JPS6180173A - Device for adjusting copying density - Google Patents

Abstract

PURPOSE:To obtain the adequate image density in the continuous copying stage of book originals by detecting respectively the ground density of the originals and setting automatically copying conditions for each block of the originals. CONSTITUTION:An original size detecting sensor 13 is rotated into an arc shape around the fulcrum of a lever 13a and the central position of the original which is held spread is detected. The original is then pre-scanned by a scanner 10 and a ground density sensor 11 and the densities at the 3 points A of the 1st sheet of the originals 2 and the 3 points B of the 2nd sheet are measured. The scanning is executed with the short return of the scanner 10 in the stage of copying the 1st sheet of the originals and the full scanning is executed for the 2nd sheet in the copying operation. The adequate images are therefore obtd. for each of the blocks of the originals even if the ground density thereof varies in the stage of continuous copying.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a copy density adjusting device, and particularly to a copy density adjusting device that can be applied to a copying machine.

[Prior art]

Conventionally, the copy density adjustment device in a copying machine scans a part of the document using a sensor, and if the scanning position is the center left center of the contact glass, it can be applied to all document sizes. The contact glass is detected by moving in the same direction as the central optical scanner.

As a result of this detection, the process conditions are controlled by detecting the same background density on both the left and right pages of the book manuscript.

Therefore, with the above method, there is a problem that in book manuscripts, the background density of the left and right pages is often different (and proper images of the left and right sides cannot be obtained during page continuous copying).

〔the purpose〕

The present invention solves the problems of the prior art described above, and provides a copy density adjustment device that can detect the background of each arbitrary block of a document to be copied and obtain an appropriate image density in continuous copy mode. The purpose is to

〔composition〕

In order to achieve the above object, the present invention detects the original background density of each arbitrary block of the original during continuous copy mode, and automatically sets various process conditions for each block of the original based on the detection results. It is characterized by

Hereinafter, a detailed explanation will be given based on one embodiment of the present invention.

In FIG. 1, a contact glass 3 serving as a stand for the original 2 and a pressure plate 4 for pressing the original 2 against the contact glass 3 are provided on the upper part of the main body 1 of the copying machine. A copying mechanism 5 centered around a drum is incorporated. An optical system 6 is arranged between the contact glass 3 and the copy mechanism 5. This optical system 6 is
an exposure lamp 7, a plurality of lenses 9a and 9a for guiding the light beam 8 from the exposure lamp 7 to the photosensitive drum; and a lens 9b.
The scanner 10 that causes the exposure lamp 7 to scan the lower surface of the contact glass 3 includes a background density detection section 1.
A sensor 11 for detecting the background density of the original is electrically connected to the sensor 1α. Further, on the lower surface of the contact glass 3, a document size detection sensor 13 is mounted on a lever integral 13α that rotates the lower surface of the contact glass 3 by a drive motor 12, and is electrically connected to a document size detection section 13AK. Allocate.

Then, as shown in FIG. 2, the document size is detected by 7?
-13 takes an arcuate locus of the contact glass 3 shown by a two-dot chain line centered on the fulcrum of the integrated lever 13α.

In explaining the operation of the above configuration, it is assumed that the document placement position is the left center reference, and that the document 2 is an 85-version book (84-page spread). That is, when a print switch (not shown) is pressed, the document size detection pin f-13 draws the circular arc locus and operates to recognize the size of the document 2 on the contact glass 3. In this case, when it is detected that the document is B4 size, since the document 2 is based on the left side, 364
It can be seen that the position of /2 = 182 mm is the center of the document. and the original size detection sensor 13
However, when the contact glass 3 is retracted outside the image area (outside the image area), the scanner 10 pre-scans the original 2 to detect the background density.

To detect the background density, human measurement is performed at three points at a predetermined gap from a position at a predetermined distance from the side edge of the document 2, as shown in FIG. 3, and the average of these measurements is determined as the background density. Since the center of the document is known in the document size detection mode described above, the background density of the second document is 1 from the left side of the contact gas 2.
Measurements are taken at three points B from a position of 82 mm plus a predetermined distance in the same way as for the first document, and the average of these measurements is determined to be the background density.

