JPS6258453U - - Google Patents

Description

[Brief Description of the Drawings] Fig. 1 is a schematic diagram showing an embodiment of an electrostatic copying machine according to the present invention, Fig. 2 is a block diagram showing an embodiment of the control means, and Fig. 3 is an embodiment of the light shielding section. bottom view showing
FIG. 4 is a characteristic diagram showing the exposure amount during the exposure operation according to the present invention, and FIG. 5 is a characteristic diagram showing the exposure amount during the exposure operation using the conventional apparatus. 1...Contact glass, 2...Optical system section, 4
...Controlling means, 27...Document density detection means, 51
...White light shielding part, 52...Gray light shielding part.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. An optical system unit that exposes a document placed on a contact glass, a detection device that detects the density of the document, and a method for copying in accordance with a detection signal output from the detection device. In an electrostatic copying machine, the electrostatic copying machine has a control means for controlling density, and a white light-shielding portion is formed at a reference position of a contact glass on which a leading edge of a document is placed, at least the detection means of the white light-shielding portion. An electrostatic copying machine characterized in that a color light shielding part is provided in a portion corresponding to the detection position of the color light shielding part, the amount of reflected light being smaller than the amount of light reflected by the white light shielding part. 2. The electrostatic copying machine according to claim 1, wherein the color light-shielding portion is a gray light-shielding portion having a brightness corresponding to the density of an average original. 3. The electrostatic copying machine according to claim 1, wherein the color light-shielding portion has a color having a wavelength outside the sensitivity wavelength band of the detection means. 4. The electrostatic copying machine according to claim 1, wherein the color light-shielding portion is disposed outward from a position serving as a reference leading edge of the document. 5. The utility model registration claim 1, wherein the detection means for detecting the density of the original is configured to detect the amount of reflected light when the original is exposed by an optical system section. Electric copying machine. 6. The electrostatic copying machine according to claim 1, wherein the control means is configured to control the amount of light from the exposure lamp in order to control the copy density. 7. The control means includes a light amount detection circuit that receives a detection signal from the document density detection means and converts it into a voltage signal, a reference voltage circuit, and a voltage signal output from the light amount detection circuit and the reference voltage circuit. a comparison circuit that compares the reference voltage output from the
Registration of a utility model characterized in that it is comprised of a limiting circuit that prevents a voltage exceeding a limit value from being applied to the exposure lamp, and a lamp voltage generation circuit that receives the output of the comparison circuit and determines the light amount of the exposure lamp. An electrostatic copying machine according to claim 6. 8. The electrostatic copying machine according to claim 1, wherein the control means is configured to control the bias voltage of the developing section in order to control the copy density.