JPH041673A - optical equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical device for stabilizing the exposure amount of an electrophotographic copying machine.

2. Description of the Related Art An example of this kind of optical device for stabilizing the exposure amount is disclosed in Japanese Patent Laid-Open No. 51-82830. That is, as shown in the main part cross section in FIG. 2, the optical sensor 1B,
Reference numeral 16 is arranged so that the light from a lamp 18 disposed within the main reflecting mirror 17 directly detects the reflected light from a plate 19 having a certain reflection density. The field inspection value is compared with a preset value, and the lamp exposure amount is corrected. Therefore, in this case, dirt, output, etc. of the lamp 18 itself are detected.

The optical sensor 20 is connected to the document table crow 2 on which the document 21 is placed.
In this case, the reflected light from main reflector 1 is detected.
7 and the dirt on the document table glass 22 are detected. Further, since the optical sensor 23 is further connected to the mirror 24, it detects dirt on the main reflecting mirror 17, the original table glass 22, and the mirror 24.

Problems to be Solved by the Invention However, with the above configuration, it is possible to detect dirt and changes over time on the main reflecting mirror, platen glass, mirror, lens, etc. in the exposure path and correct the exposure amount. The problem is that if the optical sensor itself becomes dirty, the exposure output of the lamp will be increased even if the main reflector, platen glass, mirror, lens, etc. are clean, which will have a negative effect on document image exposure. It had Furthermore, the heat generated by the lamp increases due to the increase in exposure output, which also poses a problem in that it also affects the bad shadow 11' caused by the heat.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide an optical device that can correct the exposure amount to a constant value with a simple configuration.

Means for Solving the Problems In order to solve the above problems, the optical device of the present invention provides patch marks for standard exposure on the lower surface of the document table upstream of the document scanning start point, and illuminates the patch marks with a lamp prior to scanning the document. The optical device is configured to irradiate light onto a photoconductor through a lens and mirror, and an illuminance sensor for inspecting lamp illuminance is provided in a non-reflective optical path of patch marks irradiated onto the photoconductor. The illuminance sensor is provided with a retractable base and a static elimination brush that cleans the illuminance sensor when the illuminance sensor is moved in and out.

According to the above-described configuration, the illuminance sensor is cleaned by the static eliminating brush when the copying machine is turned on, when copying every copy, or when copying a predetermined number of copies, thereby preventing dirt and aging of the optical system. Power changes can be detected accurately and the exposure amount can be corrected to a stable value.

EXAMPLE Hereinafter, an optical device according to an example of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration diagram of an optical device according to an embodiment of the present invention. In the figure, 1 is a document table on which a platen glass is arranged, and there is a certain density close to white on the upstream side of the document scanning start point on the bottom surface. Standard exposure patch marks are provided. 3 is a main reflecting mirror in which a lamp 4 for exposure is disposed; 5, 6, 7, 8.
Reference numerals 9 and 10 indicate mirrors, and reference numeral 11 indicates a lens, and the light reflected by the lamp is imaged on the photoreceptor 12 through these reflection exposure optical paths.

Reference numeral 13 denotes an illuminance sensor disposed so as to be able to move in and out of the above-mentioned reflective exposure optical path, and 14 denotes a static eliminator made of carbon fiber or the like, which is provided outside the reflective exposure optical path and cleans the surface by contacting the illuminance sensor when the illuminance sensor goes in and out. It's a brush.

Dust electrostatically adheres to the illuminance sensor 13 because a minute current flows through it, but the surface is always clean because it is cleaned by a static eliminating brush when entering and leaving the reflective exposure optical path. Therefore, it is possible to accurately detect dirt on the lamp, main reflector, mirror, lens, etc., as well as changes in lamp output.
By correcting the exposure output of the lamp to an appropriate value, the amount of exposure can be made constant. Further, it is possible to prevent an increase in the exposure output of the lamp due to erroneous detection of the exposure amount due to dirt on the illuminance sensor itself, and it is possible to prevent adverse effects of document image exposure. Furthermore, since the exposure output of the lamp can be adjusted appropriately, adverse effects caused by heat generation can be prevented.

The illuminance sensor 13 is moved in and out of the reflected exposure optical path using an unillustrated inlay mechanism when the equipment is powered on, and the exposure output of the lamp 4 is corrected based on the detected value at this time.

However, the present invention is not limited to this, and it may be set to come and go when each copy is made or when a predetermined number of copies are made.

Effects of the Invention As detailed above, according to the present invention, the surface of the illuminance sensor that enters and exits the reflected exposure optical path immediately before the exposure incident on the photoreceptor is cleaned with a static eliminating brush, thereby eliminating the need for the lamp and main reflecting mirror. , dirt on the optical system such as lenses and mirrors, and changes in lamp output can be detected accurately at all times, and the exposure output of the lamp can be compensated for to be appropriate.
The original image exposure is stabilized to a constant level, and good image formation is possible. Furthermore, since it is possible to prevent the exposure output of the lamp from being erroneously increased, it is also possible to prevent the adverse effects of heat generation on the apparatus.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an optical device in an embodiment of the present invention;
FIG. 2 is a sectional view of a main part of a conventional optical device. 1... Original table, 2... Patch mark, 3...
...Main reflecting mirror, 4...Lamp, 5, 6, 7, 8, 9
．． 10... Mirror, 11... Lens, 12...
- Photoreceptor, 13... Illuminance sensor, 14... Static elimination brush.

Claims (1)

[Claims] An optical device in which patch marks for standard exposure are provided on the lower surface of the document table upstream of the original scanning start point, and prior to scanning the original, the patch marks are irradiated with a lamp and exposed onto the photoreceptor through a lens and mirror. An illuminance sensor for detecting lamp illuminance is removably disposed in the reflection exposure optical path of the patch mark irradiated onto the photoconductor, and static elimination is provided to clean the illuminance sensor when the illuminance sensor is moved in and out. An optical device characterized by having a brush arranged therein.