JPH02193164A - Digital copying machine - Google Patents

Abstract

PURPOSE:To carry out high speed and low speed copying by providing a means to vary the processing speed of an electrophotographic process and a means to vary the scanning speed of the sub scanning direction of an optical scanner, responding to the varied speed. CONSTITUTION:A condition setting memory part 104, etc., for a processing speed setting part 101 is connected to CPU 100 inside a main controller. The processing speed of the electrophotographic process, including the rotation speed of a photosensitive drum and/or a fixing roller can be set arbitrarily by an operator or a servicing person, with an inputting means provided in the operating part of the copying device main body. When the copying speed is made variable on the user side, since the scanning speed in the sub scanning direction of the optical scanner is changed responding to the varied speed so that there is no deviation generating in the sub scanning direction, a copied image is not deviated in the sub scanning direction and there is not possibility of stretching or shrinking. Thus, high speed copying and low speed copying can be carried out while securing the image quality.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a digital copying machine, and more specifically,
The present invention relates to a digital copying machine that can vary the processing speed of an electrophotographic process.

[Conventional technology]

Conventionally, in general, when an electrophotographic copying machine is designed, the scanning speed of the reading scanner and the processing speed of the electrophotographic process are fixed at a certain speed, and copies are made at the set speed.

Therefore, when changing the magnification, the so-called mirror zoom magnification is changed by changing the relative position of the lens and mirror and changing the image speed.
A zoom lens was used that changed the magnification by changing the position and scanning speed. On the other hand, in these methods,
Since the copying speed does not become faster, there are some models in which the operating speed of the scanner or photoreceptor is made variable in order to copy efficiently.

An example of this is the invention disclosed in Japanese Unexamined Patent Publication No. 57-68851. The present invention aims to increase the copying speed in the same magnification mode and other variable magnification modes by controlling the rotational speed of the drum and the scanning speed of the scanning means in accordance with input data for specifying and selecting the variable magnification ratio. There is. As for its configuration, when the preprocessing is completed and copying operation begins, the rotational speed of the photoreceptor drum, exposure lamp, mirror system, etc.
This controls the scanning speed of the lens, etc. When 1x data is sent, the sequence computer determines this and increases the speed of the photoreceptor drum, and delays the photoreceptor drum by 30ms when changing magnification for reduction/enlargement. Then, the lens is set at the desired position, and when changing the magnification, the drum is rotated one more revolution to achieve a break-in operation and to stabilize the potential when switching from high speed to low speed.

On the other hand, in an analog copying machine, when the scanning speed of the reading scanner is kept constant and the processing speed of the copying process is increased, the image information of the read document is directly incident on the photoreceptor via the optical system, which is similar to the known electrophotographic method. Since the image is visualized through a process and transferred to a transfer medium such as transfer paper to obtain a copy image, the boundaries of the image are stretched and the image becomes blurred. However, digital copiers perform analog/digital conversion and manage dots in units of dots, so if you perform the same operation, the image will be stretched in the sub-scanning direction, but the dots themselves will be clear and the image will be blurry. Nothing happens.

[Problem to be solved by the invention]

By the way, in general, as mentioned above, the electrophotographic process is processed at a constant speed, or it may be processed at a different speed when changing the magnification. When a user wants something of excellent quality, there is no way for the user to select it.

This invention was made in view of the actual state of the prior art, and its purpose is to allow the user to set the copying speed freely to a certain extent, ensure image quality through digital processing, and perform high-speed and low-speed copying. The objective is to provide a digital copying machine that can perform the following tasks.

[Means to solve the problem]

The above object is to form an image of the image information of the document on a photoelectric conversion element through the optical scanner, convert the image information from analog to digital based on the formed image, and convert the image information to digital. A means for extracting an image signal, a means for processing and processing the extracted image signal, a means for replacing the processed and processed image signal with an optical signal and exposing it on a photoreceptor, and an electrophotographic method for converting the exposed image into an electrophotographic image. In a digital copying machine having means for obtaining a copied image by developing the image through a process and transferring and fixing it to a transfer medium, a means for making the processing speed of the electrophotographic process variable, and a means for making the processing speed of the electrophotographic process variable; This is achieved by including means for varying the scanning speed of the optical scanner in the sub-scanning direction to a scanning speed that does not cause deviation in the sub-scanning direction in response to the speed.

