JPS6177078A - Electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To obtain selectively copies, which can be erased easily and have characters not blurred neither erased in case of normal handling, and normally fixed copies by constituting a copying machine so that normally fixed copies and half fixed copies can be selected. CONSTITUTION:When a mode selecting key on an operation panel is operated to select the half fixing mode, the pressing force of a pressuring roll 22 to a fixing roll 21 is reduced to a prescribed pressing force for the half fixing mode. As the result, a toner image on transfer paper held between and carried by the fixing roll 21 and the pressuring roll 22 is half fixed and is ejected to a copy tray. When a refixing mode selecting key on the operation panel is operated to select the refixing mode, the pressuring force of the pressuring roll 22 is set to a pressuring force for normal fixing, and half fixed copies are fixed completely and are ejected to the copy tray.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field This invention involves transferring a toner image formed on a photoconductor by an electrostatic photographic process to a transfer paper, and then transferring the transfer paper to a heat fixing device. The present invention relates to an electrophotographic copying machine that fuses and fixes the toner image onto a transfer paper by passing the toner image therethrough.

It is often necessary to make some corrections to copies made from original documents by prior art electrophotographic copiers. In such a case,
In the past, the areas to be corrected were pasted on blank paper, coated with correction fluid, or scratched with an FD knife, etc., and then the corrected text or figures were written on the areas. Such work is extremely troublesome, hinders business efficiency, and has the disadvantage that the corrected copies become difficult to see.

In such a case, it would be extremely convenient if the copied image could be easily erased with an eraser or the like, like a pencil-drawn image. However, after the toner image formed on the photoconductor is transferred to the transfer paper using the photocopying process using a photocopier, the toner image is fused and fixed to the transfer paper by the fixing device. It stays firmly in place and cannot be erased with regular erasers.

Therefore, an electrophotographic copying machine is equipped with a mode in which the unfixed toner image transferred onto the transfer paper is fixed and discharged, and a mode in which the unfixed toner image is discharged without being fixed. When making a copy that requires correction by partially erasing the copy, a copying machine has been proposed that allows the user to select a mode in which the copy is ejected in an unfixed state.

However, unfixed toner images are simply electrostatically attracted to the transfer paper, and while it is true that unnecessary images can be easily erased, even when rubbed unwillingly with hands or clothes, etc. If you place a plastic ruler or press the area with your fingers to draw another character or image on the erased area, toner will adhere to it, and unfixed copies may be stacked on top of each other. When stored, the toner image is not easy to handle because it is offset to the back side of the upper sheet and the upper and lower sheets are misaligned, causing rubbing of the toner image.

Purpose of the present invention In view of the above-mentioned circumstances, the present invention provides a method for easily erasing toner images on copies that require correction with an eraser, etc. In the usual several steps, the letters,
Two objects of the present invention are to provide a single-child photocopying machine having an energy-saving configuration and capable of selectively producing easily-handled copies without images being rubbed or erased, and normally fixed copies. .

In addition, the purpose is to solve various problems related to this. These intermittent points and configurations for solving them will be made clear in the detailed description that follows.

Structure: In order to achieve the above object, the electrophotographic i-natsushaiso according to the present invention has a normal fixing mode for obtaining copies with normal fixing properties using the same fixing device, and a semi-fixing copy mode. The present invention is characterized in that it has a semi-fixing mode for obtaining a fixed image, and is provided with a mode selection key that can arbitrarily select one of these modes.

As is clear from the above, this semi-fixing property means that the toner image is like a pencil-drawn image and can be easily erased with an eraser, and that the image does not rub off, become distorted, or disappear under normal handling. , refers to a state in which the material is fixed to a degree of p that does not adhere to other objects.

By the way, the fixation of toner images in electronic ventrilograph machines is
Generally, this is carried out by heating an unfixed toner image, or by applying heat and pressure to melt the toner and fuse it to the transfer paper.

Therefore, in order to obtain a semi-fixable copy, the fusing temperature must be controlled to be lower than the normal constant @ temperature, or the fusing must be performed using a pressure lower than that used for normal fusing. Bye.

Hereinafter, the present invention will be explained in detail based on the embodiments shown in the drawings.

FIG. 1 is a diagram showing the overall schematic configuration of an embodiment of an electrophotographic copying machine according to the present invention.

A document placed on a contact glass 1 provided on the top surface of the copying machine is optically scanned by left and right swinging illumination units 2, and an image is formed on a photoreceptor drum 5 via a lens 3 and a mirror 4. The photoreceptor is exposed to light.

Around the photoconductor drum 5, in the order of rotation direction indicated by the arrow, there are a charger 6, an erase unit 7, the exposure position,
Developing unit 8, transfer charger 9, separation conveyance belt 1
0, a static elimination charger 11, and a cleaning unit 12 are arranged. Upper, middle, and lower paper feed trays 13114.degree. 15 are provided on the right side of the copying machine, and transfer paper is fed through a paper feed path 16 to a transfer section constituted by the transfer charger 9. The toner image formed on the surface of the photoreceptor drum by each of the above-mentioned process units by a known still photography process is transferred to the transfer paper fed at the same timing by the transfer charger 9, and transferred to the separation conveyance unit 1.
After being conveyed to the fixing unit 17 by 0 and fixed,
The paper is discharged onto the copy receiver 18, or, if double-sided copying is to be performed, the paper is reversed and discharged onto the intermediate copy receiver 19.

The configuration described so far is no different from a conventional copying machine.

Now, the fixing unit 17 of the copying machine of this embodiment is a heat roller type fixing device, and as shown in detail in FIG.
A pressure roller 22 that can be pressed into and released from this is provided. The pressing force of the pressure roller 22 is applied by a cam follower 24 provided at the tip of a lever 23 that supports the pressure roller 22.
It is made variable by a fan-shaped cam 25 that engages with. The fan-shaped cam 25 [as shown in Fig. 31ffl] is rotated to two predetermined positions by a rotary lean lens 26, whereby the cam 7 lower 24 is displaced as shown by the arrow in Fig. 2. The pressing force of the pressing roller 22 is switchable. The operation panel of the copying machine is provided with a mode selection key that can arbitrarily select between a normal fixing mode and a semi-fixing mode.The rotary toner maid 26 is turned on and off by operating this selection key.

Furthermore, in this embodiment of the copying machine, as shown in FIG.
An opening 27 into which paper can be inserted from outside the machine is provided in the casing on the receiving side of the intermediate copy receiver 19, and a transport roller 28 is provided inside the opening 27.
A paper transport path 29 is provided that extends from a transport path that leads to a normal transfer section on the discharge side of the intermediate copy receiver 19 to a branched direct fixing unit 17 . Normal conveyance path 16
A conveyance path switching pawl 30 is provided at the branch point between the conveyance path 29 and the conveyance path 29 . Feed rollers made of a material such as sponge whose friction coefficient and pressing force are not very large are provided at key points of the conveyance path 29. Further, a re-fixing mode selection key is provided on the operation panel, and by operating this key, the above-mentioned conveyance path switching claw 3o is moved to a position for guiding the paper to the conveyance path 29, and the pressure roller 22 is also applied. Set the pressure to the pressure for normal fixing.

Below are the effects when making semi-fixable copies using this device? explain.

When the operator selects the semi-fixing mode by operating the mode selection key on the operating panel, the rotary solenoid 26 turns on, rotates the fan-shaped cam 25, and moves the cam follower 24 that engages with it to the position shown in FIG. is moved to the right to reduce the pressing force of the pressure roller 22 against the fixing roller 21 to the pressing force in a predetermined semi-fixing mode. As a result, the toner image on the transfer paper sandwiched and conveyed by the fixing roller 21 and the pressure roller 22 is fixed in a semi-fixed state and is discharged onto the copy receiver 18.

