JPH0682932A - Exposing device for image forming device - Google Patents

Abstract

(57) [Summary] [Object] To provide an exposure apparatus capable of solving a shortage of light quantity at both ends of a document and obtaining a uniform light quantity distribution. A lamp unit 21 having a plurality of lamps 24 supported on a substrate 25 and electrically connected in series, and light from each lamp 24 is reflected to guide the light to an illuminated portion of a document on a document table. It is composed of upper and lower reflection plates 22 and 23 having a divided structure, and holding grooves 26 and 27 formed in the reflection plates 22 and 23 for holding a lamp unit. Both ends of the lamp project more than the other lamps. The upper and lower reflectors 2
The second and second reflecting surfaces are configured to correspond to the lamp position.
The focus is in agreement. Therefore, a uniform light amount distribution can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure device of an image forming apparatus, and more particularly to an exposure device which efficiently irradiates a document irradiation surface.

[0002]

2. Description of the Related Art An electrophotographic copying machine or the like has an exposure device which irradiates a document surface with light in order to read an image of a document placed on a transparent glass plate and projects reflected light from the document onto a photoconductor. It is provided.

For example, as shown in FIG. 5, this exposure apparatus comprises a lamp 24 for irradiating an original 4 placed on an original placing table 2 made of a transparent glass plate and reflecting plates 22, 23. The reflected light of the original document exposed by the exposure device is projected onto the photosensitive drum 3 via the rod lens array 29. As a result, an electrostatic latent image is formed on the uniformly charged surface of the photoconductor 3.

As a conventional exposure apparatus, the one shown in FIGS. 7 to 9 has been implemented.

In the lamp unit shown in FIG. 7, a plurality of lamps 24 are supported and connected in the longitudinal direction on a substrate 25 in order to illuminate a predetermined width of a document.

The lamp unit as described above is fixed and held so that the respective lamps are positioned at the first focal point of the reflecting plate, so that the light from the lamp illuminates the original document on the original table via the reflecting plate. To do.

In the lamp unit shown in FIG. 8, the lamps 24a at both ends are fixed and held in a state of being brought close to the document surface.

FIG. 9 shows a reflector having a conventional structure. Generally, the reflector 40 is formed in an elliptical shape, and is a system in which the lamp unit 42 is arranged at the first focal point 41 and the reflected light is condensed at the second focal point 43. The second focus 4
The document is placed at the position of 3, and the reflected light from the document is projected onto the photoconductor 3 via the rod lens array 29 which is the optical means of FIG.

[0009]

As described above, in the conventional lamp unit composed of a plurality of lamps, the positions of the bright spots may fluctuate in the vertical and vertical directions as compared with a single lamp composed of one lamp. large. This is because the positions of the respective lamps are positioned separately with respect to the reflector. Also,
When the lamp is brought closer to the original surface in order to increase the brightness, the ripple becomes large and it becomes impossible to obtain a uniform light quantity distribution. On the other hand, when the lamp is moved away to solve the ripple, there is no overlapping of light at both ends, and the light amount is greatly reduced.

In order to solve the above problems, the present invention provides
By providing the reflecting surface of the reflecting plate corresponding to the lamp position,
An exposure apparatus having a function similar to that of a single lamp is provided.

[0011]

In order to achieve the above object, the exposure apparatus of the present invention is composed of a large number of lamps and reflectors, and in a lamp unit composed of a large number of lamps, both ends are It is characterized in that the lamp is brought close to the document surface and a reflecting surface having a second focal point corresponding to the position of the lamp is provided.

[0012]

According to the exposure apparatus constructed as described above, since the reflecting plate corresponding to the lamp position is constructed, the light from the lamp unit whose both ends are brought close to the original surface is an ellipse of each reflecting surface. The second focal position, which has a different shape but is a condensing position, is reflected by a reflecting plate having the same position. A uniform amount of light is obtained by this reflection.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing an exposure apparatus of the present invention, FIG. 2 is a sectional view showing an exposure apparatus of another embodiment, and FIG. 3 is a sectional view showing a reflection optical path of a sub-ref surface in the exposure apparatus of FIG.
FIG. 4 is a perspective view showing only the shape points so that the appearance of the exposure apparatus according to the present invention can be easily understood.

FIG. 5 shows an image forming apparatus such as a copying machine in which the exposure apparatus of the present invention is used. In the image forming apparatus, a movable document placing table 2 is arranged on an upper surface of an image forming apparatus main body 1.

The above-mentioned exposure device is arranged below the above-mentioned document placing table 2, the surface of the document placing table 2 obliquely above the exposing device is the original irradiation surface, and the photoconductor 3 is arranged directly below this original irradiation surface 2. ing.

