JPH01109367A - Copying machine - Google Patents

Abstract

PURPOSE:To minimize the amount of white toner used in the case of the use of a color copy form by reproducing the white part of an original with a white toner by copying only when the degree of white of the copy form is lower than a certain degree and the area ratio of the white part on an original is lower than a prescribed value. CONSTITUTION:A color sensor 14 which detects the degree of white of the copy form is arranged above a form supply cassette 16 of a copying machine provided with three developing units 8, 9, and 10 where white, black, and red toners are stored, and a white ratio detecting means 30 which detects the area ratio of the white part on the original is arranged in an optical system 32. In case of an original like a photograph original where the area ratio of the white part to the other part is lower than the prescribed value, the demand for reproducing in white of the white part on the copy form like a color copy form whose degree of white is lower than the certain degree is met by copy reproducing with the white toner developing unit 8. In this case, the white toner is used only for a part corresponding to the white part of the original to minimize the amount of the white toner used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a copying machine equipped with a plurality of toner developing devices including a white toner developing device.

(Prior Art) Copying machines equipped with a plurality of toner developing units and capable of copying not only black but also colors such as red and blue have already been put into practice. Moreover, not only white paper but also color vapor may be used as copy paper.

Conventionally, to reproduce the white portion of a document, the background color of the copy paper has been used as a substitute, and this portion has not been specifically imaged.

(Problems to be Solved by the Invention) In the above conventional example, when white paper is used as copy paper, the background color is white, so there is no problem in reproducing the white part of the original, but color copying When paper is used, there may be problems in reproducing white parts of the original.

For example, when it is desired to reproduce a white portion of a document image as white, such as a photographic document, it is inconvenient to use the color background color of copy paper instead.

On the other hand, in cases where there is no need to reproduce white parts as white, such as when characters are printed on a blank sheet of paper, if you intentionally reproduce this using white toner, you will end up wasting the white toner. instead, the copy process doubles,
A problem arises in that the copying time becomes long.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a copying machine equipped with a plurality of toner developing devices including a white toner developing device. ratio detection means;
a color detection means for detecting the degree of whiteness of the copy paper; and a color detection means for detecting the degree of whiteness of the copy paper; A copying machine characterized by comprising a control means for copying and reproducing.

(Function) According to the present invention, in a document such as a photographic document in which the area ratio of a white portion in the document is smaller than a predetermined value (for example, 50χ), the white portion is replaced with a sheet of color copy paper whose whiteness is below a certain level. The request for reproduction in white on copy paper can be made possible by copy reproduction using white toner. In this case, it is only necessary to use white toner for the portion corresponding to the white portion of the document, so the amount of white toner used can be kept to the minimum necessary.

On the other hand, even when using white paper or monochrome copy paper as copy paper, if the area occupied by white parts is large, such as text originals, normal copying without using white toner is performed. The white part of the original is reproduced by the background color of the copy paper.

Copying using white toner requires multiple copy cycles, including copy cycles using white toner and copy cycles using other colors. On the other hand, in copying without using white toner, a copy cycle using white toner is not necessary, and time loss can be eliminated.

(Embodiment) The embodiment of the present invention shown in FIGS. 1 to 6 is a copying machine equipped with three developing units 8, 9, and 10, and a paper conveyance path capable of composite copying and double-sided copying. It's about machines.

In FIG. 1, reference numeral 1 denotes a photosensitive drum, around which are a cleaning device 4, a main eraser lamp 5, a charging device 6, an LED array 7, a first developer 8, a second developer 9, and a third developer. 10, a transfer charger 2, and a separation charger 3 are arranged.

Photosensitive drum 1 charged by the charger 6
In this case, the image of the original on the original platen glass 31 is transferred to the optical system 32.
is exposed to light to form an electrostatic latent image. And 3
The toner supplied from the developing device selected from among the developing devices 8.9.10 adheres to the electrostatic latent image, and the photosensitive drum 1
A toner image is formed thereon. This toner image is transferred onto the copy paper in the transfer charge mode 2, and is separated from the photosensitive drum 1 along with the copy paper in the separation charge mode 3.

Reference numeral 16 denotes a paper feed cassette, and the copy paper stored in the paper feed cassette 16 is sent out to a paper conveyance path by a paper feed roller 15, passes through an intermediate roller 17, and reaches a timing roller 18. The copy paper sent out from the roller 18 passes through a transfer section 2 and a separation section 3, during which the toner image on the photosensitive drum 1 is transferred, and then passes through a fixing roller 20, during which the toner image is fixed. In the case of normal one-sided copying, the paper is guided as it is by the paper ejection roller 25 and ejected to the paper ejection tray 21.

