JPH0561303A - Image forming device - Google Patents

Abstract

PURPOSE:To extremely facilitate the adjustment of density at the time of forming the image of a photographic original through the operation of a signal density-setting means while keeping the gradation of the image of the photographic original satisfactory by providing an image formation mode selecting mode. CONSTITUTION:The number of copies and a magnification are inputted through a consol panel 31 and a copying density is set by sliding a sliding volume 31e. Thereafter by turning on a copy key 31b, a signal instructing the start of copying is inputted to a CPU 70. Here, in the normal image-formation mode, the CPU 70 controls an exposure lamp 36 by the sliding of the sliding volume 31e and the copy density is set by adjusting the exposure carried out by the exposure lamp 36. On the other hand, in the photographic image formation mode, the adjustment of copy density is carried out by turning on the photographic original mode key 31d on the consol panel 31, thereby causing the CPU 70 to control an electrifying device 13, varing an electrification grid bias value and varing the amount of the electrification of a photosensitive drum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine for forming an image on a copy sheet at a set image density based on image information written on an original.

[0002]

2. Description of the Related Art Generally, when copying is performed in an image forming apparatus, that is, a copying apparatus, an image of a document placed on a document table is exposed and scanned by an exposure scanning device having an exposure lamp.
The reflected light from the original is guided to the image carrier whose surface is uniformly charged to form an electrostatic latent image on the image carrier. A developer such as toner is supplied from the developing device to the electrostatic latent image to visualize the image of the original document, and the transfer device copies the visualized image of the original document (toner image). Transfer it onto paper such as paper. Then, the image of the document is fixed on the sheet by the fixing device.

Such a copying machine is provided with a switch such as a slide volume control which is composed of a variable resistor for manually correcting the density of a copied image by changing the exposure amount of the exposure lamp. And
To increase the density of the copy image, slide the slide volume in the direction in which the exposure amount of the exposure lamp decreases. To decrease the density of the copy image, expose the slide volume to the exposure lamp. It is moved in the direction in which the amount increases.

By the way, when copying an image having gradation such as a photo original using such a copying apparatus, the density of the copied image may be changed. in this case,
When the density of the copy image is changed by changing the exposure amount of the exposure lamp by the conventional method as described above, the gradation of the image is not maintained and the halftone reproducibility is poor. ..

[0005]

As described above, in the prior art, the copying density of the copied image was changed only by changing the exposure amount of the exposure lamp. Therefore, when copying a photographic original. However, there is a problem in that the gradation of the image cannot be kept good.

Therefore, according to the present invention, by operating one density setting means, the exposure amount is adjusted in the normal original mode and the charge amount is adjusted in the photographic original mode, so that the image of the photographic original is adjusted. An object of the present invention is to provide an image forming apparatus capable of extremely easily adjusting the density at the time of forming and maintaining good gradation of an image on a photographic document.

[0007]

In order to achieve the above object, an image forming apparatus of the present invention comprises an exposing means for exposing an image on a document, a charging means for charging an image carrier, and an exposing means for exposing by the exposing means. Image forming means for forming the formed image of the original on the image carrier, output means for outputting density setting information used for setting the density of the image formed by the image forming means, and the original for the original. Image forming mode selecting means for selectively switching between a photographic image forming mode for forming an image of a photographic original and a normal image forming mode for forming an image of a normal original according to the type of image, and the image forming mode selecting means. When the photographic image forming mode is selected by, the belt is adjusted so that the amount of charge on the image carrier is adjusted based on the density setting information output from the output means. When the normal image forming mode is selected by the image forming mode selecting unit, the exposure amount of the document to the image is adjusted based on the density setting information output from the output unit. And a control unit for controlling the exposure unit.

