JPH0462382B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an image density control device for a copying machine, and more particularly, a manual density control mechanism that changes the density of a copied image by changing the image density control level through an external operation; The present invention relates to an image density control device for a copying machine equipped with an automatic image density control mechanism that keeps the density of a copied image constant by varying the image density control level during execution of a copying operation according to the image density.

PRIOR ART In recent years, electrophotographic copying machines, etc., control the exposure amount, developing bias voltage (hereinafter simply referred to as "developing bias"), etc. according to the image and color condition of the original, and automatically achieve an appropriate copy image density. Some devices have been proposed or provided that are equipped with an automatic concentration control mechanism to obtain the following.

On the other hand, depending on the user's preferences and the purpose of copying, it may be necessary to adjust the density manually instead of using such automatic control.
Regarding concentration control, it was common to use both automatic and manual methods.

However, even if there are two methods, automatic and manual, for example, if you look at a copy image obtained with automatic density control and decide that density adjustment is necessary, what density adjustment should you make for the original? Whether replication was performed at the level or because it is automatic control,
On the contrary, it is difficult for some users to understand, and in the end, it is necessary to take a test shot once at the manual density standard level and then readjust to the desired density, which is inconvenient as the test shot becomes a useless copy. It was hot.

Purpose The present invention has been made in view of the above points, and it is possible to adjust the level when executing manual concentration control by displaying the control level in association with the control level in manual control when automatic concentration control is executed. It is an object of the present invention to provide an image density control device that can easily perform image density control.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 schematically shows the configuration of an electrophotographic copying machine 1 as an example of a copying machine equipped with an image density control device of the present invention. A photoreceptor drum 10 is supported at approximately the center of the main body of the copying machine so as to be rotatable in a counterclockwise direction.
1, a charging charger 12, a developing device 13, a transfer charger 14, a separation charger 15, a cleaning device 16, etc. are arranged in this order.

In the scanning optical system 20, the exposure lamp 21 and the first scanning mirror 22 move integrally to the left in the figure, and the second and third scanning mirrors 23 and 24 also move to the left at half the speed. The imaging lens 25 and the fixed mirror 2 scan the surface of the original (not shown) by moving.
6, an original image is projected onto a rotating photoreceptor drum 10.

By passing through the steps of charging, image exposure, and development, a toner image corresponding to the original image is formed on the surface of the photoreceptor drum 10, and this toner image is transferred to the copy paper conveyance system 30 at the transfer charger 14. The image is transferred onto copy paper that is conveyed in synchronization with the image forming operation by the paper feed roller 31, timing roller 32, and the like.

The copy paper that has passed through the transfer process is separated from the surface of the photoreceptor drum 10 by a separating charger 15, and after the image is fixed by a fixing roller 33, it is discharged onto a tray 34 to complete the copying.

In the above copying operation, it is well known that the light intensity of the exposure lamp 21 or the developing bias in the developing device 13 affects the density of the copied image. As will be described later, the copying machine 1 is equipped with a mechanism (manual density control) for making the light emission intensity of the lamp 21 variable by external operation and adjusting the density of the copied image.

The copying machine 1 of the present invention is provided with a mechanism for obtaining an image of uniform density regardless of the condition of the image on the original, the quality of the paper, the difference in color, etc. Specifically, during scanning by the scanning optical system 20, the intensity of reflected light from the document surface is detected by the light receiving element 27 (see FIG. 2).
A mechanism (automatic density control mechanism) that controls the light emission intensity of the lamp 21 so that the reflected light intensity is constant in accordance with the detected value, thereby making the density of the copied image constant. We are prepared.

Figure 2 shows the light receiving element 2 used for automatic density control.
7 is a plan view schematically showing an example of the arrangement of the light receiving element 27, which is located outside the optical path of image exposure passing through the lens 25, receives reflected light from the document, and adjusts the output level according to the detected intensity. changes.

FIG. 3 shows the main parts of the operation panel 50 of the copying machine 1. As shown in FIG. Automatic density control mode is AE key 5
1, the auto display 52 lights up. Manual concentration control mode is
The setting is made by pressing the AE key 51 again or by pressing the light intensity increase (UP) key 53 or light intensity decrease (DN) key 54 for manual density control. At this time, the auto display 52 turns off and the manual The light intensity of the lamp 21 is controlled at the density level indicated by lighting any of the density indicators 55 in the control mode. Details of the control will be described later.

FIG. 4 is a circuit diagram showing the relationship between a microcomputer system that controls the operation of the copying machine 1 described above and image density, etc., various input switches, light emitting diodes for display, and the like.

