JPH0240668A - Exposing device in image forming device - Google Patents

Abstract

PURPOSE:To eliminate the need to adjust the moving of a scale plate on an original platen by fitting an image-forming lens which exposes and scans on the surface of an original in the direction of optical axis and orthogonal to the optical axis with the aid of adjusting members which are parallelly movable independently. CONSTITUTION:An optical axis adjusting plate 32, which is a first adjusting member which places a lens frame 31, is provided with oblong holes 32A and 32B orthogonal and parallel to the optical axis XX. A pair of oblong holes 32A is provided over the lens frame 31, which is integrally fixed by a set screw S1 with the aid of fitting arm 31A with respect to the optical axis adjusting plate 32. By turning an eccentric shaft member 33C in condition where the set screw which fixes the optical axis adjusting plate 32 is loosened, the optical axis adjusting plate 32 is parallelly moved in orthogonal direction of the optical axis XX by the use of that eccentric shaft part. After each optical axis is associated with on the surface of image-forming, the set screw 32 is driven and the optical axis adjusting plate 32 is fixed. By moving and adjusting a focusing adjusting plate 34 and the optical axis adjusting plate 32, the image-forming lens can correctly form the image of an original at unmagnification in condition where the optical axis in horizontal direction on a photosensitive body is associated with.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a method for adjusting an optical system in an exposure device of an image forming apparatus.

[Background of the invention]

The image on the original surface needs to be copied onto the transfer material with the same vertical and horizontal positions, but due to accumulation of assembly errors of the various parts that make up the path from the document table to the photoreceptor, the photoreceptor It is unavoidable that the image above will be projected slightly off-center vertically and horizontally.

Vertical misalignment can be corrected by adjusting the feeding timing of the transfer material, but for horizontal misalignment, there is no suitable means and we have no choice but to move the scale plate, which serves as a reference for the document position on the document table. Then, a method is adopted in which the original document itself is placed with a shift in the horizontal direction.

[Problem that the invention seeks to solve]

However, the range of movement of the scale plate is structurally limited and is not aesthetically preferable. Furthermore, when an accessory device such as an automatic document feeder (ADF) is installed, it is necessary to horizontally align the document. However, it was not possible to say that this was an appropriate method because it required positional adjustment for each individual.

An object of the present invention is to solve this problem and provide an exposure device for an image forming apparatus that can adjust the horizontal centering of a projected image without any restrictions while the scale plate is fixed at a specified position. That is.

[Failure to solve the problem]

The above purpose is to independently scan the imaging lens in two directions, an optical axis and a direction perpendicular to the optical axis. This is achieved by an exposure device of an image forming apparatus, which is attached to the image forming apparatus via an adjustment member that is movable in parallel.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1-3.

FIG. 3 shows the configuration of an image forming apparatus equipped with an exposure device of the present invention, in which 10 is a first mirror unit with a built-in illumination lamp, and 20 is a second mirror unit with two mirrors arranged in a 7-shape.
A mirror unit, 30 is a lens unit, 50 is a third mirror unit that reflects the optical image from the lens unit 30, and the second mirror unit 20 moves in the same direction as the first mirror unit IO at a speed of 1/2. By moving, the screen of the document placed on the document table is exposed and scanned, and its optical image is projected onto the circumferential surface of the photosensitive drum 60 via the lens unit 30 and the third mirror unit 50.

As is well known, the circumferential surface of the photosensitive drum 60 is charged in advance and rotated in synchronization with the exposure scan described above.
An electrostatic latent image corresponding to the image on the document sheet is formed on the circumferential surface thereof, and the image device 70 converts the electrostatic latent image into a toner image and transfers it to the transfer paper fed by the paper feeding device 80 . The transfer paper to which the toner image has been transferred passes through the fixing device 90, completes the copy, and is discharged.

FIG. 2 shows a cross-sectional structure of the exposure apparatus, and FIG. 1 shows a planar structure of the lens unit 30.

31 is a lens frame housing the imaging lens L; 31A is a pair of mounting arms protruding from the bottom of the lens frame 31; 32 is an optical axis adjustment plate that is a first adjustment member on which the lens frame 31 is placed;
32A and 32B are elongated holes provided in the optical axis adjustment plate 32 in a direction perpendicular and parallel to the optical axis xx, respectively;
A pair of elongated holes 32A are provided at positions sandwiching the lens frame 31.

The lens frame 31 is integrally fixed to the optical axis adjusting plate 32 via the mounting arm 31A with a set screw Sl.

33 is a dustproof housing that integrally accommodates the lens frame 31 and the optical axis adjustment plate 32, 33A and 33B are openings provided in the front and rear walls of the housing 33, and 33C is a rotatable bottom surface thereof. The eccentric shaft part is fitted into the elongated hole 32B of the optical axis adjusting plate 32.

Reference numeral 34 denotes a focus adjustment plate which is a second adjustment member for fixing the housing 33 together; 34A and 34B are elongated holes provided in the focus adjustment plate 34 in parallel and perpendicular directions to the optical axis xx, respectively; A pair of holes 34A are provided at positions sandwiching the elongated hole 34B.

