JPS63205673A - Illuminating device for electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To permit inexpensive and efficient irradiation of a slit-shaped illumination region with decreased labor for adjustment and without degrading the efficiency of illumination by providing an elliptical cylindrical area constituted of an upper reflecting mirror and lower reflecting mirror to a state of permitting adjustment of the position with respect to a light source. CONSTITUTION:The reflecting mirror is constituted of the upper reflecting mirror 5, the lower reflecting mirror 4 and a 3rd reflecting mirror 10. The upper reflecting mirror 5 and the lower reflecting mirror 4 are integrated and a bar-shaped light source 3 is provided to the focal position of the two reflecting mirrors. The reflected light from the mirror 4 irradiates directly the illumination region and the light from the mirror 5 irradiates the illumination region via the mirror 10. A bracket 15 is provided to the upper part of the mirror 5 so that the bracket 15 can be fixed to a bar-shaped light source holding frame 16 by using an adjusting screw 17. The reflecting mirror is, therefore, movable in an arrow X direction with respect to the bar-shaped light source 3 provided in the fixed position. The screw 17 is loosened and the reflecting mirror is moved at the time of adjusting the luminous flux of the bar-shaped light source. The reflecting mirror can be fixed by tightening the screw in the position where the adequate luminous flux is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an illumination device for an electrophotographic copying machine, and in particular is configured to uniformly illuminate a narrow slit-shaped document illumination area. This invention relates to a lighting device for an electrophotographic copying machine.

(Prior art) In a slit exposure type electrophotographic copying machine, a long rod-shaped light source is used in a direction perpendicular to the scanning direction of the original, and the image surface of the original is illuminated with a narrow width in the scanning direction, and the light is reflected. It is necessary to irradiate light onto a light-receiving surface such as a photoreceptor drum. In this case, it is necessary to efficiently illuminate the slit-shaped illumination area with a uniform integral value of illuminance.

The lighting method for this slit-shaped lighting area is as follows:
2. Description of the Related Art Conventionally, it has been known to provide illumination using a rod-shaped light source in which segment-shaped light emitting sources are arranged in a straight line, and an elliptical cylindrical reflecting mirror provided to surround the rod-shaped light source.

As the above-mentioned slit-shaped illumination device, one shown in FIG. 5 is generally used. In the illumination device shown in FIG. 5, a document 2 is placed on a transparent document tray 1. place In addition, the light from the rod-shaped light source 3 has a substantially elliptical cylindrical upper surface reflection 115 and a lower surface reflection 114.
is provided at the first focal point 6 of the lens.

The light beam 7 from the rod-shaped light source 3 is reflected by the lower reflecting mirror 4 and illuminates the slit-shaped illumination area 8. Further, the light beam 9 from the rod-shaped light source 3 is reflected by the third reflection aio provided on the opposite side of the illumination area with respect to the rod-shaped light source via the upper surface reflection 115, so that the illumination area 8 is irradiated. has been done.

(Problems to be Solved by the Invention) In such devices, in order to efficiently illuminate a relatively narrow illumination area, it is better to use a light source with a small cross-sectional area, but for practical purposes, a linear halogen lamp is preferable. A light source called However, since the above-mentioned halogen lamp mainly outputs infrared rays, its light utilization efficiency is extremely low for photoreceptors that are sensitive in the visible range, which reduces the light source consumption of copying machines. It has the disadvantage of increasing power consumption.

Therefore, when using such a light source, the temperature of the copying machine's original table becomes high, causing discomfort to the operator, and the temperature inside the copying machine itself increases, causing damage to the components, etc. may cause thermal damage to
Furthermore, there have been other disadvantages such as having an adverse effect on the toner image forming process.

On the other hand, in order to reduce the power consumption of the above-mentioned rod-shaped light source, it is necessary to improve the light reflection efficiency of the reflector, and as shown in Figure 7, the illumination is slightly defocused. illumination of the area 8, thereby providing uniform light over the entire width of the slit, as shown in FIG. 6, and illumination area 8, as shown in FIGS. It has been considered to focus the light sharply on the center of the illumination area 8.

However, when configured as described above, there are the following disadvantages.

That is, the segment-shaped light emitting portion of a linear halogen lamp often has eccentricity with respect to the lamp axis due to manufacturing variations. Furthermore, due to the manufacturing technology of each reflecting mirror, it is difficult to obtain an ideal elliptical cross-sectional shape, and there is an internal problem that variations in cross-sectional shape are likely to occur due to quality control during processing and other causes. are doing.

In addition, when these members are assembled, variations in assembly, such as mounting positions, may occur.

