JPS60179718A - Quantity of light controlling device - Google Patents

Abstract

PURPOSE:To stably obtain the most suitable quantity of light, by controlling the quantity of light in accordance with a detected output after a prescribed time has passed from the commencement of power supply to a light source. CONSTITUTION:The photosensitive body of a drum 32 is composed of an insulating layer, photoconductive layer, and conductive layer from the surface and, when a surface charged with electricity by a charger 35 reaches its exposure surface, plus electric charges are removed by a minus charger 36 and optical image and a high-contrast electrostatic latent image is formed on the drum surface with light from a lamp 60. The latent image is developed to an apparent image at a developing area and transferred to a transfer paper by the plus electric potential of a transfer charger 39. The drum 32 surface is succeedingly cleaned with a blade 53 after completing the transfer and subjected to memory removal by removing the electricity on the surface with a charger 58. A platen 31 moves in the direction opposite to the arrow after an original is exposed and returns to the position shown in the figure. Therefore, malfunction in the control can be eliminated and stable quantity of light control can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a light amount control device, and particularly to a light amount control device effective for controlling the amount of light emitted from a light source for exposing a document in a copying machine or the like.

[Prior art]

Generally, in a copying machine or the like, in order to obtain a copy, an image of an original is exposed to light using a light source such as a fluorine lamp or a fluorescent lamp provided in the machine. In such a copying apparatus, the amount of light from the light source has a considerable effect on the density of the reproduced image, and it is necessary to stabilize the amount of light.

A control method for keeping the amount of light from a light source constant involves voltage control to keep the voltage applied to the light source constant. Therefore, it is difficult to obtain stable exposure with a predetermined amount of light by simply keeping the applied voltage constant.

Therefore, it is possible to detect the amount of light emitted by the light source and use this to control the energization of the light source, but if the energization is controlled based on the data detected when the light source's light emission is unstable,
There is also a possibility that the light source may be energized more than necessary, or hunting may occur.

〔the purpose〕

The present invention has been made in view of the above points, and provides a light amount control device that can stably obtain an optimal amount of light from a light source. and a control means for controlling energization of the light source according to the detection output of the detection means, and the control means controls according to the detection output a predetermined time after the start of energization of the light source. The present invention provides a light amount control device that operates.

Inside 31 is a platen on which a document is placed and moves back and forth; 32 is a rotatable drum having a seamless photoreceptor around its periphery;
9 is a fluorescent lamp for exposing the document image on the platen 31 onto the drum 32; 35 is a corona charger that charges the photoreceptor surface in advance; 36 is a corona charger that removes negative charge from the photoreceptor surface together with the exposed image; 38 is an electrostatic A developing device for developing a latent image, 39 a charger for transferring the developed image onto a transfer paper 40, 41 a cassette storing a large number of transfer papers 40 and detachable from the main body, 42 a stand for manually feeding the transfer paper 40;
43 is a roller that feeds the transfer paper from the cassette; 44 is a roller that feeds the transfer paper from the manual feed table 42; 45.46
4 is a microswitch for detecting manual transfer paper; 47 is a registration roller for aligning the leading edge of the transfer paper with the leading edge of the drum image; 48 is a roller for separating the transfer paper from the drum;
9 is a belt for conveying the transfer paper, 50 is a fixing roller, and 51 is a roller for discharging the transfer paper onto the tray 52.

53 is a blade cleaner that removes residual toner from the drum; 54 is a magnetic roller that collects the toner removed by the blade 53; 57 is a container that stores the toner collected by the roller 54; and 58 is a negative charger that removes the residual charge from the drum. The corona charger 60 is a lamp that directly applies light to the drum surface, and the reference numeral 13 is a short focus lens array that focuses the reflected light from the document of the fluorescent lamp 9 on the drum surface.