As mentioned above, this semi-fixed state is such that it can be easily erased with an eraser like a pencil-written document, and is set to such a fixed state that the image will not rub or come off even with normal handling. The pressing force of the pressure roller in the semi-fixing mode is determined accordingly.

The resulting copy can therefore be easily modified.

However, if a semi-fixed copy is stored as is, it will be difficult to maintain its perfect condition because it will be touched by human hands over time or the sheets will be rubbed against each other. Therefore, it is desirable to make the necessary corrections and then completely fix them.

Therefore, when the re-fixing mode is selected using the re-fixing mode selection key on the operation panel of the copying machine, the conveyance path switching claw 30 is switched to the position where it guides the paper toward the conveyance path 29, and the corrected paper is transferred from the paper insertion slot. When a semi-fixed copy is inserted, the copy is ejected to the intermediate copy tray 19 by the conveyance roller 28, inserted into the conveyance path 29 by the paper feed roller of the intermediate copy tray, and transferred to the fixing unit 17 by the conveyance roller provided on the conveyance path. sent. At this time, the fixing unit 17
Since the pressing force of the pressure roller 22 is usually a pressing force for fixing, the semi-fixing copy is completely fixed and discharged to the copy receiver 18.

A semi-fixable copy can be obtained by changing the fixing temperature, the nip width between the fixing roller and the pressure roller, and the passing speed of the fixing section, in addition to changing the pressing force of the fixing roller shown in the above embodiment. Of these, the nip width changes in relation to the fixing pressure. Furthermore, it is practically difficult to change only the passing speed of the fixing section separately from other conveyance paths. Therefore, in addition to changing the pressing force, it is highly possible to change the fixing temperature. In the case of a flash fixing device, the degree of fixing can be changed by changing the amount of light 2.

Fixing conditions such as pressing force and fixing temperature to obtain an optimal semi-fixing copy vary depending on the type of transfer paper.

Therefore, it is preferable to set fixing conditions in advance according to the type of transfer paper, and to change the fixing conditions by inputting a transfer paper type designation key.

Also, in the semi-fixing mode, special transfer paper or toner suitable for the semi-fixing mode may be used.

Next, an embodiment of an electrophotographic copying machine that obtains semi-fixed copies by changing the fixing temperature will be described.

FIG. 4 is a diagram showing the fixing unit 17 of the implementation row and its vicinity. The fixing unit 17 includes a fixing roller 21 that has a heater 20 inside and a pressure roller 22 that comes into pressure contact with the fixing roller 21.
The heat roller fixing device is similar to the above embodiment, but the pressing force of the pressure roller 22 is not dependent on the variable pressing force cam, but is applied by the pressure spring 32, and the pressing force at the time of pressing is It has become a constant. Instead, the fusing temperature is controlled to a predetermined temperature for both fusing modes in order to obtain a normal fusing copy and a semi-fusing copy. In this embodiment, the fixing control temperature for the normal fixing mode is 185C, and the fixing control temperature fl for the semi-fixing mode is set to 140C. The fixing temperature is controlled by the fourth
The actual temperature of the fixing roller 21 is detected by the thermistor 33 shown in the figure, and the heater 20 is controlled by the control circuit shown in FIG.
■Turn the power on and off twice.

In the control circuit shown in FIG. 5 and the control flow shown in FIG. 6, fixing is controlled by connecting the thermistor TH (33 in FIG. 4) and resistor R1, applying cc to both ends, and
Input C to A/D s VDEF of CPU36,
This is done by inputting the voltage 1 between TH and R1 to A/DIN. The data input to the A/D IN inputs the predetermined temperature of the fixing roller 21 (semi-fixing mode VT) programmed in advance for each fixing mode.
l 40C: On humidity 140C, normal fixing mode V7
H1s 5 C: ON temperature 185C) is compared, and if the input value is below the VTR corresponding to each mode, the heater on output is set to L. If it exceeds H1VTR, the heater on output is set to L (Figure 6 (b) reference).