In the case of composite copying, the copy paper leaving the fixing roller 20 is guided to path a by the action of the switching claw 26, then guided to the path C by the action of the switching claw 22, and then passed through the tray introducing roller 27. , guided to the intermediate tray 24. The copy paper temporarily stored in the intermediate tray 24 is sent through the paper feed roller 23 and the intermediate roller 28 to the timing roller 18 again, and the toner image on the photosensitive drum 1 is transferred again by the transfer charger 2. In this way, a composite copy is performed, and in the case of double composition, the paper is directly guided to the paper discharge tray 21. In the case of triple synthesis, the same transport path is circulated once again.

In the case of double-sided copying, the copy paper that leaves the fixing roller 20 is guided to path a by the function of the switching pawl 26, then guided to the path via the forward/reverse roller 29 by the function of the changeover pawl 22, and then transferred to the path a. The reverse rotation of the reversing roller 29 moves the switchback and guides it to the passage C. Thereafter, it is led to the transfer charger 2 again through the same transport path as the composite copy.

Each developing device 8.9.10 can contain toner of any color.For example, a service person or user can use the developing device 8.9.10.
9.10 is configured to give color identification information using a dip switch according to the color of the toner stored in the toner. The 3-bit code generated by this dip switch is input to the CPO 20G, which will be described later, from color discrimination sections 11, 12, and 13 arranged corresponding to each developing device, and the H and L signals are input to the CPO 20G.
The toner color is identified by the combination of 0
In this embodiment, the first developing device 8 contains white toner, the second developing device 9 contains black toner, and the third developing device 10 contains red toner.

A color sensor (color detection means) 14 is arranged above the paper feed cassette 16 to detect the degree of whiteness of the stored copy paper. The output of this color sensor 14 is
00 analog boat, and color identification is performed on software.

Note that since the color sensor 14 is well known, its explanation will be omitted. Further, the optical system 32 is provided with white ratio detection means 30 for detecting the area ratio of the white portion of the document. As the detection means 30, a conventionally used AH sensor (original density detection sensor) can be used, and this is used in this embodiment. The output of the AE sensor 30 is input to an analog board of the CPU 200, and the area ratio is determined on software.

FIG. 2 shows the control circuit of this embodiment.

As the CPU (control means) 200, a 1-chip microcomputer with a built-in A/D converter is used. Output signals from the CPU 200 are outputted from the PAO to PA3 to the respective driver ICs 201 for controlling development bias switching, main motor drive, paper feed roller drive, and timing roller drive. Also CPO200
From the output boats pco to PC2, each developer 8.9.
A signal for controlling the clutch that drives 10 is output to each driver 202.

CPU200 (7) Input Capo) PBO~PB2, P
u3 to PB5 and PA5 to PA7 each have a developing device 8.
The 3-bit color identification information of 9 and 10 is input, and based on this, the CPU 200 identifies the color of the toner contained in each developing device 8, 9, and 10. The input ports ^No and ANI are analog ports, and are connected to the color sensor 14 and A, respectively.
A signal from the E-sensor 30 is input, and based on this input level, the CPU 200 determines the color of the copy paper using software.

Next, the control procedure of this embodiment will be explained according to the flowcharts shown in FIGS. 3 to 5.

FIG. 3 shows the main routine for controlling the copying machine by the CPO 200. When the power is turned on, the C
Clearing the RAM inside the PO200 and making initial settings for the standard copy mode
Set an internal timer of 200.

This timer regulates the time required for the following controls, that is, the time for one routine. In step #3, inputs are made to the operation panel and switches, sensors, etc. in each part of the copying machine, and in the next step #4, display data regarding the operation keys among them is set.
In step 5, it is determined whether or not copying is possible, and if possible, normal copy control (including standby state control) is performed in step #6, and if not, abnormal processing is performed in step #7. conduct. Thereafter, in step #8, control signals, display signals, etc. are outputted, and finally, in step #9, it is determined whether or not the internal timer has expired, and if the internal timer has finished, the process returns to step #2 and the above processing is performed again.

The copy control subroutine of step #6 is executed as shown in FIG. In this subroutine, before the standard copy mode, a preliminary scan is performed to determine the black and white area ratio of the document, and a copy status counter is provided in connection with this. This copy status counter is set to one of 0.1.2, and the processing system is selected based on this value.

