JPH0651410A - Exposing device for image forming device - Google Patents

Abstract

PURPOSE:To effectively irradiate an original reading area without causing large difference on condensing distribution characteristics at a condensing position by constituting a reflector of many flat surfaces. CONSTITUTION:An original on an original platen 2 is illuminated by an exposing device constituted of a lamp unit 21 and the reflectors 22 and 23. In this case, a substrate 25 to which a lamp 25 is electrically connected is held by holding grooves 26 and 27 provided on upper and lower reflectors 22 and 23. The reflecting surface of the lower reflector 23 is divided into three, inclined surfaces thetaare made different so that the reflecting angles of light beams from the lamp 24 are made respectively different as to respective reflecting flat surfaces 23a-23c. Especially, the reflecting flat surface 23a which is nearest to the lamp 24 is set to a tilt angle theta1, the reflecting flat surface 23b is set to the tilt angle theta2 and the reflecting flat surface 23c which is farthest to the lamp 24 is set to the tilt angle theta3, and relation among the respective tilt angles is theta1<theta2<theta3.

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 provided with a reflection plate which reflects light from a lamp unit.

[0002]

2. Description of the Related Art An exposure device is provided for irradiating a document surface with light for reading an image of a document placed on a transparent glass plate and for reading reflected light from the document.

For example, the exposure apparatus may be an electrophotographic copying machine or the like, as shown in FIG.
As shown in FIG. 2, a lamp 24 for irradiating a document 4 placed on a document table 2 made of a transparent glass plate and a reflector 2
It consists of 2, 23.

The reflected light of the original document exposed by the exposure device is projected onto the photosensitive drum 3 through 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, those shown in FIGS. 6 and 7 have been implemented.

In the lamp unit shown in FIG. 6, a plurality of lamps 24 are supported on a substrate 25 in the longitudinal direction in order to irradiate a predetermined width of an original and are electrically connected.

The lamp unit as described above is fixed and held so that each lamp is positioned at the first focal point of the reflecting plate having the elliptical reflecting surface, so that the light from the lamp is placed on the original placing table. Illuminate the original directly and through the reflector.

FIG. 7 shows a reflector having a conventional structure. In general, the reflection plate 40 has an elliptical reflection surface, and 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 document reading portion is located at the position of the second focal point 43, 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 exposure apparatus, in a lamp unit composed of a plurality of lamps, the positions of the bright spots are located above and below and above and below that of a single lamp composed of one lamp. The degree of variation is large. This is because the positions of the respective lamps are positioned separately with respect to the reflector. In the case of the conventional elliptical reflector, when the bright spot deviates from the first focal point, it becomes a random ray locus, which has a great influence on the light condensing property of the document on the document table on the reading section.

As an effect of the above, when the light of the lamp unit is reflected by the reflecting plate and the surface of the original is illuminated, the illuminance above a predetermined level cannot be obtained and the amount of light reflected from the original guided to the rod lens array is insufficient. To do.

In order to solve the above problems, the present invention provides
An object of the present invention is to provide an exposure apparatus in which a plurality of lamps are provided, and a predetermined illuminance of a reading area of a document can be obtained similarly to a single lamp.

[0012]

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 the reflecting angles of the reflectors are made different by reflecting planes. It is characterized by being configured.

Further, the reflecting plate of the present invention is characterized in that the width of the reflecting surface becomes wider and the inclination angle becomes smaller as each reflecting plane becomes closer to the lamp.

[0014]

According to the exposure apparatus constructed as described above, since the reflecting plate is composed of a large number of reflecting planes, the light reflected by each reflecting plane is reflected so as to concentrate on the reading area of the original. It The reflection plane near the lamp reflects light to the reading area of the original and illuminates a wide range. Further, as the distance from the lamp increases, the irradiation area by the reflection plane is gradually irradiated so as to coincide with the central portion of the reading area. Therefore, a uniform illuminance distribution can be obtained around the document reading area. Further, even if the positions of a large number of lamps are deviated, it does not affect the illuminance distribution as a whole so much that it has the same function as a single lamp.

[0015]

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 shows the reflection state of the reflection plate of the present invention in FIG. 1, FIG. 3 is a graph showing illuminance, and FIG. 4 is a lamp position shift. The cross-sectional view which shows the irradiation ray locus in the case is shown.

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 document placing table 2, the surface of the document placing table 2 obliquely above the exposing device is used as the document irradiation surface, and the photoconductor 3 is arranged directly below this document 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
The image is transferred by the transfer device 10 to the sheet supplied from the sheet through the registration roller 9. 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.

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

The lower reflecting plate has a hole 28 for removing static electricity, an opening 30 for accommodating the rod lens array 29, and a guide plate 31 for preventing the static electricity from wrapping around the static electricity removing hole 28. Is provided.

