JPH0843962A - Mirror unit of scanning exposure equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a mirror unit of a scanning type exposure apparatus that can obtain a clear image with high resolution without being in a "frontward" posture when driven. [Structure] A pair of mirror supports 3 supporting both ends of an elongated flat mirror M for guiding reflected light from an original is a frame member 1.
In the mirror unit of the scanning exposure apparatus, which is fixed to both ends of the frame, the frame member 1 is driven along the horizontal guide surface G, and the level of the line of action of the force for driving the frame member 1 is above the guide surface. The weight distribution of the frame member 1 is such that the weight below the horizontal center line of the frame member is greater than the weight above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mirror unit of a scanning type exposure apparatus built in a reverse copying type plate making camera or the like.

[0002]

2. Description of the Related Art A scanning type exposure apparatus is used in a reverse copying type plate making camera, an electrophotographic copying machine, or the like. An example of the scanning type exposure apparatus used for the plate making camera will be described with reference to FIG. 3. On the upper surface of the casing 5, for example, a transparent glass platen 6 on which a document 7 having a maximum A ₃ size can be placed. Are arranged and it is a table top type. The scanning unit 4 has a variable speed V just below the document table 6.
It is arranged so that it can be moved. This scanning unit 4
It is a two-lamp type in which two tube-shaped light source lamps 41 each surrounded by a gutter-shaped mirror 42 are attached, and the original 7 is scanned in a slit shape, but a plane mirror M ₁ is arranged below. There is. Therefore, when the scanning unit 4 moves, the entire surface of the original 7 is scanned, and the reflected light of the original 7 is emitted in the horizontal direction by the mirror M ₁ .

The first mirror unit MU ₁ and the second mirror unit MU ₂ are a pair of long rectangular plane mirrors M.
₂ , M ₃ and a pair of plane mirrors M ₄ and M ₅ are mounted in a roof shape at an angle of 45 °, and optical axes are arranged on both sides of the lens L in the horizontal direction. Therefore, the reflected light of the original 7 reflected by the mirror M ₁ is reflected by the mirrors M ₂ and M ₃ and is incident on the lens L, and the light emitted from the lens L is reflected by the mirrors M ₄ and M ₅ , and is further a plane mirror. The light is reflected by M ₆ and emitted from the opening 51 on the lower surface of the casing 5.

Directly below the casing 5 is a conveyor 8 which moves horizontally at a speed V ₀ , and which has a mirror M.
_The light reflected in the vertical direction at ₆ is placed on the conveyor 8 and forms an image on the moving photosensitive material 9. First mirror unit M
U ₁ moves in the same direction as the scanning unit 4 at a speed of 1/2 V, that is, half the speed of the scanning unit 4, so that the optical path length from the document 7 to the lens L does not change with the movement of the scanning unit 4. Has become.

[0005]

As described above, the mirror unit MU to which the elongated flat mirror M is attached moves, but in order to obtain a clear image with high resolution, the mirror unit MU tilts during the movement. Without having to move smoothly in an accurate posture. By the way, in the mirror unit MU, both ends of the flat mirrors M ₂ and M ₃ arranged in a roof shape at an angle of 45 ° are supported by a pair of mirror supports.
The mirror supports are fixed to both ends of a frame member which is parallel to the plane mirrors M ₂ and M ₃ . A pulley is attached to the frame member, and the drive wire wound around the pulley drives the frame member along the horizontal guide surface. Therefore, although the shaft of the pulley is the level of the line of action of the force that drives the frame member, the level of the line of action of the force does not coincide with the guide surface and is often above the guide surface due to the structure.

Therefore, during driving, the mirror unit MU
, A rotational moment of (level of line of action of force and length of guide surface) × (driving force) acts on the guide surface as a fulcrum, and the mirror unit MU takes a somewhat “frontward leaning” posture.
For this reason, the reflected light does not become a completely horizontal light, does not enter the plane mirror of the mirror unit of the next stage at an angle of exactly 45 °, and there is a problem that a clear image with high resolution cannot be obtained.

In view of this, the present invention is a scanning type in which the reflected light does not enter the "frontward" posture at the time of driving, and the reflected light is incident on the mirror of the next stage at an angle of exactly 45 ° to obtain a clear image with high resolution. An object is to provide a mirror unit of an exposure apparatus.

[0008]

In order to achieve the above object, the present invention provides a pair of mirror support members for supporting both ends of an elongated flat mirror for guiding reflected light from a document. In the mirror unit of the scanning exposure apparatus in which the frame member is driven along the horizontal guide surface and the level of the line of action of the force for driving the frame member is above the guide surface, the weight distribution of the frame member is fixed. The weight below the horizontal center line of the frame member is greater than the weight above.

