JPS62172338A - Copying machine with variable magnification - Google Patents

Abstract

PURPOSE:To improve the accuracy of copying magnification by detecting a reference size pattern by an image sensor, comparing the output signal of the image sensor with a specified copying magnification value and driving a zoom lens in a direction minimizing the error of the copying magnification. CONSTITUTION:An original platen 1 consisting of a glass plate is arranged on the upper surface of a copying machine body and a scanner for scanning the lower part of the platen 1 in the horizontal direction is arranged under the platen 1. The scanner consists of mirrors 5-7 and forms the image of an original set up on the platen 1 on the surface of a photosensitive drum 9 through a zoom lens 4 and a reflector 8. The reference size pattern 3 is formed on the upper surface of the platen 1 by printing or the like, and when the scanner is set up on a stop position, the mirror 5 is located on a position 5a, the pattern 3 is formed on the surface of the image sensor 11 arranged adjacently to the drum 9. Whether there is an error in the position of the lens 4 or not is detected on the basis of an output signal from the sensor 11 and the specified copying magnification and the lens 4 is driven in the direction minimizing the error.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a variable magnification copying machine that allows copying to be performed by setting a copying magnification with extremely high precision.

<Summary of the Invention> The present invention includes an optical system that images an original placed on a document table onto a photoreceptor via a zoom lens, and changes the position of the zoom lens according to a specified copying magnification. In a copying machine that forms an original image at a specified copying magnification on the photoconductor, a pattern serving as a reference dimension is provided on or near the document table, and a pattern corresponding to this standard dimension is provided on the photoconductor side. An image sensor that receives an image of a pattern is provided, and feedback is provided to the position control of the zoom lens according to the output signal of the image sensor and a specified copying magnification.

<Prior Art and Its Disadvantages> Conventionally, copying machines with a zoom function that can copy at any copying magnification have been used. This type of copying machine is effective when organizing materials by copying several manuscripts of different sizes onto copy paper of the same size, or when using drawings by enlarging or reducing them depending on the purpose. .

However, conventionally used copying machines with a zoom function can only change the copy magnification in 1% steps at most, and are not suitable for cases where highly accurate copy magnification is required. For example, when cutting and pasting another drawing onto a drawing of a predetermined size, it is required to be able to set the copy magnification in steps of about 0.1%. In conventional copying machines, it has been difficult to set the copying magnification with such high precision due to variations in mechanical accuracy and variations in zoom lens characteristics.

<Objective of the Invention> An object of the present invention is to provide a variable magnification copying machine that achieves high precision copying magnification without particularly improving variations in mechanical accuracy or variations in zoom lens characteristics.

<Configuration and Effects of the Invention> The present invention provides an optical system that images an original placed on a document table onto a photoconductor via a zoom lens, and a zoom that moves the zoom lens according to a designated copying magnification. A copying machine comprising a lens driving means, a reference dimension pattern is provided on or near the document table, an image sensor is provided close to the photoreceptor to receive an image of the reference dimension pattern, and the zoom The lens driving means includes an error detection means for determining a driving error of the zoom lens according to the output signal of the image sensor and the specified copying magnification, and a correction for correcting the driving error of the zoom lens according to this error. It is characterized by having a means.

With the above configuration, the image sensor can receive an image of the reference dimension pattern provided on the document table through the zoom lens. Therefore, the magnification of the image on the photoreceptor relative to the original can be determined from the output signal of this image sensor. If there is an error between this magnification and the specified copy magnification, the actual copy magnification is approximated to the specified copy magnification with extremely high accuracy by driving the zoom lens in the direction that minimizes the error. be able to.

<Embodiment> FIGS. 1(A) and 1(B) are diagrams showing the configuration of a variable magnification copying machine which is an embodiment of the present invention, and FIG. 1(A) is a top view;
(B) is a front view.

A document table 1 made of a glass plate is provided on the top surface of the copying machine main body, and a scanner is provided for horizontally scanning the lower part of the document table. The scanner consists of mirrors 5, 6, and 7, and the image of the document placed on the document table is transferred to a photosensitive drum 90 via a zoom lens 4 and a reflector 8.
Form an image on the surface. 5a represents the position of the mirror 5 in its initial state, and the reference dimension pattern 3 is formed on the document table above it. As shown in FIG. 3, this standard dimension pattern is formed by printing or pasting a film on the upper surface of the document table 1 made of a glass plate, and the upper part is formed by a mask 2.
covered by 1. That is, the original is placed with point P in the figure as the end of the original table.