By the way, in order to improve thermal efficiency of the fixing unit, the fixing roller and pressure roller are usually surrounded by a casing to prevent heat from escaping outside the fixing unit. The core material of the fixing roller is thickened to have a considerable heat capacity so that the temperature of the fixing roller does not drop due to heat being taken away by the paper and the toner carried thereon. Therefore, copy 2 in normal fixing mode.
When switching from the previous state to semi-fixing mode, the fixing roller's control temperature drops from 185C in normal fixing mode to 140C in semi-fixing mode, and it takes a long time before copying in semi-fixing mode becomes possible. There is a problem that it takes.

Copying machines are usually equipped with a cooling fan, which is operated during copying, in order to prevent the internal temperature from rising during copying. In the present invention, when the normal fixing mode is switched to the semi-fixing mode using this cooling fan, the cooling fan e is operated until the temperature from the fixing port to the fixing port falls to the control temperature in the semi-fixing mode. The present invention is characterized in that the temperature of the fixing section is intentionally lowered. In Fig. 4, the in-machine cooling fan 3 is located directly above the fixing unit
A duct 35 is connected to the fixing unit 4 and has a slit in the wall facing the fixing unit, and when an in-machine cooling fan 34 is operated, lice flow inside the fixing unit and cool it down. .

Mutual switching between the fixing mode and the semi-fixing mode is performed by a key switch (SWI in FIG. 5) on the operating section. The flow in that case will be explained with reference to the flowcharts in FIGS. 6(a), 6(b), and 6(c). In FIG. 6(a), when the key switch SWI is turned on and the CPU reads it, the CPU
U1'j Shifts the mode to the opposite mode to the previous mode. When the semi-fixing mode is entered by key reception, the mode is set to semi-fixing, and at the same time, a semi-fixing mode start flag indicating transition to the semi-fixing mode is set to H. In the flow shown in FIG. 6(b), the semi-fixing mode start flag is set to L when the fixing temperature drops to 140C and the heater is turned on for the first time. When the semi-fixing mode start flag is H, the cooling fan is turned on.

Therefore, the cooling fan is driven when transitioning from the normal fixing mode to the semi-fixing mode (see FIG. 6(c)).

Figure 7 shows that when switching between normal fixing mode and 6 quick arrival mode, the temperature of the ¥ deposition roller is the control temperature 1 in normal fixing mode.
FIG. 3 is a curve diagram showing a comparison between a case where the cooling fan is driven (solid line) and a case where the cooling fan is not driven (broken line). As is clear from the figure, by driving the in-machine cooling fan when transitioning from normal fixing mode to semi-fixing mode, the temperature drop time of the fixing roller is significantly shortened.
Downtime can be significantly reduced.

This invention not only uses a heat roller fixing device, but also performs fixing by sliding unfixed transfer paper in contact with the surface of a hot plate having a considerable heat capacity that is heated to a controlled temperature by a heater and maintained at that temperature. It can also be applied to a fixing device.

In a fixing device such as the above-mentioned heat roller fixing device, which performs fixing by moving a transfer paper carrying an unfixed toner image into contact with a member heated to a predetermined temperature by an internal heater, When fixing is performed, the heat of a fixing member such as a fixing roller is absorbed by the transfer paper and toner, and the temperature of the fixing member fluctuates. As already mentioned, in order to compensate for this, the temperature of the fixing member is conventionally detected by a thermistor or the like and the heater is controlled to maintain a predetermined control and blackness. However, in semi-fixing mode, the controlled fixing temperature is lower than in normal fixing mode.
It is necessary to control the temperature near the temperature at which off-cent etc. occur. For this reason, there is a problem in that the margin in the temperature control TATL is small, and when the temperature of the fixing roller falls below the control lower limit due to continuous sheet feeding, offset etc. occur, leading to image staining.