The reflection surface of the lower reflection plate 23 is divided into three, and the reflection planes 23a, 23b, 23 are respectively formed.
In c, the inclined surface θ is different so that the reflection angle of the light from the lamp 24 is different. Particularly, the reflection plane 23a closest to the lamp 24 has an inclination angle θ1 and the reflection plane 23b
Is the inclination angle θ2, and the reflection plane 23c farthest from the lamp 24
Is set to an inclination angle θ3, and each inclination angle is θ1 <θ2 <θ3
Have a relationship. The inclination angles θ1, θ2, θ3 of the reflection planes 23a, 23b, 23c are determined by the rod lens array 29.
Is set so that the projection area reading width D of the document that can be projected on the photoconductor 3 can be effectively irradiated.

Further, each of the reflection planes 23a, 23b, 23c
Is formed so that the width of its reflection surface becomes gradually smaller.

In the above structure, FIGS. 2A to 2C are used.
Each of the three reflecting planes 23a, 23b, 23
The light reflection state by c is shown. FIG. 2A shows the irradiation state of the reflected light by the reflection plane 23a on the original surface. The light reflected by the reflection plane 23a is the rod of the document.
Irradiation is performed with the projection width D by the lens array 29 as the central portion, and the width of the irradiation area is a.

FIG. 2B shows the irradiation state of the light reflected by the reflection plane 23b on the original surface. The light reflected by the reflection plane 23b irradiates the projection width D of the document as a center, and also illuminates the width b of the area within the irradiation area a of the reflection surface 23a and narrower than that.

FIG. 2C shows the irradiation state of the light reflected by the reflection plane 23c on the original surface. The reflection plane 23c irradiates the irradiation area width D of the original document as a center as in the case of the reflection planes 23a and 23b, and also irradiates the irradiation area width b of the reflection plane 23b with a width c which is narrower than the irradiation area width b.

Therefore, FIG. 3 shows the light quantity characteristic of the exposure apparatus according to the present invention when the original surface is illuminated. As shown in FIG. 2, the drawing shows the illuminance distribution for the exposure part (projection part) when the light from the lamp 24 is applied to the document surface by the reflector 23 or the like. The projection width D of the rod lens array 29 is, for example, 4.66 mm, and the illuminance at the center is the highest. Therefore, the rod lens array 2
In FIG. 9, a predetermined amount of light is obtained within the projection width D.

In FIG. 3, the amount of light is shown as mV by photoelectrically converting it when measuring the exposed surface of the original.

FIG. 4 shows the loci of irradiation rays when the positions of the lamps are displaced with respect to a plurality of lamps. Reference numeral 50 is a normal lamp position and 51 is a deviated lamp position. In the case of the exposure apparatus composed of a large number of reflection planes 23a, 23b, 23c, the position error of the lamp bright spot does not cause a large difference in the irradiation area. It is the extent to which the right and left are slightly shifted in the irradiation region. However, although not shown in the case of the conventional elliptical reflecting surface, the position of the lamp deviates from the first focal point to form a random ray locus, and therefore the position of the lamp deviates to form a random ray locus. Irradiation on the surface is not constant, and the irradiation area is not only shifted to the left and right. Therefore, the illuminance distribution as shown in FIG. 3 cannot be obtained. The exposure apparatus of the present invention can always obtain a stable illuminance distribution as shown in FIG.

[0032]

As described above, according to the present invention, even if a large number of lamps are provided, the reflecting plate is composed of a large number of planes, so that a large difference does not occur in the condensing distribution characteristic at the condensing position. Thus, the original reading area can be effectively illuminated.

[Brief description of drawings]

FIG. 1 is a sectional view showing an exposure apparatus according to the present invention.

2A and 2B are views for explaining the reflection state of the reflection surface of the present invention in FIG. 1, and FIGS. 2A to 2C are operation explanatory diagrams showing a document irradiation area by a reflection plane.

FIG. 3 is a graph showing an illuminance distribution of the exposure apparatus according to the present invention.

FIG. 4 is a sectional view showing a locus of irradiation light rays when the lamp position is displaced in the exposure apparatus of 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 perspective view of a lamp unit used in the exposure apparatus of the present invention.

FIG. 7 is a sectional view of an exposure apparatus having a conventional structure.

[Explanation of symbols]

 21 Lamp Unit 22 Upper Reflector 23 Lower Reflector 23a Reflective Plane 23b Reflective Plane 23c Reflective Plane 24 Lamp 25 Substrate

Claims (2)

[Claims] 1. A lamp unit provided with a plurality of lamps for illuminating 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. An exposure apparatus provided with an image forming apparatus comprising a plurality of reflecting planes having different reflection angles of a reflecting surface of a reflecting plate that reflects light from the lamp unit to a predetermined position. apparatus. 2. The exposure apparatus for an image forming apparatus according to claim 1, wherein the number of the reflection planes is such that the width of the reflection plane is wider and the inclination angle of the reflection plane is smaller as it is closer to the lamp.