Further, in the image forming apparatus of the present invention, the exposure means for exposing the image of the original, the charging means for charging the image carrier, the standard exposure amount information indicating the standard exposure amount by the exposure means, and Storage means for storing standard charge amount information indicating a standard charge amount by the charging means, image forming means for forming an image of the original document exposed by the exposing means on the image carrier, and image forming Output means for outputting density setting information used for setting the density of the image formed by the means, a photographic image forming mode for forming an image of the photographic original according to the type of the image of the original,
Image forming mode selecting means for selectively switching between a normal image forming mode for forming an image of a normal document and a photo image forming mode selected by the image forming mode selecting means are stored in the storage means. The exposure unit is controlled so that the image of the original is exposed based on the standard exposure amount information, and the charge amount to the image carrier is adjusted based on the density setting information output from the output unit. When the normal image forming mode is selected by the image forming mode selecting unit, the charging of the image carrier is performed based on the standard charge amount information stored in the storage unit. The charging unit is controlled so as to perform the adjustment of the exposure amount to the image of the document based on the density setting information output from the output unit. Characterized by comprising a control means for controlling said exposing means Migihitsuji.

[0009]

When a document is copied using the image forming apparatus of the present invention, in the normal image forming mode, the exposure amount by the exposing unit is adjusted based on the density setting information output from the output unit, and the exposure is performed. The image of the document is exposed by the amount, and the image of the document is formed. When the photographic image forming mode is selected by the image forming mode selecting unit, based on the density setting information output from the output unit,
The amount of charge by the charging means is adjusted, the image carrier is charged with the amount of charge, and an image of the original is formed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic explanatory view of an image forming apparatus 10. An exposure position 1 by a charging device 13 and an optical device 14 is provided around a photosensitive drum 12 in a substantially central portion of a main body 11.
4a, a developing device 16, a transfer peeling charger 17, a cleaning device 18, and a charge eliminating lamp 20 are provided. The charging device 13 uniformly charges the surface of the photosensitive drum 12. Further, the optical device 14, which is a portion surrounded by a broken line in FIG. 1, exposes the image of the original document, guides the image of the original document onto the photosensitive drum 12, and forms an electrostatic latent image of the image of the original document. The developing device 16 makes the electrostatic latent image visible by supplying a developer such as toner to the electrostatic latent image on the photosensitive drum 12. The transfer peeling charger 17 transfers the toner image on the photoconductor drum 12 onto the paper and peels the paper from the photoconductor drum 12. The cleaning device 18 includes the photoconductor drum 12
The static elimination lamp 2 is for removing the residual toner on the top.
0 is for removing charges on the photoconductor.

On the right side of the main body 11, there are provided cassettes 21a and 21b for accommodating the sheet P and a manual paper feed table 21c. And in the main body 11, the cassette 21
a, 21b and the manual paper feed table 21c are picked up by the pickup rollers 22a, 22b, 22c, and the fed sheet paper P is guided to the paper discharge tray 23 on the left side of the main body through the photoconductor drum 12 (see FIG. 1) (indicated by the one-dot chain line in 1) is formed. The first and second separation rollers 25a and 25b, the pair of registration rollers 2 are provided on the upstream side of the photosensitive drum 12 in the paper transport path 24.
6 is provided, and a conveyor belt 27, a fixing roller pair 28, and a paper discharge roller pair 30 are provided on the downstream side. Further, on the upper surface of the main body 11, there is a document table 34 on which the document D is placed, a white platen sheet 35a, a document cover 35 for covering the document table 34 is provided, and an operation panel 31 is provided. Further, on the leading edge side of the document around the document table 34,
A document scale 32 that serves as a guide when the document D is placed is provided.

On the operation panel 31, as shown in FIG. 2, numerical values such as the number of copies and copy magnification, an LED display section 31a for displaying a message from the CPU, and an instruction to start the copying operation are given. Copy key 31b, number of copies,
A ten-key pad 31c for setting the copy magnification and the like are provided, and a photograph manuscript mode key 30d for switching the control of the CPU 70 to a photograph manuscript mode for performing copying in the photograph mode described later and a copy density for setting the copy density. Various keys and switches such as a slide knob 30e including a variable resistor are provided.