The original 4 on the original table 2 is exposed by an exposure device 13 including a lamp unit 21 and reflectors 22 and 23.
Illuminated by. Light reflected from the original 4 is
The photoconductor 3 is exposed through the lens array 29. The surface of the photoconductor 3 is uniformly charged by the charger 7, and the reflected light from the document is exposed through the rod lens array 29 to form an electrostatic latent image on the surface. To be done. This electrostatic latent image is transferred to the developing device 14
The toner is attached after being developed with the developer supplied in.

The toner image on the photoconductor 3 is stored in the manual paper feed unit 8
Transferring device 1 to the sheet supplied from registration roller 9 from registration roller 9
It is transcribed with 0. The sheet on which the toner image has been transferred is separated from the photoconductor 3 and conveyed to the fixing device 11 via a guide unit (not shown), and after fixing, discharged to the outside of the copying machine.

The exposure apparatus of the present invention in the image forming apparatus having the above structure will be described in detail.

As shown in FIG. 1, in the exposure apparatus of the present invention, 22 is an upper reflector, 23 is a lower reflector, and a substrate 25, in which lamps 24 and 24a are electrically connected in series, is attached to the upper and lower reflectors 22, Holding grooves 26, 27 provided in 23
Holding by.

A reflector plate 22-2 corresponding to the lamp 24 is provided.
The reflectors 23-2 and 22-1 and 23-1, which correspond to the lamps 24a at both ends, are 22-1 and 23-1, respectively. Lamps 24 and 24
a is located at the first focal point of each of the reflection plates 22-2, 23-2 and 22-1, 23-1, and the second focal point 5 which is the condensing point.
Is the plurality of reflectors 22-2, 23-2 and 22-1,
All of 23-1 also have a reflecting surface shape that is in the same position.
The second focus 5 rod lens array 29 is positioned on the document table, and the reflected light from the document surface is projected onto the photoconductor by the rod lens array 29 with minimal scattering.

The elliptical reflector shown in FIG. 2 also has the same function as in FIG.

1 and 2 show the optical path of the main reflected light, but FIG. 3 shows the reflected optical path from the sub-ref surface. For example, 15 is a sub-ref surface corresponding to the central lamp, 1
6 is a sub-ref surface corresponding to both ends.

In the above structure, in order to solve the ripple and obtain a uniform light amount distribution, the lamp 24a is brought close to the original surface at both ends as shown in FIGS. 1, 2, 3 and 8. It has been already known that the amount of light is increased by the means. However, by providing the reflection plates 22-2, 23-2 and 22-1, 23-1, which correspond to the lamp positions, the shortage of the light quantity at the end portions is eliminated and a uniform light quantity distribution can be obtained.

Reflecting plates 22-2 corresponding to the central lamp 24
The light reflected by 23-2 is focused on the second focal point 5, 5. Similarly, the reflectors 22-1, 23-1, which correspond to the lamps 24a at both ends, are also focused on the second focal point 5.

Although the reflectors 22-2, 23-2 and 21-1, 231-1 have different shapes, they are constructed so that the second focal points are all at the same position.

The second focal point position 5 is located directly above the rod lens array 29, and the reflected light from the second focal point 5 is transmitted to the photoconductor 3 via the rod lens array 29. Projected.

FIG. 4 is an external perspective view of the reflector of the present invention, which is easy to understand and is shown only by the shape points. Therefore, the shape is not limited to that shown in the figure.

[0029]

As described above, according to the present invention, the ripples are eliminated by bringing the lamps at both ends close to the original surface and providing the reflectors corresponding to the lamp positions at the center and both ends.
A uniform light quantity distribution can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an exposure apparatus of an embodiment of the present invention.

FIG. 2 is a sectional view showing an exposure apparatus according to another embodiment of the present invention.

FIG. 3 is a sectional view showing a reflected light path on a sub-ref surface in the exposure apparatus of FIG.

FIG. 4 is an external perspective view of an exposure apparatus according to the present invention.

FIG. 5 is a sectional view of an image forming apparatus using the exposure apparatus of the present invention.

FIG. 6 is a view showing a light distribution distribution with respect to a longitudinal direction of the exposure apparatus.

FIG. 7 is a diagram showing a shortage of light amount at an end of a conventional lamp unit.

FIG. 8 is an explanatory diagram of a lamp unit used in the exposure apparatus of the present invention.

FIG. 9 is an explanatory diagram of a conventional exposure apparatus.

[Explanation of symbols]

 22 Upper Reflector 23 Lower Reflector 24, 24a Lamp

Claims (1)

[Claims] 1. A lamp unit provided with a plurality of lamps arranged in parallel to illuminate a predetermined width of an original to be placed, and a reflector for reflecting light from the lamp unit and guiding the light to a specific position of the original. In this exposure apparatus, the lamps at both ends of the lamp unit are provided closer to the original than the other lamps, and the second focal point of the reflecting plate corresponding to the lamps at both ends is set to the first focal point of the reflecting plate corresponding to the other lamps. An exposure apparatus for an image forming apparatus, which is configured to match two focal points.