JPH0452928B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable magnification exposure device for a copying machine such as an electrophotographic copying machine.

[Conventional technology]

Generally, in the case of a slit exposure type copying machine, since the amount of light at the periphery is reduced, the number of turns at both ends of the halogen lamp is increased to compensate for the brightness of the periphery compared to the center. This correction is made with the assumption that the image will be copied at the same magnification, so if the position of the lens and mirror is displaced as in the case of variable magnification copying, the angle of incidence on the lens will be different, and depending on the variable magnification ratio, the center of the image may be different. The surrounding area may become too bright compared to the other area, and there is also a risk of uneven density in the image.

In order to solve this problem, conventional methods have been adopted, such as re-compensating for changes in the peripheral illuminance ratio each time the magnification is changed by moving and inserting a fixed-shaped plate into the optical path, or replacing the fixed slit each time the magnification is changed. However, in the case of , it was difficult to achieve precision when moving and inserting a fixed-shaped plate, and in the case of , it was not possible to handle multiple magnifications.

[Purpose and structure of the invention]

The present invention is intended to solve the above-mentioned conventional drawbacks, and provides a slit exposure type copying machine in which the light source is corrected so that the periphery of the slit becomes brighter than the center of the slit. The light shielding member is constituted by two plate-shaped bodies that are pivotally connected at the center in the longitudinal direction of the slit and movable at both ends, and an actuating member that displaces the light shielding member according to the magnification ratio, A copying machine that has a simple configuration that can be moved integrally with the imaging lens, so that it can accurately compensate for changes in the peripheral illuminance ratio when changing magnification, and can also respond to displacement at each stage. The purpose of the present invention is to provide a variable magnification exposure apparatus.

〔Example〕

Next, the present invention will be described based on an embodiment shown in the accompanying drawings.

Reference numeral 1 denotes a unit frame, and the unit frame 1 is reinforced by two parallel shafts 4 and 5 extending between the front and rear side plates 2 and 3 near both ends thereof. A shape slide frame 6 and a shape slide frame 7 are slidably fitted to one of the shafts 4 so that their groove sides are engaged with each other. Further, on the other shaft 5, the other end of the lens base plate 8 whose one end is fixed to the shaped slide frame 6 and the other end of the mirror frame 9 whose one end is fixed to the shaped slide frame 7 are attached to the roller 1.
0,11.

12 is a first mirror attached to a mirror frame 13 fixed to the rear of the unit frame 1; 14 is a second mirror attached to the rear surface of the mirror frame 9 that moves together with the slide frame 7; 15 is the slide frame of the type mentioned above. Pin 1 is attached to the front of the lens base plate 8 that moves together with 6.
This is an in-mirror lens attached to a movable plate 17 provided so as to be movable in the vertical direction using 6 as a fulcrum.
The in-mirror lens 15 is a document table glass (not shown) illuminated by a light source lamp (not shown).
The reflected light from the upper document surface is condensed and reflected through the first mirror 12 and the second mirror 14, and the unit frame 1
An image can be formed on a photoreceptor 21 through a through hole 20 provided in the bottom plate of the unit frame 1 via a third mirror 19 attached to a mirror frame 18 fixed to the front of the unit frame 1.

A slit 22 is arranged to cross the optical path connecting the in-mirror lens 15 and the third mirror 19, and the slit 22 is provided with a light shielding member 23 that defines its opening. This light shielding member 23 is attached to a frame 24 having a slit 22.
Two plate-shaped bodies 2 that are pivotally connected via a pin 25 at the center in the longitudinal direction of 2 and are movable at both ends.
It consists of 6.

A protrusion 27 is provided on each of the displacement sides of the two plate-like bodies 26 in a protruding manner. The protrusion 27 is attached to the frame 2
Lever 2 fixed to a shaft 28 inserted between the side plates of 4
The plate-shaped body 26 engages with a protrusion 30 protruding from the free end of the plate-shaped body 26 by its own weight. Further, a lever 31 is fixed to the outer end of the shaft 28, and the lever 31 rotates its tip roller 32 to the inclined cam surface 33' of the actuating member 33.
It is in sliding contact with the As the operating member 33 slides, the outer lever 31 swings, and the coaxial inner lever 29 moves in conjunction with this. Thus, the protrusion 2 engaged with the protrusion 30 on the free end side of the inner lever 29
The two plate-like bodies 26 having the number 7 rotate around the pin 25 as shown by the two-dot chain line in FIG. That is, the light shielding member 23 consisting of two plate-shaped bodies is displaced by the operation of the actuating member 33 at both ends of the slit 22. This actuating member 33 has its base end fixed to the slide frame 6, so that it slides integrally with the slide frame 6.

34 is a wire stretched between two pulleys 35 and 36, both ends of which are connected to the slide frame 6, and are run in forward and reverse directions by a drive motor (not shown) connected to the pulley 35. The slide frame 6 is slid along the shaft 4.

