JP2509339Y2 - Variable magnification exposure device in image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a variable power exposure apparatus in an image forming apparatus such as a copying machine, and more particularly to a light blocking structure of an optical member.

(Prior Art) As is well known, in a copying machine, which is one of image forming apparatuses, there are cases in which the size of a document image is changed and a so-called enlarged or reduced image is copied. The position of a reflecting mirror (hereinafter referred to as a mirror), which is an optical member in the exposure scanning system, or a lens is changed.

That is, FIG. 8 shows the overall structure of a copying machine provided with the above-mentioned exposure scanning system. In this copying machine 1, a belt-shaped photosensitive member 2 which is movable in the direction of the arrow shown is arranged. ing.

Around the photoconductor 2, a charging device 3, an exposure device 4, a developing device 5, and a transfer / separation device 6 for executing a copying process are arranged along the moving direction, and transfer in the moving direction is performed. A cleaning device 7 is provided behind the separating device 6, a fixing device 8 and a paper discharging device 9 are provided in the vicinity of the transferring / separating device 6, and the transferring / separating device 6 is provided.
The sheet feeding devices 10 are respectively arranged in front of the confluence positions with the.

The exposure device 4 described above is provided for introducing the light source lamp 4A and the reflecting mirror 4B, which are located in the vicinity of the document placing table 1A provided on the upper part of the copying machine main body, and the reflected light from the document placing table 1A into the photoconductor 1. First mirror 4C, lens 4D, and second mirror 4E
It consists of and.

In this exposure apparatus 4, the amount of movement (ΔL) of the optical member required during zooming is represented by ΔL≈ (1-1 / m) f, where f is the lens focal length, and m is the magnification. A graph of this movement amount is shown in FIG.

FIG. 9 shows the amount of vertical movement in the main body of the copying machine with the vertical axis as the reference (position indicated by "0" in the figure) at the same size, and the horizontal axis shows the magnification. There is.

In FIG. 9, the amount indicated by the chain double-dashed line A is the result obtained from the above equation, and from this result, a large change in the moving amount is required at the time of reduction / magnification.

Therefore, if the movement of the optical member is limited to the first mirror 4C in view of such an actual situation, the position of the first mirror 4C at the time of reduction shown by the chain double-dashed line in FIG. Since it is located on the lower side and approaches the photoconductor 2, the places where the charging device 3 and the cleaning device 7 are placed are restricted. Therefore, in order to eliminate such a problem, it is necessary to raise the position of the document placing table 1A upward in the sense of moving it away from the photoconductor 2, and as a result, the height of the copying machine body is increased, and the document setting is performed. There is a problem in the operability in the case of.

If the optical path length for zooming is set by moving only the lens 4D instead of moving the first mirror 4C, the position of the lens at the time of reduction shown by the chain double-dashed line in FIG. It is necessary to move further to the left side than that, and as a result, when the second mirror 4E is approached, a part of the projected image may not fit inside the second mirror 4E and may be chipped. Therefore, in order to eliminate such a problem, it is necessary to secure a space for moving the position of the second mirror 4E in the main body of the copying machine to a position where the projected image does not drop as the lens moves. Next to
This causes a new problem that the size of the copying machine main body in the horizontal direction is expanded and the copying machine becomes larger.

Therefore, in order to solve such a problem, by interlocking the lens with the movement of the first mirror described above,
It has been considered to reduce the area occupied by the exposure device in the copying machine by moving only the first mirror and the lens.

(Problems to be solved by the invention) However, in the case of such a structure, or in the case of the moving structure of each optical member alone as described above, the flare phenomenon is caused by the intrusion of ambient light into the optical member. There is a problem of causing it.

That is, in the movement path of the optical member, the optical members are positioned so as to overlap each other, thereby preventing light from leaking, but there is a limit to the arrangement configuration. I couldn't hope for complete shading.

Therefore, conventionally, on the surface facing the optical member in the housing that forms the above-described movement path, electrostatic flocking is performed, or, although it has been proposed to perform matte coating to prevent light reflection, For example, as a light source,
In the case of flash exposure using a xenon lamp, reflection could not be completely blocked due to the intense light.

Therefore, an object of the present invention is to provide a structure capable of completely preventing leak light from entering a moving path of an optical member in the exposure apparatus in view of the above-mentioned problem in the exposure apparatus which constitutes the variable magnification exposure scanning system. Another object is to obtain a variable power exposure device in an image forming apparatus.

(Means for Solving the Problem) In order to achieve this object, the present invention is to project the reflected light from the document surface onto a photoconductor through a plurality of reflecting mirrors and a lens located between the reflecting mirrors. Equipped with optical components of
In the variable power exposure apparatus capable of displacing the positions of these optical members at the time of varying the magnification, the first reflecting mirror of the plurality of reflecting mirrors that first reflects the reflected light from the document surface and the first reflecting mirror. A first reflecting mirror holding member for movably supporting the reflecting mirror in the state of being parallel to the optical axis direction of the reflecting mirror, and a lens positioned behind the first reflecting mirror holding member for the first reflecting mirror holding member. A lens holding member that moves in the moving direction of the first reflecting mirror holding member by an amount according to the ratio obtained from the moving amount of the first reflecting mirror, and a first reflecting member including a housing in which both the first reflecting mirror and the lens are arranged. A mirror support unit, and a surface on which the lens is disposed in the first reflecting mirror unit has a surface substantially perpendicular to the incident direction of the reflected light and a surface opposite to the surface as an inclined surface. , The right-angled surface faces the inclined surface While reflecting light, it is characterized in that the inclined surface is formed a serrated irregular portion respectively forming a light path for reflecting the reflected light toward the perpendicular surface.

(Operation) In the present invention, when the reflected light that is advancing is incident on the right-angled surface of the concavo-convex portion on the sawtooth, if the reflected light has a slight angle, it is directed from the right-angled surface to the inclined surface. It is reflected and reflected toward the incident side on the inclined surface. Further, when the reflected light is incident on the inclined surface, if the reflected light has a slight angle as described above, the reflected light is reflected toward the right-angled surface and is reflected toward the incident side on the right-angled surface.

(Embodiment) Hereinafter, the embodiment of the present invention will be described in detail with reference to FIGS.

First, in describing the embodiments of the present invention, a copying machine as an image forming apparatus including a variable-magnification exposure apparatus, which is an example of an apparatus to which the embodiments of the present invention are applied, will be described. The light-shielding structure, which is a feature of the invention, will be described.

FIG. 1 is a perspective view showing the details of the exposure apparatus 4 shown in FIG. 8, and the same structural parts as those shown in FIG. 8 are designated by the same reference numerals.

That is, the first reflecting mirror (hereinafter referred to as the first mirror) 4C
Is tilted at an angle that can set a predetermined reflection optical path,
It is held by the mirror support unit 11. The first mirror support unit 11 is composed of a housing including a holding portion 11A of the first mirror 4C and a holding portion 11B of a lens 4D, which will be described later, and the first mirror holding portion 11A is provided on an inclined bottom plate 11A1. The first mirror 4C is placed and fixed.

The lens holding portion 11B described above is formed of a housing that is continuous with a part of the first mirror holding portion 11A, and is provided on a part of the inclined bottom plate 11A1 of the first mirror holding portion 11A and a wall portion of the holding portion 11A. It has a pair of guide shafts 11B1 and 11B2, one end of which is inserted into the provided fitting portion and which is parallel to the reflection optical axis of the first mirror 4C.

The guide shafts 11B1 and 11B2 are slidably supported by lens holding members 12 having the positions of these guide shafts as end portions in the width direction, and the central position between the guide shafts in the lens holding member 12 is set. Has a lens 4D attached.

The lens holding member 12 described above is provided with a support shaft 12A projecting along the width direction at one end in the width direction.
A rotatable cam follower 12B is attached to the tip of 2A. The cam follower 12B is fitted in the cam groove 13A formed in the cam plate 13 provided in the immovable portion of the copying machine main body, and is displaced according to the shape of the cam groove 13A during movement. The lens holding member 12 is configured to perform

The above-mentioned cam groove 13A has a shape including a stroke based on the criteria described in FIG. 9 and next.

That is, in the present embodiment, regarding the movement of the lens 4C, the movement amount (ΔL ') of the first mirror supporting unit 11 from the position at the same magnification is set to ΔL' = g (m), and based on the function of magnification. The actual amount of movement obtained from this function is as shown by the solid line B in FIG. The lens side is also moved according to the amount of movement of the first mirror 4C, and the amount of movement is within the range shown by hatching in FIG.

In other words, such a setting is intended to eliminate the adverse effect in the case of only the movement of the first mirror or the movement of only the lens by performing the movement of the first mirror 4C and the movement of the lens in correspondence with each other. As for the actual movement amount of each optical member, for example, at the time of reduction, the movement amount of the first mirror 4C is the same as that of the conventional movement amount shown in FIG. The amount of movement is 40 to 60%, and the amount of movement substantially equal to this amount of movement is set as the amount of movement of the lens, and when enlarging, 100 to 120% of the conventional amount of movement shown in FIG. It is set to%.

Therefore, if the shape of the cam groove 13A is set according to such a reference, it is possible to reduce the movement amount of the first mirror 4C and the movement amount of the lens, and thus, the copying machine. This will eliminate the incentive for the larger size of.

Such movement of the first mirror support unit 11 is performed by the mechanism whose details are shown in FIG.

That is, a boss portion 110 is formed on the side wall of the first mirror support unit 11, and a stationary shaft 14 extending vertically in the copying machine body is fitted in the boss portion 110. , The first mirror support unit via this immovable shaft 14
11 is supported so that it can move up and down.

And, as shown in the second illustration, locking teeth 110A facing the position of the boss portion 110 are fixed to the above-mentioned side wall,
The teeth of the cog belt 15 mesh with the locking teeth 110A. Therefore, the cog belt 15 can use the boss portion 110 as a backup member, so that the engagement with the locking teeth 110A can be maintained in a firm state.

On the other hand, the above-mentioned cog belt 15 is, as shown in the second illustration,
It is hung on a pair of belt pulleys 16 and 17, and can be moved according to the rotation direction of the pulleys.

Therefore, one of the belt pulleys 16 is supported coaxially with the worm wheel 18, and the worm wheel 18 has a drive motor 19 composed of a pulse motor capable of rotating in the forward and reverse directions.
The worm gear 20 fixed to the output shaft 19A of is engaged with.

In FIG. 2, reference numeral 21 indicates a spreading member of the cog belt 15. The stretching member 21 supports a support plate 21a that rotatably supports the other shaft 17 of the belt pulley, and the support plate 21a. A tension spring 23 hung between the upper end and one of the pins 22, 22 'which are planted in the immovable portion in the copying machine, and a fixing screw for fixing the support plate 21a after vertically adjusting its position. 241 of the cog belt 15 is prevented from being loosened by pulling the other side 17 of the belt pulley downward through the support plate 21a by the biasing force of the tension spring 23 in the figure.

On the other hand, in the first mirror support unit 11, one end portion in the direction parallel to the width direction of the lens holding member 12 described above is supported by the boss portion 110 in a cantilever shape, and the other end is attached to the side wall. The eccentric sleeve 111, to which the tip of the supported shaft is fitted, is fitted in the longitudinal slot 24a formed in the immovable portion 24 in the main body of the copying machine so that it can slide in the vertical direction. In this first mirror support unit 11, by rotating the eccentric sleeve 111 in the elongated hole 24a, the position of the other end in the width direction can be displaced and the deviation of the optical axis with respect to the lens 4D can be adjusted.

Further, the first mirror support unit 11 having such a support structure is in a state in which the other end in the width direction is not locked at all, so that a structure for preventing inadvertent sliding is provided.

