JPH11167171A - Copier - Google Patents

Abstract

(57) [Problem] To provide a copying machine that is smaller in size than a conventional copying machine and has a simple structure. SOLUTION: A lens fixing member 1 movable in a scanning direction.
1, a projection lens 7 for exposing the photosensitive member to light from a light source reflected from the sheet is fixed. The amount of light reflected from the sheet toward the photoconductor from the projection lens 7 is adjusted by projecting an end of the lens fixing member 11 in the vertical direction forward or backward in the scanning direction of the projection lens 7. The light amount adjusting member 12 is slidably held in the scanning direction. Then, by locking the locking piece 15 provided on the light amount adjusting member 12 with the locking member 16 fixed to the main body with the movement of the lens fixing member 11, the light amount adjusting member 12 is slid, The end of the adjustment member 12 is projected forward or backward in the scanning direction of the projection lens 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine capable of changing a copying magnification, and more particularly to an adjustment of an exposure amount exposed to a photosensitive member.

[0002]

2. Description of the Related Art Conventionally, in a copying machine in which the copying magnification can be changed, a light source, a photosensitive member, and a projection lens for exposing the photosensitive member to light from a light source reflected from a sheet are arranged inside a main body. In some cases, the projection lens is moved in the scanning direction in accordance with the copy magnification.

Here, an optical lens generally has such a characteristic that the amount of light at the periphery of the image forming surface is attenuated in proportion to cosin ^{4 of the} incident angle θ. Therefore, when such an optical lens is used as a projection lens, the illuminance distribution on the exposed surface of the photoreceptor has a light amount unevenness such that it is bright at the center and dark at the periphery. This is undesirable because it appears as unevenness.

Therefore, in order to prevent the density unevenness of the copied image, for example, a light-shielding plate that covers a central portion more than a peripheral portion at a constant distance from the projection lens is always attached to the original side of the lens. Alternatively, a method is provided in which the illuminance on the exposed surface at the center and the end is made uniform by providing the illuminance on either the photoconductor side or the photoconductor side. With this configuration, even if the angle of view changes during zooming, the illuminance on the exposed surface can be made uniform.

In such a configuration, the accuracy of the shape of the light-shielding plate becomes extremely severe unless a light-shielding plate is provided at a position where the light beam is opened to some extent. In general, a light-shielding plate is provided with a gap of about 30 to 40 mm from the end face of the lens so as to make it possible.

In order to realize a wide range of zoom magnification in recent years, for example, a copier employing a so-called mirror zoom system in which, for example, a single focus lens is used, and a lens and a mirror are moved to a predetermined position to perform magnification conversion. is there. In the case of this method, for example, in the case of a six-mirror method, if the first to sixth mirrors are arranged in order from the document surface side, the fourth mirror
The magnification is changed by moving the mirror and the fifth mirror to change the total optical path length.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a copying machine which is smaller in size and has a simpler structure than such a conventional copying machine.

[0008]

According to the present invention, a light source, a photoreceptor, and a projection lens for exposing the photoreceptor to light from the light source reflected from a sheet are provided inside a main body. In a copying machine in which the projection lens is moved in the scanning direction according to the copy magnification, the projection lens is fixed, and a lens fixing member movable in the scanning direction, and the lens fixing member is moved in the scanning direction. The projection lens is slidably held, and the end of the projection lens is projected forward or rearward in the scanning direction by a predetermined amount in the vertical direction to adjust the amount of reflected light from the sheet toward the photoconductor from the projection lens. A light amount adjusting member to be fixed, a locking member fixed to the main body, and provided on the light amount adjusting member, and locked with the locking member with the movement of the lens fixing member,
A locking piece that slides the light amount adjustment member so that an end protrudes forward or rearward in the scanning direction of the projection lens.

Further, the present invention is characterized in that the light quantity adjusting member is formed of a black flexible member.

[0010] In the present invention, the light amount adjusting member may be made of PET.
It is characterized by being formed of a film.

Further, the present invention is characterized in that the locking member and the locking piece are elastically locked.

Further, the present invention is characterized in that the locking member is formed of an elastic member.

Further, the present invention is characterized in that the locking piece is formed of an elastic member.

Further, as in the present invention, a projection lens for exposing a photosensitive member to light from a light source reflected from a sheet is fixed to a lens fixing member movable in the scanning direction, and an end is attached to the lens fixing member. By projecting a predetermined amount in the vertical direction forward or backward in the scanning direction of the projection lens, a light amount adjustment member that adjusts the amount of reflected light from the sheet toward the photoconductor from the projection lens is slidably held in the scanning direction. To do. Then, by locking the locking piece provided on the light amount adjustment member with the movement of the lens fixing member to the locking member fixed to the main body, the light amount adjustment member is slid, and the end of the light amount adjustment member is moved. Is projected forward or backward in the scanning direction of the projection lens.

[0015]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view of an analog type electrophotographic copying machine which is an example of the copying machine according to the present embodiment.

In FIG. 1, reference numeral 100 denotes an electrophotographic copying machine main body (hereinafter referred to as main body); 50, an exposure lamp 51 as a light source; a reflector 52; a first mirror 1, a second mirror 2, a third mirror;
A first scanning optical unit provided with the mirror 3, and a second scanning optical unit 60 provided with the fourth mirror 5 and the fifth mirror 5. Reference numeral 6 denotes a sixth mirror, 19 denotes an original table glass on which an original is placed, 7 denotes a projection lens (hereinafter, referred to as a lens), 9 denotes a photosensitive drum, and 10 denotes a fixing device.

When a document (not shown) on the document table glass 19 is irradiated by the exposure lamp 51, reflected light from the document is passed through the first mirror 1, the second mirror 2, and the third mirror 3 to the lens 7. After being incident, the light is exposed on a photosensitive drum 9 via a fourth mirror 4, a fifth mirror 5, and a sixth mirror 6. Further, thereafter, the electrostatic latent image formed by exposing the photosensitive drum to light is visualized by a known electrophotographic image forming method, and is transferred to a recording material such as paper. It is established by.

In FIG. 1, reference numeral 20a denotes a mirror stand that holds the second and third mirrors 2 and 3, and FIG. 2 shows a state in which the mirror stand 20a is at the home position before scanning starts. Reference numeral 20b denotes a mirror table in a state where scanning of a full-size document has been completed.

The first scanning optical unit 50 shown in FIG.
Further, the position of the second scanning optical unit 60 is a position where copying at the same magnification (100%) is possible. Here, the electrophotographic copying machine according to the present embodiment is capable of changing the copying magnification, and changes the total optical path length so as to obtain a scaled image and changes the optical path length before and after the lens. It is.

In such a copying machine, for example,
To make a 0% reduced copy, the first scanning optical unit 5
The 0 and second scanning optical units 60 are arranged as shown in FIG. That is, the lens 7 is largely moved to the fourth mirror side as compared with the position at the same magnification shown in FIG.
The fourth and fifth mirrors 4 and 5 also move in the same direction as the lens 7.

Incidentally, the lens 7 is fixed to a lens base 11 which is a lens fixing member as shown in FIG.
Here, the lens mount 11 is slidably held by a lens mount rail 17 and is fixed to a lens drive belt 18 stretched by a drive gear 18a driven by a dedicated motor M1 and a driven gear 18b. ing. When the dedicated motor M1 is driven, the drive is transmitted to the lens driving belt 18 via the driving gear portion 18a, whereby the lens driving belt 18 moves. While sliding in the scanning direction indicated by the arrow A or the arrow B.

The fourth and fifth mirrors 4 and 5 are also driven completely independently of the lens 7 by another dedicated motor M2 and gears 18c and 18d, and slide in the scanning direction while being guided by the rail 17a. It has become.

FIG. 3 is a top view of the optical system of the copying machine.
In the figure, reference numeral 12 denotes a light amount adjusting member, and the light amount adjusting member 12 is attached to a lower portion of the lens base 11.
Here, the light amount adjusting member 12 is formed of a black flexible PET film, for example, and is slidably held in the scanning direction by an inner guide 14 and an outer guide 13 as shown in FIG. I have.