Reference numeral 37 denotes a spring member interposed to expand between the inner frames 6a and 7a of the slide frame 6 and slide frame 7, and the spring member 37 is a coil-shaped member fitted to the shaft 4. The slide frame 6 is pressed forward (to the right) and the slide frame 7 is pressed backward (to the left). Reference numeral 38 denotes an L-shaped lever rotatably attached to a suitable position on the slide frame 6 via a shaft rod 39, and the horizontal arm 38a of the L-shaped lever 38 is installed on the bottom plate of the unit frame 1 via a roller 40 at its tip. The vertical arm 38b comes into sliding contact with the cam surface of the curved cam 41, and the vertical arm 38b comes into contact with the rear edge of the protrusion 43 protruding from the shaped slide frame 7 through its tip roller 42 against the elastic force of the spring member 37. are in contact with each other. Therefore, when the in-mirror lens 15 shaped slide frame 6 is pulled forward by the wire 34, the tip roller 4 of the vertical arm 38b of the L-shaped lever 38 moves forward.
2 pushes the protrusion 43 forward, so the slide frame 7 in the form of the second mirror 14 moves forward against the spring member 37. In this case, since the horizontal arm 38a of the L-shaped lever 38 is rotated counterclockwise by the curved cam 41 during the movement, the amount of movement of the shaped slide frame 7 is determined by the amount of rotation of the horizontal arm 38a of the L-shaped lever 38. The amount of movement is smaller than the amount of movement. In addition, the shape slide frame 6
When the slide frame 7 slides backward from the reference point, the slide frame 7 moves backward due to the elastic force of the spring member 37, but the L-shaped lever 38 is moved backward by the curved cam 41 during the backward movement process. It decreases by the amount of rotation clockwise. This is to effectively create a difference in the amount of movement required between the in-mirror lens 15 and the second mirror 14 during zooming, since the amount of movement required is different.

Next, the operation of the above embodiment will be explained.

An in-mirror lens 15 and a slide frame are attached via a movable plate 17 to a lens base plate 8 that moves integrally with a slide frame 6 that slides along shafts 4 and 5 provided between the front and rear side plates of the unit frame 1. The initial position of the second mirror 14 attached to the mirror frame 9 which is movable together with the mirror 7 is set to the same-size copying position, and when changing the magnification, it moves forward or backward depending on the initial position. When the copy start button is pressed with the in-mirror lens 15 and the second mirror 14 in the initial position described above, the glass on the document table moves together with the document, and the light emitted from the light source lamp is reflected off the document surface. The light passes through the first mirror 12, the second mirror 14, the in-mirror lens 15, and the third mirror 1.
9 and forms an image on the photoreceptor 21. This photoreceptor 2
The amount of peripheral light of 1 is corrected by a cosine fourth power ratio by a light shielding member 23 that defines the opening of a slit 22 in the optical path connecting the in-mirror lens 15 and the third mirror 19. That is, the tip roller 31 of the outer lever 30, which is coaxial with the inner lever 29 with which the protrusions 27 of the two plate-shaped bodies 26 constituting the light shielding member 23 engage, is an actuating member 33 whose base end is fixed to the shaped slide frame 6.
At approximately the midpoint of the inclined cam surface 33', the outer portions of the two plate-shaped bodies 26 are made to protrude from both sides of the slit opening.

Next, when performing variable magnification copying, the setting button is pressed to specify the magnification, and the drive motor is driven to move the in-mirror lens 15 together with the shaped slide frame 6 in a predetermined direction according to the variable magnification. This movement of the shaped slide frame 6 causes the shaped slide frame 7 to move in conjunction with the second mirror 14 by the required amount. When the copy start button is pressed in this state, the document table glass moves together with the document, and the reflected light emitted from the light source lamp and reflected from the document surface is transferred to the first mirror 1 as described above.
2. The image is formed as a magnified image on the photoreceptor 21 through the second mirror 14, the in-mirror lens 15, and the third mirror 19. In this case, since the actuating member 33 also slides together with the shaped slide frame 6, the light shielding member 23 that defines the slit opening is displaced at both ends of the slit in accordance with the magnification, thereby correcting the amount of light around the slit.

When the copying magnification is further changed, the same operation as described above is repeated, and the sprocket opening corresponding to the set magnification can be accurately obtained.

〔Effect of the invention〕

As described above, the present invention provides a slit exposure type copying machine in which a light source is corrected so that the periphery of the slit becomes brighter than the center of the slit. The actuating member, which is composed of two plate-shaped bodies pivoted at the center in terms of direction and movable at both ends, moves integrally with the imaging lens, and displaces the light shielding member according to the magnification ratio. Since it is characterized in that it is provided in such a way that it can be adjusted, it is possible to accurately correct a change in the peripheral illuminance ratio when changing the magnification, and it is also possible to cope well with multi-step magnification changing. Moreover, since the structure is simple, it can be manufactured at low cost, and has various excellent effects.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a partially cutaway perspective view of an optical system unit, Fig. 2 is a side sectional view, Fig. 3 is a perspective view of a lens sliding part, and Fig. 4 is a light shielding member. 5 is a perspective view of the operating mechanism thereof, and FIG. 5 is a front view of the light shielding member in an operating state. 1... Unit frame, 4, 5... Shaft, 6...
... shaped slide frame, 7... shaped slide frame, 22
... Slit, 23 ... Light shielding member, 26 ... Plate-shaped body, 33 ... Operation member.

Claims (1)

[Claims] 1. In a slit exposure type copying machine in which the light source is corrected so that the periphery of the slit is brighter than the center of the slit, the light shielding member that defines the lower edge of the slit is placed at the center in the longitudinal direction of the slit. It is composed of two plate-shaped bodies that are pivotally connected and movable at both ends, and an actuating member that displaces the light shielding member according to a magnification ratio is provided so as to be movable integrally with the imaging lens. A variable magnification exposure device for a copying machine, which is characterized by: