JPS60165872A - Proper density setting system in picture processing - Google Patents

Abstract

PURPOSE:To attain proper picture processing without trial copying by updating the state of initial density set automatically at reset and power-on into proper density detected a check of frequency or the like. CONSTITUTION:When the power is turned on, the initial state is set at first and a 1min timer is activated during standby and when the time is over, the density is set automatically to a middle value. When 2hr are elapsed, ''proper exposure state correction'' and ''exposure state counter clear'' are conducted, the 2hr timer is reset, the proper exposure position is detected automatically and set to the proper density. If a characteristic change takes place in a photosensitivity body 3 or the like and the proper density is shifted from the position of a mark MB, the density level is updated automatically to a correct level by this processing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to the setting of image reading density, recording density, etc. when processing an image, such as for copying, and particularly relates to automatic setting of appropriate density.

(2) Prior Art For example, in an electrostatic recording type electrophotographic copying machine, a photoreceptor is used in the image reproduction process, but the charging characteristics, that is, the image reproduction characteristics of this type of photoreceptor change considerably over time. In addition, when the original image reading optical system used in this type of device becomes dirty due to changes over time, the amount of exposure to the photoreceptor changes.If this type of characteristic change occurs, the recorded image The concentration of changes. Therefore, in order to always make copies with proper density, it is necessary to readjust the density setting.

In general, this type of apparatus is equipped with a manual operation function to handle various types of originals with different densities, and also to cope with density changes as described above. In the initial state immediately after the power is turned on, the concentration is set to a predetermined state adjusted in advance at a factory or the like.

Therefore, under normal conditions, copies can be made at appropriate density immediately after the power is turned on. However, if the characteristics of the device change due to changes over time, the initial concentration will deviate from the appropriate concentration. changes), and after confirming that the results are correct, make a predetermined copy, which is a wasteful and troublesome task.

(1) Purpose It is an object of the present invention to perform appropriate image processing without performing trial copying or the like even if the characteristics of the apparatus change due to changes over time.

■Configuration If the initial density deviates from the appropriate density due to changes over time, the operator of the device will have to perform key operations to adjust the density, and the set density when image processing is actually performed is considered to be close to the appropriate density. be able to. Therefore, 1. For example, if the set density is step-like, if the number of times the setting state is used for image processing for each set density of each step is memorized, the appropriate density can be determined by comparing the frequency. . That is, the state with the highest frequency is the state of appropriate concentration. If the density setting is continuously variable, the setting state may be quantized by A/D conversion and then stored and determined. Also, the frequency can be detected by counting the number of times; instead, by integrating the time.

Therefore, if the state of the initial density, which is automatically set at the time of resetting and turning on the power, is updated to the appropriate density number detected by checking the frequency, etc., image processing can be performed at the appropriate density at all times.

For example, there are devices, such as copying machines, that are kept powered on all the time depending on their use, and do not require manual reset for a long time. In such a case, it is preferable to perform an automatic reset every predetermined time or every predetermined process, and to set the initial density to an appropriate density.

For example, in the case of a copying machine, there are cases in which one copy is made from one original, and there are cases in which many copies are made from one original. In order to measure the frequency of density used, it is preferable to count the density for each document.

In the latter case, the operation will be more stable after a large number of copies have been made, especially immediately after the power is turned on, and the operator may make appropriate density adjustments during copying. Therefore, in one preferred embodiment of the present invention,
At the final stage of the series of processes, the set density is detected and the frequency is counted for each document.

The present invention will be described in detail below with reference to one drawing.

FIG. 1a shows a schematic configuration of one type of copying machine embodying the present invention.

The schematic structure of the apparatus will be explained with reference to FIG. 1a.

1 is the contact glass on which the original is placed. An optical scanning system 2 including an illumination lamp LP is provided below the contact glass 1, and an image formed by light reflected from the original is formed on the photoreceptor drum 3 via the optical scanning system 2. The photosensitive drum 3 rotates in the direction of the hour hand in FIG. 1a.

The paper feed system has two stages, and recording paper is fed from a selected one of paper feed cassettes 4 and 5 by paper feed rollers 6 and 7. The fed paper passes between the registration roller 8 and the tip folding roller 9 and is then placed on the photoreceptor drum 3.
be guided by.

Around the photoreceptor drum 3, a charger 10° eraser ll, 1!1. Statue @l 2. Pre-transfer static elimination lamp &P
Sensor 13. Transfer charger 142 Separation charger 15
．． Separation claw 16. Fur brush 17. A static elimination lamp 18 and the like are arranged.

