JPH0497382A - Electrophotographic copying device - Google Patents

Abstract

PURPOSE:To shorten the waiting time of a user and to improve the efficiency of a copying operation by setting a start-up time after applying a power source or a start-up time after releasing a standby mode the shortest in accordance with a copying mode. CONSTITUTION:At the start-up time of a fixing means, the start-up temperatures T1 and T2 of the fixing means 11 at which it is possible to transmit a copying start command are set to be a specified temperature which the means 11 should attain after a time that is from commanding the start of copying until a transfer paper reaches the means 11 in the copying mode for every copying mode. Therefore, the means 11 just rises to a fixing temperature T when the leading edge of the transfer paper reaches the means 11 even though a necessary time from commanding the start of copying until the leading edge of the transfer paper reaches the means 11 is different in every copying mode. Thus, the waiting time is made minimum in every copying mode and heat efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrophotographic copying machine that has a heat fixing device and has copying modes in which the time required for transfer paper to arrive at the fixing device after the start of a copying operation is different. Regarding.

As various functions have been added to copying machines, the number of copying machines that have a large number of copying modes is gradually increasing. Along with this, some copying machines have been introduced in which the time it takes for transfer paper to reach a fixing device after the start of a copying operation by issuing a copying command varies depending on the copying mode.

FIG. 1 is a diagram showing the overall general configuration of an example of a full-color copying machine using a one-color separation image overlapping transfer method. An original placed on a contact glass 1 is sequentially exposed onto a photoreceptor drum 4 through an exposure optical system 2 and a color separation filter 3 that can be switched and inserted into the optical path of the exposure system 2 to form color-separated light images. The latent image thus formed is developed by three primary color developing units 5Y, 5M, and 5C15B of yellow, magenta, cyan, and black, which are sequentially provided in contact with the photoreceptor tram 4.
The images are superimposed and transferred onto a transfer paper which is wound and held by a transfer tram 7 which is in contact with the photosensitive stage tram 4 and rotates at the same linear speed. Incidentally, by displacing a portion of the lens and mirror of the exposure optical system as shown by the chain lines before scanning, variable magnification copying is also possible. The transfer paper is fed to the transfer tram 7 from a paper feed unit 6 consisting of a plurality of paper feed centers, its leading edge is clamped, and the paper is electrostatically attracted to the periphery of the transfer drum 7 to determine the number of colors of toner images to be superimposed. After the toner image of a predetermined number of colors has been transferred, the toner image is separated from the transfer drum 7 by the separation charger 85 and the separation claw 9, and is conveyed to the heat roller fixing device 11 by the conveyor belt 10, where it is fixed and removed from the machine. is discharged.

When making a black and white copy with this copying device, an image is formed by developing it with the black developing device 5B in one exposure, rotating the transfer drum 7 once, transferring the black toner image, separating it, and fixing it. Ru. In addition, when copying single colors of red, green, and blue that are not included in the toner built into the developing device, the toner images of each of the two colors yellow and magenta, cyan and yellow, and cyan and magenta should be superimposed and transferred. This is done by

(1) Using the transfer drum in this way, there is a black-and-white mode with one copy per rotation, a color monochrome mode with two copies per rotation,
In the full color copy mode in which toner images of three to four colors are superimposed in three or four rotations, the time from the start of the copying operation until the leading edge of the transfer paper reaches the fixing device is different.

(2) Depending on the copying machine, in addition to the number of overlapping transfers,
In some cases, the process speed for black copies is different from the process speed for copies of other colors due to the spectral sensitivity and developing ability of the photoreceptor.

(3) If the machine has an automatic mode (automatic paper selection, automatic magnification selection, etc.) and a manual mode set by the user, and it takes time to determine the document size, etc., the automatic mode may take longer to reach the fixing device1. (4) In addition to the above-mentioned configuration, a full-color copying machine that does not use a transfer drum develops the three colors of yellow, magenta, and cyan in sequence on a photoreceptor and transfers them to transfer paper at once. There are fixing methods, and three-color toner images formed sequentially on a photoreceptor are superimposed and transferred to an intermediate transfer member, and -
There is a method in which the image is transferred to transfer paper at the same time. In these cases, full-color copying generally takes more time than monochrome copying.

(5) It goes without saying that in an apparatus having a plurality of paper feed cassettes as in the example shown in FIG. 1, the longer the paper feed path length is, the longer it takes than the shorter one.

(6) Furthermore, in a machine that has a high-speed mode with a high process speed and a high-quality low-speed mode with a low process speed, the low-speed mode is naturally slower.

As mentioned above, although there are differences in the time it takes for the leading edge of the transfer paper to arrive at the fixing device after the start of the copying operation depending on the various copying modes, conventionally, the startup temperature of the fixing device is
- The temperature of the fixing device is set to allow fixing, and when this temperature is reached, a copy start command can be issued.

In any case, it takes some time from the copy start command until the leading edge of the transfer paper reaches the fixing device, so if the heat source of the fixing device is turned on during that time, the temperature of the fixing device will rise. In consideration of this, various proposals have been made in the past to make it possible to shorten the waiting time, ie, the rise time, from when the power is turned on until a copy start command can be issued.