Input port P ₅ of microcomputer 100
~ _P8 shows the AE group 51 on the operation panel 50, UP
Switches SW ₁ , SW ₂ , SW ₃ corresponding to the key 53 and DN key 54, respectively, and a switch SW ₄ for detecting opening/closing of the document cover 28 in order to determine whether a document has been replaced or forgotten are connected to the output port PA. ~
The PD includes a decoder 101 and current limiting resistors R ₁₁ to _{R 20}
The light emitting diodes LED ₁ to LED ₅ for displaying the image density level are connected through the current limiting resistor.
A light emitting diode LED ₆ for automatic concentration control display is connected via _R26 . In addition, light emitting diode
The LEDs ₁ to ₅ are configured as a pair of two colors, for example red and green, and one of them is selectively controlled to light up.

Output port PE of microcomputer 100
A phase control circuit 103 is connected to the PI via a driver 102 and resistors R ₂₁ to R ₂₅ for setting the light level.
is connected, and the output of the above-mentioned light receiving element 27 is further input to the phase control circuit 103. The phase control circuit 103 triggers the switching element 104 via the pulse transformer PT, and controls the light amount of the lamp 21 based on the trigger timing.

In this control, in automatic concentration control mode,
The phase control circuit 103 operates to automatically control the light amount so that the output of _the light receiving element 27 reaches a predetermined target _value level. Light emission is controlled at a fixed control phase level.

The output of the phase control circuit 103 is also input to the input ports P ₁ to _{P 4} of the microcomputer 100 via the A/D converter 105, so that the exposure control level is determined when the timing signal is output from the output port PK. This displays the control level when the automatic concentration control mode is executed. Details regarding this display will be described later.

Note that the microcomputer 100 also executes other operations such as sequence control of the copying machine 1, but the relationship between the microcomputer 100 and the drive mechanism and image forming mechanism of the copying machine 1 for this purpose is not covered by the present invention. Since these are not directly related, illustration and explanation in FIG. 4 will be omitted, and only a simple illustration will be made in the flowchart of FIG. 15.

5 to 15 are flowcharts showing the control processing procedure executed by the microcomputer 100, and FIG. 5 shows the processing procedure in general.

In FIG. 5, step (#1) (hereinafter S
Marked as #1. The same applies to other step numbers), where the initialization processing of the memory, registers, flags, etc. in the microcomputer 100 is performed when the power is turned on. (S#2) is a process of presetting predetermined data for variable control items of the copying machine 1, a specific example of which is shown in FIG. In FIG. 6, in (S#201), the initial settings of the copying machine operation mode such as number of copies = 1, copy magnification = 1x, paper feed section = upper stage, etc. are performed, and in (S#202), density control is performed. Select the automatic control mode as the mode, and set the initial exposure level to "3" as the intermediate position.
(see figure 4) and cause the light emitting diodes LED ₆ and LED ₃ (see figure 4) of the corresponding display sections to emit light. In this case, red is selected as the light emitting color of the light emitting diode LED ₃ . Note that the actual display output is executed by the process shown in (S#403) in FIG.

(S#3) in FIG. 5 is a process associated with various key inputs, and a specific example thereof is shown in FIG. In FIG. 7, (S#301) is a copy flag determination step. As shown in FIG. 15, the copy flag is set to "1" from the start of the copying operation to the end of the scanning movement, and is set to "0" otherwise. Therefore, as a result of the process (S#301), key inputs during scanning movement of the optical system 20 are not accepted. (S
In #302), the presence or absence of exposure control level data is determined based on the data flag. As shown in (S#401) to (S#406) in FIG. 8, the data flag is used to store exposure control level data when copying is performed in automatic density control mode. Then, it is set to "1".
When the data flag is "0", it means that the copying operation has not yet been executed in the automatic density control mode, so in (S#303), the standard level "3" is selected.
is set as a temporary exposure level. When the data flag is "1", the data set in the storage section is set as the exposure level (S#304). These data are stored, for example, in a predetermined area of the RAM in (S#311), and read out as necessary when performing display or exposure control. (S
#305) ~ (S#310) are UP key SW ₁ , 53DN
The processing when the keys SW ₂ and 54 are operated is shown. That is, UP
When the key 53 or DN key 54 is pressed, the exposure level set at that time is increased or decreased by one step, and the auto flag is set to "0" to enter the manual density control mode. If the UP key 53 and DN key 54 are not operated (S
#309) sets the auto flag to "1" and continues the automatic concentration control mode. In addition, auto flag =
The auto flag may be set to "0" by pressing the AE key 51 when it is "1". Also,
When switching to manual density control mode after copying in automatic density control mode, if the original remains as it is (original cover switch SW ₄ remains closed), the level displayed at that time will be the highest level during automatic density control mode. Alternatively, an average control level (described later) may be displayed.