this? To prevent this - In a single-child photocopying machine that allows you to select between normal fixing mode and semi-fixing mode using the mode selection key, if semi-fixing mode is selected using the mode selection key, the number of consecutive copies that can be input using the numeric keypad, etc. ?
, the number of sheets should be limited to a number that will cause the temperature of the fixing roller to rise or fall to a temperature that causes offset, etc. due to continuous paper feeding. If pressing is prohibited until the temperature reaches the set temperature in the semi-fixing mode, it is possible to prevent copying from being performed at a temperature where offset or the like may occur. If the power is turned off or a jam is cleared while the semi-fusing mode has already been selected using the mode selection key, the humidity of the fixing device will be set to a predetermined half that will not cause offset etc. after the power is turned on or after the jam is cleared. By prohibiting the print key from being pressed until the fixing temperature rises to the fixing temperature in the fixing mode, it is possible to prevent occurrences of offcent and the like.

FIG. 8 shows an example of a control circuit for carrying out the above-mentioned control 3. In the figure, 81 to S16 are key inputs (numeric keypad, cassette selection key, mode selection key, etc.) on the operation unit. The control unit 41 is composed of a CPU, its peripheral ICs, and drivers. The display section 42 displays information such as the number of sheets set using a light emitting diode or a fluorescent lamp. The temperature control section 43 controls the heater of the fixing section using input from the thermistor TH33 to control the temperature of the fixing section. ■, ■, ■, ■ are the above key inputs 5l-
This is the pulse output for making 316 into a guinamisoku.

FIG. 9 is a 70-chart illustrating an example of an operation for limiting the number of continuous copies in the semi-fixing mode to a predetermined number or less, and here shows a column for limiting the number of copies to five. In the figure, ■ to [phase] indicate the flow order of 70-, and the following description will be made with reference to these numbers.

First, the operation for limiting the number of copies will be explained when the "semi-fixing mode" is selected and the number of copies to be copied and E-cents are added.

■ Determine whether the key has been pressed (input) or not, and if the key has been pressed completely, proceed to YES.

■■■ Determine which key block from ■ to ■ is the key block, and if ■, proceed to ■ YES, ■ Keys 81 to S
It is determined which key of 4 was pressed and the data matching that key is sent to (CPSET). In addition, in ■, S
When l is pressed, ga, 1 in S2, 2 in S3, S
4 is the data of 3? cent.

■■ Similarly, when the key block is ■ or ■, data corresponding to the key determined to have been pressed is set in (CPSET).

■ Check flag 2 to determine whether "semi-fixing mode" is selected, and if it is selected, proceed to YES; If it is larger than ``5j'', proceed to YES and enter ``5'' in the G set number data counter (CPSET).
” 2 sets, and this \ limits the number of sets to 5.

Next, after the set number of sheets has been set, "Semi-fixing mode"
The operation for limiting the number of sheets when the selection key is pressed will be explained.

■ The control section 41 receives the humidity condition signal of the fixing device from the temperature control section 43 in FIG. 8, and determines whether the fixing device has reached the set temperature. If so, proceed to YES, ■ Determine whether or not the "semi-fixation mode" selection key has been pressed, and if it has been pressed, proceed to YES, and set the flag indicating that "[phase] 1 fast arrival mode" has been selected. and display a message on the display to indicate that it has been selected.■
Proceed to.

■ The rest is the same as the above explanation.

As described above, when the semi-fixing mode is selected, the number of sheets that can be continuously copied is limited, so that occurrence of offset etc. due to a decrease in fixing temperature is prevented.