In the initial settings, the copy status counter is set to 0, and based on the determination of the copy status counter in step #20, step #21. to move to. Step #2
In step 1, it is determined whether or not copying has started, that is, whether the print button has been pressed. If YES, preliminary scan control is performed in step #22.
After determining the black and white area ratio of the document based on the analog input from the AB sensor 30 in step #23, the status counter is set to 1 in step #24, and the process returns to the main routine. If copy start has not been performed in step #21, the process immediately returns to the main routine.

In the next cycle, the copy status counter is set to 1, so after this is determined in step #20, the process moves to step #25.

In this step #25, paper feeding and conveyance control is performed in step #25.
In step 26, the photosensitive drum l and its surrounding equipment are controlled, in step #27, the optical system 32 is controlled, in step #28, each developing device 8, 9, and 10 is controlled, and then in step #29, the status counter is After setting the value to 2, the program returns to the main routine.

In the next cycle, the copy status counter is set to 2, so after this is determined in step #20, the process moves to step #30.
In step #31, it is determined whether or not copying of the set number of copies has been completed, and if it has been completed, the status counter is set to 0 in step #31 and the process returns to the main routine. If the set number of copies is multiple, the status counter is set to 1 in step #32 and the process returns to the main routine, so preliminary scanning and black-and-white area ratio determination are performed for the first copy, and the second These operations will not be performed for subsequent copies.

The developer subroutine of step #28 is shown in FIG.
1) to (6) in FIG.

This subroutine is controlled according to input from each sensor, etc., and the developing unit status counter (GCT) is 0 to 4.
have. This subroutine will be explained by taking as an example the case where the document is a photo document in which the area ratio of the white portion is smaller than a predetermined value, the copy paper is color paper, the set number of copies is 1, and black copying is to be performed.

In the initial setting, GCT=0 is set, and processing A is selected in step #40. In step #41, it is determined whether the copy paper is white based on the information from the color sensor 14, and then in step #42, it is determined whether the area ratio of the white portion of the document is smaller than a predetermined value. . In this case, color paper is used, and the white portion ratio of the document is smaller than the predetermined value, so 1 is set in flag I in step #43, 0 is set in flag ■ in step #45, and then GCT is set in step #46. After setting it to 1, return to the main routine. Note that when it is determined in step #41 that the copy paper is white, and when it is determined in step #42 that the white portion ratio of the document is equal to or greater than a predetermined value, the flag ■ is set to 0 in step #44, and then the paper is processed in step #4. Proceed to step 45.

In the next cycle, since it is GCT-1, processing B is selected in step #40.

In step #50, it is determined whether the flag I is O or not. In this case, the flag is I-1 (color copy paper and original white has low specific gravity), so the process moves to step #54, where the flag ■=0 It is determined whether or not. Since the flag ■==0, the process moves to step #51 and black toner developer (second developer) 9 is selected, then the bias level is set to 1 in step #52, and the GCT is set to 2 in step #53. After that, return to the main routine. Incidentally, when it is determined in step #50 that the flag is l-0 (white copy paper or original white ratio is important), the process immediately moves to step #51. When flag ll-1 is determined in step #54, the process moves to step #55, where white toner developer (first developer) 8 is selected, and then, after setting the bias level to 2 in step #56, step # 53.

In the next cycle, since GCT=2, processing C is selected in step #40.

In step #60, it is determined whether or not to start image formation, and in the case of starting image formation, the selected developing device is turned on in step #61.
In this case, the black toner developing device 9 is selected, so development is performed using black toner. Then step #
After setting GCT to 3 in step 62, the process returns to the main routine. Note that if it is determined in step #60 that image formation has not started, the process directly returns to the main routine.
Further, when the white toner developing device 8 is selected, development with white toner is performed.

In the next cycle, since GCT is -3, processing is selected in step #40.

In step #63, it is determined whether or not image formation is complete.

In this case, since development is being performed by the black toner developing device 9, the process does not end but returns directly to the main routine. This process is repeated until a normal copy of the photographic manuscript is made with black toner on the color copy paper. As described above, the development at this time is carried out by normal positive-positive development, and the developing bias is selected to be bias level 1, which is suitable for this positive-positive development. In this way, development with black toner is performed, and when it is determined in step #63 that the image forming operation has entered the end process, a timer ■ is set in step #64, and then OCT is set to 4 in step #65. After that, return to the main routine. Said timer I
is used to set the time it takes for the photosensitive drum l to pass through the developing device at the end of charging position.

In the next cycle, since GCT is 4, processing E is selected in step #40.