Explain the operation. When a copy switch (not shown) is turned on, the fluorescent lamp 9 starts lighting, the platen 31Fi starts moving forward in the direction of the arrow, and the document on the platen 31 starts slit exposure. The image reflected from the document by the fluorescent lamp 9 is slit-exposed onto the drum 32 via a short focus lens array. The photoreceptor of the drum 32 is composed of an insulating layer, a photoconductive layer, and a conductive layer from the surface, and when the surface charged by the charger 35 reaches the exposed surface, the positive charge is eliminated by the negative charger 36 and the amount of light. When that surface reaches the uniformly exposed surface, the light from the lamp 60 forms a high contrast electrostatic latent image on the drum surface. Toner is applied to the development area to develop the latent image.

The visible image is transferred to the transfer paper by the positive potential of the transfer charger in the transfer area. The transfer paper is one sheet separated from the cassette 41 and fed by the timing operation of the paper feed roller 43, and is passed through the transfer area by the registration roller 47 at the same speed as the circumferential speed of the drum.

After the transfer, the transfer paper is separated by a roller 48, sent to a fixing roller 50 by a belt 49, where the image is fixed, and then discharged onto a tray 52 by a roller 51. After the transfer is completed, the drum surface is subsequently cleaned by the blade 53, and the charger 58 eliminates the charge and removes the memory.

Further, the platen 31' moves in the direction opposite to the arrow after the original a-exposure is completed, and returns to the position shown in the figure.

FIG. 2 is a diagram showing the configuration of the exposure section of the copying machine shown in the first figure. Note that this is a view of the first illustrated device from the back side, and that the directions are reversed.

That is, FIG. 2 shows the installation state of the light intensity/PWM conversion elements (for example, ABC sensor manufactured by TRW 0PTRON, hereinafter referred to as aBC sensor) 15 and 16 in this embodiment, and 9 is a fluorescent lamp.

Reference numeral 10 denotes a contact glass on which a document is placed, 11 a contact glass on which the document IO is placed, and 12 a contact glass 1 with light emitted from a fluorescent lamp 9.
Reflection casting 1.1 for efficiently irradiating the original lO on 1
3 is a short focus lens A 1/A for forming an optical image of the reflected light 1 of the original 10 onto a photoreceptor (not shown); 14 is A;
A cover 18 masks direct light from the fluorescent lamp 9 to the BC sensor 16, and is a standard reflector (white) used as an initial reference value when using AE. Further, arrow A indicates the direction of movement of the document table including the contact glass 11 during the exposure travel strain of the W document.

FIG. 3 is a block diagram of a control section which is an embodiment of the present invention.
7 (in this embodiment, it is controlled by NEC 87AD).

Incidentally, a signal PW which is directly related to the present invention and which triggers the high frequency stabilizer 8 which outputs a high frequency signal with a predetermined period.
has a pulse width calculated and determined by the output port, and has a predetermined frequency (IKH2 in this embodiment)
), and the fluorescent lamp 9 is stably controlled based on this. The operating waveforms of the trigger signal Pw and the fluorescent lamp drive current IL output from the high frequency ballast 8 at this time are shown in FIG. T is the output period of the trigger signal Pw, which is 1 msec (IKl(Z)) in this embodiment. Also, t is the pulse width determined by the above-mentioned CPU 17. During this period t, a high frequency signal of a predetermined frequency (25 KHz in this embodiment) generated from inside the high frequency ballast 8 is applied to the fluorescent lamp 9, thereby lighting the fluorescent lamp 9.

) From the output port FAI of the CPU 17, A B C,
*A light intensity/PWM (pulse width modulation) conversion start signal for the enclosures 15 and 16 is output. This signal causes ABC sensors 15 and 16 to be connected to resistor R1, capacitor CI and resistor R.
3. Light intensity/PWM conversion is performed within the range determined by the frequency (f=i) set by the capacitor c2 and the resistors R2 and R4.

