JPH02127634A - Original illumination device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an original illumination device that automatically measures the density of an original in an image forming apparatus or the like.

(Prior Art) Generally, when measuring the density of a document, the document is illuminated by lighting the illumination device at a predetermined amount of light at the home position or at a position moved several millimeters to several centimeters from the home position. The reflected light is once detected by a measuring means, and the density of a predetermined area of the document is measured.

(Problem to be Solved by the Invention) However, the reflected light from the lamp that illuminates a predetermined area of the document is diffusely reflected by the document white board, etc., and reaches the density measuring means via a reflective mirror, so that The density of the original cannot always be measured at the position where the optimum amount of light (the strongest amount of reflected light) can be obtained because the density changes due to adjustments to the position of the home position sensor and the position of the reflection mirror. Ta.

For this reason, during the manufacturing process of the document illumination device, it is desirable to adjust the position so that the density of the document can always be measured with the optimum light intensity. When this happens, errors occur in the position adjustment.

This invention is intended to solve the above-mentioned problems.The present invention memorizes the position of the illumination means when the strongest amount of reflected light is obtained, and automatically moves the illumination means to the memorized position when measuring the density of the document thereafter. Therefore, it is an object of the present invention to provide an original illuminating device that can always measure the original density using the strongest amount of reflected light.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes an illumination means that moves at a predetermined speed and illuminates a document, an optical path means that guides reflected light during illumination to a light receiving section, and a A density measuring means for measuring the density of a predetermined area of a document, a density storing means for storing the density, a comparison/calculating means for comparing and calculating a plurality of density measurement values, and a position detection of the illumination means at the time of density measurement. a position detecting means for detecting the position of the illuminating means; a position storing means for storing the position of the illuminating means detected by the position detecting means; and a controlling means for automatically moving the illuminating means to a position where the strongest reflected light μ is obtained. It is something.

(Function) The function of the present invention based on the above configuration is to sequentially measure the amount of light reflected from the original by the illumination means with the density measuring means, compare and calculate the measured values, and store the position δ of the illumination means to detect the strongest reflection. The illumination means is automatically moved to the position where the light is obtained.

(Example) Next, the present invention will be described based on an example shown in the accompanying drawings.

Figure m1 is a sectional view of an image forming apparatus 200 to which the present invention is applied. In the figure, an original l is illuminated by an illumination means S consisting of an illumination lamp 2 and reflectors 3a and 3b, and the reflected light is transmitted through a slit 4.m1. 1st. Second. 3rd and 4th mirrors 5, 6, 7.8
The photoreceptor drum (light receiving section) 10 is exposed to light by an optical path means K such as a zoom lens 9. SI is an AE sensor (density measuring means) that measures the density of the original by reflected light when illuminating the original, and S2 is a home position sensor (density measuring means) that detects whether the illumination means S is located at the home position.
26 is a white board for determining the position of the document l.

The photosensitive drum IO is uniformly charged by the -order charger 11 and then exposed to one image, and the charges in the non-image area are erased by exposure from the exposure lamp 12. Thereafter, the electrostatic latent image on the photosensitive drum 10 is visualized by the developing device 13, and the developed image is transferred from the cassette 14 onto the transfer material 17 fed by the paper feed roller 15 and the registration roller 16. The image is transferred by being charged by the transfer charger 18.

This transfer material 17 is conveyed by a conveyor belt 19, fixed by a fixing device 20, and discharged onto a tray 2z by a discharge roller 21. After the transfer, the photoreceptor drum 10 is charged with a charger 23 to eliminate residual toner, and then cleaned by a cleaner 24 and roughly erased by an erase lamp 25.
The residual charge is removed by the process to prepare for the next copy.

Note that this image forming apparatus is capable of stepless magnification by moving the zoom lens 9.

FIG. 2 shows a moving mechanism of the optical system including the illumination means S. A stepping motor 50 and a clutch 51 . A wire 28 is wound around the pulley 27 which is connected to the pulley 56 through the wire 57 . This wire 28
is wound around pulleys 29 and 30 that are rotatably supported by the main body of the image forming apparatus 200, and further wound around a double pulley 32 that is rotatably supported by the support 31 of the second mirror 6. and both ends 28a.

28b is fixed to the main body.

On the other hand, the first mirror 5 and the support body 33 of the illumination lamp 2 are
It is fixed to the wire 28 by a mounting bracket 34. A detection plate 33a is provided on this support 33, and a home position sensor S detects passage of the detection plate 33a.
2 to control the mechanical operation.