For example, Japanese Patent Application Laid-Open No. 61-17566 describes a first set temperature at which fixing can be performed, and a temperature at which the transfer paper reaches the first set temperature after pressing the copy start switch until the transfer paper reaches the fixing device. A fixing device is disclosed in which a second set temperature is provided, the fixing device is placed on standby at the second set temperature, and a copy start switch can be pressed at this temperature.

Furthermore, Japanese Patent Application Laid-Open No. 62-6286 discloses that the time required for the leading edge of the transfer paper to reach the fixing unit after the start of feeding of the transfer paper from the paper feeding unit precedes the time when the fixing device reaches the fixing temperature. A fixing device is disclosed that outputs a ready signal at a time point to enable a copy start switch to be pressed.

Furthermore, Japanese Patent Application Laid-Open No. 63-293577 discloses that the temperature rise curve of the fixing means is estimated and the temperature of the fixing means reaches a set value when the transfer paper enters the fixing means. An image forming apparatus has been disclosed that is provided with means for adjusting the timing at which the transfer paper enters the fixing device, such as adjusting the stop time of the document table according to the temperature of the fixing device.

The last of the three cases mentioned above is aimed at small-sized copying machines that are used in private offices and are used infrequently, and the power switch must be turned on each time a copy is made. The purpose is to eliminate the user's waiting time by allowing the user to press the copy start switch from the moment the power is turned on. However, since the time it takes for the fixing device to reach the fixing temperature after the power is turned on does not change, it is thought that there is almost no substantial benefit to be gained in spite of the increased cost of the control device.

The other two cases have slightly different expressions, but are generally based on the same technical idea. In anticipation of the rise in temperature, the copy start switch can be pressed when the temperature reaches a certain temperature lower than the fixing temperature, or at a certain time before the fixing temperature is reached.

However, in any case, even if the copying machine has multiple copying modes, the temperature of the fuser that enables the copy start switch to be pressed, or the point before the fixing temperature is reached, is the same. However, there is no method that takes this point into consideration, even though the time required from the start of the copying operation until the leading edge of the transfer paper reaches the fixing device differs depending on the copying mode.

Additionally, some recent copying machines have a low-temperature standby mode (also called preheating mode) in which the holding temperature of the fixing device is lower than the fixing temperature when the power is on and the machine is on standby between copies to save power. Proposed. When copying, the preheating mode is canceled, the temperature of the fuser is raised, and fusing is performed when the predetermined fixing temperature is reached.Even in this case, with conventional copiers, after the preheating mode is canceled, Conventionally, the copy start switch can only be pressed once the fixing device reaches the fixing temperature.

Problems to be Solved by the Invention The present invention takes into account the above-mentioned circumstances of the conventionally implemented and proposed setting of a rising temperature that enables the copying start switch to be pressed after the temperature of the fixing device of a copying machine has risen. In a copying machine that has multiple copying modes in which the time it takes for the leading edge of the transfer paper to reach the fixing device after the start of copying operation is different, when starting up the fixing device after turning on the power for each copying mode,
Another object of the present invention is to provide an electrophotographic copying apparatus having a fixing device that can reduce the waiting time of a user as much as possible when starting up a copying machine having a standby mode at a temperature lower than the fixing temperature after canceling the standby mode. Take it as a challenge.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a heating fixing means that is capable of fixing transfer paper at a predetermined fixing temperature by energizing a heat source and raising the temperature when the main body of the apparatus is powered on. In an electrophotographic copying apparatus having a plurality of copying modes in which the copying operation is started by a copying start command and the time until the transfer paper reaches the fixing means after the copying start command is different, when the fixing means starts up, the copying operation is started. The rise temperature of the fixing means that enables the transmission of the start command is determined for each of the copying modes described above. It is characterized in that the temperature is set to reach the fixing temperature.

If the copying machine has a standby mode in which the temperature of the fixing means is maintained at a constant temperature lower than the fixing temperature, the same applies to the rising temperature when the standby mode is released.

Function Since the rise temperature is set as described above, even though the time required from the copy start command to the leading edge of the transfer paper reaching the fixing means differs depending on the copying mode, the time required for the leading edge of the transfer paper to reach the fixing means will be the same. The fixing means rises to just the fixing temperature, allowing the waiting time to be minimized for each copying mode and improving thermal efficiency.

Embodiments Below, embodiments of the present invention will be described in detail based on the drawings.

First, using the superimposed transfer type full-color copying machine described in FIG. 1 as an example, it will be explained that the time from the start of copying until the leading edge of the transfer paper reaches the fixing device differs depending on the copying mode.

FIG. 2 shows a comparison of the times t1 and t2 from when the print switch is turned on to when the leading edge of the transfer paper reaches the fixing device in the monochrome copy mode and the multicolor superimposed copy mode, respectively.

In the multicolor mode, it takes an extra time t3 for the transfer drum to rotate twice than in the monochrome mode.

Figure 3 shows a comparison of the time required for black copying and monochromatic color copying using a copying machine whose process speed for black copying is faster than for copying other colors. Compared to the time t1, the time t2 required for color copying is increased by an increase amount t3 due to the decrease in the linear speed.