Note that the pulse width of the PWM signal is set to 200 μsec. PO2 is A that converts the direct source end of the fluorescent lamp 9 into PWM.
The PWM (No. 1 metal input port) from the B C sensor 15 is used, and the CPU 17 is satisfied with the pulse width 1i-event of this PWM No. 8. ABC sensor 16 that converts into PWM
This is an interrupt terminal and an input port for inputting the PWM signal from y56.
Used as child IN'T2. CPLI17 is this PWM
Due to the rising edge of the signal, a W+J request is made from the INTl side, and PO2 (INT2) nilitD
An interrupt request is issued due to the falling edge of the pw MIN signal that is inconsistent with the m operation. Therefore, when an interrupt request is received from INTl, the count of a predetermined counter is completely started, and the count of the counter is stopped when an interrupt request from PO2 occurs.
It is possible to perform a pulse I+11115i of the M signal. However, this pulse width side foot method using an interrupt counter is used because the CPU 17 used in this C$1/11 has only one channel of event pulse width measurement mode, and is equipped with multiple channels It is clear that if a CPU is used, it is possible to measure the pulse widths of two systems using events. The CP is driven by a motor that moves the document table including the 19-piece contact glass 11.
The drive is controlled by the output of output port PA2 of U17. Note that 2o is a driver.

In terms of control, the rise time from the start of lighting until the amount of light became stable was approximately 100 ms.

FIG. 6 is a sequence flowchart showing the CPUI 7 control procedure of this embodiment, and the program of this flowchart is stored in the built-in ROMK of the CPUI 7 in advance. -! Note that FIG. 5 (a) and (b) are timing charts showing each timer and input/output signals shown in this flowchart, and FIG. 8 (a) shows the state immediately after the start of exposure. (b) shows the state after the light amount has stabilized.First, at 5TEPI, the trigger signal Pw necessary for exposure control
Initializes the RAM, Ilo, etc. with an initial pulse width of Go back and repeat this judgment. Further, when an exposure-on signal is obtained, the process advances to 5TEP3. STEP: Turn on the signal for triggering the high frequency stabilizer 8 of pAw (output cap for VC). This causes the fluorescent lamp 9 to start high frequency lighting. Next, the light intensity of the lit fluorescent lamp 9 is measured,
If the light amount is measured immediately after the lighting starts, the light amount information will vary and it will be difficult to obtain an appropriate value. Therefore, S.T.E.
After a predetermined time of output of the lighting signal at P3 (main start), an internal timer (300
μsec) Start TMI. And 5TEP6
At step 3, it is determined whether or not the internal timer TM statement has timed up. If not, this determination is repeated, and when the time has expired, the process proceeds to 5TEP7. 5T
EP7 is an ABC sensor 5 that measures direct light from a fluorescent lamp 9.
Set the input port (PO2) that inputs the PWM signal from PO2 to pulse width measurement mode. On the other hand, at 5TEP8, interrupts are permitted for the interrupt terminal lNTl and the input port PCB (initial mode setting is INT2), which inputs the PWM signal from the ABC sensor 16 that measures the reflected light from the document 10. 5
In TEP9, the light amount of the ABC sensor 5.16/
A start signal for performing PWM conversion is output from output port FAI. In this way, since the amount of light is detected a predetermined time after the start of lighting, it is possible to eliminate the influence of variations in the amount of light at the initial stage of lighting. At this point, the document table is at the position shown in the second figure, and the ABC sensor 6 detects the reflected light from the standard reflector 18.

Up to this point, ABC sensor 5.16 has a frequency determined by resistor R1, capacitor C1, resistor R3 and capacitor C2 shown in FIG.
) and each performs light amount/PWM conversion within a dynamic range determined by resistors R2 and R4.