In the figure, the solid line on the left shows the lens 7 (lens base 1) at the same magnification, and the broken line on the right shows the lens 7 at the time of 50% reduction.
In the state where the lens 7 is at the position at the same magnification on the left side, for example, the light amount adjusting member 12 includes flanges 13 formed at both ends of the outer guide 13 in the scanning direction.
a and 13b are gently curved and upright along the flange 13a on the photosensitive drum side in the optical path.

FIG. 5 (a) is a view of this state as viewed from the second scanning optical unit side. As shown in FIG. The light is shielded from the lower end to the vicinity of the center. And
As described above, by increasing the light blocking at the center of the lens 7 and reducing the light blocking at both ends, the illuminance on the photosensitive drum surface can be made uniform.

FIG. 5 (b) is a view of the above state as viewed from the first scanning optical unit side. As shown in FIG. 5, the light amount adjusting member 12 is lowered and the state where the light beam is blocked is described. is not. In addition, the position does not interfere with the third mirror 3 (see FIG. 1).

On the other hand, in FIG. 4, reference numeral 15 denotes a locking piece projecting from one end (see FIG. 3) of the light amount adjusting member 12 perpendicular to the scanning direction, and reference numeral 16 denotes a moving orbit of the lens 7. This is a leaf spring that is a locking member. 21 is the lens base 11
The stopper piece 15 is configured to project between the two stoppers 21 at a predetermined interval on the bottom surface thereof.

Then, when the lens 7 moves in the direction of arrow A shown in the figure, the locking piece 15 of the light quantity adjusting member 12 comes into contact with the leaf spring 16 soon. Here, the spring force of the leaf spring 16 is larger than the holding force (mainly frictional force) between the inner guide 14 and the outer guide 13 that hold the light amount adjusting member 12.

For this reason, when the lens 7 further moves after the locking piece 15 hits the leaf spring 16 as described above, the locking piece 15 remains in contact with the leaf spring 16, so that the light amount The adjustment member 12 moves relatively to the lens 7 in the direction shown by the arrow B.

Thereafter, when the light amount adjusting member 12 further moves, the locking piece 15 is eventually moved to the one stopper 21.
Comes into contact with Here, the locking piece 15
When abuts against the stopper 21, the light amount adjusting member 12
As shown in the figure, the first scanning optical unit side, which is opposite to that at the time of equal magnification, is in a rising state, and the second scanning optical unit side is in a low state. As a result, contrary to the case of the same magnification, the first scanning optical unit performs the light shielding for the light amount correction and the second scanning optical unit does not block the light beam.

When the stopper 21 comes into contact with the stopper 21 as described above, a force for moving the lens base 11 is applied to the locking piece 15, and this force causes the leaf spring 16 to bend as shown in FIG.
The locking piece 15 slips through.

Next, a description will be given of the movement of the light amount adjusting member 12 when performing a reduced copy in the copying machine configured as described above.

In this case, the lens base 11 moves in the direction of arrow A shown in FIG. 4, and the locking piece 15 comes into contact with the leaf spring 16 and is held at the contact position by the spring force of the leaf spring 16. . As a result, the light amount adjusting member 12 moves in the direction indicated by the arrow B relative to the lens 7. Thereafter, the locking piece 15 hits the stopper 21 and the light amount adjusting member 12
Is restricted from moving with respect to the lens 7.

As a result, the light amount adjusting member 12 is in a state opposite to that at the time of equal magnification, that is, the end portion of the light amount adjusting member 12 flexes along the flange 13b of the outer guide 13 on the first scanning optical portion side. And stand upright. Thus, the light amount adjusting member 12 shields the light from the lower end to the vicinity of the center of the lens 7 on the first scanning optical unit side, so that the illuminance on the photosensitive drum surface can be made uniform.