Effects As described above, the present invention provides a semi-fixed copy that forms a toner image on transfer paper that can be easily erased with an eraser or the like, but will not be disturbed or rubbed by normal handling. Normally, constant magnification is obtained by a fixing device that increases the magnification by ↑, making it easier to correct images on copies, and
Various problems that occur when selecting the semi-fixing mode can be solved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of an electrophotographic copying machine according to the present invention, FIG. 2 is a cross-sectional view showing the fixing device in detail, and FIG.
The figure is a sectional view taken along the line 1-11 in FIG. 2, FIG. 4 is a sectional view showing the vicinity of the fixing device according to another embodiment of the present invention, FIG. 5 is a fixing temperature control circuit diagram, and FIG. The control flowchart, FIG. 7, is a curve diagram showing the change curve of the fixing temperature over time when the apparatus is switched from the normal fixing mode to the semi-fixing mode, with respect to when the in-machine cooling fan is operated and when it is stopped. The figure is a block diagram of a control circuit for limiting the number of continuous copies in the semi-fixing mode, and FIG. 9 is a control flowchart thereof. 5... Photosensitive drum (photoconductor) 17... Fixing unit (fixing device) 20... Heat source 21... Fixing roller (heating member having a considerable heat capacity) 22... Pressure roller, 25... variable pressure cam 29
...Semi-fixing copy re-fixing conveyance path 34...In-machine cooling fan SWI...Fixing mode selection key Figure 1

Claims (9)

[Claims] (1) A toner image formed on a photoconductor by an electrostatic photographic process is transferred to a transfer paper, and the transfer paper is passed through a heat fixing device to fuse and fix the toner image to the transfer paper. The electrophotographic copying machine has a normal fixing mode for obtaining copies with normal fixing properties using the above-mentioned fixing device, and a semi-fixing mode for obtaining copies with semi-fixing properties using the same fixing device. An electrophotographic copying machine characterized by being provided with an arbitrarily selectable mode selection key. (2) The above-mentioned fixing device has a fixing roller having an internal heat source and a pressure roller in pressure contact with the fixing roller, and is a device that fixes the unfixed transfer paper by passing the unfixed transfer paper between the pair of rollers. 2. The electrophotographic copying machine according to claim 1, wherein fixing in the semi-fixing mode is performed by reducing the pressing force of the pressure roller compared to that in the normal fixing mode. (3) The electrophotographic copying machine according to claim 1, wherein the fixing in the semi-fixing mode is performed by lowering the fixing temperature of the fixing device compared to that in the normal fixing mode. (4) The above-mentioned fixing device is a device that heats and fixes the transfer paper by bringing it into contact with a heating member having a considerable heat capacity, and the electrophotographic copying machine is equipped with an internal cooling fan,
When switching from the normal fixing mode to the semi-fixing mode, the cooling fan is operated until the temperature of the fixing section falls to a preset fixing section temperature in the semi-fixing mode. The electrophotographic copying machine according to item 1. (5) The fixing conditions in the semi-fixing mode described above are made variable, the fixing conditions are set in advance according to the type of transfer paper, a designated key is provided for inputting the type of transfer paper, and the type of transfer paper is input using the designated key. 2. The electrophotographic copying machine according to claim 1, wherein the fixing is performed under the preset fixing conditions. (6) The electronic photograph according to claim 1, characterized in that when the semi-fixing mode is selected using the mode selection key, the number of consecutive copies that can be input is limited to a predetermined number or less. Copy machine. (7) The above-mentioned mode selection key is prohibited from being pressed until the temperature of the fixing device reaches the set fixing temperature in the semi-fixing mode after the power is turned on or after the jam is cleared. The electrophotographic copying machine according to item 1. (8) If the semi-fixing mode is selected using the mode selection key above, pressing the print key is prohibited after the power is turned on or after clearing a jam until the temperature of the fixing device reaches the specified fixing temperature in the semi-fixing mode. An electrophotographic copying machine according to claim 1, characterized in that the electrophotographic copying machine is configured such that: (9) An electronic device that transfers a toner image formed on a photoconductor by an electrostatic photographic process onto a transfer paper, and causes the transfer paper to pass through a fixing device to fuse and fix the toner image to the transfer paper. In the photocopying machine, a normal fixing mode for obtaining normal fixing copies by the fixing device;
It has a semi-fixing mode for obtaining semi-fixing copies using the same fixing device, and also allows transfer paper inserted from outside the copying machine to be discharged through only the fixing device, separate from the normal transfer paper conveyance path. An electrophotographic copying machine characterized by being provided with a transfer paper conveyance path that allows for.