Based on the rising edge of the PWM signal output from the ABC sensor 15 that measures the amount of direct light from the fluorescent lamp 9, the CPU
Start counting the reference frequency (1.5 μsec in this example) obtained by dividing the oscillation frequency inside I7,
The above-mentioned ABC sensor 15 is stopped by the falling edge of the above-mentioned PWM signal, and the above-mentioned ABC sensor 15 is stopped by the event pulse width measurement mode which is the mode of PO2. The high-level width (pulse width) of the PWM signal output from can be measured. AB also measures the amount of reflected light from the original lO.
To measure the pulse width of the PWM signal output from the C7 sensor 16, first check whether an interrupt is generated by the rising edge of the PWM signal (by the rising edge interrupt function on the interrupt terminal NTl side). At this point, the CPU 7 starts counting the software timer. To explain this software timer in detail, it first consists of an instruction to add a predetermined RAM-M and a branch instruction to add the predetermined RAM until a predetermined condition is reached. In the example, the minimum resolution is approximately 4 μsec), and the timer using the above-mentioned event is a different timer.The predetermined RAM is RO, P as shown in the flowchart shown in the sixth figure. The predetermined condition is the falling edge of the P and WM signals described below.
In the above case, the signal is input by the same person and is started by the interrupt function of DINTll, where an interrupt is generated at the falling edge of the PWM signal by INT2, which is the mode of PO2 (an input capo which is a different terminal from the interrupt terminal lNTl). Stop the software timer.

Therefore, through these operations, the CPU 7 converts the amount of light reflected from the original document 10 to the high level width of the PWM signal converted by the ABC sensor 16, and converts the amount of direct light from the fluorescent lamp 9 using the ABC sensor 15. It is possible to measure the width of the high level of the PWM signal. However, as mentioned above, if a CPU with multiple functions similar to the pulse width measurement mode is used, pulse width measurement becomes even easier. is also possible. Furthermore, in the example explained above, since the pulse width is at most 200 μsec as mentioned above, all processing has been completed or not completed until the internal timer ffTMl (300p sea) of 5TEPlO time-up. If there is an abnormal situation, a notification may be made.

Next, at 8TEP1O, determine the time-up of the internal tie-fTM1, and repeat this determination until the time-up.
Go back and proceed to 5TEPII due to time up.

5TEPII is ABC sensor 15.16 light intensity/PWM
Change start signal - turn off the unusual output boat FAI. 5TEP12 disables the constant pulse width ll1li mode of the manual boat PC5, and in STgP13 disables interrupts of each terminal in the pulse width measurement mode of the interrupt terminal PC NT1-human boat PC3.

Next, in 5TEP14, the FLAG (flag) is determined.As will be described later, the FLAG indicates that the fluorescent lamp 9 has a predetermined light intensity (in this embodiment, the stable light intensity of the fluorescent lamp 9 is set to 100).
The FLAG does not turn on and remains at 0 until reaching 80%), and is set to 1 when the fluorescent lamp 9 reaches a predetermined amount of light. Until the fluorescent lamp 9 reaches a predetermined amount of light, the lamp is at full power (in this embodiment, it is 15φ0
．． This is a control switching FLAG for starting PWM control for stabilizing the fluorescent lamp 9 and applying AE (automatic exposure) driving when the fluorescent lamp 9 is driven at approximately IA) and a predetermined light amount is reached. Therefore, when FLAG is not set, proceed to 5TEP26, and compare the data corresponding to the predetermined light amount (80% light amount) with the stored measurement data obtained by measuring the direct light amount of the fluorescent lamp 9 as described above, If the measurement data is less than the predetermined light amount, proceed to 5TEP28 without performing FLAG processing, and if it is greater than the predetermined light amount, proceed to 5TEP28.
After setting rFLAG in 27-1, KSTEP2
In step 7-2, the amount of light reflected from the original standard reflector 18 is converted into predetermined data (reference light amount) according to the conversion table stored in the built-in ROM of the CPU 17, calculated in advance from the measured ROP value, and the standard Memorize the amount of light. The document table (including the contact glass 11) is stopped in the state shown in FIG. 2 until the fluorescent lamp 9 reaches a predetermined light intensity (SO%), and when it reaches the predetermined light intensity (80%), the standard reflection Based on the amount of light reflected from the plate 18, the amount of light f for exposing the original is set, and the original table starts moving in the direction of arrow A shown in FIG. 2, entering the normal copying process mode.

