46
is disposed lower than the roller
44
.
As shown in
FIGS. 1 and 2
, a roller
50
is disposed at the conveyor
42
so as to face the roller
46
. The printing plate
12
which has been fed to the conveyor
42
is conveyed along the conveyor belt
48
, nipped by the roller
46
and the roller
50
, and then fed out from the conveyor
42
.
At the recording section
22
, a rotating drum
54
is mounted on a mount
52
, and a recording head portion
56
is disposed so as to face the rotating drum
54
. Further, at the image exposure device
10
, a puncher
58
is disposed above the recording section
22
(the rotating drum
54
) so as to oppose the rollers
46
and
50
of the conveyor
42
.
As shown in
FIG. 2
, an opening
60
is formed at the puncher
58
. The printing plate
12
is held at the conveyor
42
such that the printing plate
12
is nipped by the rollers
46
and
50
and the leading edge of the printing plate
12
is inserted into the opening
60
of the puncher
58
. As a position-determiner, the puncher
50
forms, for example, a notch at a predetermined position of the leading edge of the printing plate
12
which has been inserted into the opening
60
. The printing plate
12
is positioned, for example, on the conveyor
42
and then fed to the puncher
58
, whereby the notch for positioning is formed at a predetermined position of the leading edge of the printing plate
12
.
When the notch has been formed in the printing plate
12
, the conveyor
42
drives the conveyor belt
48
inversely, and then pulls the leading edge of the printing plate
12
out from the opening
60
of the puncher
58
. The conveyor
42
is swingable by an unillustrated swinging means with the roller
44
side as an axis. When the printing plate
12
has been pulled out from the puncher
58
, the conveyer swings (shown by a double-dashed line in
FIGS. 1 and 2
) and then feeds the printing plate
12
to the recording section
22
after the leading edge of the printing plate
12
has been directed to a predetermined position at the outer circumferential surface of the rotating drum
54
.
Due to a driving force of an unilllustrated driving means, the rotating drum
54
provided at the recording section
22
is driven to rotate at a predetermined rotational speed in the direction in which the printing plate
12
is mounted and exposed (the direction of arrow B in
FIGS. 1 and 2
) or in the direction in which the printing plate
12
is removed from the rotating drum
12
(the direction of arrow C in
FIGS. 1 and 2
) which opposes the direction in which the printing plate
12
is mounted and exposed.
As shown in
FIG. 2
, a leading edge chuck
62
is mounted at a predetermined position of the outer circumferential surface of the rotating drum
54
. At the recording section
22
, when the printing plate
12
is mounted to the rotating drum
54
, the rotating drum
54
is stopped at a position at which the leading edge chuck
62
opposes the leading edge of the printing plate
12
fed along the conveyor
42
(i.e., a position at which the printing plate is mounted to the rotating drum
54
).
At the recording section
22
, a setting cam
64
is provided which opposes the leading edge chuck
62
at a position at which the printing plate
12
is attached to the rotating drum
54
. Due to a rotation of the setting cam
64
, the leading edge chuck
62
at an end thereof is pressed, whereby the printing plate
12
becomes insertable between the leading edge chuck
62
and the circumferential surface of the rotating drum
54
. At the recording section
22
, in a state in which the leading edge of the printing plate
12
has been inserted between the leading edge chuck
62
and the rotating drum
54
, the setting cam
64
is returned to its original position so that the end of the leading edge chuck
62
is no longer pressed, whereby the leading edge of the printing plate
12
is nipped and held between the leading edge chuck
62
and the circumferential surface of the rotating drum
54
.
At the image exposure device
10
, an unillustrated positioning pin, which projects from the circumferential surface of the rotating drum
54
at a predetermined position thereof, enters the notch which has been formed at the leading edge of the printing plate
12
so that the printing plate
12
is positioned with respect to the rotating drum
54
.
At the circumference of the rotating drum
54
, a squeeze roller
66
is disposed in a mounting/exposure direction (i.e., the direction of arrow B), further downstream than the position at which the printing plate
12
is mounted. The squeeze roller
66
is moved toward the rotating drum
54
to press the printing plate
12
wound around the rotating drum
54
toward the rotating drum
54
, whereby the printing plate
12
contacts the circumferential surface of the rotating drum
54
.
At the recording section
22
, a trailing edge chuck detaching unit
68
is provided in a mounting/exposure direction of the rotating drum
54
, further upstream than the squeeze roller
66
. A removal cam
70
is disposed at the downstream side of the rotating drum
54
in the direction of the arrow B. At the trailing edge chuck detaching unit
68
, a trailing edge chuck
74
is disposed detachably at the tip end of a shaft
72
that projects toward the rotating drum
54
.