When the scanner is at the stop position, the mirror 5 is at the position 5a', and by lighting the copy lamp 10 at this time, the reference dimension pattern is detected by the image sensor 11 provided close to the photoreceptor drum 9. imaged on the surface of

At this time, the size of the image formed on the image sensor is determined by the position of the zoom lens 4, and the actual copying magnification can be determined from the relationship with the reference dimension pattern. In addition,
As shown in FIG. 2, the image sensor 11 is provided at the same distance as the optical path of the light incident on the photoreceptor drum, thereby eliminating the need for error correction due to optical path differences.The zoom lens 4 is driven along a step motor and is As shown, by moving along the optical axis, the composite focal length can be changed while the original image and the reference dimension pattern are formed on the photosensitive drum 9 and the image sensor 11. In this embodiment, it is detected whether there is an error in the position of the zoom lens 4 based on the output signal of the image sensor 11 and the specified copying magnification, and the lens motor is driven in the direction where the error is minimized.

The copying process of this copying machine is similar to that of a conventional copying machine. First, the paper stacked in the paper feed cassette 12 is pulled out by the paper feed roller 13 toward the paper transport roller 14. The paper conveyance roller 14 sends out the leading edge of the paper to the transfer section at a predetermined timing. A toner image is transferred to the sheet of paper by a transfer charger 15, peeled off from the photoreceptor drum by a peeling charger 16, conveyed by a conveying unit 17, and fixed by a fixing roller 18.

After fixing, the paper is transferred to a paper ejection tray 20 by a paper ejection roller 19.
The paper is ejected to

FIG. 4 shows a block diagram of the control section of the copying machine.The overall control is performed by program processing of the CPU 100, and the control program is written in the ROM 101 in advance. When the program is executed, the RAM 102 is used as a working area for registers, flags, etc.

The I10 boat 103 is a boat for controlling various input/output devices.

The line sensor 11 is a CCD with 2000 to 4000 elements, and the output signal of this sensor is read out by the interface 104. The lens motor 107 is a motor for moving the position of the zoom lens, and is composed of a step motor. By driving the step motor for one step, the zoom lens is moved by a distance corresponding to a change in copying magnification of less than 0.1% (for example, 0.05%). The driver 106 generates driving pulse signals according to instructions from the CPU OO. The key-powered device 108 is a key-powered device that includes a numeric keypad, a magnification key, a key for instructing the start of printing, and the like. copy lamp 1
0 is a lamp for illuminating the document table from below, and is controlled on and off by the driver 109.

The ready lamp 112 is a lamp indicating that the print key is in a valid state, and is controlled to be turned on and off by the driver 111. 114 is a group of various sensors such as a sensor that detects that the lens is in the initial position, and is controlled by the interface 113.

FIGS. 5A to 5D are flowcharts showing the processing procedure of the control section.

First, the position of the zoom lens is initialized (n10) as shown in FIG. This process is performed by moving the zoom lens in front of and behind the home position sensor, and stopping the lens motor when the output signal of the home position sensor changes.

After that, other mechanical systems are initialized, and memory is also initialized (n12). After completing these initializations, turn on the ready lamp and read the keys (n
14-=n 16). If there is any key input, processing will be performed according to the input key. If the operated key is a numeric keypad, the input value is placed in register R as shown in FIG. 5(B).

If the operated key is a magnification key, it is determined whether the contents of the register R are less than a predetermined maximum magnification Z□, as shown in FIG. It is determined whether the value exceeds the minimum magnification Z ta i n (n 20−=n 22). If these conditions are satisfied, the contents of register R are input to register Z representing the copy magnification (n24). Furthermore, this register Z
The amount of rotation of the motor required to move the zoom lens, that is, the number of steps, is calculated from the value input in , and the lens motor is driven (n26-=n28). Note that the copy magnification and the distance from the home position of the zoom lens have a predetermined relationship and can be determined by calculation or table search.

In this way, the position of the zoom lens is controlled according to the copying magnification specified from the numeric keypad, but this control is coarse movement, and strictly speaking, it depends on variations in the precision of the mechanism that moves the zoom lens and the characteristics of the zoom lens. It is not always possible to obtain the specified magnification due to variations in the

After that, if the print key is operated, first turn off the ready lamp, turn on the copy lamp, and read the line sensor as shown in Fig. 5 (D) (n 30-n
32-=n 34). (At this time, the scanner has not yet started scanning.

