JPH09222823A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten time from a start to a finish of a copy using a new kind of paper from paper kind changing operation by arranging a control means to select whether a fixing temperature is changed or paper feed speed is changed according to a preset kind of paper. SOLUTION: A control means 10 can select whether a fixing control temperature is changed or paper feed speed (copying speed) is changed according to a kind of paper selected by a paper kind setting means to set a kind of paper of transfer paper 5 on which an image is formed. At fixing time, when paper is changed (selected) to a kind of paper requiring a high quantity of heat from paper requiring a low quantity of heat, the total copying time is shortened when copying operation is performed after waiting until a fixing temperature becomes sufficiently high when plural sheets are copied at one time. On the other hand, time until a copy finishes is shortened by the extent that waiting time is shortened by delaying copying speed simultaneously when a copy is started without waiting until the fixing temperature becomes sufficiently high when only a single sheet to several sheets are copied.

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 provided with a heat fixing device for fixing unfixed toner on a transfer paper, and particularly when the paper type of the transfer paper is changed, the fixing temperature is changed. The present invention relates to an image forming apparatus that prevents a long waiting time from the change of the fixing temperature to the first copying, which is a drawback of the image forming apparatus.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus such as a copying machine, a printer or a facsimile machine, an electrostatic latent image formed on a photoconductor is visualized by a toner from a developing device, and then the toner is used. An image is formed by transferring and fixing the image on a transfer paper. A thermal fixing device is generally used as the fixing means. The thermal fixing device includes a heat roller having a heater therein and a pressure roller in pressure contact with the heat roller. The fixing is performed by passing the transfer paper holding the unfixed toner onto the sheet. The temperature of the heat roller is measured by a temperature detecting means such as a thermistor, and by outputting the measured temperature data to the control means of the image forming apparatus,
The control unit controls the heater temperature of the heat roller based on the temperature data. JP-A-6-161175 discloses that
In order to shorten the time from when the power of the image forming apparatus is turned on to when copying is possible, fixing (paper passing) is performed before the fixing temperature of the heat roller reaches a predetermined fixing temperature (when it reaches a predetermined low temperature). ) Is started and the operation speed of the transfer paper conveyance speed (scanning optical system, photoconductor, transfer paper conveyance mechanism, heat fixing device) at the time of passing the paper is slowed down.

By the way, it is well known that it is necessary to change the fixing control temperature depending on the type of transfer paper. For example,
Tracing paper and thick paper require more heat than plain paper, so when these paper types are selected, the fixing temperature is raised, and conversely, film and thin paper are selected. There is an image forming apparatus having a function of lowering the fixing temperature in the case of the above. The above publication proposes that in order to shorten the waiting time until the start of the first copy after the power is turned on, copying can be performed from a state of low fixing temperature, and in this case, it is slower than the normal copying speed. However, in this publication, when changing the paper type of the transfer paper used in the copy operation up to that point, no consideration is given to shortening the time from the change of the paper type to the end of copying. It has not been. In other words, even if the waiting time from power-on to the first copy is shortened, the paper type used in the preceding copy operation is changed to another paper type (especially with a different heat capacity) in the next copy operation. When changing to a different paper type, it is a one-handed task if you have to wait for a long time until the fixing temperature rises or falls until the fixing temperature becomes suitable for the changed paper type.

[0004]

FIG. 5 is a diagram showing an example of controlling the fixing temperature when changing the paper type, and is an example of changing only the fixing temperature while keeping the copy speed constant. T _T means tracing paper, T _N means plain paper, and T _F means film. When the power of the image forming apparatus is turned on, the temperature of the heat roller gradually rises from the state where both the temperature and the time are “0”, and the temperature becomes a temperature at which the film can be fixed first, and then the plain paper, The temperature becomes the fixing temperature in the order of tracing paper. For example, when the temperature of the heat roller of the fixing device is controlled for tracing paper, if an operation for switching the paper type to film is performed at a certain point (t6), copying can be started. Is at the time of t8, and it takes a long time from the high temperature to the low temperature. On the contrary, when the heat roller temperature is set low for the film and the paper type is switched to tracing paper,
The waiting time from t6 to t7 is required. In this way, even if the paper type is changed as in the past, if you try to change only the fixing temperature without changing the copy speed, there is a problem that the time from the change of paper type to the start of copying becomes long. is there.

