JPS58118662A - Image controlling device - Google Patents

Abstract

PURPOSE:To eliminate the roughness in the ground of copies and to shorten the detecting time, by controlling the copying conditions in accordance with the density of the leading part of an original when the difference in density between a referential reflecting section and the leading part of the original is less than a prescribed value. CONSTITUTION:A CPU23 knows that a referential white plate is scanned by an optical system using a detecion signal S4 sent from a scanner position detector 21, and reads a digital signal S2 corresponding to the amount of reflected light FO of the white plate and stores the digital signal S2 in a memory 25. Then, the CPU23 knows the time required for the optical system to scan the leading part of an original from the signal S4 sent from the detector 21, and reads the digital signal S2 corresponding to the amount of reflected light F1 from the leading part of the original, and then, compares the digital signal S2 corresponding to the amount of reflected light FO stored in the memory 25. The CPU23 generates a control signal which is an object to be controlled by a program based on the compared result, and outputs the signal to a developing bias power source 26 through an input and output port 22. The power source applies a voltage corresponding to the control signal upon a developing sleeve.

Description

[Detailed description of the invention] The present invention relates to an image control device in a copying machine.

As an image control device in a copying machine, one that detects the reflected light from the reference and C-turns and controls the image bias voltage accordingly is known from U.S. Pat. No. 3,438,705. ing. Shiroki Shiko's copying apparatus controls the bowl bias voltage regardless of the background density of the original, so when copying a colored original such as colored paper or a blue to diazo copy with a background, the background of the copy will be smeared. In addition, there is a device that detects the reflected light from a predetermined part of the document and opens the visual image bias voltage according to the maximum value.
This is known from Japanese Patent No. 5031. However, since this device detects the reflected light from a part of the document, if that part has a dark pattern, the quality will be poor. Furthermore, the time it takes to detect the light reflected from the document is the same as the time it takes to devour the document, which slows down the copying speed.

It is an object of the present invention to provide an image control +1'l device that does not require any of the above-mentioned components and can be made at almost the same cost as the conventional one.

The present invention will be described below by way of examples with reference to the drawings.

Fig. 1 shows an example of a copying apparatus to which the present invention is applied.

The reference white plate 1 constitutes a reference reflection section, is placed on the right side of the document 3 on the document table 2, and is not attached to the end of the document table 2. Light source 41. During exposure, the fan 1 mirror 5 and the fan z mirror 6' are driven by the drive device from the initial position to the left at a constant speed, so that the reference white plate 1 and the original 3 are not scanned in sequence, and the light source 4 is driven to the reference white. The plate 1 and the original 3 are sequentially illuminated, and the reflected light passes through the fan 1 mirror 5, the fan 2 mirror 6, the through lens 7, the spear 3 mirror 8, the spear 4 mirror 9, and then the photoreceptor dome 10 and detection z&1
1. The photoreceptor drum 10 is rotationally driven by a driving device and charged to a certain level by a charging corona discharger 12. After that, the charge removal lamp 13 removes the charge from the non-image forming area, and the original image is exposed to light to form a latent image as described above. This latent image is developed by a bowl plate 15 having a developing sleeve 14, and exposed to light by a transfer corona discharger 17, which is a transfer paper fed from a paper feeder via a registration roller 16. The image on the photosensitive drum 10 is transferred and separated from the photosensitive drum 0 by a separating corona discharger ]8. The image on this transfer paper P is fixed by a fixing device, and when it is copied externally, it is removed.After the transfer paper is separated, the photoreceptor drum 10 is cleaned by a cleaning blade [9], and the static electricity is removed by a charge removal lamp 20, and then the next copy is made. Prepare for.

Figure 2 shows an embodiment of the present invention.

The scanner position detector 21 detects that the optical systems 4 to 6 are in the position to scan the reference white plate 1 in the copying apparatus, and the detection signal S4 is sent to the input/output board 2.
2 to the central processing unit 23. The output signal S1 of the above detector 1 is the analog/digital converter 2.
4, it is changed to digital signal S2 and sent to input/output port 2.
2 to the central processing unit 23. The central processing unit 23 receives the signal S4 from the scanner position detector 21.
It is known that the reference white plate 1 is being scanned by the optical systems 4 to 6, and the digital signal 82'1 corresponding to the reflected light kFo of the reference white plate 1 is read and stored in the memory 25 (or internal register). After that, the central processing unit 2
3 determines the time during which the optical systems 4 to 6 scan the leading edge 3a of the original 3 from the signal s4 from the scanner position detector 21, and detects the reflected light frF+ of the leading edge 3a of the original 3.
Read the digital signal S2 corresponding to the digital signal S2 corresponding to the amount of reflected light FO of the reference white plate 1 and store it in the memory 25. voltage) and outputs this control signal to the developing bias power supply 26 via the input/output port 22.The developing bias power supply 26 applies the developing bias voltage according to the control signal to the imager 15.
3J [applied to sleeve 14]. In this case, the central processing unit 23 sets the developing bias voltage according to FO when Fl <FQ - f4) fo: an arbitrary light amount, and Fl ≧FD - f.

When it is, the developing bias voltage is set according to Fl. Therefore, the leading edge of the document is transferred to the solid area (for example, I
D > 1), Fi < FO - fO, and the developing bias voltage is set to a value corresponding to FO, and the poor's 14
m doesn't get worse. Manuscripts or colored paper using regular white paper,
When copying a colored original such as a diazo copy with a blue background, F1≧FO−fO and the developing bias voltage is F1.
is set to a value that corresponds to this, and the background of the copy will not be smudged.

Note that the reference reflecting portion does not necessarily have to be white, and may be gray or the like. Alternatively, the reference white plate 1 and the original 3 may be scanned by fixing the optical systems 4 to 6 and moving the original table 2, and the object to be controlled may be the amount of light or the like.

As described above, according to the present invention, when the density difference between the reference reflective part and the leading edge of the original is less than a predetermined value, the copying conditions are controlled according to the density of the leading edge of the original, so that the copying conditions can be controlled according to the density of the leading edge of the original. When copying a colored original such as a colored original, the background of the copy will not be smeared.

Furthermore, when the density difference is greater than a predetermined value, the copying conditions are controlled according to the density of the reference reflective portion σ), so that poor reproduction does not deteriorate even if there is a solid area at the leading edge of the document. Furthermore, since the difference in density between the reference reflective part and the leading edge of the document is detected, the cost can be reduced to approximately the same as in the conventional method, although detection takes time.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an example of a copying apparatus, and Figure 2 is a block diagram showing an embodiment of the present invention. l... Reference white plate, 11... Detector, 21... Scanner position detector, 22... Input/output boat, 23...
...Central processing unit, 24...Analog/digital converter, 25...Memory, 26...Development bias power supply.

Claims (1)

[Scope of Claims] 1. A copying apparatus having a scanning means for scanning a document, which includes: a reference reflecting section that generates noise prior to scanning the document by the scanning means; and detecting light reflected from the reference reflecting section and the document. and detecting means for detecting the difference in performance between the reference reflecting section and the leading edge of the document from the output signal of the detecting means, and when the difference in density is less than a predetermined value, the copying condition is set according to the density of the leading edge of the document. and means for controlling the image density by controlling the image density according to the density of the reference reflecting section that sets the copying condition when the density difference is equal to or greater than a predetermined value. 2. An image control device according to claim 1, which controls image bias voltage as control of copying conditions.