Next, 5TEP2BK 1. -+-( Fluorescent lamp 9 lKH2
In order to perform PWM control at the frequency of
Start the internal timer ETMI, which has been set as much as possible (700 psec in this embodiment), and set the time-up of this internal timer ETMI to 1000 psec.
The KH2 reference frequency is used. At 5TEP25, it is determined whether the internal timer ETMI has timed up, and if the time has not expired, the determination is repeated; if the time has expired, the process returns to 5TEP2. The timing chart in FIG. 8(a) shows the operation of each part in a state where the predetermined amount of light has not yet been reached after the exposure has been turned on.

Also, if FLAG is 1 in the determination of FLAG in 5TEP14, the process advances to 5TEPls-1, and in S TEP15-1, the document table movement amount detecting means (not shown) (also by counting the number of pulses of a pulse generator that generates pulses due to the rotation of the motor) The CPU 17 determines whether the amount of movement of the document table input to the PCI has reached a predetermined amount.

By the way, the feedback timing of AE control, which is automatic density control in real time, is normally determined by the width given to the document surface of the means for applying the feedback, that is, in this embodiment, since it is performed on the light intensity side of the fluorescent lamp @+, the feedback timing is short. It is obtained from the relationship between the slit width of the focusing lens array, the focal point, and the reflected light detection position. However, whether these values are added or subtracted depends on the moving direction of the document table and the positional relationship between the short focus lens array and the reflected light detection element. Preferably someone who can read things well.

If the predetermined distance has not been reached, proceed to STEPM6, use the previous predetermined data (reference light amount), and measure the predetermined distance FC.
If it has been reached, the manuscript 1 mentioned above in 5TEP15-2
0 reflected light amount - is calculated in advance from the measured ROP value and R
Conversion is performed into predetermined data (reference scene) using a conversion table stored in the OM.

Thereby, the reference light amount is updated according to the image density of the original cloth sieve.

To explain these processes in detail, the short focal length lens eye 13 and the reflected light detection element 16 are positioned as shown in FIG. In the figure, a is the slit width of the short focus lens array.
btliABc is the slit width of the sensor 16, and a and b
The positions of each part are determined so that they are equal. When each part is positioned as shown in this figure, the predetermined distance ll? (S
TEP15-1) corresponds to a (=b). That is, the incident light to the ABC sensor 16 is guided by the short focal length lens array 13 onto the photoreceptor at a distance M,
It is from an area a ahead, and is also ahead in time. Therefore, in order to correct the amount of deviation (a) between the detection area of the reflected light from the document by the ABC sensor 16 and the transmission area of the reflected light of the document by the short focus lens array 13, the light amount control by reflected light detection is performed. This is to delay the time by the amount of the shift. That is, the current amount of light emitted by the fluorescent lamp 90 is determined by the reference light amount data obtained immediately before, and the reference light amount based on the currently detected reflected light is set to the amount of light emitted immediately thereafter. By doing so, the original is exposed with a light amount corresponding to the density of the original (including the background) at the exposure position. Therefore, copying according to the density of the original can be automatically executed without the operator's intervention.

Next, 5TEP16.5TEP1.7.5TEP18.
5TEPI 9. In the processing of 5TEP20 and 5TEP21, first, the above-mentioned direct light amount measurement data of the fluorescent lamp 9 is compared with the above-mentioned reference light amount, and the trigger signal PW, which is set as an initial value in 5TEPI, is used to perform PWM control of the fluorescent lamp 9. PWM pulse width (in this example, the initial value is 780μEle, and the actual internal timer T
4 80 p sec minus 300 p sec of MI
e), processing is performed based on the following conditions. First, if the comparison results of the fluorescent lamp 10 direct light amount measurement data and the reference light amount based on the reflected light amount are equal, the current P
Processing for the WM pulse is not performed; if it is greater than or equal to 1 (corresponding to 1.5 μsec), the PWM pulse is subtracted by 1 (corresponding to 1.5 μsec), and if it is less than the PWM pulse, f] is added. In the embodiment, addition and subtraction are performed one at a time, but the number is not limited to this), and the newly obtained pulse width data of PWM○ is transferred to the internal timer TMΦ and the timer start cell.