Next, a schematic perspective view of the optical device 14 is shown in FIG.
Shown in. The optical device 14 has an exposure lamp 3 for exposing an original.
6, a first carriage 38a as an exposure scanning means for mounting the first mirror 37a, and a second mirror 37b.
And a second mirror 37c (shown in FIG. 1)
A carriage 38b is provided. The first and second carriages 38a and 38b are scanning motors composed of pulse motors via a driving belt 45, a wire fixing portion 49, and a wire 48 which are wound between fixed first and second pulleys 43 and 44. 41 guide shaft 50
It is adapted to reciprocate at a speed of [2: 1] along a and the guide rail 50b.

Next, FIG. 4 shows a block diagram of a control system of the image forming apparatus 10 of the present invention. The CPU 70 receives signals from the copy key 31b, the ten-key pad 31c, the photo original mode key 31d, and the A / D converter 75 on the operation panel 31, and information such as an operating state is input from the CPU 70 on the operation panel 31. It is output to the LED display unit 31a.
Further, the A / D converter 75 has a slide volume 31
It is connected to the variable resistor of e and slide volume 3
The information on the position of 1e is digitally converted and output to the CPU 70. Further, the CPU 70 has a ROM 73 in which a control program for controlling the entire image forming apparatus 10, standard data of exposure amount, standard data of charge amount, and the like are stored,
A RAM 74 for storing information on the position of the slide volume 31e output from the A / D converter 75 and the like is connected. Further, the CPU 70 is connected to the exposure lamp 36 via a D / A converter 77, an amplifier 78, and a lamp regulator 79, and controls the exposure amount of the exposure lamp 36. Further, the CPU 70 has a D / A converter 8
0, an amplifier 81, and a high-voltage power supply 82, and is connected to the charging device 13.
Control the amount of charge to the. That is, the CPU 70 is the RAM
The exposure amount of the exposure lamp 36 and the charging amount by the charging device 13 are controlled based on the information of the variable resistance of the slide volume 31e stored in 74. Further, the CPU 70 is connected to the image forming unit 76 including the photosensitive drum 12 and the developing device 16 and the like around the photosensitive drum 12, and also controls this.

Next, the operation when the document D is copied using the image forming apparatus 10 having the above-mentioned structure will be described. First, the operator places the document D at a predetermined position on the document table 34, and then closes the document cover 35. Then, after inputting the number of copies and the magnification from the ten keys 31c of the operation panel 31 and setting the copy density by sliding the slide volume control 31e, a signal for instructing the CPU 70 to start copying is given by turning on the copy key 31b. Is entered. As a result, the CPU 70 starts the copy operation in the main body 11. Here, in the normal image forming mode, the CPU 70 controls the exposure lamp 36 by sliding the slide volume 31e, and the exposure amount by the exposure lamp 36 is adjusted to set the copy density. .. By the way, when adjusting the copy density of the formed image when forming an image having gradation such as a photographic image, it is necessary to adjust the density by adjusting the exposure amount when exposing the original. However, it is difficult to reproduce the gradation of a photographic image, and in order to adjust the density of the formed photographic image while maintaining the gradation, the photosensitive drum 1
It is known that it is preferable to change the sensitivity of the photoconductor drum 12 by adjusting the charge amount with respect to 2. Therefore, in the image forming apparatus 10 of the present embodiment, when the photo original mode is pressed by pressing the photo original mode key 31d on the operation panel 31, the CPU 70 charges the copy density when adjusting the copy density. By controlling the device 13, the charging grid bias value is changed, and the charging amount of the photosensitive drum 12 is changed.

Now, in the main body 11, the photosensitive drum 12 is sequentially rotated, charged, exposed, and developed to form a toner image, and reaches the transfer peeling charger 17. On the other hand, in synchronization with this, the paper P is fed from one of the selected cassettes 21a and 21b, and is fed to the transfer peeling charger 17 through the registration roller pair 26 at the timing when the front end is aligned with the toner image on the photoconductor 12. Be done. After the transfer of the toner image, the paper P separated from the photoconductor 12 is fixed by the fixing roller pair 28, and is discharged onto the paper discharge tray 23 by the paper discharge roller pair 30 to complete the copying.