The end on the side of the second scanning optical unit is lowered so as not to interfere with the fourth mirror (see FIG. 2), and the light flux between the fourth and fifth mirrors (see FIG. 2). It is a position that will not be blocked.

As described above, the end of the light amount adjusting member 12 is projected forward or backward in the scanning direction of the lens 7 in accordance with the movement of the lens base 11 to block a part of the light beam, thereby achieving an arbitrary copy magnification. On the other hand, the light amount distribution on the photosensitive drum can be substantially flattened. Thus, a device having a wide zoom range can be reduced in size with a simple structure. In addition, the lens 7 can be moved to a predetermined position in a short time even when changing the magnification or during recovery after a jam, so that the user does not have to wait.

In the case where the same-size copy or the enlarged copy is performed after the reduced copy, the operation reverse to the above-described operation is performed.
The light-amount adjusting member 12 performs light-shielding for light-amount correction on the second scanning optical unit side, and does not block light beams on the first scanning optical unit side.

On the other hand, when the locking piece 15 is not in contact with either of the stoppers 21, the light amount adjusting member 12
This means that the light beam is blocked on both sides of the lens 7. At this time, the light amount adjusting member 12 is deviated to one side,
The light blocking amount when the light beam of the lens 7 is blocked by only one of the lenses 7 is almost the same. Therefore, no matter where the light amount adjusting member 12 is located, an appropriate light amount distribution correction amount can be obtained.

In the above description, the case where the locking member is constituted by a leaf spring so that the locking member and the locking piece 15 are elastically locked has been described, but the present invention is not limited thereto. Not limited to this, the locking piece 15 may be formed of an elastic member.

[0041]

As described above, according to the present invention, a part of the light beam is blocked by projecting the end of the light amount adjusting member forward or backward in the scanning direction of the projection lens with the movement of the lens fixing member. Thus, the light amount distribution on the photoconductor can be substantially flattened for an arbitrary copy magnification. Thus, the device can be downsized and the structure can be simplified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an analog electrophotographic copying machine which is an example of a copying machine according to an embodiment.

FIG. 2 is a diagram showing positions of a projection lens and fourth and fifth mirrors at the time of 50% reduction copying in the electrophotographic copying machine.

FIG. 3 is a top view of an optical system of the electrophotographic copying machine.

FIG. 4 is a side view of a main part of the electrophotographic copying machine.

5A is a view of the projection lens of the electrophotographic copying machine as viewed from a second scanning optical unit side, and FIG. 5B is a view of the projection lens as viewed from a first scanning optical unit side.

FIG. 6 is a diagram illustrating a sliding operation of a light amount adjusting member of the electrophotographic copying machine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 7 lens 9 photosensitive drum 11 lens base 12 light amount adjusting member 15 locking piece 16 leaf spring 50 first scanning optical unit 51 exposure lamp 100 main body

Claims (6)

[Claims] 1. A light source, a photoconductor, and a projection lens for exposing the photoconductor to light from the light source reflected from a sheet are disposed inside a main body. A copying machine configured to move the projection lens in the scanning direction, wherein the projection lens is fixed, the lens fixing member is movable in the scanning direction, and the lens fixing member is slidably held in the scanning direction. A light amount adjusting member for projecting an end of the projection lens forward or rearward in the scanning direction in a vertical direction by a predetermined amount to adjust the amount of light reflected from the sheet toward the photoconductor from the projection lens; And a locking member fixed to the light amount adjusting member, and locked with the locking member in accordance with the movement of the lens fixing member, so as to be forward or rearward in the scanning direction of the projection lens. Copier, characterized in that the end portion is provided with a locking piece sliding the light amount adjusting member so as to protrude. 2. The copying machine according to claim 1, wherein said light amount adjusting member is formed of a black flexible member. 3. The copying machine according to claim 2, wherein said light amount adjusting member is formed of a PET film. 4. A copying machine according to claim 1, wherein said locking member and said locking piece are elastically locked. 5. The copying machine according to claim 4, wherein said locking member is formed of an elastic member. 6. The copying machine according to claim 4, wherein said locking piece is formed of an elastic member.