JPH0287133A - Variable magnification copying device - Google Patents

Abstract

PURPOSE:To eliminate deficiency in exposure and decrease in exposure scanning speed by starting the exposure of an original at an exposure start position. CONSTITUTION:When an original platen fixed position indication member 43 comes to the position of a position detection sensor 44, the position detection sensor 41 sends out a signal to a CPU 47. Namely, when the position detection sensor 41 detects the relative movement position between an original and an exposure system, its detection signal is inputted to the CPU 47 as an exposure start position control means. A signal of copy magnification is also inputted to the CPU 47 and the exposure start position of the original is determined by the CPU 47, so that the original begins to be exposed at the position. Consequently, the deficiency in the exposure of an original exposure start end part is eliminated in reduction magnification mode and an unnecessary exposure time is eliminated in enlargement magnification mode to shorten a copying time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable magnification copying apparatus for selectively forming an image of a document at an arbitrary magnification.

[Prior Art] In conventional general PPC copying machines, the exposure width of slit exposure may be small because the photosensitive drum has good sensitivity. Therefore, in the case of reduction or enlargement copying, even if the slit width on the photosensitive drum is kept constant, there is little variation in the exposure width on the document surface required for slit exposure, and there is no possibility of underexposure or overexposure at the leading edge of the document. It was hardly a problem.

By the way, when the photosensitive pressure sensitive recording medium known from U.S. Pat. In order to avoid heat concentration on the document, it is common practice to make the slit wide.

[Problems to be Solved by the Invention] FIG. 3 shows the slit exposure state in full-size copying. When the original 44 is moved in the direction of arrow X and scanned, exposure is started from the time when the left edge of the original reaches point A.

However, in the case of reduced copying, as shown in Figure 4, if exposure is started from point A in the same way as when using full-size copies, the exposure time between A and B in the figure in the initial stage of exposure will be shorter than in other parts of the original, resulting in underexposure. Put it away.

Furthermore, in the case of enlarged copying, as shown in Fig. 5, if exposure is started from point A in the same way as in the case of full-size copying, the area between CA in the figure at the initial stage of exposure will not be imaged on the photosensitive pressure-sensitive recording medium, resulting in wasted exposure. Since the exposure scanning speed is slow, the overall copying speed becomes long.

[Means for Solving the Problems] In order to solve the above problems, the variable magnification copying apparatus of the present invention scans an original by slit exposure to selectively form an image of the original at a certain magnification on a photosensitive recording medium. In a variable magnification copying apparatus configured to and an exposure start position control means for determining an exposure start position of the document, and is configured such that exposure of the document is started from the exposure start position.

[Operation] According to the present invention having the above configuration, when the relative movement position between the original and the exposure system is detected by the position detection sensor,
The detection signal is input to the CPU, which is an exposure start position control means. On the other hand, a copy magnification signal is also input to the CPU,
The exposure start position of the document is determined by the CPU based on the human power signals, and the exposure of the document is started from this position.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic diagram of an exposure device of a copying machine using the photosensitive pressure-sensitive recording medium.

At the top of the exposure device is a document platen glass 2 that can be moved left and right.
and a document table cover 1, and a document table fixed position indicating member 44 is fixed to the lower surface of the document table glass. A document table position detection sensor 41 for reading a document table fixed position indicating member 44 is fixed to the main body of the copying machine.

Next, the case of copying will be explained with reference to the control block diagram shown in FIG. 2 and FIG. 1. When a copy start button (not shown) is pressed, the original platen glass 2 located at the center of the copying machine is moved to the right by the original platen driving device 46 in response to a command from the CPU 47.

Then, the document table fixed position indicating member 44 is connected to the position detection sensor 41.
When the position matches the position, the position detection sensor 41 outputs a signal to the CPU 47. On the other hand, the copy magnification is input to the CPU, and even after receiving the detection signal from the detection sensor 41, the document glass 2 is moved by the document table drive device 46 for a predetermined period of time in accordance with the input copy magnification. controlled to move. In the case of equal-size copying, the copying is stopped when the equal-size exposure start position 45b on the document platen moving glass 2 and the exposure start point 49 fixed to the main body coincide.

Thereafter, the document platen driving device 46 is driven in reverse according to a command from the CPU 47, and the document platen glass 2 moves to the left.
Exposure begins. Next, in the case of reduction copying, when the user sets the desired reduction magnification using the copy magnification setting switch 48, the lens 9 and the two reflection mirrors 11 are moved parallel to the optical axis by a magnification changer (not shown), and the photosensitive pressure sensitive Recording medium 3
A reduced image of the original is formed on 7. Next, when the copy start button is pressed, the original platen glass 2 moves in substantially the same way as when copying at the same size, and stops when the reduction exposure start position 45a and the exposure start point 49 fixed to the main body coincide. , exposure is performed from the reduction exposure start position 45a. As a result, the original between 45a and 45b can be exposed to the same amount of light as the other original parts.

Furthermore, in the case of enlarged copying, the user can press the copy magnification setting switch 4.
When the desired magnification is set by 8, the lens 9 and the two reflecting mirrors 11 are moved parallel to the optical axis by a variable magnification device (not shown), and a reduced image of the original is formed on the photosensitive and pressure sensitive recording medium 37. Then press the copy start button,
The original platen glass 2 moves approximately in the same way as when copying at the same size, and moves to an enlarged exposure start position 45c and an exposure start point 4 fixed to the main body side.
Match 9. Then, the enlarged exposure start position 45
Exposure starts from c. As a result, compared to the original size, it is 45
For documents between c and 45b, copying time can be shortened without unnecessary exposure.

Although the above embodiment has been described with a fixed magnification for each of reduction and enlargement, it is also possible to set a plurality of magnifications for each, and it is also possible to change the magnification steplessly.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, when the reduction magnification is used, the underexposure at the exposure start end of the document can be resolved, and a good image can be obtained by uniform exposure.

Further, when the magnification is increased, unnecessary exposure time can be omitted, and copying time can be shortened.

[Brief explanation of drawings]

FIG. 1 is an overview diagram of an exposure device of a copying machine embodying the present invention, and FIG. 2 is a control block diagram for determining the exposure position of the document platen.
FIG. 3 shows a state diagram of the exposure system at the same magnification, FIG. 4 shows a state diagram of the exposure system at the time of reduction, and FIG. 5 shows a state diagram of the exposure system at the time of enlargement. In the figure, 1 is an original platen cover, 2 is an original platen glass, 9 is a lens, 11 is a reflection mirror, 1 is an exposure platen slit, 37 is a photosensitive pressure sensitive recording medium, 41 is a position detection sensor, and 43 is an original platen fixing Position indicating member, 44 is the document surface, 45a is the reduction exposure start position, 45b is the equal confidence light start position, 45c is the enlargement exposure start position, 46 is the document platen driving device, 47 is the CPU, 48
is the copy machine magnification setting switch.

Claims (1)

[Claims] 1. In a variable magnification copying apparatus that scans an original by slit exposure to selectively form an image of the original on a photosensitive recording medium at a certain magnification, the relative relationship between the original and the exposure system a position detection sensor that detects a moving position; and an exposure start position control means that determines an exposure start position of the document based on an input signal of a detection signal of the position detection sensor and a preselected copying magnification; A variable magnification copying apparatus characterized in that it is configured to start exposing an original from a starting position.