[Effect]

According to the above means, when the copying speed is made variable on the user side, the scanning speed of the optical scanner in the sub-scanning direction is changed correspondingly to the variable speed so that deviation in the sub-scanning direction does not occur. , the copied image is shifted in the sub-scanning direction,
There is no risk of expansion or contraction. Furthermore, since the image is managed in dot units, there is no risk of the copied image becoming blurred.

Note that since the scanning speed in the main scanning direction is constant, the optical system in the main scanning direction and the control of the optical system do not become complicated.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a system of a digital copying machine according to an embodiment, and FIG. 2 is a schematic block diagram showing the internal structure of the digital copying machine.

In FIG. 2, the digital copying machine 1 according to the embodiment includes a copying machine main body part 3, a scanner part 5, and an automatic document feeder (
(hereinafter referred to as ADF) 7.

The scanner section 5 includes a light source 9 , a reflector 13 that reflects the light from the light source 9 and irradiates it onto the original 89 from the lower surface side of the contact glass 11 , and a one-dimensional solid-state image element 15 that directs the reflected light from the original 89 to the original 89 . The first mirror 17, the second mirror 19, and the third
The light source 9, the reflecting mirror 13, and the first mirror 17 constitute the first scanner 27, and the second mirror 19 and the third mirror 2 constitute the optical system 25 consisting of the mirror 21 and the lens 23.
1 constitutes the second scanner 29. This scanner section 5 is also provided with a scanner control section 31, which controls the scanning speed of the first and second scanners 27 and 29, and converts image information obtained by the -dimensional solid-state image sensor 15 into digital information. C of the main controller 65, which will be described later.
PU (Central Processing Unit) 100
Output to.

The copying machine main body 3 includes an image forming section 33, a paper feeding section 35,
It mainly consists of a paper discharge section 37.

The image forming section 33 includes a polygon mirror 41 and a reflecting mirror 43 that guide laser light incident from a laser emitting section (not shown) toward the photoreceptor drum 39, and a charger 45 disposed along the outer periphery of the photoreceptor drum 39. , potential sensor 47
, a developing device 49 , a density sensor 51 , a transfer/separation charger 53 , a cleaning section 55 including a cleaning blade and a static elimination lamp, and a fixing roller 57 , and a motor 59 for driving the polygon mirror 41 . , a polygon mirror control section 61 that controls this motor 59, a main motor 63 that rotationally drives the photosensitive drum 39, fixing roller 57, and other transport rollers in the copying machine main body 3, and each of these sections. The main controller section 65 is also provided.

The paper feed section 35 includes a paper feed tray 67 and a paper feed roller 69, and a paper feed sensor 71 and a registration roller 73 are arranged downstream of the paper feed roller 69 in the conveying direction.

The paper ejection section 37 includes a sorter 75 provided on the downstream side of the fixing roller 57 in the transport direction, and is driven by a sorter motor 77 to collect transfer paper transported into the sorter 75 via a paper ejection sensor 79 and a paper ejection roller 81. Paper is ejected into a designated bin.

The ADF 7 is mainly composed of a document tray 83, a paper feed roller 85, and a document conveyance belt 87 driven by a driving roller and a driven roller, and automatically contacts the document 89 placed on the document tray 83. After the original 8 is guided onto the glass 11 and copied, the original 8 is placed on the original tray 83 again.
It is designed to return 9.

The scanner unit 5 also includes a facsimile control unit 93 that receives facsimile signals via a telephone 95, outputs the received facsimile signals to the scanner control unit 31, and visualizes the transmitted image signals. It is now possible to convert

The control system for the digital copying machine configured as described above includes a CPU 100 in the main controller 65, a processing speed setting section 101, an external signal input section 102, various sensor input sections 103, a condition setting memory section 104, and a clock generation section 105. ,ADF! IIJ Part 106, Suki Part 06 Part 3
1, an image information input section 107, a write control section 108, a printer control section 109, a usage condition memory section 110, a sorter control section 111, a display section 112, etc. are connected.

The processing speed setting section 101 allows an operator or a service person to arbitrarily set the electrophotographic process including the rotational speed of the photosensitive drum 39 and/or the fixing roller 57 using an input means provided in an operation section (not shown) of the copying machine main body 3. It allows the processing speed to be set, and uses a rotating dial or sliding analog input means.