Note that the processing of the detected value of the document size or the detected value of the background density differs depending on the function and size of the copying machine, and various measures can be taken, examples of which will be described later.

The background density data of the first original and the background density data of the second original are stored in the RAM in the central control unit C.

Then, the scanner 10 enters the copy operation mode, and the scanner 10
When copying the second original, perform a short return (that is, return at a distance that can scan one original) (see Figure 4 (α)), and when copying the second original, perform a full scan ( (See Figure 4(b)). In the copy operation during the short return, known charging, exposure, erasing, transfer, and resolution are performed at the normal copy timing, and the developing bias at this time is controlled by the developing bias control unit 14 to adjust the background density of the first document. Control accordingly. In the second copy operation, the scanner 10 blankly scans the length of the first document from the home position, and after the blank scan, operates at the normal copy timing. At this time, the developing bias is set to the side by the developing bias control section 14 at a value corresponding to the background density of the second document.

By causing the above-described operation, even if the original 2 has a photograph on the left side and text on the right side, a copy image can be obtained for each at the appropriate density.

Next, the operation of the above embodiment will be explained with reference to charts 70 in FIGS. 6 and 7 and FIGS. 8 to 10.

Specifically, referring to FIG. 10, the document size detection sensor 13 is activated by the drive motor 12 by turning on the print switch. In the flowchart of FIG. 6, the size check is all managed by a timer, but it may also be performed in pulses by using a pulse motor.

At the time-up point of the timer TA+TE+TO*TD*TF, the sensor output is rHJ or "LJ," and the paper size is determined by determining whether or not there is paper above the sensor 13 at that time.In this embodiment, is with paper and rLJ is without paper.

When detecting the background density, if the paper size in the original size data is A5 or smaller, it is determined that copying is not possible. Timer T4 is used to measure the background density of the first and second originals.
Accordingly, the measurement timing is adjusted from the end of the density data measurement of the first document to the area of the second document. Timer T
4 is set each time at a time corresponding to each pre-certified code based on the code-converted data stored in RA and M, as shown in FIG.

In this embodiment, the data is read three times and averaged, but the measurement points and calculation methods vary depending on the machine.

As shown in FIG. 8, M4. After M5 is code-converted and stored in RAM, a phenomenon bias is determined corresponding to each code.

Next, regarding the bee mode, before the exposure lamp 7 is restarted in the copy routine, the developing bias value corresponding to FIG. 8 is output to the developing sleeve. After that, the description is omitted because it is a well-known copy mode. Then, the copying operation for the second copy is also performed in the same manner using the developing bias value corresponding to the data M5. [Effect] As explained above, according to the present invention, in the continuous copy mode, copying of the original is performed. It is possible to provide a copying density adjusting device that can obtain an appropriate image for each block even if the background density of each block is extremely different.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a front view illustrating the outline of the main body of the copying machine, FIG. 2 is a diagram showing the relationship between the contact glass and the document size detection sensor, and FIG. is a diagram showing the relationship between the original and background c degree detection, Figure 4 (
α), FIG. 4(h) is a diagram showing the relationship between the original and the copying operation, FIG. 5 is a block diagram of the system 41, and FIGS. FIG. 8 is a diagram showing the relationship between background density data and bias value, FIG. 9 is a diagram showing the relationship between paper size data and the set time of timer T4, and FIG. 10 is a diagram for explaining document size detection. 1...copying machine body, 2... manuscript, 5...
. . . Copying means, 11 . . . Background density detection sensor, 13 . . . Original size detection sensor, C.
...Central control section. Figure 8) jl, Figure 9

Claims (1)

[Claims] A copying machine having a means for successively copying arbitrary blocks of a book document placed on a document stand in a double-page spread state and successively copying arbitrary blocks of the document with a single copy instruction, and a document background density detection means, A copy density adjusting device characterized in that, in continuous copy mode, the document background density of each arbitrary block of the document is detected, and various process conditions are automatically set for each block of the document based on the detection results.