To explain the general copying process, the photosensitive drum 3 is charged to a uniform potential by the charger lo, and when it is irradiated with reflected light from the original, the surface potential changes depending on the light intensity. An electrostatic latent image is formed. This electrostatic latent image is made visible by toner when it passes through the i-imager 12. The fed recording paper is sent by registration rollers 8 at a predetermined timing according to the rotation of the photoreceptor drum 3, and overlaps the surface of the photoreceptor drum 3 on which the toner image is formed. Thereafter, a predetermined voltage is applied to the transfer charger 14, whereby the toner image is transferred from the photosensitive drum 3 to the recording paper side. Furthermore, the recording paper onto which the toner image has been transferred is separated from the photosensitive drum 3 by the separation charger 15 and directed toward the conveyor belt 19 . Then, the recording paper passes through a fixing roller 20 having a built-in heater to fix the toner image thereon, and then heads to a copy tray 22 via a paper ejection roller 21.

FIG. 1b &; shows a schematic view of the operating panel 8° of the apparatus of FIG. 1a. Referring to FIG. 1b, the operation panel 80 includes a copy paper size indicator light 83 and 84° paper cassette selection keys 85 and 86. Paper feed position indicator lights 87 and 88.
Numeric keypad (0-9) 81° Clear stop key 93. Print key & copy allowed/not allowed indicator light 92. Number of copies &
Set number display 82. Copy density display @91. Dark key (key to increase density) 89. Equipped with 90 light keys (keys for reducing density), etc.

FIG. 1C shows the copy density display 91 DEG dark key 89 and light key 9o of FIG. 1B. Referring to FIG. 1c, seven levels of copy density are displayed in this example. A mark MA provided in the center of the copy density display 91 indicates the proper density position, and is always open.
Place li! (the position of density 4 on the display 91). The marks MB are provided at seven density positions on the display 91, and one of them is displayed. In the illustrated state, the mark MB is at the appropriate density level I! (Density 4) is displayed. When you operate dark key 89, mark M
The position of B, that is, the set density changes to the darker side, and from Lie 1 to
When the key 90 is operated, the color changes to the thinner side.

In this embodiment, the copy density is adjusted by changing the exposure amount of the illumination lamp LP of the optical scanning system 2.

FIG. 2 shows the configuration of the lamp control unit LCU that controls the energization of the illumination lamp LP.

Referring to FIG. 2, the lamp control unit LC
U is equipped with a bridge rectifier ST1', an effective value detection circuit, an error amplification circuit, a power synchronization circuit, a voltage comparison circuit, a switching circuit, and the like. Briefly explain the operation. Power applied from a commercial AC power source (AClooV) is full-wave rectified by a bridge rectifier ST. An effective value detection circuit detects the effective value of the applied voltage, and an error amplification circuit amplifies the difference between this voltage and a dimming voltage set from the outside.

The output signal, that is, the error voltage, and the zero-crossing signal output from the power supply synchronization circuit (outputted at the zero-crossing timing of the power supply waveform) are compared by the voltage comparator circuit, and depending on the result, the transistor Q of the switching circuit is
8 is on/off controlled.

One end of the lighting lamp LP is directly connected to one output terminal of the rectifier ST, and the other end is connected to another output terminal of the rectifier STl via a transistor 8, etc., so that the transistor Q8 is turned on/off. Depending on the off, lighting LP
energization is controlled on/off. In this example, for each half wave of the power supply waveform, from the zero cross timing of the power supply waveform,
The lighting lamp LP is energized until the phase timing determined according to the power supply voltage and the dimming voltage. Therefore, the lighting lamp LP
The applied power, that is, the amount of fog light is determined by the dimming voltage. Note that when a low level L is applied to the input terminal of the inverter INI, energization of the lighting lamp LP is prohibited.

The dimming voltage that determines the exposure amount is set according to a 4-bit dimming control signal output from a control device (not shown). That is, when the dimming control signal is applied to the control input terminal of the analog switch AMX, the analog switch AMX grounds one of the 15 output terminals according to the 4-bit control signal.

These output terminals are connected to the error amplifier circuit through resistors with different resistance values, so if the grounded terminal changes, the voltage division ratio of the voltage divider circuit connected to one end of the error amplifier changes. The voltage applied to one end of the error amplifier, ie the dimming voltage, changes. That is, in this example, by changing the setting of the dimming control signal applied to the lamp control unit LCU, it is possible to adjust the density in 15 steps.

In this example, the value (effective value) of the voltage applied to the lighting lamp LP is set as shown in Table 1 below, depending on the combination of each pin 1-data of the applied 4-bit dimming control signal. be done.