The above mechanism moves the first mirror 5 at a moving speed V, while the second mirror 6 is moved at a moving speed V/2.

Next, a mechanism for moving the zoom lens 9 will be explained. The zoom lens 9 is supported by a lens holder 36, and the lens holder 36 is movable by a rail shaft 37 and rollers 38. Further, the lens holder 36 is connected to a wire 40 by a mounting bracket 39, and the wire 40 is connected to a clutch 51 by a motor 50. The zoom lens 9 is configured to be moved by being moved by a pulley 42 that is rotationally driven via a pulley 58 and a wire 59. 1 does not show the loop at the other end of the wire 40, and the stop position of the zoom lens 9 is determined by calculation from the position where the position detection section 36a provided on the holder 36 passes the sensor 43. Ru. Furthermore, a gear 44 attached to a zoom ring (not shown) is meshed with a rack 45, and the focal length of the zoom lens 9 can be changed by rotating the zoom ring as the zoom lens 9 moves. It is done.

Figure i3 is a block diagram showing the main circuit configuration of the above embodiment. ioo is an operation unit including copy modes such as reduction and enlargement, transfer paper selection buttons, etc., and the operation unit 100 includes a microcomputer 101a and a ROM (fixed storage device) 101b.

The main body control unit lO1, which is connected to the main body control unit (control means) 101 including a RAM (uniform speed retrieval storage device) 101c, is connected to the AE sensor S1 and the home position sensor S2, and also controls the illumination. A light amount control unit 103 and a stepping motor 50 that control the light amount of the lamp 2
The motor drive unit 102 is connected to a motor drive unit 102 that drives the motors.

The ROMI Ol b built in the main body control unit 101 is
Stores the measured values of the AE sensor S+ and stores them in RAM10.
1c is for comparing and calculating the measured values. Also,
The RAM stores the position of the lighting means S detected by the home position sensor S2.

Next, the operation of the above embodiment will be explained based on the flowchart of FIG.

First, the operator places a document with the same density on the document table (for example, copy paper) on the document table, and presses the operation section 10.
0 to issue a command to start the operation mode of this embodiment, the stepping motor 50 is driven via the motor/drive unit 102, regardless of whether the illumination means S is in the Bauhm position or not. The detection plate 33a is correctly set at the home position (step 2), which is a position where the detection plate 33a has moved several steps by the number of steps of the stepping motor 50 from the position detected by the backward movement. In terms of body A, when the detection plate 33a provided on the support body 33 crosses the home position sensor S2 (usually stopped in this state), the output signal 5CHP of the home position sensor S2 is "1". and
When this is not the case, 5CHP becomes 10'', so support 3
When 5CHP = 1 after moving 3 backwards, support 33
is located at the home position of the 0th order,
Turn on the illumination lamp 2 (with step (su),
When the illumination means S is advanced by 1 meter (step ■), the main body control unit 101 takes in the output of the AE sensor Sl at that time (step (4)), and the RAMI 01c stores the amount of advancement and the output value of the AE sensor Sl. do. Then, it is determined whether the illumination means S has moved forward by a predetermined amount (step ■).
a, 3b, and 5.6 are moved above the AE sensor S] and the reflected light from the original l cannot be measured.

Here, if the robot has not moved forward by a predetermined amount, steps (2) and (2) are repeated. Through this repetition, data on the relationship between the position and the amount of light as shown in FIG. 5 is obtained.

This is because, as shown in FIG. 6, the light from the illumination lamp 2 is diffusely reflected by the reflectors 3a, 3b and the white board 26 to illuminate the original l. As the distance increases, the diffusely reflected light decreases,
This is because the measurement level of the AE sensor s1 becomes low.

When all the reflected light amount measurements have been completed, the data with the largest amount of reflected light is selected from the sampled data, and the amount of advance, that is, the position, of the illumination means 2 at that time is stored in the RAM 101c (step ■). The means S is returned to the home position, the illumination lamp 2 is turned off, and the operation is completed (step 2).

Thereafter, at the time of data sampling in the normal AE mode, the illumination means S will automatically advance based on the amount of advance stored in the main body control section 101 at this time.