(S#4) in FIG. 5 is a step for displaying the exposure level and processing data;
Figure 3 shows the details. In Fig. 8, when the auto flag = "0", that is, in the manual concentration control mode, the light emitting diode LED ₆ of the auto display 52 is turned off in (S#402), and the light emitted corresponds to the level set manually. Turn on the diode.
This display level is set at (S#311) in FIG.

On the other hand, when the auto flag = "1", that is, in the automatic density control mode, the auto display is turned on in (S#403), the copy flag is determined in (S#404),
If it is "0", proceed to (S#450); if it is "1", proceed to the following steps (S#405). (S#450)
These are steps related to display and data processing other than during scanning operations, and the details thereof are shown in FIGS. 9 to 13.

(S#405) to (S#415) therefore, when the copying operation is executed in automatic density control mode,
It shows the processing executed during scanning movement of the optical system 20. (S#405) is the process of shifting exposure control level data to storage means, (S#406)
1 and 2 respectively show the process of setting the data flag to "1" accordingly. This exposure control level is determined by the light receiving element 2 as explained in FIG.
When the phase control circuit 103 controls the phase angle of the voltage waveform supplied to the lamp 21 in response to the output of the lamp 21 in order to bring it to a predetermined target level, the control output is sent to the microcomputer via the A/D converter 105. 100, and the control level is associated with the manual density control level and processed as exposure level data. In addition,
The output of the A/D converter 105 is output from the output port PK of the microcomputer 100 once per routine.
It is taken in from the input port by the data request signal output to the destination, and the processes (S#405) to (S#415) are executed every time the data request signal is output, and the processing time ( The exposure control level taken in during the scanning movement time is displayed each time, and the number of times it appears is counted.

As mentioned above, Fig. 9 shows the (S#404) of Fig. 8.
Then, when the copy flag is determined to be “0”,
A routine for displaying exposure levels and processing data is shown. In FIG. 9, in (S#451), the exposure level data flag is first determined. When the data flag = "0", the exposure operation has not yet started even in automatic density control mode, so (S#458), (S#202) in Figure 6 or The temporary exposure level "3" (standard level or intermediate level) set in (S#303) is displayed. Therefore, when the exposure lamp 21 is turned on in the automatic density control mode in conjunction with a copying operation, at least the first phase control is performed at level "3" and thereafter phase control is performed in accordance with the amount of reflected light. In the process of FIG. 8, the provisional level "3" is not counted. When the data flag is "1" in (S#451), the process proceeds to (S#452) where the data processing flag is determined. The data processing flag is set to "1" in (S#602) in FIG. 15, and is set to "0" with the execution of the data processing (described later) in FIG. 10 or 12. In some cases, the data processing flag = “1” means that the data is unprocessed, and in that case, (S
#453) to perform data processing.

FIG. 10 and FIG. 12 each show a specific example of data processing. The data processing referred to here refers to the determination of the exposure level during the scanning movement executed in (S#405) to (S#415) in FIG. level) or the average value of the level (simple average or weighted average multiplied by frequency), minimum level value, and maximum level value.
The example shown in Figure 0 (the process for displaying it (S#454) is shown in Figure 11) is to display green light emitting diodes between the controlled minimum level and maximum level when copying. displayed.
Among these, the maximum level or the average level is displayed by lighting a red light emitting diode, and the example shown in Fig. 12 (the processing for this display is shown in the first
Shown in Figure 3. ) lights up the green light emitting diodes only at the minimum and maximum levels, and displays the maximum or average level in red. As the average level, after a predetermined calculation, the level value closest to it or a value obtained by rounding down the decimal point of the calculation result is selected.

(S#453) When executing data processing, the 10th, 1st
As shown in Figure 2, an auto clear timer is set. The auto clear timer is a timer that defines a time interval for clearing the display and returning to the initial setting state according to the time-up.

(S#455) in FIG. 9 is a step for determining the end of the auto clear timer set in (S#453). When the auto clear timer ends, (S
#456) clears the contents of the storage means for storing the count value of the level counter, the data flag, and other key input memories to "0", sets the auto flag to "1", and turns off the exposure level display. The processing to do so is executed. When the auto clear timer ends, (S#301) ~ in Figure 7
As a result of the process (S#303), the exposure level display becomes "3".