[0009]

The weight distribution of the frame member is such that the weight below the horizontal center line of the frame member is greater than the weight above it, that is, the weight below the guide surface of the mirror unit is greater. When a rotation moment that causes a "front bend" is applied to the unit, a rotation moment in the opposite direction acts to cancel the rotation moment that causes a "front bend". Therefore, the mirror unit moves in an accurate posture without being "curved forward" when driven, so that the reflected light is incident on the mirror of the next stage at an angle of exactly 45 ° and a clear image with high resolution is obtained. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the embodiments shown in the drawings. FIG. 1 shows a side view of a mirror unit for a scanning type exposure apparatus incorporated in the reversal copying type plate making camera shown in FIG.
Driven horizontally along. Two elongated flat mirrors M, M are arranged to face each other at an angle of 45 °, and both ends of the flat mirror M each have a pair of mirror supports 3 (only one mirror support 3 is shown). Is fixed by a mounting bracket (not shown). And the mirror support 3
Are fixed to both ends of the frame member 1 parallel to the plane mirror M.

A pulley 21 and two sliders 23 that slide on the guide surface G are attached to the plate-shaped auxiliary frame 2. Then, the frame member 1 is fixed to the auxiliary frame 2 after adjusting the height with the adjusting screw 13. A wire 22 is wound around the pulley 21.
When the slider 23 is pulled by, the slider 23 slides on the guide surface G, and the mirror unit is driven in the horizontal direction along the guide surface G. Therefore, the axial center of the pulley 21 is the level in the force acting direction, and this level is located above the guide surface G.

The adjusting screw 1 is attached to the upper end of the frame member 1.
Although a short upper horizontal portion 12 is formed for attaching 3, the lower end of the frame member 1 is bent in an L shape to form a lower horizontal portion 11 longer than the upper horizontal portion 12. In other words, the weight distribution of the frame member 1 is such that the weight below the horizontal center line is greater than the weight above. The lower horizontal portion 11 may be attached in an inverted T shape as shown in FIG. 2 (A).
As shown in (B), a round bar 14 is used instead of the lower horizontal portion 11.
May be fixed to the lower end of the frame member 1, in short,
The weight below the horizontal center line may be greater than the weight above.

Therefore, when the mirror unit is pulled by the wire 22 and moves horizontally along the guide surface G, the level in the acting direction of the force for driving the mirror unit is located above the guide surface G. So the front slider 2
The rotation moment with 3 as the fulcrum acts as shown by the arrow, and the mirror unit tries to become "frontward".

At this time, however, the weight distribution of the frame member 1 is such that the weight below the horizontal center line is greater than the weight above, so that an anti-rotation moment in the direction of the arrow acts and the above rotation moment is Cancel. Therefore, when the mirror unit is driven, the mirror unit does not take the "frontward" posture and moves in an accurate posture, so that the reflected light is incident on the plane mirror of the next stage mirror unit at an angle of exactly 45 ° and the resolution is reduced. A high clear image can be obtained. In the above embodiment, the example of the mirror unit for the scanning type exposure apparatus incorporated in the plate making camera in which the two plane mirrors are attached at the angle of 45 ° is shown. Obviously, it may be a mirror unit mounted on the mirror support at a predetermined angle.

[0015]

As described above, in the mirror unit of the scanning type exposure apparatus of the present invention, the weight distribution of the frame member, to which a pair of mirror supports for supporting both ends of the plane mirror is fixed, is adjusted horizontally. Since the weight below the center line in the direction is larger than the weight above, the mirror unit will be in the "forward leaning" posture when moving even if the level of the line of action of the force that drives the frame member is above the guide surface. Since it moves in an accurate posture without a problem, a clear image with high resolution can be obtained.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of another embodiment.

FIG. 3 is an explanatory diagram of a scanning exposure apparatus.

[Explanation of symbols]

 1 Frame Member 2 Auxiliary Frame 21 Pulley 22 Wire 23 Slider 3 Mirror Support M Mirror G Guide Surface

Claims (1)

[Claims] 1. A pair of mirror supports for supporting both ends of an elongated flat mirror for guiding reflected light from a document are fixed to both ends of a frame member, and the frame member is provided along a horizontal guide surface. In the mirror unit of the scanning type exposure apparatus in which the level of the line of action of the force that drives the frame member is above the guide surface, the weight of the frame member below the horizontal center line is above the weight of the frame member. A mirror unit for a scanning exposure apparatus, which is characterized by being larger.