Assembling parts that have many problems as mentioned above,
When configured as a light source, a slit-shaped illumination area 8
The illuminance distribution in the scanning direction is shown by curve a in FIG. To give an example of this, if the halogen lamp deviates from the designed position by 0.5 degrees, the integral value of illuminance in the scanning direction changes by about 20 to 30%. Then, the focal position of the light is not fixed at the center and shifts in the lateral direction, making it impossible to irradiate the illumination area 8 with uniform light, and as shown in the curved line, a sharp Naturally, it becomes impossible to obtain a luminous flux.

Further, the graph shown in FIG. 11 is a graph showing the integrated value of illuminance shown in FIG. 10, viewed in a direction perpendicular to the scanning direction. As can be seen from this graph, in the length direction of the rod-shaped light source, uneven illuminance occurs due to variations in the lamp segments, which can cause problems such as uneven image density. This tends to cause roughness of the background on the copy.

Conventionally, in order to prevent the above-mentioned inconvenience from occurring, a method has been proposed in which the rod-shaped light source is accurately mounted at the designed position, as shown in Japanese Utility Model Application Publication No. 56-5134. In this case, the member that holds the lamp is in the position! ! Since it also serves as an adjustment mechanism, it has disadvantages such as a complicated structure and an increase in the manufacturing cost of the parts.

In addition to the above-mentioned conventional example, there is also a
As shown in Japanese Unexamined Patent Publication No. 45, Japanese Utility Model Application No. 59-71342, etc., a method has been proposed in which a light shielding plate is provided between a rod-shaped light source or a reflecting mirror and a document mounting table. However, this method has disadvantages such as increased power consumption of the light source because the luminous flux is blocked.
There are drawbacks such as the need for a lot of work in adjusting the light shielding plate.

(Objective of the Invention) The present invention solves the drawbacks of the conventionally used devices as described above. It is an object of the present invention to provide an illumination device that can illuminate a slit-shaped illumination area.

(Means and Effects for Solving the Problems) The illumination device for an electrophotographic copying machine of the present invention is composed of a rod-shaped light source, and an upper surface reflecting mirror and an F-surface reflecting mirror provided so as to surround the rod-shaped light source. , the upper surface reflecting mirror and the lower surface reflecting mirror constitute a substantially elliptical four-sided mirror, the center of the rod-shaped light source is provided at the common focal point of the two reflecting mirrors, and the light reflected by the upper surface reflecting mirror is transmitted through a third reflecting mirror. This device is configured to irradiate the illumination area and also directly irradiate the illumination area with the reflected light from the lower reflecting mirror.

The illumination device for an electrophotographic copying machine of the present invention includes an elliptical cylindrical mirror composed of an upper reflecting mirror and a lower reflecting mirror.
The position is adjustable with respect to the light source.

Furthermore, the illumination II of the electrophotographic copying machine of the present invention is configured such that the upper surface reflecting mirror or the lower surface reflecting mirror is movable with respect to the holding frame of the rod-shaped light source, so that they can be moved independently.

Therefore, in the illumination device for an electrophotographic copying machine of the present invention, the adjustment work of the upper surface reflector or the lower surface reflector for irradiating the illumination area with light can be easily performed, and there is no need to use a light shielding plate or the like. Therefore, it is possible to obtain a device that can uniformly illuminate a slit-shaped illumination area without reducing illumination efficiency.

(Embodiment) The configuration of the illumination device for an electrophotographic copying machine of the present invention will be described according to the illustrated embodiment.

As shown in FIG. 1, the reflecting mirror of the present invention has a top reflecting mirror 1i5,
It is composed of a lower surface reflection 1i4 and a third reflection 110. Then, the upper surface reflecting mirror 5 and the lower surface reflecting mirror 111114 and i
A rod-shaped light source 3 is provided at the focal point of the definition [t, the reflected light from the F-plane reflection 1[4 directly irradiates the illumination area, and the light from the lower surface 1115 is transmitted through the third anti-gN110. the illumination area.

In the illumination device for an electrophotographic copying machine according to the present invention, the above-mentioned mirror 13114.5 is integrally formed, but one racket 15 is provided above the top reflector 1i5, and the bracket 15 is attached to a rod-shaped light source holding frame. 1111 against 16
It is constructed so that it can be fixed using screws 17.

Therefore, the reflecting mirror in the embodiment of the present invention is movable in the direction of the arrow X with respect to the rod-shaped light I[3 provided at a fixed position, and when adjusting the luminous flux of the rod-shaped light source,
Loosen the awi screw 17, move the reflector, and tighten the screw to fix it at a position where an appropriate luminous flux can be obtained.