(S#5) in FIG. 5 shows the control output process of the power supplied to the exposure lamp 21, and the details are shown in FIG. 14. The processing shown in FIG. 14 basically shows control that is processed by software among the phase control operations described in the explanation of FIG. 4. That is, the light amount control for the exposure lamp 21 is performed while the copy flag is "1" (from the start of copying to the end of scanning), and when the manual density control mode (auto flag = "0") is in effect, the selected exposure level is controlled. It makes a judgment and outputs the level corresponding to it. The level output is configured to provide a control voltage corresponding to the level to the phase control circuit 103 via the driver 102 in FIG. 4 by selecting one of the resistors R ₂₁ to _{R 25} . . On the other hand, in automatic concentration control mode (auto flag = "1"), microcomputer 1
00 executes processing for providing a mode signal to the phase control circuit 103. As a result, the phase control circuit 103 is associated with the light receiving element 27 and controls the phase of the power supplied to the lamp 21 so that the output of the light receiving element 27 is constant.

(S#6) in FIG. 5 is a processing step for sequence control of copying operations, an example of which is shown in FIG. In the figure, when it is determined that the print switch (not shown) is turned on, the copying operation starts, the copy flag and data processing flag are set to "1", and the exposure lamp 21 is turned on (S
#602). At this time, the scanning system 20 starts scanning at the same time or with a slight delay. Next, the scanning system 20
With the output of the return signal, the copy flag is set to "0" and the exposure lamp 21 is turned off.

Regarding the series of processes described above, the display of the exposure level in relation to the operation of the copying machine can be summarized as follows.

First, when the power is turned on, the auto display 52 is turned on, exposure level "3" is selected, and the light emitting diode LED ₃ lights up in red. When a copying operation starts in the automatic density control mode, the light amount of the exposure lamp 21 is controlled according to the output of the light receiving element 27, and the light amount control level of the lamp 21 is associated with the manual density control level based on the state of the phase control. It makes a judgment and lights up the corresponding light emitting diode (green). The lighting at this time may be continued while the exposure lamp 21 is on, or it may be turned on each time exposure level data is input, and the previously lit lamps may be turned off.

Next, when the scanning movement of the scanning optical system 20 is completed, the copy flag becomes "0" and data processing is performed. As a result, the maximum value or average value of the exposure level of automatic density control for the document is displayed in red, and the maximum value and minimum value are displayed in green. When switching to manual density control in this state, the exposure level can be automatically set to the level displayed in red indicating the maximum value or average value as long as the document cover switch SW ₄ remains closed. In addition, after the exposure is completed, the level display and data count are cleared by the completion of the auto clear timer, and the exposure control level and display are set to intermediate (standard).
is set to “3”.

Effects As explained above, the present invention displays the average or maximum value of the image density control level on the display means after the automatic density control mechanism executes the copying operation, thereby improving the quality of copying performed by the automatic density control mechanism. After execution, when copying the same document again using the manual density control mechanism, it is possible to easily determine the image density control level to be set.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing the configuration of a copying machine;
FIG. 2 is a plan view schematically showing an example of the arrangement of light receiving elements for measuring the intensity of reflected light of an original image, FIG. 3 is a plan view showing the main parts of the operation panel of the copying machine, and FIG.
The figure is a circuit diagram showing the relationship between the microcomputer of the control circuit, various displays, switches, etc., Figure 5 is a main flowchart that generally shows the control processing procedure in the microcomputer, and Figures 6 to 15 are: This is a flowchart specifically showing the processing contents of each step in the main flowchart of FIG. 5. 1... Copying machine, 10... Photosensitive drum, 21...
...Exposure lamp, 27...Light receiving element, 50...Operation panel, 51...AE key, 52...Auto display,
53... Light intensity increase (UP) key, 54... Light intensity decrease (DN) key, 55... Level display, 100...
... Microcomputer, 103 ... Phase control circuit, LED ₁ to LED ₅ ... Light emitting diode for level display, LED ₆ ... Light emitting diode for automatic display.

Claims (1)

[Scope of Claims] 1. A manual density control mechanism that changes the density of a copied image by changing the image density control level through an external operation, and a manual density control mechanism that changes the density of a copied image during execution of a copying operation according to the density of the original. In a copying machine equipped with an automatic density control mechanism that makes the density of a copied image constant by varying the density, a display means for displaying an image density control level by the manual density control mechanism, and a copying operation by the automatic density control mechanism. storage means for storing a plurality of image density control levels varied during execution; after execution of a copying operation by an automatic density control mechanism, at least the average or maximum of the plurality of image density control levels stored in the storage means; and display control means for displaying the image density control level on the display means. 2. The display control means displays a combination of a minimum level and a maximum level on the display means among the plurality of image density control levels stored in the storage means. Image density control device.