FIG. 4 is a diagram showing a comparison between manual document feeding and automatic document feeding. The time t2 required for automatic document feeding is the time t3 required to detect the document size.
The required time t1 for manual operation is longer than that for manual operation.

Note that tl, t2, and t in FIGS. 2, 3, and 4, respectively.
3 are unrelated, and merely qualitatively indicate that the time from when the print switch is turned on until the leading edge of the transfer paper reaches the fixing device differs depending on the copying mode, for example, tl and t2. Furthermore, the differences between the modes shown in 1 are just a few examples, and as mentioned above, the required time varies depending on the various copy methods.

FIG. 5 is a curve diagram showing the temperature rise characteristics with respect to time during startup of a certain fixing device.

The fixing heater is turned on by turning on the power switch of the device, and the temperature of the fixing device, which was initially at the temperature To, gradually rises and reaches the fixing temperature T after a period of time. Thereafter, the temperature of the fixing device is maintained at a predetermined fixing temperature T by controlling the heater on and off using a thermistor.

Now, as explained in the examples of FIGS. 2 to 4, depending on the copy mode, the time from the start of the copying operation until the leading edge of the transfer paper reaches the fixing device is, for example, a short time 1. and for a long time
2 are different. Therefore, as shown in FIG. 5, from the point P when the fixing temperature rises to T after the power switch is turned on,
Assume that the temperature of the fixing device becomes TI and T2 lower than the fixing temperature T at time points P1 and P, which are hours before time and t2, respectively.

In this way, when copying is performed at the copying point where the time required for the leading edge of the transfer paper to reach the fixing device after the start of copying is t1 and t2, respectively, T1 and T2 are respectively the rising temperatures, and the fixing device reaches these temperatures. If it is possible to press the copy start switch at this point, if the copy start switch is pressed at this point and the copying operation is started, the temperature of the fixing device will rise when the leading edge of the transfer paper is attached to the fixing device after t or t2 hours. has just risen to the fixing temperature T, so good fixing can be performed.

Needless to say, the time required for the leading edge of the transfer paper to reach the fixing device after copying starts is 1. , 12, for example, in the copy mode at t4, the rise temperature may be set to a temperature that is different from T1 and t2 and corresponds to 4.

Next, an embodiment in which the present invention is applied to a copying machine having a standby mode will be described with reference to a curve diagram showing the relationship between time and temperature shown in FIG. The process up to the end of the first copy is the same as the embodiment described in FIG.

The copying machine of this embodiment has a residual heat key, and when this key is pressed, the fixing device enters a standby mode, and the heater is controlled on and off to maintain a standby temperature T5 lower than the fixing temperature T. To copy again, press the residual heat key to turn off the standby mode, the set temperature becomes the fixing temperature T, the heater is turned on, and the temperature of the fixing device rises.At this time, the atmospheric temperature The time t when rising from
The predetermined fixing temperature T is reached in a shorter time t compared to . In this case as well, depending on the copy mode, T is lower than the fixing temperature T by the temperature that rises during the time t1, t2 from the start of copying until the leading edge of the transfer paper reaches the fixing device.
By setting , T, to the rise temperature, the rise time can be reduced by t, t2. In this case as well, it goes without saying that the rise temperature can be set variously depending on the copy mode.

Effects As described above, according to the present invention, the start-up time after turning on the power or the start-up time after canceling the standby mode can be set to the shortest depending on the copy mode, and the waiting time for the user can be shortened. , the efficiency of copying work can be improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the overall schematic configuration of an example of a full-color copying machine as an example of an electrophotographic copying apparatus to which the present invention is applied, and FIGS. 2 to 4 show the differences between various modes in the copying machine. A graph explaining an example of the difference in time from the start of copying until the leading edge of the transfer paper reaches the fixing device, FIG. 5 is a curve diagram explaining how to set the start-up temperature of the present invention, and FIG. 6 shows the standby mode. FIG. 3 is a similar curve diagram for a copying machine having the following. 0Y, Photoreceptor drum 5M, 5C15B Paper feeding device/Fixing device Fixing temperature Proxy Developing device 7...Transfer drum rising temperature K.'-2~--/\,...;1゜th

Claims (2)

[Claims] (1) The device has a heat fixing means that is energized and heated when the main unit is powered on, and can fix the transfer paper at a predetermined fixing temperature.The copying operation is started by a copy start command, and the copy is made. In an electrophotographic copying apparatus having a plurality of copying modes in which the time required for the transfer paper to reach the fixing means after a start command is different, when the fixing means starts up, the rising temperature of the fixing means that enables the transmission of a copy start command is set as follows. For each of the above copying modes, the temperature is such that the fixing means should reach the predetermined fixing temperature after the time from the copy start command in that mode until the transfer paper reaches the fixing means. Copying equipment. (2) The copying apparatus described above has a standby mode in which the temperature of the fixing means is maintained at a temperature lower than a predetermined fixing temperature during standby, and the rise temperature mentioned above is the rise temperature of the fixing means when the standby mode is released. Claim 1 characterized in that
The electrophotographic copying device described in .