The present invention has been made in view of the above problems of the prior art. When the paper type of the transfer paper is changed, the time from the paper type changing operation to the start and end of copying using the new paper type. The purpose is to shorten. That is, when a paper type that requires a high amount of heat for fixing is selected, it is faster to raise the fixing temperature and then perform the copying operation when copying multiple sheets at once, but only one sheet is copied. In such a case, even if the copying speed is slowed down and copying is performed, the waiting time is short and the time required to complete copying is shortened. It is an object of the present invention to shorten the time required from the change to the end of copying when the paper type is changed in this way. According to the second copying mode tendency of the device, which of the modes, the fixing temperature changing mode and the sheet passing speed (copying speed), generally terminates copying earlier. The purpose is to improve the operability by making a judgment and selecting a mode that ends early. Next, when changing from a paper type requiring a high amount of heat to a paper type requiring a low amount of heat, the waiting time for the heat roller to cool down is long. However, there is a limit to increasing the copying speed. In the normal setting, copying is performed at a speed as high as possible in order to improve productivity, and therefore there is a limit to further increasing the copying speed in order to reduce the amount of heat applied to the transfer paper. According to the third aspect, a lower fixing amount than the conventionally used high fixing temperature is used as a normal control temperature, and a normal copying speed is set to be slower than the conventional one, so that the heat amount must be low. An object of the present invention is to make it possible to shorten the waiting time by increasing the copying speed even when copying is performed by switching to the paper type.

[0006]

In order to achieve the above object, the invention of claim 1 is to pass a transfer paper holding unfixed toner through a nip portion between a heat roller and a pressure roller to pass the transfer paper. A thermal fixing device for fixing the toner and a means for detecting the temperature of the heat roller are provided, and when the temperature of the heat roller exceeds a fixable temperature, the transfer paper is passed at a speed according to the temperature. In the image forming apparatus including the control unit, the paper type setting unit for setting the paper type of the transfer paper to be image-formed, the control unit fixing according to the paper type set by the paper type setting unit. It is characterized by selecting whether to change the temperature or the sheet passing speed. According to a second aspect of the present invention, in the first aspect, there is provided storage means for storing the operation mode of the image forming apparatus, and the control means is based on the history of the operation mode stored in the storage means. It is characterized by further comprising display means for judging which of the fixing control temperature and the sheet passing speed should be changed and displaying the judgment result. According to a third aspect of the present invention, in the first aspect, the control means changes the sheet passing speed.
When the mode is selected, the fixing temperature is controlled to be lower than that when the mode for changing the fixing temperature is selected, and the operation speed is also slowed down.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. FIG. 1 is a schematic view of an example of a fixing device to which the present invention is applied. The fixing device includes a heater 1a.
When the transfer paper 5 holding the unfixed toner 4 is passed through the nip portion, it has a heat roller 1 having a pressure roller 2, a pressure roller 2, and a temperature detecting means 3 for detecting the temperature of the heat roller 1. The toner is fixed by applying pressure while heating. The control means (main controller) 10 of the image forming apparatus main body controls the heater controller 11 based on the temperature data from the temperature detection means 3 to control the temperature of the heater 1a. Further, the control means 10 controls driving of a motor (main motor or the like) which is a driving source of the heat roller 1 or controls other controlled objects. FIG. 2 is a diagram showing an example of an operation unit used in an image forming apparatus equipped with the fixing device of the present invention. This operation unit includes a paper type switching key (paper type setting means) 15 and a mode selection key 16 , A display unit 17 and the like.

[0008] In an embodiment of the present invention corresponding to claim 1,
The control means 10 changes the fixing control temperature or the paper passing speed (copy speed) according to the paper type selected by the paper type setting means for setting the paper type of the transfer paper to be image-formed. The feature is that it can be selected.
The mode selection key 16 in FIG. 2 is a key for the operator to make this selection. When a paper type that requires a high amount of heat is selected (changed) from a paper that requires a low amount of heat for fixing, when copying multiple sheets at once, wait until the fixing temperature becomes sufficiently high before copying. By doing so, the total copying time will be shorter.On the other hand, when copying only one to several sheets, start copying without waiting until the fixing temperature becomes sufficiently high, and at the same time slow the copying speed. ,
The time until the end of copying is shortened as the waiting time is shortened. In this way, the operator can select the one that finishes earlier according to the number of copies, and when the paper type is changed in this way, the time from the change to the copy end time can be shortened.

Next, in another embodiment of the present invention, when a speed variable mode for changing the sheet passing speed while keeping the fixing temperature constant is selected, the control means 10 changes the temperature by changing the fixing temperature. It is characterized in that the fixing temperature is controlled to be lower than that when the mode is selected and the operation speed is slowed down. That is,
FIG. 3 is a diagram showing an advantage in the case where control is performed to change the copy speed while keeping the fixing temperature constant in the fixing device of the present invention having the above configuration. In this embodiment, the normal fixing temperature is set to the fixing heat amount. The temperature is set to a low value (temperature T _F ) in accordance with the low film and the copying speed (paper passing speed) is set to a low value. Copying to film, plain paper, and tracing paper is possible at t1 ', and t
When the copying to the film is started in 2 ', it ends in t3'. Further, when the copying onto the plain paper is started at t2 ', it ends at t4'. Further, when the copying to the tracing paper is started at t2 ', it ends at t5'. For example, in the case of plain _{paper, {(T N / T F} ) -T N}
The copy time is longer by xt _copy (= t4'-t3 '), but the copy start time is earlier than that in the conventional example of FIG. 5, so that the copy time can be shortened as a result. . In other words, even if the paper type is changed, the rise time is unnecessary and the copy time is shortened. However,
This can be said only when the number of copies is one to several.

