JPH0560106B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a color recording device that records an image by heating and fixing a monochrome or multicolor unfixed image onto a recording material. FIG. 1 is a schematic diagram of an example of a color separation type electrophotographic color copying machine. Reciprocating document table glass 30
Place the original to be copied on top with the image side facing down, and press the numeric keypad 1 on the operation panel 10 (Figure 2).
4, the number of copies to be copied is set using the full color copy switch 11 or the monochrome copy switch 12, and other necessary copying conditions are set, and the copy switch 13 is pressed. In the full color copy mode, the original platen glass 30 reciprocates three times for each copy, and the original surface receives slit illumination from the slit illumination section 31 three times in total. Further, each time the document platen glass 30 completes each forward movement, the filters of the color separation filter device 40 disposed in the imaging optical systems 34 to 39 are sequentially switched. In the imaging optical system, 34 is an original illumination light source;
5, 36, 38, and 39 are reflecting mirrors, and 37 is an imaging lens. Reference numeral 16 denotes a drum-shaped electrophotographic sightseeing drum that is rotated at a predetermined circumferential speed in the direction of the arrow. The drum 16 undergoes prior history removal by a pre-exposure/static eliminator 45,
Uniformly charged with positive or negative electricity by the primary discharger 41, 2
The secondary discharger 42 has a DC of opposite polarity to the primary discharger 41.
Light image exposure from optical systems 34 and 39 while receiving corona discharge or AC corona discharge (slit exposure)
Then, the entire surface is exposed by the entire surface exposure device 43, so that electrostatic latent images of high potential contrast corresponding to the exposure light image pattern are sequentially formed on the peripheral surface thereof. Thus, the electrostatic latent image of the first color separated image of the original image generated by the first forward movement of the original platen glass 30 is transferred to the drum 1.
The latent images are formed on six sides, and the latent images are developed by the first color toner developer 44a. On the other hand, only one sheet of the transfer material 6 is fed from the first recording material cassette 48 or the second recording material cassette 49 to the transfer drum 45, and is wound around the circumferential surface of the transfer drum with the leading edge portion held by a gripper. held in state. The first color toner image on the photosensitive drum surface is sequentially transferred onto the transfer material surface by the transfer discharge device 46. The transfer material continues to be wound around the transfer drum 45 and held there. The photosensitive drum 16 continues to be driven to rotate, and a cleaner 47 removes the residual toner image after transfer. Next, as the document platen glass 30 moves forward a second time, an electrostatic latent image of a second color separated image of the document image is formed on the surface of the photosensitive drum, and the second color toner developer 44
b, and the color toner image is subsequently held on the peripheral surface of the transfer drum, and is aligned and superimposed on the surface of the transfer material to which the first color toner image has already been transferred. Next, in the same way, a document platen glass 30 is placed on the photosensitive drum surface.
With the third forward movement, an electrostatic latent image of the third color separation image of the original image is formed, and the third color toner developer 4
4c, the color toner image is subsequently held on the peripheral surface of the transfer drum, aligned with the surface of the transfer material to which the first and second color toner images have already been transferred, and further transferred in an overlapping manner. After the transfer material receives the color toner transfer three times, the gripper is released and the transfer material is separated from the transfer drum by the separation member 5.
The toner images are sequentially separated by 0, introduced into a heat fixing device 52 by a conveyance device 51, where the toner image is fixed, and then discharged to a tray 53 outside the machine as a color copy. In the monochrome copy mode, the document table glass 30 reciprocates once for each copy, the filter of the color separation filter device 40 is switched to a neutral filter, and the first to third color toner developers 44a Copying is performed by operating a pre-specified developing device among the developing devices 44c to 44c, and a monochrome copy of the original image is output to the tray 53. FIG. 3 is a schematic diagram showing a conventional heat fixing device, in which 1 is a fixing roller, for example, a metal pipe 1a.
It has a structure in which the surface of the HTV silicone rubber layer 1b is coated. Reference numeral 2 denotes a pressure roller, which is constructed by, for example, a metal pipe 2a whose surface is coated with an HTV silicone rubber layer 2b. 3 is a heater built into the fixing roller 1; 4 is a temperature detection member such as a thermistor for detecting the surface temperature of the fixing roller 1; Now, when the recording material 6 carrying the unfixed toner image 5 passes between the fixing roller 1 and the pressure roller 2, the toner image 5 is heated and fixed on the recording material 6 by the heat supplied from the heater 3. The temperature of each roller 1 and 2 is set to a temperature that can be heated and melted according to the characteristics of each toner, for example, the temperature of the fixing roller 1 is 180°C, and the temperature of the pressure roller 2 is 160°C.
The heater 3 is turned on and off based on the detection signal, and temperature control is performed to maintain the above-mentioned set temperature. As described above, in the conventional heat fixing device, the temperature of the fixing roller 1 is set higher than the temperature of the pressure roller 2. Furthermore, in this case, if the fixing operation is performed continuously, the heat of the fixing roller 1 is absorbed by the recording material 6 and is not transmitted to the pressure roller 2, so the temperature of the pressure roller 2 decreases. . In particular, in an electrophotographic color copying apparatus such as the example shown in FIG. 1, three or four colors of toner are used for full color copying, so the amount of toner on the recording material is significantly different from that for monochrome copying.
In particular, the unfixed toner image during full color copying is, for example, yellow toner, magenta toner, magenta toner, etc.
If it has a three-layered structure of cyan toner,
Since the amount of toner is large, the yellow toner on the upper side that contacts the fixing roller 1 is easily dissolved, but the cyan toner on the lower side, that is, near the surface of the recording material is difficult to dissolve. Therefore, if the fixing roller 1 is set at a high temperature in order to melt the entire toner well, development occurs in which the toner surface is offset to the fixing roller 1.
For this reason, during full-color copying, a high-temperature backside heater is required to heat the recording material from the surface. On the other hand, when making monochrome copies, the fixing conditions described above are not required, so in order to save power,
The temperature of the pressure roller 2 can be set low. The present invention has been proposed in view of the above, and for example, when performing multi-color copying such as full color, which requires a large amount of toner, as in an electrophotographic color copying device, the temperature of the pressure roller is set higher than the temperature of the fixing roller, and the toner is By setting the temperature of the pressure roller lower than the temperature of the fixing roller when printing a small amount of monochrome, toner color mixing improves during full color printing, improving image quality and fixing performance, and preventing offset. The object of the present invention is to obtain a color recording device that can achieve power saving during operation. FIG. 4 is a schematic diagram showing an embodiment of the present invention, and the same parts as in FIG. 3 are given the same reference numerals. Fourth
In the figure, 7 is a heater built into the fixing roller 1, and 8 and 9 are heaters built into the pressure roller 2. Here, for example, heater 7 is 700W, heater 8 is 600W, and heater 9 is 200W, and depending on the combination of these heaters, each roller 1, 2 during full color copying and monochrome copying.
control the temperature to a predetermined temperature. That is, when the copying switch 11 is selected for full-color copying, the heater control circuit 17 starts energizing all the heaters 7 to 9, and the thermistor 4 detects the temperature of the heated fixing roller 1. The detection signal connects and disconnects the circuits of the heaters 7 to 9 to control the temperature of the fixing roller 1.
Control the temperature to 140℃. At this time, the temperature of the pressure roller 2 becomes 150° C. due to the distribution of the wattage of the heater 7 and the same wattage of 8 and 9. Furthermore, when the copying switch 12 is selected for monochrome copying, the heater control circuit 1
7 starts energizing the heaters 7 and 9, and the temperature of the fixing roller 1 changes according to the detection signal from the thermistor 4.
The temperature is controlled to 140℃. At this time, the temperature of the pressure roller 2 becomes 120° C. depending on the wattage distribution of the heaters 7 and 9. The temperature setting matrix is shown in the table below.