That is, in FIG. 1 and FIG. 3, the bosses 110 and pulleys 25, 26 are disposed at the respective ends in the width direction of the first mirror support unit 11 at positions opposite to the bosses 110, respectively. , 26 are wired with a wire 27 without interfering with the optical path to the lens 4D. And
This wire 27, as shown in FIGS. 2 and 3,
One end of the pulley 28 is fixed to a pin 28 that is locked to an immovable portion in the main body of the copying machine, and the other end bypasses the upper peripheral surface of one of the pulleys 25 and the lower peripheral surface of the other pulley 26. Then, it is fixed to the immovable part 24 of the copying machine.

Therefore, by installing such a wire 27, the first
The other end of the mirror support unit 11 in the width direction, that is, the end without the boss 110 is suspended from and supported by the immovable portion of the copying machine body. The pin 28 fixing one end of the wire 27 has a screw formed on its shaft as shown in FIG. 3, and the tip projection amount of the pin 28 via this screw can be adjusted. To correct the backlash and flexure generated in the first mirror support unit 11
It does not interfere with the vertical movement of the mirror support unit 11. The reference numerals 29 and 30 in FIG. 3 indicate nuts for fixing the pin 28.

The exposure apparatus is provided with a light shielding structure which is a feature of the embodiment of the present invention, the details of which are shown in FIGS. 1 and 4.

That is, at the position on the lower surface of the lens holding member 12 facing the inner surface of the lens holding portion 11B, the light shielding plate 120 is attached, and on the inner surface of the housing forming the lens holding portion 11B,
For example, a sawtooth-shaped concave-convex portion 12 having a surface substantially perpendicular to the incident direction of projection light and an opposite surface continuous to the surface as an inclined surface
1 is formed. By such uneven portions 121, the disturbance light that has entered the lens holding portion 11B is prevented from traveling and is less likely to leak to the rear in the traveling direction. That is, the uneven portion 12
If there is reflected light traveling toward 1, the reflected light can be reflected toward the inclined surface when first entering the surface at a right angle. The reflected light reflected from the right-angled surface to the inclined surface is reflected on the inclined surface, so that it can be reflected in the direction of the first incidence on the side opposite to the photoconductor side. Also, when the reflected light first enters the inclined surface,
It can be reflected toward a plane perpendicular to the inclined surface. The reflected light reflected from the inclined surface to the right-angled surface can be reflected on the right-angled surface, so that it can be reflected in the first incident direction on the side opposite to the photoconductor side. Note that, in order to more reliably prevent such intrusion of ambient light, a low-reflection coating may be applied to the surface of the light shielding plate 120 facing the concave and convex portion 121. Further, the shape of the concave-convex portion 121 may be a rectangular tooth shape or a triangle, as long as the convex portion has a small apex and the concave portion has a deep depth.

On the other hand, in the boss portion 110 of the above-mentioned first mirror support unit 11, as shown in FIG. 1 and FIG. 5 (A),
A feeler 112 is attached, and a home sensor 31 composed of a photo-electric element is arranged on the immovable portion 24 of the copying machine main body corresponding to the feeler 112.

The home sensor 31 is for detecting the position of the first mirror unit 11 at the same magnification, and the feeler 11
The time when 2 is shielded is detected as the expansion time including the same magnification, the output signal is output as (HIGH), and conversely, the time when it does not correspond to the feeler 112 is detected as the reduction time, and Output the output signal as (LOW).

The home sensor 31 is supported by a bracket 32 whose top portion is bent at a right angle.
It has a guide pin 32A fitted in a long hole 32a having a long axis parallel to the moving direction of the first mirror support unit 11, and as shown in FIG. 5 (B), this guide pin 32A penetrates through. It is pressed against the immovable portion 24 via the disc spring washer 32b. An adjusting screw 33 having an axial direction parallel to the moving direction of the first mirror supporting unit 11 is penetrated through the top of the bracket 32, and the adjusting screw 33 is rotated to adjust the protrusion amount. Thus, the corresponding position between the bracket 32 and the home sensor 31 can be adjusted, and after the adjustment is completed, the fixing screw 32B located on the same side as the guide pin 32A can be tightened for accurate position adjustment.