The analog value of the processing speed set by such an input means is further converted into a digital value in the analog/digital conversion section of the photoreceptor speed setting section 101, and the CP
It is input to the U100 side. The aforementioned facsimile control section 9
The facsimile signal from 3 and the signal from the host computer are sent to the CPU 100 via the external signal input section 102.
Detection information from the jam sensor, environment sensor, surface potential sensor 47, toner concentration sensor, etc. is input to the CPU 100 from the various sensor input section 103.

Furthermore, image MFT processing, magnification changing processing, photoreceptor characteristics,
Information and setting conditions regarding opening performance, main motor control, etc. are input and output between the condition setting memory unit 104 and the CPU OO. Also, a charging charger 45, a developing device 49, a transfer/separation charger 53, a cleaning section 5
A process condition control unit 113 instructs process conditions to 5.
Process conditions are input from the CPU 100 via the printer control unit 109, and the write control unit 108
The writing conditions are input in .

In the digital copying machine 1 configured as described above, when a stack of originals 89 is placed on the original tray 83 of the ADF 7 and a print switch (not shown) on the operation unit is pressed, the originals 89 are fed from the original tray 83. The document 89 is guided by the roller 85 to the document conveyance belt 87 side.
is placed on the contact glass 11 of the scanner section 5 and positioned. Then, the light source 9 is turned on, and the first and second scanners 27 and 29 scan to guide the reflected image of the original 89 toward the one-dimensional solid-state image sensor 15.

The reflected image of the document 89 guided to the dimensional solid-state image sensor 15 is photoelectrically converted there, and the photoelectrically converted information is input to the scanner control section 31 . The information manually entered into the scanner control section 31 is converted into digital values here, and is sequentially transmitted from the main controller section 65 of the copying machine main body 3 to the polygon mirror 4.
1 and the polygon mirror controller 61 .

Then, the laser light emitted from the laser emitting section is reflected by the reflecting mirror 43.
The light is guided to the photoreceptor drum 39 and developed by a developing device 49. In parallel with this, the copy paper 91 as a transfer medium is transferred to the registration rollers 73 in synchronization with the rotation of the photoreceptor drum 39.
is synchronized and guided to the photoreceptor drum 39 side, the original image visualized on the photoreceptor drum 39 is transferred to copy paper 91, fixed by fixing roller 57, and discharged to the sorter 75 side. . Since the copying process during this time is a known electronic copying process, a detailed explanation will be omitted.

In the above system, the digital signal is 4 in both the main scanning direction (laser writing direction) and the sub-scanning direction (paper passing direction).
Processed at 00dp 1X400dpi. here,
When changing the speed in the sub-scanning direction in the processing speed setting unit 101, if the speed in the main scanning direction is also changed, the processing speed of image processing such as increasing the speed of bit information and the rotation speed of the polygon mirror 41 must be changed, which increases costs. It gets expensive. Therefore, the speed in the main scanning direction is assumed to be constant. On the other hand, in a method in which the signals read by the scanner section 5 are sequentially written without being stored in the memory, if the rotation speed of the photoreceptor drum 39 is changed to adjust the magnification, the density in the sub-scanning direction will differ from that of the original document. . Therefore, in this embodiment, as shown in the explanatory diagrams of FIGS. 3 and 4, at high speed (FIG. 3(b)
) is the read information according to the amount of change ΔV of the set speed with respect to the standard speed V (Figure 3 (a)), Δv / v%
On the other hand, if you want to slow it down (Fig. 3 (C)), increase Δv/v% and sample finely. Therefore, if the unit feed amount at the speed V is β, the feed amount at high speed is (1+Δv/v)ffi, and the feed amount at low speed is (1−Δv/v)a. In line with this, from the normal time shown in Figure 4(a),
The sub-scanning speed of the reading scanner is changed to correspond to the high speed shown in FIG. 3(b).

Note that when the scanning speed in the sub-scanning direction is changed by changing the rotational speed of the photoreceptor drum 39 in this way, the fixing conditions such as light amount, potential, developing bias value, transfer current, cleaning pressure, pressure, and temperature are changed accordingly. In this embodiment, it is configured to be controlled by the aforementioned CPU 100 shown in FIG. The main control points are listed below.