On the other hand, after the transfer is completed, the cleaning device 18 removes the residual toner from the photoconductor 12, and the charge removal lamp 20 is put into the next copy ready state to repeat the required number of copies. When the required number of copies is completed, the operator takes out the original D from the original table 34 and places the next original.

Next, the flow of control by the CPU 70 when copying is performed in the image forming apparatus 10 of the present embodiment will be described with reference to the flowcharts of FIGS. First, by referring to the input signal from the operation panel 31, when it is confirmed that the setting of the copy conditions such as the number of copies and the copy magnification is completed (step 1), it waits until the copy key 31b is pressed. (Step 2). Then, when it is confirmed that the copy key 31b is turned on, the CPU 70 A / D-converts the variable resistance value of the slide volume 31e (step 3) to change the A / D-converted slide volume 31e. RA is the resistance
The data is stored in M74 as data D (step 4). Subsequently, it is determined whether the photo original mode key 31d is pressed (step 5) to determine the normal original mode or the photo original mode. Then, when the photo original mode is turned on (that is, in the photo original mode), the CPU 70 uses the data D (A / D conversion value of the variable resistance value of the slide volume 31e) stored in the RAM 74. Along with reading (step 6), the exposure amount standard data D1 is read from the ROM 73 (step 7). Subsequently, the value of the data D read in step 6 is converted by the D / A converter 80, and a voltage is applied to the charging device 13 from the high voltage power supply 82 according to the value obtained by amplifying the value by the amplifier 81. The photosensitive drum 12 is charged with this voltage (step 8). In addition, the value of the exposure amount standard data D1 read in step 7 is set to D /
According to the value converted by the A converter 77 and amplified by the amplifier 78, the value is changed from the lamp regulator 79 to the exposure lamp 3
6, the voltage is applied to the exposure lamp 3
6 is turned on and the document D is exposed (step 9). Then, the copy of the document D is executed with the charge amount and the exposure amount described above (step 10). When it is determined that the copy number set in step 1 has been completed (step 11), the process ends. If it is determined in step 11 that copying has not been completed, the operations of steps 8 to 10 described above are repeated.

If it is determined in step 5 that the photo original mode key 31d is not pressed (that is, the normal original mode is selected), first, C
The PU 70 stores the data D stored in the RAM 74.
(A / D conversion value of the variable resistance value of the slide volume 31e) is read (step 12), and the ROM is also read.
The charge amount standard data D2 is read from 73 (step 1
3). Then, the value of the charge amount standard data D2 read in step 13 is converted by the D / A converter 80, and the value is amplified by the amplifier 81, and the voltage is applied from the high voltage power supply 82 to the charging device 13 according to the value. Is applied, and the photosensitive drum 12 is charged with this voltage (step 14). Further, the value of the data D read in step 12 is set to the D / A converter 7
7, the voltage is applied from the lamp regulator 79 to the exposure lamp 36 according to the value obtained by the conversion by the amplifier 78, and the exposure lamp 36 is turned on to expose the document D (step 15). .. Then, the copy of the document D is executed with the above-described charge amount and exposure amount (step 16). When it is determined that the copy number set in step 1 has been completed (step 17), the process ends. If it is determined in step 17 that copying has not been completed, the above-described steps 14 to 16 are repeated.

As described in detail above, in the image forming apparatus 10 of this embodiment, when the photo original mode is set by pressing the photo original mode key 31d, the value of the variable resistance of the slide volume 31e is changed. Based on this, the charging grid bias value when the charging device 13 charges the photosensitive drum 12 is determined. That is, the copy density of the photographic document is adjusted by adjusting the charge amount of the photoconductor drum 12 (that is, changing the sensitivity of the photoconductor drum 12). Therefore, it is possible to correct the density of the photographic image while maintaining the gradation.

When the photo original mode 31d is not turned on, that is, when the normal original mode is set,
The exposure amount when the exposure lamp 36 exposes the document is determined based on the value of the variable resistance of the slide volume 31e. That is, since the copy density of a normal original such as a character original is adjusted by adjusting the exposure amount of the exposure lamp 36, the resolution of the character image is not lost.