In such a position adjustment structure of the bracket 32 with respect to the home sensor 31, while the position adjustment is performed, since the bracket 32 is kept pressed by the immovable portion 24 by the disc spring washer 32b, when the fixing screw 32B is loosened. To
The bracket 32 does not float from the immovable portion 24. Therefore, when the fixing screw 32B is tightened again, the bracket 32
It does not occur that the position of the home sensor 31 in the adjusted bracket 32 is accurately adjusted to the position of the feeler 112 without causing the problem that the position is displaced due to the rotation moment generated at the time of fastening, which is likely to occur when the It is possible to maintain it.

The drive for moving the first mirror support unit 11 described above is performed by the drive motor 19 capable of rotating in the forward and reverse directions shown in FIG.
This is shown in Figures and 7.

That is, in the present embodiment, the movement start position of the first mirror support unit 11, that is, the initial position is set to the position at the same magnification detected by the home sensor 31 shown in FIG. 5, and is moved from an arbitrary position. Also in the case of performing, after returning to the initial position once, the movement to the position according to the magnification is started.

That is, FIG. 6 shows the position of the first mirror support unit 11 at the same magnification, the position at the time of enlarging, the position at the time of reducing, and the position at the time of overrun by the symbols ,. First mirror support unit 11 in position 11
Is for the purpose of canceling the backlash of the gear or the hysteresis of the home sensor 31 in the mechanism for driving this kind of moving body, in other words, for the purpose of stabilizing the return condition to the initial position, it is operated from one direction and stopped. I am allowed to do it.

By the way, in the above-mentioned return operation to the initial position,
In the case of the position shown by ,, even though the initial position is once reached, it is further moved to the overrun position and then moved toward the initial position. This is because the feeler 11 in the first mirror support unit 11 depends on the moving direction of the first mirror support unit 11.
This is to prevent an error from occurring in the corresponding position between 2 and the home sensor 31.

That is, in FIG. 6, for example, the moving direction of the first mirror support unit 11 is opposite between the case of moving from the enlarged position to the initial position and the case of moving from the contracted position to the initial position. When moving in the direction of gravity, the home sensor 31 at the time when it corresponds to the home sensor 31 may be caused by the difference in the vibration generated during the movement.
The operating speed of may differ. Therefore, the acceleration changes as a cause of the speed fluctuation, and as a result, the tension applied to the cog belt 15 also changes, the extension amount of the cog belt 15 also changes, and the position after stopping shifts. There is a fear that accurate movement detection to the initial position cannot be performed. Therefore, in the present embodiment, by performing the movement operation to the initial position by the above-described method, the movement condition for the home sensor 31 in all cases to move to the initial position from a position of equal size or other than this. Is made constant.

By doing this, for example, by operating at a low speed or increasing the overrun amount, the double action as described above, that is, once the initial position is reached, the double action is performed to move the initial position again. It is also possible not to carry out the operation of moving to the position. However, in this case, there is a drawback that the operation time becomes long, but in the present embodiment, it is possible to perform a reliable initial operation without causing such a drawback. The position can be detected. Further, even when a metal wire or the like is used, it is effective when applied when there is a risk that the wire will be stretched.

Then, such movement control is executed based on the flowchart shown in FIG.

That is, although this control is not shown, the drive motor 19
Is done to the driver of the home sensor
The output of 31 is "HIGH", the so-called first mirror support unit 11
Is output at the same size position or at the enlarged position, the output of the home sensor 31 is reversed,
The drive motor 19 is rotated in reverse until the so-called output becomes (LOW), and the first mirror support unit 11 is lowered. Also,
When the output of the home sensor 31 is (LOW), that is, when the so-called first mirror support unit 11 is in the contracted position, the home sensor 31
The drive motor 19 is rotated forward until the output of 31 becomes (HIGH) to raise the first mirror support unit 11, and when the output of the home sensor 31 becomes (HAIGH), for an arbitrary time, that is, within the driver. For a time (about 10 to 50 ms) corresponding to the access time for processing, and then the home sensor 31
Rotate in reverse until the output of turns to (LOW). In this way, when moving from each position, the drive motor 19 is reversely rotated and stopped within an arbitrary time after the output of the home sensor 31 becomes (LOW). The overrun amount at this time is 0.5 to 5 mm, and is 2 mm in this embodiment.
In order to suppress an operation error due to mechanical vibration, the drive motor 19 is normally rotated and stopped until the output of the home sensor 31 becomes (HIGH) after the stop for an arbitrary time described above.