When the paper type switching key (paper type setting means) 15 shown in FIG. 2 is selected, the fixing temperature is not changed.
Since the stand-by waiting time becomes unnecessary and only the transfer speed (copy speed) of the transfer paper is changed according to the paper type, the result as shown in FIG. 1 is obtained. When a plurality of sheets (a large number of sheets) are to be copied in such a speed variable mode, the mode selection key 16 is operated to set the temperature variable mode and the copying is performed in a mode in which the fixing temperature is increased. Next, in another embodiment of the present invention, a storage means for storing the operation mode of the image forming apparatus is provided, and the control means is based on the history of the operation mode stored in the storage means. It is characterized in that it is provided with a display means for judging which of the fixing control temperature and the sheet passing speed should be changed and displaying the judgment result. The flowchart of FIG. 4 shows the operation of this embodiment. In step 1, the necessary amount of copy mode data is accumulated before the history contents (copy mode data) of the operation mode stored in the storage means are confirmed. It is determined whether or not there is. If the required amount is stored, it is determined in step 2 whether the average time from power ON to copy start is greater or less than a predetermined value from the data (the frequency of power ON / OFF is also checked). . If the number is small, the frequency at which the paper type is switched, that is, the frequency used for each paper type is checked (ST3). When the number of switching is large, the speed change mode (speed variable mode) flag is set. In this mode, the fixing standby time is shortened by changing the speed while keeping the fixing temperature constant. In step 5, if the current mode is not the speed change mode, a display indicating that the mode should be changed is displayed. In step 2, when the average time from power-on to copy start is long, the speed change mode flag is set (ST7). If the number of paper type switching is small in step 3, or if the average number of copies per job is large in step 8, the process proceeds to step 9 to reset the speed change mode flag, that is, control to change the temperature. If the average number of copies per job is small, the process proceeds to step 4 and shifts to a mode in which the speed is changed.

[0011]

As described above, according to the first aspect of the invention, it is possible to arbitrarily select whether the paper type changes the fixing temperature or the paper passing speed (copying speed). When selecting a paper type that requires a large amount of heat, when copying multiple sheets at once, it is faster to wait until the fixing temperature rises before performing the copying operation. In the case of copying a number of sheets, the waiting time can be shortened even if the copying speed is slowed down, and the time until the copying is completed is shortened. For this reason, the operator can select the one that finishes earlier, and when the paper type is changed in this way, the time from the change to the copy end time can be shortened. According to the second aspect, it is possible to improve the operability by notifying which mode is suitable for the operating environment of the user from the tendency of the past copying mode of the device.

Next, when the type of paper requiring a particularly high amount of heat is changed to the type of paper requiring a low amount of heat, the waiting time for the heat roller to cool sufficiently increases, while increasing the copying speed. There was a limit. Further, conventionally, in a normal copying operation, copying is performed at a speed as high as possible, so it is difficult to perform copying at a higher speed in order to reduce the amount of heat applied to the paper. In view of this, in the third aspect, the control is performed at a temperature lower than the conventional fixing temperature at all times, and the copying speed is slowed, so that the waiting time can be shortened even for a paper type that requires a low heat quantity.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of an example of a thermal fixing device and a control system thereof to which the present invention is applied.

FIG. 2 is a configuration diagram of an example of a display unit used in the image forming apparatus of the present invention.

FIG. 3 is a diagram for explaining advantages of the present invention.

FIG. 4 is a flowchart showing a control procedure according to one embodiment of the present invention.

FIG. 5 is a diagram showing a defect of a conventional example.

[Explanation of symbols]

1a heater, 1 heat roller, 2 pressure roller, 3
Temperature detection means, 4 unfixed toner, 5 transfer paper, 10
Control means (main controller), 15 Paper type switching key (paper type setting means), 16 Mode selection key, 17
Display,

Claims (3)

[Claims] 1. A heat fixing device for fixing unfixed toner by passing it through a nip portion between the heat roller and the pressure roller, and means for detecting the temperature of the heat roller. An image forming apparatus having a control means for feeding the transfer paper at a speed according to the temperature of the heat roller when the temperature of the heat roller exceeds a temperature at which the transfer paper can be fixed. The paper type setting means for setting the paper type is provided, and the control means selects whether to change the fixing temperature or the paper passing speed according to the paper type set by the paper type setting means. A characteristic image forming apparatus. 2. The image forming apparatus according to claim 1, further comprising storage means for storing an operation mode of the image forming apparatus, wherein the control means fixes based on a history of the operation mode stored in the storage means. An image forming apparatus comprising: a display unit that determines which of a control temperature and a sheet passing speed should be changed and displays a result of the determination. 3. The fixing device according to claim 1, wherein when the control means selects the mode for changing the sheet passing speed, the fixing temperature is controlled to be lower than that when the mode for changing the fixing temperature is selected. An image forming apparatus characterized in that the operating speed is also slowed.