Further, at the recording section
22
, when the trailing edge of the printing plate
12
which has been wound around the rotating drum
54
reaches a position at which the trailing edge of the printing plate
12
opposes the trailing edge chuck detaching unit
68
, the rotation of the rotating drum
54
temporarily stops and the trailing edge chuck
74
is attached at a predetermined position of the rotating drum
54
. Thus, the trailing edge of the printing plate
12
which has been wound around the rotating drum
54
is nipped between the trailing edge chuck
74
and the rotating drum
54
, and fixed thereto.
At the outer circumferential surface of the rotating drum
54
, there are formed unillustrated adsorbing grooves for adsorbing and holding the printing plate
12
which has been wound around the rotating drum
54
. At the recording section
22
, the leading edge and the trailing edge of the printing plate
12
in the transporting direction thereof are respectively fixed by the leading edge chuck
62
and the trailing edge chuck
74
, and are adsorbed by a negative pressure supplied to the suction grooves to thereby adhere the printing plate
12
onto the circumferential surface of the rotating drum
54
.
At the recording section
22
, when the printing plate
12
is positioned at the rotating drum
54
and wound therearound, the squeeze roller
66
is made to separate from the rotating drum
54
. While the rotating drum
54
is made to rotate at a predetermined rotational speed, synchronous with the rotation of the rotating drum
54
, a light beam which has been transmitted from the recording head portion
56
and modulated on the basis of image data is irradiated onto the printing plate
12
. Thus, the printing plate
12
is scanned and exposed on the basis of the image data, and an image is formed at a predetermined position of the printing plate
12
.
At the recording section
22
, when the scanning and exposing of the printing plate
12
have been completed, the rotating drum
54
stops at a position where the trailing edge chuck
74
is removed from the rotating drum
54
. T he trailing edge chuck
74
is removed from the rotating drum
54
in a state in which the printing plate
12
is nipped by the squeeze roller
66
between the rotating drum
54
and the squeeze roller
66
so that the nipping of the trailing edge of the printing plate
12
is cancelled.
At the recording section
22
, when the trailing edge chuck
74
is removed from the rotating drum
54
, the rotating drum
54
rotates in a direction in which the printing plate
12
is taken off. Accordingly, the printing plate
12
is fed from between the squeeze roller
66
and the rotating drum
54
.
As shown in
FIG. 1
, the discharge buffer section
24
is disposed above the recording section
22
. Due to a rotation of the rotating drum
54
in the direction in which the printing plate
12
is taken out, the printing plate
12
is fed from the trailing edge side thereof toward the discharge buffer section
24
. Further, at the recording section
22
, when the rotating drum
54
has rotated in the direction in which the printing plate
12
is taken out, so that the leading edge chuck
62
has reached the position at which the printing plate
12
is taken out and at which the leading edge chuck
62
opposes the removal cam
70
, the rotating drum
54
is stopped, and the removal cam
70
rotates at this position. Accordingly, the nipping of the leading edge of the printing plate
12
between the leading edge chuck
62
and the rotating drum
54
is cancelled so that the printing plate
12
is removed from the rotating drum
54
.
At the discharge buffer section
22
, a discharging roller
78
is provided at an inner side of a discharging outlet
76
formed in the machine casing
14
. A plurality of small rollers (for example, five small rollers
80
A,
80
B,
80
C,
80
D, and
80
E) is disposed around the periphery of the discharging roller
78
. The conveyor belt
82
is thus wound between the small rollers
80
A to
80
E around the ejection roller
78
in a range of between about ½ to about ¾ the circumference of the ejection roller
78
.
The small roller
80
A is disposed so as to protrude toward the squeeze roller
66
side of the recording section
22
, and a roller
84
is disposed so as to face the small roller
80
A. The printing plate
12
fed from the recording section
22
is guided to and nipped between the small roller
80
A and the roller
84
.
At the discharge buffer section
24
, the discharging roller
78
is driven to rotate in the direction in which the printing plate
12
is pulled out (in the direction of arrow D). Thus, the printing plate
12
which is nipped between the small roller
80
A and the roller
84
is pulled out from the recording section
22
, and at the same time, the printing plate
12
is guided between the discharging roller
78
and the conveyor belt
82
. Then, the printing plate
12
is nipped between the discharging roller
78
and the conveyor belt
82
, and is wound around the discharging roller
78
. At this time, at the discharge buffer section
24
, the leading edge of the printing plate
12
(i.e., the trailing edge side at the time the printing plate
12
is fed out from the recording section
22
) is nipped between the small roller
80
A and the roller
84
so that the printing plate
12
which has been wound around the discharging roller
78
is temporarily held.