Table 1 H is high level, L is low level.
Fig. 2a shows a schematic operation of the copying machine shown in Fig. a, mainly focusing on density adjustment. The operation will be explained with reference to each drawing.

When the power is turned on, initial settings are performed first. Specifically, it clears the memory contents, initializes the state of the I10 boat, initializes the initial values of each register, and sets the 2-hour timer (
start). During standby, "standby processing" and "density key reading" are performed to read the states of various keys on the operation panel 80 and perform processing according to the results.2 Read the states of various sensors (not shown) and perform processing according to the results. Displays operating status, setting status, etc. Note that the "standby processing" includes r-exposure control J and "density display" processing, which will be described later.

When the copying machine is in a state where copying is possible, "Copying enabled" is displayed and the state of the print key 92 is read. If the print key 92 is not pressed, the standby state is maintained,
When the print key is pressed, "copy processing" is performed.

In "Copy Processing".

Performs copy process control operations, etc. This process includes "density key reading J, r exposure $ control" and "r exposure display"
It also includes each process.

When the number of copies processed since the print key was pressed reaches the set number, "exposure state count" processing is performed. During standby, a one-minute timer is activated and the time-up is monitored. When the 1 minute timer times out,
Automatically set the density setting to the center. For example, if the current set density is 3 (the mark MB in Figure 1c is displayed at the density 3 position), the set density is shifted one step lighter, and the mark MB display position is changed to the density 4 position. Return to

After 2 hours, "appropriate exposure state correction" and r@
Clear the light status counter and reset the 2-hour timer. Each time this process is performed, the appropriate exposure position is automatically detected, and the density level corresponding to the position of density 4 displayed on the display 91 is set to the appropriate density. If the characteristics of the photoreceptor 3 etc. change during the previous two hours,
If the appropriate density deviates from the position of the mark MB, the density level is automatically updated to the correct level through this process. After this, turn on the power again, clear stop key 93
When the button is pressed, the one-minute timer times up, etc., the copy density is automatically set to the appropriate density (density 4).

Next, the operation of each subroutine will be explained, and the function assignments of the main registers used here are as follows.

RL: Density register: Indicates the value of seven density levels set by the dark key 89 and light key 90. The initial value is 4.

MIN, MAX: Minimum value, maximum value of density...Here, they are 1 and 7 (fixed values), respectively.

RCN1 to RCN7: Frequency registers each hold the number of times density levels 1 to 7 are used.

RA: Accumulator RB: Contains the most frequent concentration level.

RC: Compensation register...This content and concentration level (R
The actual exposure level is obtained by adding L). 0-8
Takes a value between. The initial value is 4.

LA, LB, LC: Flags: Used to determine the current state in density key reading processing.

Density key reading will be explained with reference to FIG. 3b.

When the density keys 89 and 90 are not pressed, O is set in each of the flags LA, LB and LC. When either of the density keys 89 and 90 is turned on, the flag LC
Check. If it is the first time, the flag LC is O.

If the dark key 89 is on, the contents of the density register RL are decremented by 1, the flags LA and LB are set to 1 and 0, respectively, the buzzer is sounded for a short time, and the 0.3 second timer is decremented.

When the dark key 89 is kept pressed, the flag LA is set to 1, so the register RL is decremented by 1 every time the 0.3 second timer times up, that is, every 0.3 seconds. However, the minimum value of RL is MIN.

If the light key 90 is on, set the flag LC to 1, increment the contents of the concentration register RL by 1, set registers LA and LB to 0 and 1, respectively, make the buzzer sound briefly, and set the 0.3 second timer. do.

When the light key 90 is held down, the flag LB is set to 1, so the register RL is updated every time the 0.3 second timer elapses, that is, every 0.3 seconds. However, the maximum value of RL is MAX.

When the lie 1-key 90 is turned off, the flag LC is set to 0.

In the "exposure control" subroutine (executed during standby processing and copying processing), the contents of the compensation register RC are added to the contents of the density register RL set as described in section 2 above, and the contents are added to the dimming register. and outputs it to the lamp control unit LCU as a dimming control signal. In the initial state, RL is 4 and the content of the compensation register RC is 4, so the dimming control signal corresponding to density number 8 in Table 1 is output, but by operating the density key 89 or 90, for example, the density register RL When the content becomes 5, a dimming control signal corresponding to density number 9 is output.

In the "density display" subroutine (executed during standby processing and copying processing), mark MB is displayed at a position corresponding to the contents of density register RL. For example, if the contents of the density register RL are set to 5 by operating the light key 90, the mark MB is displayed at the density 5 position in FIG. 1C.