In the embodiments described above, the drive motor 50 was a stepping motor, and the stop position of the illumination means S was accurate. However, an embodiment will be described in which the most commonly used DC motor is used. Even if a DC motor rotates at a low speed, it cannot achieve stopping precision like a stepping motor, but if it is moving at a constant speed, its position can be determined accurately in terms of time, so you can take advantage of that point. The operation will be explained below based on the flowchart shown in FIG. 8. However, in this embodiment, the motor drive section 102 shown in FIG. do.

As in the previous embodiment, a white original is placed on the original table, and the operation unit 100 is operated to start the reflected light amount measurement operation. First, the illumination means S is set to the home position. In this case, the DC motor is driven at a constant speed over a distance where the illumination means S moves a few millimeters. The detection plate 33a is removed from the home position sensor S2,
Return to the home position from more than a few centimeters away.

The timer is activated from the point where the home position sensor S2 detects the detection plate 33a, and is stopped when the home position sensor S2 has entered the LC layer. This position becomes the home position (step [phase]), although the 1-2 layer intestines will vary depending on the machine.

Next, the illumination lamp 2 is turned on, and the control unit 10
Write O as an initial value to the processing variable X of the microcomputer in 1 (step ■), and advance the lighting means S (
Step Q), the speed at this time is slow, just like the step [phase], it becomes constant over a few millimeters,
When the detection plate 33a passes through the home position sensor S2, the speed is constant. Detection plate 33a
Waits for it to escape from sensor S2 (step o).

Furthermore, start an addition timer for count value X (
step [phase]), this timer is a well-known one that is configured by interrupts of a microcomputer in the control unit IO1, and has a resolution of step qΦ of the illumination means S.

Just match the time it takes to advance by 1■ when you move with @.

Wait for the timer to be incremented, i.e. wait for the illumination means S to move 1 mm, then the value of X and the constant Y
(Step O).

This value of Y is the limit value at which data can be sampled, as in the previous embodiment. The count value X and the output sample value of the AE sensor S1 at this time are stored in the RAM (step O), and steps [phase] to 0 are repeated until the count value 111jx becomes equal to Y. When all the data samples have been sampled, the best value of the data (the value with the strongest amount of reflected light) is determined, the value of X at that time is stored in RAM (step O), the illumination means S is returned to its home position, and the The lamp 2 is turned off to end the operation (step O).

Thereafter, the illumination means S will automatically move based on the value of X at the time of AE sampling during normal copying.

In the above embodiment, the light-receiving unit IO is a photoreceptor drum, and the application is applied to a device that forms an electrostatic latent image on the photoreceptor drum 10. However, the present invention is not limited to this. It can also be a department.

(Effects of the Invention) Since the present invention is configured as described above, by measuring the amount of reflected light from the -degree original, A
During E processing, an excellent effect is achieved in that the illumination means can always be automatically moved to a position where the strongest amount of reflected light is obtained, that is, a position most suitable for document density measurement. Therefore, even if the position adjustment becomes incorrect when a service person replaces parts or performs readjustment in the event of a failure, there will be no problem as long as the operation of this embodiment is performed.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 to 8 show embodiments of the present invention. FIG. 1 is a sectional view of an image forming apparatus to which the present invention is applied, and FIG. 2 is a cross-sectional view of an optical system including an illumination means. Partially omitted perspective view showing the moving mechanism, 3rd
The figure is a block diagram showing the main circuit configuration of the image forming apparatus shown in Figure 1, Figures 4 and 8 are flowcharts showing the operation, and Figure 5 is the relationship between the forward distance of the illumination means and the amount of light measured by the AE sensor. 6 and 7 are sectional views of essential parts showing movement of the illumination means. Explanation of symbols l... Original IO... Photosensitive drum (light receiving section) lot... Main body control section (control means) 101a... Microcomputer ■ b... ROM C... RAM 5...・Illumination means Sl...AE sensor (concentration measurement means) S2...Home position sensor (position detection means) Patent applicant Canon Co., Ltd.

Claims (1)

[Scope of Claims] An illumination device that moves at a predetermined speed to illuminate the document; an optical path device that guides reflected light during illumination to a light receiving section; and a density measurement device that measures the density of a predetermined area of the document based on the amount of reflected light. , a concentration storage means for storing concentration, a comparison/calculation means for comparing and calculating a plurality of measured concentration values, a position detection means for detecting the position of the illumination means at the time of concentration measurement, and a position detected by the position detection means. A document illumination device comprising: a position storage means for storing the position of the illumination means; and a control means for automatically moving the illumination means to a position where the strongest amount of reflected light is obtained.