Since the present embodiment has the structure as described above, the first mirror support unit 11 moves between the lens holding members 12 according to the set magnification, and the lens holding member 12 moves in conjunction with this movement.

Then, for example, when the lens 4D has moved to the above-described predetermined position, the uneven portion 121 formed on the inner wall surface of the lens holding portion 11B causes the light to be reflected within the uneven surface even if the light leaks. By repeating the above, the backward movement is blocked.

As described above, according to the present invention, in the exposure apparatus that projects the original image on the photoconductor through the plurality of reflecting mirrors and the lens positioned between these reflecting mirrors, the reflection is performed in accordance with the variable magnification. After the mirror and the lens have moved to a predetermined position, the disturbance light near the lens does not travel to the back of the lens, in other words, to the photoconductor side, by preventing the disturbance light from being reflected in the concave and convex portion. It is possible to prevent the flare phenomenon from occurring on the body.

[Brief description of drawings]

FIG. 1 is a perspective view showing an essential part of an exposure apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view showing a drive mechanism of the essential part shown in FIG. 1, and FIG. 3 is a reference numeral III in FIG. Arrow view in the direction indicated by,
4 is a cross-sectional view taken along the line IV-IV in FIG. 3, and FIG. 5 (A) is a perspective view showing details of a portion indicated by reference V in FIG. 2; B) is a symbol B in FIG. 5 (A)
-B is a sectional view taken along the arrow direction, FIG. 6 is a diagram for explaining the operation of the drive mechanism shown in FIG. 2, and FIG. 7 is a view for explaining the operation of the drive mechanism shown in FIG. FIG. 8 is a flow chart, FIG. 8 is a model diagram for explaining an example of an image forming apparatus using a variable-magnification exposure apparatus, and FIG. 9 is a line diagram for explaining a moving state of optical members in the exposure apparatus during variable magnification. Is. 1 ... Copier, 2 ... Photoconductor, 4 ... Exposure device, 4C ...
1st mirror, 4D ... Lens, 11 ... 1st mirror support unit, 11A ... 1st mirror holding part, 11B ... Lens holding part, 11B1, 11B2 ... Guide shaft, 12 ... Lens holding member,
12B …… Cam follower, 13 …… Fixed part, 13A …… Cam groove,
15 …… Cog belt, 16, 17 …… Belt pulley, 18 ……
Worm wheel, drive motor, 20 ... Worm gear,
31 …… Home sensor, 110 …… Boss portion, 110A …… Locking teeth, 120 …… Light shielding plate, 121 …… Uneven portion.

Claims (1)

(57) [Scope of utility model registration request] 1. An optical member for projecting light reflected from a document surface onto a photoconductor through a plurality of reflecting mirrors and lenses positioned between the reflecting mirrors, and the positions of these optical members during zooming. In the variable power exposure apparatus capable of displacing the first reflecting mirror and the first reflecting mirror of the plurality of reflecting mirrors, the first reflecting mirror reflects the reflected light from the document surface first. A first reflecting mirror holding member that movably supports the lens in a state parallel to the axial direction, and a lens located behind the first reflecting mirror holding member according to a ratio obtained from the moving amount of the first reflecting mirror holding member. A lens holding member for moving the first reflecting mirror holding member in the moving direction of the first reflecting mirror holding member, and a first reflecting mirror support unit configured by a housing in which both the first reflecting mirror and the lens are arranged, The above in one reflector unit On the surface where the lens is arranged, a surface substantially perpendicular to the incident direction of the reflected light and an opposite surface continuous to this surface are inclined surfaces, and the perpendicular surface reflects the reflected light toward the inclined surface. A variable-magnification exposure apparatus in an image forming apparatus, wherein saw-toothed concavo-convex portions are formed to form optical paths that reflect reflected light toward a surface having an inclined surface at a right angle.