Further, in the image forming apparatus 10 of this embodiment, the same slide volume 3 is used for the density adjustment in the photo original mode and the density adjustment in the normal original mode.
Since it can be performed by 1e, the operability at the time of adjusting the concentration can be extremely improved.

Furthermore, in the image forming apparatus of this embodiment, when the image density is corrected in the normal original mode, the exposure amount of the exposure lamp 36 is changed according to the output from the slide volume 31e. At this time, the charge amount by the charging device 13 is previously stored in the ROM 7
This is performed based on the charge amount standard data D2 stored in 0. Further, when the image density is corrected in the photo original mode, the charging amount by the charging device 13 is changed according to the output from the slide volume 31e.
At this time, the exposure amount from the exposure lamp 36 is set to R in advance.
This is performed based on the exposure amount standard data D1 stored in the OM 70. As a result, the slide volume 31
The correspondence between the density setting information output from e and the actual image forming density is always constant.

【The invention's effect】

As described in detail above, according to the present invention,
By operating one density setting unit, the exposure amount can be adjusted in the normal mode and the charge amount can be adjusted in the photo original mode, so it is extremely easy to adjust the density when forming an image on a photo original. In addition to the above, the density adjustment in the normal mode and the density adjustment in the photo original mode can be performed by the same density setting means, so that an image forming apparatus with extremely high operability can be provided.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of the entire image forming apparatus according to the present exemplary embodiment.

FIG. 2 is a plan view of an operation panel of the image forming apparatus of this embodiment.

FIG. 3 is a schematic perspective view of an exposure device of the image forming apparatus of this embodiment.

FIG. 4 is a schematic block diagram of a control system of the image forming apparatus of this embodiment.

FIG. 5 is a flowchart showing a flow of control of operation by the image forming apparatus of this embodiment.

[Explanation of symbols]

 10 Image Forming Device 13 Charging Device 31 Operation Panel 31b Copy Key 31d Photo Original Mode Key 31e Exposure Lamp 70 CPU 73 RAM 74 ROM

Claims (2)

[Claims] 1. An exposure unit that exposes an image of a document, a charging unit that charges an image carrier, and an image forming unit that forms an image of the document exposed by the exposure unit on the image carrier. Output means for outputting density setting information used for setting the density of the image formed by the image forming means; a photographic image forming mode for forming an image of a photographic original according to the type of the image of the original; Image forming mode selecting means for selectively switching between a normal image forming mode for forming an image of a normal document, and a density output from the output means when the photographic image forming mode is selected by the image forming mode selecting means. The charging unit is controlled so as to adjust the amount of charge on the image carrier based on the setting information, and the normal image formation is performed by the image formation mode selection unit. And a control means for controlling the exposure means so as to adjust the exposure amount to the image of the document based on the density setting information output from the output means. A characteristic image forming apparatus. 2. An exposure unit for exposing an image on a document, a charging unit for charging an image carrier, standard exposure amount information indicating a standard exposure amount by the exposure unit, and a standard charging by the charging unit. Storage means for storing standard charge amount information indicating the amount, image forming means for forming an image of the original document exposed by the exposing means on the image carrier, and image forming means for forming the image of the original formed by the image forming means. Outputting means for outputting density setting information used for setting the density, a photographic image forming mode for forming an image of a photographic original according to the type of image of the original, and a normal image forming for forming an image of a normal original Image forming mode selecting means for selectively switching the mode, and when the photographic image forming mode is selected by the image forming mode selecting means, it is stored in the storage means. The exposure unit is controlled so that the image of the original is exposed based on the standard exposure amount information that is stored, and the amount of charge on the image carrier is adjusted based on the density setting information output from the output unit. When the normal image forming mode is selected by the image forming mode selecting unit, the charging unit is controlled so as to perform the charging to the image carrier based on the standard charge amount information stored in the storage unit. And a control means for controlling the exposure means so as to adjust the exposure amount to the image of the document based on the density setting information output from the output means. An image forming apparatus characterized by the above.