In step #70, it is determined whether or not the timer ■ has ended;
If it has not finished, return to the main routine. When the timer ■ ends, the black toner developer 9 is turned off in the next step #71, and then in step #72 it is determined whether or not the set number of copies has been completed.In this case, the set number of copies is one, so the process ends. It is determined that Step #7
Proceed to step #3, where it is determined whether the flag is I-1 or not.In the case of 0, the flag is I-1, so proceed to step #74, and determine whether the flag is I-1 or not. Determine whether it is 0 or not. Since flag ■ is set to 0 (step #45), step #7
The program proceeds to step #5, where the flag ■ is changed to 1, and then, in step #76, GCT is set to 1, and the process returns to the main routine. This completes the development with black toner. If it is determined in step #72 that the number of copies has not been completed, the process jumps to step #76 so that development with black toner is performed for the required number of copies. Further, when the flag is determined to be 1-0 in step #73, and when the flag is determined to be 11-1 in step #74, GCT is set to 0 in step #77 and the process returns to the main routine.

Although the normal copying process using black toner has been described above, in this example, the process moves to a copying process using white toner next, and composite copying is performed. The copy paper that has been copied with black toner passes through a conveyance path for composite copying, and is now ready to be copied with white toner. As mentioned above, this process is 0CT-1, flag I=
1, the program starts with flag II=1.

Therefore, in step #40 of the developer subroutine, processing B is selected from the beginning, and in steps #50 and #54, white toner developer 8 is selected, and the bias level is selected as 2 (steps #55, #56). ). In the next process C1 process D1 process E, development with white toner is performed in step #61, and after it is determined in step #63 that the white toner developing operation has entered the end process, the copying process with toner is completed after a predetermined period of time. and set GCT to 0 in step #77.
and return to the main routine. At the time of return, the flag I-1 and flag If-1 remain set.

The copying process using the white toner is performed using negative-positive development, that is, reversal development. That is, using toner having the same polarity as the charged potential of the photosensitive drum 1, and as shown in FIG. By applying a bias potential (level 2) ■ of a similar potential,
A developing potential difference is provided between the minimum potential of the image area on the photosensitive drum 1 (corresponding to the white part of the original, and becomes a potential close to Ov by exposure) vl and the bias potential, and an image corresponding to the white part of the original is created. The white toner is made to adhere to the lowest potential area. In this way, on color copy paper,
The white parts of the original are reproduced in white using white toner.

Through the above two composite copying steps, the white portion of the original image is reproduced as white using white toner, and the non-white portion is reproduced as white using black toner on the color copy paper.

The above example is for an original with a small white area ratio, color copy paper used, the number of copies set to 1, and black copy, but if the original has a large white area ratio or white copy paper is When used, only the normal copying process using the black toner developer 9 is executed (flag I-
0, step #50→#51). Further, when the set number of copies is a plurality of copies, a normal copying process using black toner for that number of copies is executed first, and then a copying process using the same number of white toners is executed. Furthermore, in the normal copying process, it is possible to make copies using color toners other than black toner.

In addition to the embodiments described above, the present invention can be configured in various embodiments. For example, when a full-color copying machine uses color copy paper, it may be equipped with a developing device for white toner in addition to magenta toner, cyan toner, and yellow toner. , the white part of the document can be reproduced with white toner during multiple transfer.

(Effects of the Invention) Since the present invention has the above-described configuration and operation, even when using copy paper such as color paper whose degree of whiteness is below a certain level, when it is desired to reproduce the white part of the original as white, that is, when the white part of the original is desired to be reproduced as white, In the case of a photo original where the area ratio of the white part of the image is smaller than a predetermined value, the white part can be reproduced as white, and at this time, the amount of white toner used can be kept to the minimum necessary. If the area ratio of the white part of the original is larger than a predetermined value and there is no need to reproduce the white part, or if white copy paper is used, there is no time loss and the wasteful use of white toner can be prevented. Copy machines can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of an embodiment of the present invention, FIG. 2 is a control block diagram, FIG. 3 is a flowchart showing the control main routine, FIG. 4 is a flowchart showing the copy control and control subroutine, and FIG. 1), Figure 5 (2), Figure 5 (3)
), FIG. 5(4), FIG. 5(5), and FIG. 5(6) are flowcharts showing the developer subroutine, respectively, and FIG. 6 is a graph explaining reversal development.

Claims (1)

[Claims] (1) In a copying machine equipped with a plurality of toner developing devices including a white toner developing device, white ratio detection means detects the area ratio of a white portion of a document; color detection means detects the degree of whiteness of copy paper; The method is characterized by comprising a control means for copying and reproducing the white portion of the document using white toner only when the degree of whiteness of the copy paper is below a certain level and the area ratio of the white portion of the document is smaller than a predetermined value. copy machine.