) Obtain the actual copying magnification in register Zr from the content read by the line sensor (n36).

Specifically, find the actual magnification as followsfl)
When the reference dimension pattern is a white or black line segment with accurate dimensions, the image received by the line sensor is the output of the COD element corresponding to the length of the line segment multiplied by the copying magnification. Therefore, by counting the number of elements at the "H" level or "L" level, the length of the line segment imaged on the line sensor is determined, and the length of the line segment imaged on the line sensor is calculated. Determining the copy magnification from the length of the line segment (2) If the reference dimension pattern provided on the document table is a black and white striped pattern with a constant pitch, a striped pattern with a size corresponding to the copy magnification is imaged on the line sensor. However, because the resolution of a line sensor is determined by the pitch between each element, so-called moiré occurs.
The line sensor outputs an interference waveform.

In other words, if the spatial frequency of the striped pattern of the reference dimension pattern is FP, and the actual copying magnification is Zr, then the spatial frequency of the striped pattern imaged on the line sensor is fp=FP/Zr.
It is expressed as If the resolution of the line sensor is FS, the output waveform of the line sensor is f-fp-FS = FP/Zr-FS Therefore, the actual copying magnification is determined as Zr = FP/ (f + FS).

The actual copy magnification Zr is determined as described above, and if this value is thicker than the specified copy magnification Z, the lens motor is driven by +1 step to lower the copy magnification (n42).
. If Zr is smaller than 2, the lens motor is driven by -1 step to increase the copying magnification (n44).

The above process from reading the line sensor to driving the lens motor is repeated, and if the actual copying magnification Zr approximates the specified copying magnification Z within a certain range, the copying process is executed and the copy is made (n38 -n46), when copying is completed, the copy lamp is turned off and the process returns to the key reading routine (148-n14→).

In the above example, the copy magnification is directly input using the numeric keypad to make a copy, but the copy magnification can be specified using the zoom up key or the zoom down key.

When the zoom up key is operated, as shown in FIG. 5(C), if the currently specified copy magnification Z is less than the predetermined upper limit of the copy magnification Z□, Z is set to 0.001.
(n50-n52) If the zoom down key is operated, subtract 0°001 from Z if the currently specified copy magnification Z exceeds the predetermined lower limit of copy magnification Z 5iri. (n 54 → n 5
6).

In the embodiment, the position of the zoom lens is finely adjusted just before the print key is operated and the copying process starts, but the fine adjustment may also be made when the copying magnification is specified, or The fine adjustment may be made only when the print key is operated immediately after the change.

Further, although the embodiment uses a pulse motor as the lens motor, it is also possible to control the position of the lens by a feedback system using a DC servo motor.

Furthermore, although the example has been described in which the reference dimension pattern is provided at the end of the document table, the reference dimension pattern may be provided near the document table, for example, on the document cover.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the overall configuration of a variable magnification copying machine according to an embodiment of the present invention, in which (A) is a Saturday/Sunday view, and (B) is a front view. Figure 2 is a diagram showing the relationship between the photoconductor of a street copying machine and a line sensor (image sensor) installed close to the photoconductor, and Figure 3 is a diagram showing the relationship between the photoconductor of a street copying machine and a line sensor (image sensor) installed in the vicinity of the photoconductor, and Figure 3 is a diagram showing the relationship between the photoconductor of a street copying machine and a line sensor (image sensor) installed in the vicinity of the photoconductor. Figure 4 is a block diagram of the control section of the copying machine, Figure 5 is a diagram showing the position of the standard dimension pattern,
Figures (A) to (D) are flowcharts showing the processing procedure of the control section. 1-Original table, 2-Original cover, 3-5 Semi-dimensional pattern, 4-Zoom lens, 5.6.7
．． 8-mirror, 9-photosensitive drum, 10-copy lamp, 11-line sensor (image sensor).

Claims (1)

[Claims] (1) Copying comprising an optical system that images an original placed on a document table onto a photoconductor via a zoom lens, and a zoom lens drive means that moves the zoom lens according to a specified copying magnification. In the machine, a reference dimension pattern is provided on the document table or in the vicinity of the document table, an image sensor is provided close to the photoconductor to receive an image of the reference dimension pattern, and the zoom lens driving means is provided with a reference dimension pattern. The present invention is characterized by comprising error detection means for determining a driving error of the zoom lens according to the output signal and the specified copying magnification, and a correction means for correcting the driving error of the zoom lens according to this error. Variable magnification copying machine.