Next, in 5TEP22, the reference frequency internal timer ETMI (700, czsec) is started, and in 5TEP23, the time-up of the internal timer ETMa started in 5TEP21 is determined.
This judgment is repeated until the internal timer ETMΦ times up, and if the time-up occurs, the process advances to 5TEP24. At 5TEP24, the output point PAa, which is the trigger signal for the high-frequency stabilizer 8, is turned off.Furthermore, at 5TEP25, it is determined whether the internal timer ETMI for the reference frequency has timed up, and this determination is made by the time aggregation method. After repeated time-up, return to 5TEP2. Then, from 5TEP3 to 5TEP described above until the exposure ON signal is turned off.
The processes up to 25 are repeated, thereby achieving stable and highly accurate light control. Based on the light spear detection by the ABC sensor 6, conditions for omitting AE control should be added, and the operator should be able to set the exposure amount manually, auto-manual switching, and the above-mentioned internal timer. In addition and subtraction during pulses of PWM for ETMa transfer, it is clear that the lower and upper limits during the pulses can be set. The operation of each part in the scene control after the fluorescent lamp 9 reaches a predetermined light intensity is shown in the time chart of FIG. 8(b). In the 81st%l(b), the pulse width is expanded to clearly show the control operation, and in actual control, the fluctuation of each pulse is μS.
It is ee order.

The present invention has been described above based on an embodiment in which the present invention is applied to a copying machine with a movable document table. However, it can also be applied to a copying machine in which the document table is fixed and the optical system moves, or to other devices other than a copying machine, such as a facsimile or a digital copying machine. Needless to say, the present invention is applicable not only to image forming apparatuses such as double, E, and other image forming apparatuses, but also to any apparatus that requires control of the amount of light from a light source. Further, although this embodiment uses a fluorescent lamp as a light source, the present invention is not limited to this, and for example, a halogen lamp or the like may be used. Further, a light source driven by a power source other than a high-frequency power source is also applicable. Furthermore, the position of the light amount detection element can be changed as appropriate depending on the mechanism of the apparatus, the sensitivity of the element, and other characteristics.

Although the present invention has been described with reference to one embodiment as described above, numerous modifications can be made within the scope of the present invention as set forth in the claims.

/ / [Effect] According to the present invention described above, control malfunctions that tend to occur during unstable lighting in automatic control of light amount can be eliminated, and stable light amount control can be executed. It is something.

[Brief explanation of the drawing]

Fig. 4 is a diagram showing the state of the fluorescent lamp drive current, Fig. 5 is a diagram showing the amount of light versus time, Fig. 6 is a flowchart showing the control program, Fig. 7 is a diagram showing the arrangement of the exposure section, 8(a) and (b) are timing charts showing the status of each part during control operation, 9 is a fluorescent lamp, 10 is a public manuscript, 16 companies' short focus lens array, 15 and 16 are optical certificates/P
WM conversion element (ABC sensor), 18 is a standard reflector, 1
7 is a CPU. Applicant Canon Co., Ltd. Agent Gi Marushima 11 units!

Claims (1)

[Claims] It has a light source that turns on when energized, a detection means that detects the amount of light emitted by the light source, and a control means that controls energization of the light source according to the detection output of the detection means, and the control means controls the energization of the light source. A light amount control device 0 characterized in that a control operation is performed according to the detection output after a predetermined time from the start.