As shown by a double-dashed line in
FIG. 1
, at the discharge buffer section
24
, the small roller
80
A and the roller
84
move to a position at which the small roller
80
A and the roller
84
face the discharging outlet
76
. At this time, the small roller
80
A and the roller
84
are moved integrally with each other so that the leading edge of the printing plate
12
is directed to the discharging outlet
76
. Further, the small roller
80
B above the small roller
80
A moves in accordance with the movement of the small roller
80
A so that a constant tension is applied to the conveyor belt
82
.
At the discharge buffer section
24
, when the leading edge of the printing plate
12
is directed to the discharging outlet
76
, the discharging roller
78
is rotated in the direction that the printing plate
12
is discharged (i.e., the opposite direction of arrow D) at a rotational speed that corresponds to the speed at which the printing paper
12
is conveyed at processing devices, such as an automatic processor and the like (not illustrated), provided adjacent to the discharging outlet
76
. Accordingly, the printing plate
12
is fed out from the discharging outlet
76
.
Image data to which the printing plate
12
is to be exposed is inputted to the image exposure device
10
thus formed. When the size and the number of the printing plates
12
on which an image exposure is carried out are determined, and when the start of the image exposure is instructed, image exposing processing of the printing plate
12
begins. The image exposure device
10
may be a kind in which an operation panel is provided at the image exposure apparatus
10
and instructions are given by operation of a switch at the operation panel, and it may be a kind in which initiation of processing by the image exposure device
10
is ordered by a signal from an image processing device that outputs image data to the image exposure device
10
.
When the image exposure device
10
has been instructed to start the processing, a specified size of the printing plate
12
is taken out from one of the cassettes
16
and placed on the conveyor
42
, and thereby fed to the recording section
22
. At this time, a notch for positioning is formed in the printing plate
12
by a puncher
58
.
At the recording section
22
, when the leading edge of the printing plate
12
is held at the rotating drum
54
by the leading edge chuck
62
, the printing plate
12
is wound around the rotating drum
54
while being squeezed by the squeeze roller
66
, and the trailing edge of the printing plate
12
is held at the rotating drum
54
by the trailing edge chuck
74
.
Thereafter, at the recording section
22
, a light beam on the basis of image data is irradiated from the recording head portion
56
onto the printing plate
12
while the rotating drum
54
is rotating at high speed, and the printing plate
12
is scanned and exposed. Namely, a predetermined region of the printing plate
12
is scanned and exposed so that an image is formed on the printing plate
12
.
When an image is formed on the printing plate
12
, the printing plate
12
is fed to the discharge buffer section
24
from the trailing edge side of the printing plate
12
while being removed from the rotating drum
54
. At the discharge buffer section
24
, once this printing plate
12
is wound around the discharging roller
78
, the discharging roller
78
is inversely driven to direct the leading edge of the printing plate
12
to the discharging outlet
76
. Thus, the printing plate
12
is fed from the discharging outlet
76
at a predetermined conveyance speed, and then discharged from the image exposure device
10
.
As shown in
FIG. 3
, at the recording section
22
, a scanning and exposing device
90
is formed by the rotating drum
54
and the recording head portion
56
. The recording head portion
56
has a recording (exposing) head
92
, and a light beam emitted from the recording head
92
is irradiated onto the printing plate
12
which has been wound around the rotating drum
54
.
The recording head
92
is formed by a stage
106
, and a light source unit
100
which is mounted to the stage
106
. The light source unit
100
is provided with a base portion
120
and a base
118
. The base portion
120
faces the stage
106
. The base
118
has a vertical wall
122
vertically disposed at an end thereof to thereby form a substantial L-shape with respect to the base
118
. At the light source unit
100
, the base portion
120
is mounted on the stage
106
at a predetermined position thereof, and fixed thereat.
At the light source unit
100
, a light source assembly
124
is mounted to the vertical wall
122
, while an optical system assembly
126
is mounted to the base portion
120
.
The light source assembly
124
is provided with light source holders
128
and
130
, and through a base plate
132
, is mounted on a surface of the vertical wall
122
at the side opposite to the rotating drum
54
(i.e., at the left side in FIG.
3
). At this light source assembly
124
, a laser diode, which is a semiconductor light-emitting element, is provided between the light source holders
128
and
130
. Further, a collimator lens is mounted to the light source holder
130
(neither the laser diode nor the collimator lens is shown).