The contents of the frequency registers RCN] to RCN7 are all cleared to 0 when the "exposure state counter clear" subroutine is executed, and any of the contents is changed during the "exposure state count processing". The "exposure state count" process is executed every time the print key 92 is pressed and when the copy process is completed.

In other words, when making one copy from one original, "exposure state count" processing is executed for each copy process, but when making multiple copies from one original, the setting The "n light state count" process is executed once for each copy of the number of sheets. In the "exposure state count" process, the third c.
As shown in the figure, the frequency register (any one of RCNl-RCN7) corresponds to the contents of the density register RL at that time.
+ Edit the contents of 1).

In the "appropriate exposure state correction" subroutine, the contents of seven frequency registers RCN1 to RCN7 are compared with each other, the register with the largest value is found, and the value corresponding to that register (RCN1, RCN2.RCN3.R
CN4. RCN5. 1 for each of RCN6 and RCN7. ．． 2, 3, 4° 5.6 and 7) in register R
The value of (RB-4) is added to the compensation register RC to update the contents of the compensation register RC.

If density level 4 is always used, the value of register RB will be 4, so the contents of compensation register RC will not change. However, due to changes in characteristics, the appropriate concentration position is now concentration level 4.
If the density level shifts from the position and the frequently used density level becomes, for example, density 6, +2 is added to RC. When the contents of the compensation register RC change, the value of the dimming control signal actually applied to the lamp control unit 7hLCU changes, so for example, when +2 is added to RC, the value of the concentration level 6 before the addition is changed. The same density as the position is obtained at the new density level 4 position. Therefore, a proper density can always be obtained at the position of the proper density mark MA (ilff 1 degree level 4).

Although not shown, the contents of the compensation register RC and exposure state counters RCN1 to RCN7 are stored in non-volatile memory, and if the previous data remains when the device is powered on, those values will be used as the initial values. is set in each register as .

Note that in the above embodiment, frequency registers RCN1 to RCN
The frequency of use of each density step is determined by the CN7, and the most frequently used density step is set. For example, if the density can be set continuously, the density level can be set by A/D. By integrating the values obtained by sampling through conversion and dividing the result by the number of sampling times to obtain an average value, it is possible to similarly determine the frequently occurring concentrations.

In addition, in the embodiment, the density level is changed by adjusting the exposure amount in the case of a copying machine, but in the case of a copying machine, it is also possible to change the density adjustment parameters such as the developing bias voltage. For example, in applications such as image reading, the present invention can be implemented by updating the threshold level of the part that converts analog signals into digital signals, updating reference data for density determination, etc. It can be implemented.

■Effects As described above, according to the present invention, the appropriate concentration is automatically determined and the processing concentration is automatically set to the appropriate state, so the device can be operated without worrying about changes in the characteristics inside the device. I can do it.

[Brief explanation of drawings]

Fig. 1a is a front view showing the configuration of one type of copying machine according to the present invention, Fig. ib is a plan view showing the operation panel of the apparatus shown in Fig. 1a, and Fig. 1C shows a part of Fig. 1b. FIG. FIG. 2 is an electrical circuit diagram showing the lamp control unit LCU of the device of FIG. 1a. Figures 3a, 3b, 3c and 3d are the first
3 is a flowchart showing an outline of the operation of the device shown in FIG. ■ = Contact glass 2: Optical scanning system 3: Photosensitive drum 10: Charger 12: Developer 14: Transfer charger 5: Separation charger 80: Operation panel 89: Dark key 90 Nilight key 91: Copy density indicator 92 Niblint key-MA ,M
B: Mark LP: Lighting light

Claims (4)

[Claims] (1) Equipped with a setting means for setting the concentration by manual operation,
In image processing that controls density according to either the density set by the setting means or a predetermined initial density; the used density setting state is memorized, and the density setting state used in the past is An appropriate density setting method for image processing, which is characterized by automatically updating the initial density state. (2) Appropriateness in the image processing according to claim (1), in which the density setting of the image processing is automatically set to the initial density state at least one of after a predetermined period of time and after each predetermined image processing. Density setting method. (3) The set density is stepwise, and the frequency with which the set density is used is counted for each step, and the set density that is used most frequently is set as the initial density. Appropriate density setting method in image processing described in item 1 or item 2). (4) When performing one process on one document image, count the frequency for each process, and when performing multiple processes on one document image, count the frequency for the last process. An appropriate density setting method in image processing according to claim (3), wherein frequency counting of density states is performed only when the density state is determined.