[Table] Fig. 5 shows an example of a three-roller configuration. Reference numeral 15 indicates an upper pressure roller, and 15 indicates a lower pressure roller, which are constructed by coating metal pipes 15a and 15a' with Teflon (trade name) layers 15a and 15b', respectively. 2 is a fixing roller that is placed on the metal pipe 2a.
It has a structure coated with an RTV silicone rubber layer 2b.
7' is a heater built into the upper pressure roller 15;
8' and 9' are heaters built into the lower pressure roller 15', 7' is 800W, 8' is 600W, and 9' is
It is 200W. In such a configuration, all heaters 7', 8', and 9' are used to perform fixing during full color, and only heaters 7' and 9' are used to obtain a predetermined temperature gradient during monochrome. control. In the embodiment described above, the thermistor 4 as a temperature detection means is brought into contact with the fixing roller 1, but as described above, if a predetermined temperature gradient of the roller is obtained in each mode, the thermistor 4 is brought into contact with the pressure roller to detect the temperature. You may go. In addition, the wattage of the heaters 7 to 9 (7' to 9') and the temperature of each roller should be selected according to the characteristics of the toner. ,2)
A heater of any wattage may be used as long as a predetermined temperature gradient of . Therefore, by installing a plurality of heaters on each roller 1, 2 (15, 2) and selectively using several of them, it is also possible to control the electric power etc. supplied to one heater. Alternatively, a predetermined temperature gradient may be obtained. As explained above, according to the present invention, the temperature of the defined roller is set higher than the temperature of the pressure roller during monochrome copying according to the state of toner on the recording material, and pressure is applied during multicolor copying such as full color copying. By setting the temperature of the roller higher than that of the fixing roller, toner color mixing becomes better during full color printing, improving image quality and fixing performance, and preventing offset, while also reducing power consumption during monochrome printing. can. As an example, when fixing 1,000 sheets of A4 recording material in full color mode, it required 5KW of power consumption, whereas in monochrome mode, power consumption was reduced to 3KW. The present invention can also be applied to a combination of a hot plate and a roller/hot plate radiant heat/radiant heating pair instead of a roller pair.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of an electrophotographic color copying machine, FIG. 2 is a plan view of an operation panel, FIG. 3 is a schematic diagram of a conventional heat fixing device, and FIG. 4 is a schematic diagram of a first embodiment. FIG. 5 is a schematic diagram of the second embodiment. 1 and 15 are fixing rollers, 2 and 15' are pressure rollers, 3, 7 to 9, and 7 to 9 are heaters, 4 is a thermistor, 5 is an unfixed toner image, and 6 is a recording material.

Claims (1)

[Scope of Claims] 1. In a color recording device that records an image by heating and fixing a monochrome or multicolor unfixed image on a recording material, in order to heat and fix the unfixed image on the recording material, A first heating means located on the image side, a second heating means located on the opposite side of the recording material to the unfixed side, and when the unfixed image is monochrome, the heating amount by the first heating means is changed to the second heating means for relatively variably controlling the amount of heating according to the unfixed image so that the amount of heating by the second heating means is made larger than the amount of heating by the first heating means when the unfixed image is multicolored; A color recording device characterized by having the following. 2. The first heating means has a heated fixing roller, and the second heating means has a heated pressure roller, and the variable control means relatively controls the surface temperature of each roller so that the unfixed image is monochromatic. 2. The color recording apparatus according to claim 1, wherein the fixing roller side is made higher when the color is multicolored, and the pressure roller side is made higher when the color is multicolored.