First, when the processing speed of the electrophotographic process is increased, as shown in the explanatory diagram in Fig. 5, image A at the standard process speed becomes image B, with a decrease in solid black density and noticeable horizontal streaks. . Therefore, it is necessary to prevent the image quality from deteriorating. Methods to prevent this image quality deterioration include: ■ changing the beam diameter in the sub-scanning direction according to the set processing speed (making the beam shape elongated in the sub-scanning direction), and ■ increasing the beam power. There are two methods, such as increasing the apparent diameter of the beam spot (power variation UN) and increasing the beam spot diameter by increasing the pulse width (pulse width modulation).

That is, by writing the image shown by A in FIG. 5 with a beam q as shown in FIG. 5 and developing it at a preset development level Assuming that line part r is obtained, the faster processing speed will result in a rough beam q as shown in the same figure, and the image produced by that beam q will be like B, so the black solid density and horizontal The streaks become noticeable, but if you increase the power of beam q as shown in figure E, the distribution of beam q becomes as shown in figure F,
The energy distribution e for the development level X is corrected. In addition, as shown in the explanatory diagram showing the correlation between the laser application time and the spot diameter in Fig. 6 and also in Fig. 5G, the laser pulse width was changed from the standard state (Fig. 6, b'). When the spot diameter is increased (Fig. 6 c, c'), Fig. 5 H
The energy distribution e is as shown in FIG. Note that the pulse width is approximately 50 na as a guide.

In this way, increasing the processing speed increases the beam diameter and improves the energy distribution e, but as the processing speed increases, the development potential decreases, so it is necessary to change the process conditions as described below. . in particular,
As the surface potential decreases as the speed increases, background smearing tends to occur in negative/positive development. Therefore, the surface potential of the photoreceptor drum 39 is monitored by the potential sensor 47,
Control is performed such as increasing the grid potential to restore the potential, lowering the bias potential, and increasing the density so that the toner adheres slightly thickly. Furthermore, since the transfer rate also decreases, the transfer current of the transfer charger 53 is increased to improve the transfer rate. In the cleaning section 55, the photosensitive drum 3
In order to increase the pressure of the cleaning blade and increase the toner discharging force as the rotation speed increases,
Increase the rotation speed of the discharge auger coil. Furthermore, when using a separate motor, it is necessary to shift the timing by taking into account the rise time of the registration roller 73 in order to match the writing standard to the photosensitive drum 39.

Note that the above control describes a laser writing system, but it is not applicable to systems that use solid-state writing elements such as LED (light emitting diode) arrays or LCD (liquid crystal display) arrays.
A similar effect can be obtained by increasing the exposure time per sub-scanning line in accordance with the linear velocity of the photoreceptor drum 39.

On the other hand, when the processing speed is reduced, the control opposite to the above is performed. In other words, the image A in FIG. 5 becomes a solid black image as shown in FIG. Therefore, in order to reduce the overlap with adjacent beams, either lower the power as shown in J in the figure and obtain an energy distribution e as shown in K in the figure, or As shown in Figure 5 and 611 (a, a'), by reducing the pulse width and narrowing the beam diameter,
Obtain an energy distribution e as shown in . Then, in parallel with this, the process conditions are reversed to those used when increasing the processing speed to obtain a proper image.

Furthermore, in those using solid writing elements such as the above-mentioned LED array or LCD array, the same effect can be obtained by reducing the exposure time per sub-scanning line in accordance with the linear velocity of the photoreceptor drum 39. can.

Furthermore, as for the fixing conditions, when the processing speed becomes low, problems such as over-fixing and curling of the transfer paper occur, so it is also necessary to change the settings of the fixing temperature and fixing pressure depending on the processing speed. Regarding this fixing, when copying to a print master document or OHP film, a slow speed is preferable in terms of fixing performance, color development, etc., so the processing speed can be selected depending on the transfer medium. There is no need to install other incidental equipment. Therefore, by allowing the user to freely set the processing speed, it is possible to reduce costs and
It has become possible to provide a digital copying machine that is compatible with a wide range of transfer media.

Note that when the processing speed is changed, various detailed controls are required depending on the speed change. For example, in response to changes in processing speed, it is necessary to coordinate lines and timing for peripheral devices such as the ADF 7, sorter 75, double-sided copying machine, facsimile machine, and printer. , is performed via the CPUI OO.