35 is a substrate of the lens unit 30 on which the focus adjustment plate 34 is placed; 35A is an eccentric shaft member rotatably attached to the substrate 35; the eccentric shaft portion thereof is fitted into the elongated portion 34B of the focus adjustment plate 34; are doing.

Further, 36 is a pair of rollers that are pivoted on the lower surface of the substrate 35, and 37 is a total of three rollers that are pivoted on the vertical surfaces of the substrate 35 through bending fittings 37A and 37B, and the rollers 36 are Guide rail 36 provided on the floor of the exposure device
One roller 37 is driven in A and guided in the optical axis xX direction.
are transferred in direct contact with the floor surface and support the substrate 35 in parallel when the substrate 35 moves in the direction of the optical axis xx force.

Reference numeral 38 designates a rack plate having teeth fixed to one side edge of the substrate 35 so as to be parallel to the optical axis XX, and reference numeral 39 represents a cam surface formed on the side line portion on the opposite side.

On the other hand, 40 is a drive gear rotated by the power of the image forming apparatus, and 41 is a large gear 41A that meshes with the drive gear 40.
42 is a stepped gear that meshes with the stepped gear 42, and small teeth *42A of the stepped gear 42 are connected to the rack plate 38.
interlocks with the tooth row.

Further, 43 is a crank member rotatably attached to the floor of the exposure apparatus by a shaft member 43A, 44 is a torsion spring that urges the crank member clockwise, and 45 and 46 are arms of the crank member 43. The rollers are each provided with a flange portion pivotally attached to the roller portion.

The roller 45 contacts the cam surface 39 of the substrate 35 and follows the curved surface thereof, and the roller 46 is positioned opposite to the end of a horizontal rod 47 that interlocks with the third mirror unit 50.

Focus adjustment by the imaging lens L and alignment of the optical axis in the lateral direction of the image are performed as follows.

First, the copying magnification is set to equal magnification, and the control system rotates the drive gear 40 to mechanically set the substrate 35 at a position corresponding to equal magnification.

Next, with the set screw S3 fixing the focus adjustment plate 34 loosened, the eccentric shaft member 35A is rotated, and the eccentric shaft portion moves the focus adjustment plate 34 in parallel to the optical axis xX direction, so that the imaging lens L is rotated. Obtain the imaging state.

If equal magnification is not achieved in the imaging state, the second mirror unit 20 is moved in the scanning direction to correct the optical path length, and the imaging adjustment is repeated again.

After completing the image formation and magnification adjustment, the set screw S3 is tightened to fix the focus adjustment plate 34.

Furthermore, with the set screw S2 that fixes the optical axis adjustment plate 32 loosened, the eccentric shaft member 33G is rotated, and the optical axis adjustment plate 32 is moved in parallel in the direction perpendicular to the optical axis XX by the eccentric shaft portion, and the optical axis adjustment plate 32 is connected. Female rear set screw S2 to match the optical axis on the image plane
to fix the optical axis adjustment plate 32.

By adjusting the movement of the focus adjustment plate 34 and the optical axis adjustment plate 32 as described above, the imaging lens L accurately focuses the image of the document onto the photoreceptor at the same magnification with the horizontal optical axis aligned. It can be visualized.

Both the focus adjustment and optical axis adjustment described above are performed while visually checking using a focus adjustment jig with a built-in light source that is attached to the accommodation position of the photoreceptor drum 60 and a focus glass jig that is attached to the image position of the document tray. .

When the copy magnification mode is selected, the drive gear 40 is rotated clockwise or counterclockwise according to the enlargement/reduction by the action of the control system, and the drive gear 40 is rotated clockwise or counterclockwise through the stepped gears 41 and 42 to generate the rack 38 or The substrate 35 is moved forward or backward in the direction of the optical axis XX. At the same time, the crank member 43 that follows the cam surface 39 rotates, and the punch 47
The third mirror unit 50, which is interlocked by pressing the
The optical mutual relationship between the image plane of the original document and the circumferential surface of the photosensitive drum 60 related to the imaging lens, which has been moved backward in the X direction and moved to the variable magnification position, is maintained.

〔Effect of the invention〕

According to the present invention, it is possible to eliminate the optical axis misalignment of the original image projected onto the photoreceptor by adjusting the optical axis of the imaging lens, which can be performed simultaneously when adjusting the focus of the rimming lens. To provide an exposure device for an image forming apparatus that has compatibility, such as eliminating the need to adjust the movement of a scale plate and omitting steps such as centering when adding an accessory device such as an ADF. It became.

[Brief explanation of the drawing]

FIG. 1 is a plan view of essential parts of an exposure apparatus of the present invention, FIG. 2 is a sectional view of the apparatus, and FIG. 3 is a schematic view of an image forming apparatus including the apparatus.

Claims (1)

[Claims] In an exposure device that scans a document surface for exposure and projects an image of the document surface onto a photoreceptor using an imaging lens, the imaging lens is independently translated in parallel in two directions, an optical axis and a direction perpendicular to the optical axis. 1. An exposure device for an image forming apparatus, characterized in that the exposure device is attached via an adjustable member.