By mounting the light source assembly
124
, in which the laser diode and the collimator lens are assembled with a distance therebetween adjusted beforehand, to the vertical wall
122
, the laser and the collimator lens are mounted at predetermined positions of the light source unit
100
. Further, a parallel plate holder
134
in which a parallel plate (not shown) is provided on the surface of the parallel plate holder
134
at a rotating drum
54
side is mounted to the vertical wall
122
. Through this parallel plate, a light beam which is emitted from the light source assembly
124
is transmitted to an optical system assembly
126
.
To the optical system assembly
126
is mounted a converging lens holder
138
in which a converging lens is assembled at a longitudinal direction end side of an elongated fixing platform
136
. Further, on the fixing platform
136
, in a sequential order from the side of the converging lens holder
138
, there are disposed: a cylindrical lens holder
140
to which a convex cylindrical lens is mounted; a uniaxial crystalline holder
142
to which a uniaxial crystalline is mounted; a cylindrical lens holder
144
to which a concave cylindrical lens is mounted; a parallel plate holder
146
to which a parallel plate is mounted; an aperture holder
148
to which an aperture is mounted; and a holder
150
to which a convex cylindrical lens and a ½ wavelength plate are mounted. Moreover, the uniaxial crystalline holder
142
is mounted to the cylindrical lens holder
144
.
At the optical system assembly
126
, the converging lens holder
138
is located at the rotating drum
54
side (at the opposite side of the vertical wall
122
). The fixing platform
136
is mounted to the base portion
120
of the base
118
. Accordingly, the light beam emitted from the light source assembly
124
is transmitted through the parallel plate, the ½ wavelength plate, the cylindrical lens, the aperture, the parallel plate, the cylindrical lens, the uniaxial crystalline, the cylindrical lens, and the converging lens, and then irradiated onto the printing plate
12
.
Beneath the stage
106
, there is provided a platform
104
. This platform
104
is mounted to the mount
52
(not shown in
FIG. 3
) through an unillustrated sub-scanning mechanism.
Synchronous with a rotation of the rotating drum
54
around which the printing plate
12
has been wound, the sub-scanning mechanism moves the exposure head
92
and the platform
104
in a sub-scanning direction which is an axial direction of the rotating drum
54
. At this time, synchronous with the rotation of the rotating drum
54
and with the movement of the exposure head
92
in the sub-scanning direction thereof, on the basis of image data, a light beam from the exposure head
92
is irradiated onto the printing plate
12
to scan and expose the same.
As the scanning and exposing device
90
, there can be used a scanning and exposing device in which the exposure head
92
which is formed by the light source unit
100
is moved in the sub-scanning direction so as to carry out scanning and exposing of the printing plate
12
. Alternatively, a scanning and exposing device can be used in which a number of the light source units
100
are disposed in the sub-scanning direction at fixed intervals, the light source units
100
being moved integrally with one another in the subscanning direction to scan and expose by using a plurality of light beams.
A position adjusting mechanism
94
is provided at the platform
104
, and through this position adjusting mechanism
94
, the stage
106
is supported by the platform
104
.
A pair of legs
106
A and
106
B is formed at the stage
106
. The leg
106
A is provided at the rotating drum
54
side (at the right side of FIG.
3
), while the leg
106
B is provided at the opposite side of the rotating drum
54
. Each of the legs
106
A and
106
B and the platform
104
are connected by plate springs
108
by which the position adjusting mechanism
94
is formed. Each of the plate springs
108
is formed in a strip shape or a rectangular plate shape. Through a bracket
152
, one end portion of each of the plate springs
108
is connected to each of the legs
106
A and
106
B, while, through a bracket
154
, the other end portion is mounted to the platform
104
.
At this time, both end portions of each of the plate springs
108
are respectively fixed to the brackets
152
and
154
by at least two screws
156
. Accordingly, the stage
106
is supported by the plate springs
108
at the platform
104
. Further, one of the surfaces of each of the plate springs
108
faces the rotating drum
54
, and the plate spring
108
can thereby elastically deform in a direction in which the plate springs
108
approach/separate from the rotating drum
54
(which is simply referred to as a direction of arrow z hereinafter). The plate spring
108
is prevented from elastically deforming in the sub-scanning direction which is the axial direction of the rotating drum
54
(an obverse-to-reverse direction of the page of FIG.
3
). Namely, the stage
106
is supported by the platform
104
through the plate springs
108
, and the stage
106
is thereby movable merely by elastically deforming the plate springs
108
in the direction of the arrow z.
A stepping motor
110
is provided at the platform
104
, and a worm gear
112
is disposed beneath the stage
106
. As shown in
FIGS. 3 and 4
, the worm gear
112
is attached to the shaft
158
whose axial direction is disposed along the aforementioned direction of the arrow z. Further, both sides of the shaft
158
between which the worm gear
112
is interposed is rotatably supported by a bracket
160
.
As shown in
FIG. 3
, an axial direction end portion of the shaft
158
is connected to a driving shaft
110
A of the stepping motor
110
. Thus, when the stepping motor
110
is operated, the worm gear
112
thereby rotates.
Above the platform
104
, a worm wheel
114
and an eccentric cam
116
are disposed between the pair of the legs
106
A and
106
B.
As shown in
FIG. 4
, the worm wheel
114
is attached to a shaft
162
and meshes with the worm gear
112
. Accordingly, as the worm gear
112
rotates, the worm wheel
114
thereby rotates integrally with the shaft
162
.
The shaft
162
is passed through brackets
164
which are mounted on the platform
104
, and supported so as to rotate freely. Further, the shaft
162
is passed through the eccentric cam
116
, and rotates integrally with the eccentric cam
116
. The position of the eccentric cam
116
through which the shaft
162
is passed is displaced from the central axis of the eccentric cam
116
. Thus, the eccentric cam
116
rotates eccentrically around the shaft
162
as a center.
As shown in
FIGS. 4 and 5
, at the eccentric cam
116
, there is provided a bearing portion
170
between an outer circumference
166
and a central axis portion
168
through which the shaft
162
has been passed. As shown in
FIG. 5
, this bearing portion
170
is generally structured such that a number of spheres
172
are disposed at the inside thereof so as to rotate freely. This bearing portion
170
allows the outer circumference
166
and the central axis portion
168
of the eccentric cam
116
to rotate relative to one another.
As shown in
FIGS. 3 and 5
, the eccentric cam
116
is disposed so as to face the leg
106
A of the stage
106
. At the leg
106
A, there is disposed a strip-shaped abutting plate
174
so as to face the outer circumferential surface of the eccentric cam
116
.
The plate springs
118
are mounted to both the platform
104
and the stage
106
(the legs
106
A and
106
B) so as to urge the leg
106
A toward the eccentric cam
116
in the direction in which the plate springs
118
separate from the rotating drum
54
. Thus, the stage
106
is held in a state in which the abutting plate
174
which is provided at the leg
106
A abuts the outer circumferential surface of the eccentric cam
116
.
As shown in
FIG. 5
, the eccentric cam
116
eccentrically rotates around the shaft
162
as a center, and the outer circumference
166
thereby moves in the direction of the arrow z (the direction in which the plate springs
118
approach/separate from the rotating drum
54
). At this time, the leg
106
A is urged by the plate springs
108
, and the leg
106
A moves in accordance with the movement of the outer circumference
166
of the eccentric cam
116
. Thus, the stage
106
moves in the direction of the arrow z.
As shown by a double-dashed line in
FIG. 5
, the outer circumference
166
of the eccentric cam
116
moves in the direction in which the plate springs
108
approach the rotating drum
54
(in the right direction of FIG.
5
), and the leg
106
A which abuts the outer circumference
166
of the eccentric cam
116
moves in resistance to the urging force of the plate springs
108
. Further, as shown in a dashed-line in
FIG. 5
, since the outer circumference
166
of the eccentric cam
116
moves in the direction in which the plate springs
108
separate from the rotating drum
54
(in the left direction of the page of FIG.
5
), the urging force of the plate springs
108
allows the leg
106
A which abuts the outer circumference
166
of the eccentric cam
116
to move in accordance with the movement of the outer circumference
166
. Accordingly, the stage
106
moves integrally with the leg
106
A.
At the scanning and exposing device
90
which has the recording head
92
thus structured, the rotating drum
54
around which the printing plate
12
has been wound is made to rotate in the main scanning direction (the direction in which the printing plate
12
is attached and exposed), and synchronous with the rotation of the rotating drum
54
and the movement along the sub-scanning direction of the stage
106
, on the basis of image data, a light beam is ejected from the light source assembly
124
.
After the light beam which is emitted from the light source assembly
124
has been transmitted through the optical filter
152
which is the ½ wavelength plate, the light beam is transmitted through the convex cylindrical lens, the aperture, the parallel plate, the concave cylindrical lens, the uniaxial crystalline, the convex cylindrical lens, and the converging lens, and is then irradiated onto the printing plate
12
which has been wound around the rotating drum
54
. As a result, on the basis of image data, an image is exposed onto the printing plate
12
.
If a distance between the exposure head
92
and the printing plate
12
changes, the light beam which has been irradiated onto the printing plate
12
may be out-of-focus. In order to prevent this focal displacement, the distance between the exposure head
92
and the rotating drum
54
must be appropriately adjusted.
At the scanning and exposing device
90
, there is disposed the position adjusting mechanism
94
between the stage
106
at which the exposure head
92
is provided, and the platform
104
, and the stage
106
is moved in the direction of the arrow z, thereby allowing the distance between the exposure head
92
and the rotating drum
54
to be adjusted.
At this position adjustment mechanism
94
, when the stepping motor
110
is driven to rotate the worm gear
112
, this rotation is decelerated, and through the worm wheel
114
, the decelerated rotation is transmitted to the shaft
162
onto which the eccentric cam
116
is fitted. When the shaft
162
rotates, the eccentric cam
116
thereby rotates eccentrically around the shaft
162
as a center, and the outer circumference
166
of the eccentric cam
116
moves in the direction of the arrow z.
The leg
106
A which is moved to the stage
106
due to the urging force from the plate springs
108
abuts this eccentric cam
116
. Thus, in accordance with the movement of the outer circumference
166
, the stage
106
, together with the leg
106
A, moves in the direction of the arrow z.
A distance between the exposure head
92
which is provided at the stage
106
and the rotating drum
54
can be appropriately adjusted by controlling the amount in which the eccentric cam
116
rotates. At this time, since a rotation of the stepping motor
110
is largely decelerated by the worm gear
112
and the worm wheel
114
, and is then transmitted to the eccentric cam
116
, a fine adjustment of the amount in which the stage
106
moves can be greatly facilitated.
The plate springs
108
urge the leg
106
A toward the outer circumference
166
of the eccentric cam
116
. At a position to which the outer circumference
166
has rotated and moved, the leg
106
A is held in a state of abutting this outer circumference
166
. Namely, when the eccentric cam
116
is held in a state in which the eccentric cam
116
has stopped rotating, the stage
106
is held at a position at which the leg
106
A abuts the outer circumference
166
.
By using the eccentric cam
116
, the stage
106
can be moved and reliably held at a desired position to which the stage
106
has moved. Accordingly, a complicated mechanism for holding the stage
106
at the desired position becomes unnecessary, and a mechanism for moving and holding the stage
106
can be structured more simply.
In a case in which the thickness of each of the plate springs
108
is about 1.6 mm, for example, the plate springs
108
can be formed so as to have a buckling load of 10 tons or more. Accordingly, as compared to a case in which the stage
106
is moved by using a rail-type moving mechanism, the plate springs
108
of the present invention exhibit a high load-resistance. Accordingly, the stage
106
can move in a stable manner when a high load is applied to the plate springs
108
. Further, due to a selection of a thickness or a material of the plate springs
108
, a reaction force (urging force) from the plate springs
108
can be changed, and the reaction force of the plate springs
108
can thereby be set on the basis of a load or the like. As a result, the stage
106
can be supported by the plate springs
108
.
The bearing portion
170
of the eccentric cam
116
allows both the outer circumference
166
on which the abutting plate
174
at the leg
106
A abuts and the central axis portion
168
which rotates integrally with the shaft
162
to rotate with one another.
When the central axis portion
168
of the eccentric cam
116
is made to rotate in order to move the stage
106
integrally with the leg
106
A, as the outer circumference
166
rotates, the abutting plate
174
and the outer circumference
166
are rubbed against one another.
In a case in which the outer circumference
166
of the eccentric cam
116
and the abutting plate
174
are rubbed against one another, when abrasion or deformation is caused onto the outer circumference
166
and/or the abutting plate
174
, the eccentric cam
116
does not rotate smoothly or the amount in which the leg
106
A moves becomes unfixed, thus leading to an appropriate control of the moving amount of the stage
106
.
At the eccentric cam
116
, there is provided the bearing portion
170
between the outer circumference
166
and the central axis portion
168
. Due to a frictional force between the outer circumference
166
and the abutting plate
174
which contacts the outer circumference
166
, the outer circumference
166
and the central axis portion
168
rotate relative to one another.
As a result, the abutting plate
174
can be held at a substantially fixed position of the outer circumference
166
in a state in which the abutting plate
174
and the outer circumference
166
make contact with each other. Accordingly, abrasion or deformation can be prevented by the outer circumference
166
and the abutting plate
174
being rubbed against one another during the rotation of the eccentric cam
116
. Therefore, since the stage
116
can move in accordance with the amount of the rotation of the eccentric cam
116
, the amount in which the stage
106
moves due to the rotation of the eccentric cam
116
can accurately be controlled.
In the present embodiment, the plate-shaped abutting plate
174
abuts the circumferential surface of the outer circumference
166
which is formed by curved surfaces. However, for example, a flat surface can be formed at a portion of the outer circumference
166
and made to abut the abutting plate
174
. Thus, a dimension in which the abutting plate
174
and the eccentric cam
116
contact each other is made larger, thereby enabling the abutting plate
174
to abut the outer circumference
166
of the eccentric cam
116
in a more stable manner. As a result, the stage
106
can be moved reliably and held at a position to which the stage
106
has moved.
In this way, at the scanning and exposing device
90
, since the distance between the printing plate
12
and the exposure head
92
can be adjusted by the position adjustment mechanism
94
using the eccentric cam
116
so as to have an appropriate distance therebetween, and be held at a position where an adjustment of the distance has been carried out, a light beam is not out-of-focus when irradiated onto the printing plate
12
so that a highly accurate image can be formed on the printing plate
12
.
The structure of the present invention is not limited to the present embodiment described above. For example, when the stage
106
is elongated along the axial direction of the rotating drum
54
, and a plurality of the light source heads
100
are mounted on the stage
106
, the position adjustment mechanism
94
can be provided at both sides of the stage
106
in the lengthwise direction thereof.
A description of the present embodiment has been made by using the plate springs
108
as an urging and holding means. However, instead of the plate springs
108
, the urging and holding means can be formed by an urging means which urges the leg
106
A toward the eccentric cam
116
, a supporting means which supports the stage
106
movably by using a guide rail, and the like.
In the present embodiment, as an example of an image forming device, a description of the image forming device
10
for forming an image on the printing plate
12
has been made. However, the present invention is not limited to a light-sensitive planographic printing plate such as the printing plate
12
. The present invention can be applied to image forming devices in which an image is formed not only on a light-sensitive planographic printing plate such as the printing plate
12
but on various recording mediums including a light-sensitive material such as a photographic film or printing paper, a light-sensitive drum, and the like.
In the present embodiment, the present invention has been applied for the purpose of moving and holding the exposure head
92
. However, the present invention can also be used to mount such a component for forming an optical system, which includes an optical component such as a lens, a light source such as an LD, a component such as a CCD for which a short stroke positional adjustment is needed, and the like.
As described above, the present invention has a simple structure that uses the urging and supporting means which supports the legs of the stage in a state in which this means urges the legs toward the eccentric cam. By using the eccentric cam, the stage can be moved and held accurately at an arbitrary position to which the stage has moved. The present invention is also structured such that the bearing portion is provided at the eccentric cam, thereby allowing the central axis portion and the outer circumference to rotate relative to one another. As a result, excellent effects can be obtained in that abrasion or deformation of a component such as the eccentric cam can be prevented, the stage can move accurately for a long period of time, and the stage can be fixed at a position to which the stage has moved.
Claims
- 1. A base structure, the base structure comprising:(A) two bases, one of which is operative to move linearly in relation to the other; (B) at least one elastic member in connection with said bases which positions said bases away from each other and maintains a space between said bases; (C) a cam element provided at one of said two bases and positioned in said space, said cam element driven to rotate; and (D) an abutting portion provided at the other of said two bases and on which said cam element abuts, (E) wherein said cam element includes: a central axis portion rotatable around a rotational axis as a center; a rolling element movably provided at said central axis portion; and a cylindrical outer ring rotatably provided with respect to said central axis portion through said rolling element, the rotational axes of said outer ring and said central axis portion being substantially parallel to one another and spaced apart from one another at a predetermined distance.
- 2. The base structure according to claim 1, wherein said rolling element includes a plurality of one of balls or rollers disposed so as to be rollable on the inner circumference of said outer ring.
- 3. The base structure according to claim 1, further comprising a driving source for driving and rotating said cam element, wherein a worm gear and a worm wheel are placed between said cam element and said driving source to transmit a driving force.
- 4. The base structure according to claim 1, wherein said bases are substantially connected relative to each other by a plurality of elastic members to enable relative movement thereof, and said elastic members generate a restoring force in accordance with the amount in which said bases have moved relative to one another during the relative movement.
- 5. The base structure according to claim 4, wherein due to said restoring force from said elastic members, a state in which said cam element abuts said abutting portion is maintained.
- 6. The base structure according to claim 4, wherein said elastic members comprise plate springs.
- 7. The base structure according to claim 1, wherein one of said bases is a platform disposed on the lower side and the other is a stage disposed on the upper side, said platform and said stage being substantially parallel to one another.
- 8. The base structure according to claim 7, wherein four corners of each of said platform and said stage are connected respectively to plate springs so that said platform and said stage can move relative to one another.
- 9. A processing device for applying a predetermined processing to an object, the processing device comprising:(I) a processing element for applying a predetermined processing to an object; and (II) a base device capable of changing a position of said processing element with respect to said object, the base device including: (a) a first base and a second base, one of said bases being operative to move linearly in relation to the other; (b) at least one elastic member in connection with said bases which positions said bases away from each other and maintains a space between said bases; (c) a cam element provided at said first base in said space and driven to rotate; and (d) an abutting portion provided at said second base and on which said cam element abuts, wherein said cam element includes: a central axis portion rotatable around a rotational axis as a center; a rolling element movably provided at said central axis portion; and a cylindrical outer ring rotatably provided with respect to said central axis portion through said rolling element, the rotational axes of said outer ring and said central axis portion being substantially parallel to one another and spaced apart from one another at a predetermined distance.
- 10. The device according to claim 9, wherein said rolling element includes a plurality of one of balls and rollers disposed so as to be rollable on the inner circumference of said outer ring.
- 11. The device according to claim 9, further comprising a driving source for driving and rotating said cam element, wherein a worm gear and a worm wheel are placed between said cam element and said driving source to transmit a driving force.
- 12. The device according to claim 9, wherein said bases are substantially connected relative to each other by a plurality of elastic members to enable a relative movement thereof, said elastic members generating a restoring force in accordance with the amount in which said bases have moved relative to one another during the relative movement, and said restoring force maintaining a state in which said cam element abuts said abutting portion.
- 13. The device according to claim 12, wherein said elastic members comprise plate springs.
- 14. The device according to claim 9, wherein said first base is a platform disposed on the lower side, and said second base is a stage disposed on the upper side, said platform and said stage are substantially parallel to one another, and four corners of each of said platform and said stage are connected respectively to plate springs so that said platform and said stage can move relative to one another.
- 15. An image forming device for forming an image on a printing plate, the image forming device comprising:(I) a rotatably mounted drum having a periphery around which a printing plate can be releasably wound and fixed; (II) a mount for rotatably supporting said drum; (III) a recording head for recording an image on a printing plate; (IV) a base device for changing a position of said recording head with respect to said rotating drum, said base device including: (a) a first base and a second base, one of the bases being fixed at said mount side and the other being fixed at said recording head side- one of the bases being operative to move linearly in relation to the other; (b) at least one elastic member in connection with said bases which positions said bases away from each other and maintains a space between said bases; (c) a cam element provided at said first base in said space and driven to rotate; and (d) an abutting portion provided at said second base and on which said cam element abuts, (e) wherein said cam element includes: a central axis portion rotatable around a rotational axis as a center; a rolling element movably provided at said central axis portion; and a cylindrical outer ring rotatably provided with respect to said central axis portion through said rolling element, the rotational axes of said outer ring and said central axis portion being substantially parallel to one, another and spaced apart from one another at a predetermined distance.
- 16. The device according to claim 15, wherein said rolling element includes a plurality of one of balls and rollers disposed so as to be rollable on the inner circumference of said outer ring.
- 17. The device according to claim 15, further comprising a driving source for driving and rotating said cam element, wherein a worm gear and a worm wheel are placed between said cam element and said driving source to transmit a driving force.
- 18. The device according to claim 15, wherein said bases are substantially connected relative to each other by a plurality of elastic members to enable a relative movement thereof, said elastic members generating a restoring force in accordance with the amount in which said bases have moved relative to one another during the relative movement, and said restoring force maintaining a state in which said cam element abuts said abutting portion.
- 19. The device according to claim 18, wherein said elastic members comprise plate springs.
- 20. The device according to claim 15, wherein said first base is a platform fixed on the mount side, said second base is a stage on which said recording head is placed, said platform and said stage are substantially parallel to one another, and four corners of each of said platform and said stage are connected respectively to plate springs so that said platform and said stage can move relative to one another.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-095684 |
Mar 2000 |
JP |
|
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4576490 |
Isobe |
Mar 1986 |
A |
4782262 |
Kiyo-Oka |
Nov 1988 |
A |
Foreign Referenced Citations (1)
Number |
Date |
Country |
6-150356 |
May 1984 |
JP |