Furthermore, since the service life of maintenance parts may vary if the processing speed changes, the above-mentioned usage condition memory section 110 is provided to store the usage conditions of these parts. In addition, when using a two-component developer, there is a problem in which the developer is biased due to a shift in the rotational speed. A gate 116 is provided at the developer intake port 115 to adjust the amount of developer so that the developer does not shift. Furthermore, in order to adjust the power of the main motor 63 to its maximum value and to make it resistant to load fluctuations even at low speeds, a dummy load is applied, and the constants of the servo system are shifted to accommodate this.

In the above explanation, we have talked about (2) and (2) in which the beam q of the light source is directly controlled, but in (2), for example, the cylindrical lens 130 whose axis length in the sub-scanning direction can be changed is exposed to light from the polygon mirror 31. body drum 3
It is also possible to set the beam diameter in the sub-scanning direction by changing the diameter of the beam in the sub-scanning direction by moving it forward and backward at an appropriate position on the optical path leading to the surface 9.

〔Effect of the invention〕

As is clear from the above description, there is a means for making the processing speed of an electrophotographic process variable, and a scanning method that does not cause deviation in the sub-scanning direction in response to the speed changed by this variable means. According to the present invention, the scanning speed in the sub-scanning direction of the optical scanner is changed so that the scanning speed in the sub-scanning direction is not caused in response to the variable speed. To provide a digital copying machine capable of performing high-speed copying and low-speed copying by allowing a user to freely set the copying speed to some extent and ensuring image quality through digital processing since the scanning speed in the sub-scanning direction of a scanner changes. Can be done. At this time, since the scanning speed in the main scanning direction is constant, the optical system in the main scanning direction and the control of the optical system do not become complicated, and the speed in the sub scanning direction of the scanner is controlled by the software on the control device side. Since the control is performed, a digital copying machine equipped with the above functions can be provided at low cost.

[Brief explanation of the drawing]

The figures are all for explaining the present invention in detail, and FIG. 1 is a configuration diagram of a system of a digital copying machine according to an embodiment, FIG. 2 is a schematic diagram showing the internal structure of the digital copying machine, and FIG. 3 is an explanatory diagram for explaining the difference in feed amount due to a change in the scanning speed in the sub-scanning direction between the scanners, and FIG. 4 is an explanatory diagram for explaining the deviation in the sub-scanning direction due to the speed displacement of the scanner. Fig. 5 is an explanatory diagram showing the relationship between scanner speed displacement, beam diameter, and image, Fig. 6 is an explanatory diagram showing the relationship between pulse width modulation and the beam diameter caused by pulse width modulation, and Fig. 7 is an explanatory diagram showing the relationship between the scanner speed displacement, beam diameter, and image. FIG. 3 is a perspective view of a main part of the developing device showing the state of a gate provided in a circulation path of the developing device. 1...Digital copier, 3...Copier main body, 5...Scanner section, 15...
-dimensional image sensor, 25...optical system, 27...
...1st Sukiyana, 29...2nd Sukiyana,
31... Scanner control unit, 33... Image forming unit, 39... Photosensitive drum, 41...
... Polygon mirror, 45 ... Charger, 49 ... Developing device, 53 ... Transfer
Separation charger, 55...Cleaning section, 5
7... Fixing roller, 65... Main controller, 89... N fA, 100...
...CPU, 101...Processing speed setting section, l
O8...Writing control unit.

Claims (1)

[Claims] an optical scanner; image information of a document is formed on a photoelectric conversion element through the optical scanner; the image information is converted from analog to digital based on the formed image; and the image information is extracted as a digital image signal means for processing and processing the extracted image signal; means for replacing the processed and processed image signal with an optical signal and exposing it onto a photoreceptor; and developing the exposed image through an electrophotographic process. and a means for obtaining a copied image by transferring and fixing onto a transfer medium, a means for making the processing speed of the electrophotographic process variable, and a means for making the processing speed of the electrophotographic process variable, and corresponding to the speed changed by the variable means. 1. A digital copying machine comprising means for varying the scanning speed of the optical scanner in the sub-scanning direction to such a scanning speed that no deviation in the sub-scanning direction occurs.