Further, in the embodiment of the present invention shown in FIG. 2, a lower mirror 111 is provided so as to be movable in the direction of the arrow Y with respect to an upper reflective mirror 115 that is fixed with a screw to the holding frame of the rod-shaped light source. ing. In this embodiment, the lower bracket 5a of the upper reflecting mirror 5 and the bracket 4a of the lower surface opposite to 01si are provided so as to be fixable with adjustment screws 17, so that the light from the rod-shaped light source 3 is directed directly to the illumination area. Lower surface reflection to illuminate! By moving 14, the amount of exposure in the illumination area can be adjusted.

The embodiments of the present invention described above all describe adjusting the amount of exposure from the rod-shaped light source in the illumination area corresponding to the image plane of the document by moving the reflecting mirror horizontally with respect to the rod-shaped light source. However, it is also possible to move the reflecting mirror in the vertical direction as in the case of FIG.

In this case, by providing the bracket 15 shown in FIG. 1 movably with respect to the vertical member of the frame, or by inserting something like a spacer between one racket of both members, the reflector vertical adjustment can be made.

The graphs shown in FIGS. 3 and 4 show the integrated value of illuminance when using the reflecting mirror configured as described above. Among these graphs, when looking at Figure 3, the integrated value of illuminance in the length direction (direction perpendicular to the scanning direction) of the rod-shaped light source 3 is compared to the case where the adjustment shown by the chain line is not performed. In the case of the present invention shown by the solid line, the value is averaged over the whole, and it is possible to prevent variations in the image in the scanning width direction.

Furthermore, as shown in Fig. 4, in the scanning direction,
A relatively sharp beam of illumination having a peak at the center of the illumination area is formed, and the clarity of the original image is improved.

In the embodiments of the present invention described above, any adjustment method such as moving the reflecting mirror parallel to the rod-shaped light source or moving one side of the reflecting mirror using the adjusting member is possible. These adjustments can be made by arranging a plurality of optical sensors in the illumination area and measuring the luminous flux.

(Effects of the Invention) Since the illumination device for an electrophotographic copying machine of the present invention has the above-described configuration, it is possible to eliminate a decrease in the efficiency of the reflecting mirror and to improve the integral value of illuminance for the illumination area. can be set uniformly.

Further, in the lighting device of the electrophotographic copying machine of the present invention,
Even if the efficiency is slightly reduced by moving one of the reflectors, the degree of decrease in efficiency is not as large as when using a light shielding plate, so the overall illuminance efficiency is lower than that of the conventional device. This makes it possible to improve the performance compared to the above.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of an illumination device for an electrophotographic copying machine according to the present invention, FIG. 2 is a sectional view showing the structure of another embodiment of the present invention, and FIGS. Figure 5 is a cross-sectional view showing the configuration of a conventional slit-shaped illumination device, and Figures 6 and 7 are graphs showing the integrated value of illuminance in the length direction of a rod-shaped light source and in the scanning direction. Figures 8 and 9 are illuminance graphs and cross-sectional views of the device when illuminating the illumination area, and Figures 10 and 11 are graphs of illuminance and cross-sectional views of the device when sharply illuminating the illumination area, respectively. 7 is a graph showing the distribution of illuminance in the scanning direction of the illumination area and in the length direction of the rod-shaped light source. Reference numerals in the figure 1...Original mounting table, 2...Original, 3.
...Bar-shaped light source, 4...Bottom reflector, 5.
...Top reflector, 6...First focal point, 7.
...Lower luminous flux, 8...Illumination area, 9.
... Upper luminous flux, 10 ... Third reflecting mirror, 15 ... Bracket, 16 ... Frame, 17 ... Adjustment screw.

Claims (2)

[Claims] (1) Consisting of a rod-shaped light source, and an upper and lower reflector surrounding the light source, the upper and lower reflectors constitute an approximately elliptical cylindrical mirror, and the common focal point of the two reflectors The center of the light source is set at
An illumination device configured to irradiate an illumination area through a reflecting mirror and to directly irradiate the illumination area with reflected light from a lower reflecting mirror, the elliptical cylinder comprising the upper reflecting mirror and the lower reflecting mirror. An illumination device for an electrophotographic copying machine, characterized in that a plane mirror is provided in a position adjustable with respect to a light source. (2) The upper surface reflecting mirror or the lower surface reflecting mirror constituting the elliptical cylindrical mirror is provided movably with respect to the rod-shaped light source holding frame, and the position with respect to the rod-shaped light source can be adjusted. An illumination device for an electrophotographic copying machine according to scope 1.