JPH0277779A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate a waste of energy and to reduce the temperature rise in the machine by energizing a fixing means only when an unfixed development image on a transfer material passes a fixation position. CONSTITUTION:A control part 4 performs signal processing and various control according to signals from an original reader 1 and a digitizer 2. Then the heat capacity of the heat generating surface 28 of the heat generating body 21 is small and is supplied with pulse electric power from a power source 7 to rise in temperature at each time, so that unfixed toner on the transfer paper is fixed by a fixing device 20 with the heat of the heat generating body. The unfixed toner image can, therefore, be fixed by supplying the electric power when it reaches a fixing heater and the fixation is carried out while the electric power is saved most.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image forming apparatus that forms an image on a transfer material using heat-meltable toner and heat-fixes the image.

[Prior Art] Conventionally, a fixing device used in this type of image forming apparatus uses a heating roller maintained at a predetermined temperature and a pressure roller having an elastic layer and in pressure contact with the heating roller. A roller fixing method is often used in which a transfer material on which an unfixed i-toner image has been formed is heated while being nipped and conveyed.

And newly, there is a drawback of the above fixing method. ■Is it necessary to always maintain the heating roller at the optimum temperature?

■Since it is necessary to heat the transfer material as well, the heat capacity of the heating roller increases.

■As a result, the energy required for fixing increases and unnecessary heat is generated, causing the temperature inside the machine to rise.

A fixing device shown in FIG. 6 has been proposed as a fixing method to solve the above problems.

This fixing device 20 is configured as follows. Reference numeral 21 denotes a heating element, which is attached to the lower surface of a base material made of a heat-resistant and electrically insulating base material such as alumina or a composite member containing the same, and has a width of 160 μm and a length (the length in the direction perpendicular to the plane of the paper). )
216 mm, and has a linear or band-shaped heating surface 28 made of, for example, Ta2N, and a sliding protective layer made of Ta205, for example, is formed on the surface of the heating surface 28.

The lower surface of the heating element 21 is smooth, and the front and rear ends are rounded to enable sliding movement with the heat-resistant sheet 23. The heat-resistant sheet 23 is made of polynisdel as a base material, and is formed to have a thickness of approximately 9 μm after being heat-resistant treated.
It is wound around 4. The heat-resistant sheet 23 is the heating element 21
The film contacts the surface of the sheet and is wound onto a winding shaft 27 via a separating roller 26 having a large curvature.

1) The heating surface 28 of the heating element 2 has a small heat capacity, and is energized in a pulsed manner to instantaneously raise the temperature to, for example, A to about 260° C. each time. By detecting the leading and trailing edges of the transfer paper P using the transfer paper detection lever 25 and the transfer paper detection sensor 29, the heat generating surface 28 can be energized at the right time when necessary, and can be used to feed the image forming apparatus. Power supply to the heating element is controlled by detecting the position of the transfer paper using a sensor or the like.

On the other hand, the pressure roller 22 has an elastic layer made of silicone rubber or the like on a core material made of metal or the like, and is driven by a drive source (not shown) to collect the unfixed material guided by the conveyance guide 10. A transfer material P having a toner image T is brought into close contact with a heating element via a heat-resistant sheet 23 that moves at the same speed as the transfer material P. Here, it is preferable that the conveyance speed of the pressure roller 22 is approximately the same as the conveyance speed during image formation, and the 8-motion speed of the heat-resistant sheet 23 is set at a value corresponding thereto.

In the fixing device having such a configuration, the toner image made of heat-meltable toner on the sheet P is first transferred to the heat-resistant sheet 2.
3, it is heated by the heating element 21, and at least its surface layer portion is completely softened and melted. After that, heating element 2
1, and while reaching the separation roller 26, the l.ner image radiates heat naturally and is cooled and solidified again. After passing through the separation roller pair 26 with a large curvature, the heat-resistant sheet 23 is transferred to the transfer paper P or 6.
181[Reru. As mentioned above, the toner T is once completely softened and melted and then assimilated again, so the cohesive force of the toner becomes very large and it behaves as a clump. In addition, when the pressure roller 2 is heated and softened and melted,
2, the toner image T penetrates the surface layer of the transfer material and is cooled and solidified, so the heat-resistant sheet [-
23 and is fixed on the transfer material P without being offset.

[Problem to be solved by the invention] However, in such a pulse energization type fixing device, in order to heat the entire area of the transfer plate to the fixing temperature and fix it, an energy key exceeding that of actually determining the toner is required. In addition, consuming more energy than necessary had the disadvantage of raising the temperature inside the aircraft.

An object of the present invention is to utilize the characteristics of a pulse energization type fixing device that can instantaneously raise the fixing temperature to A-temperature, avoid unnecessary energization, eliminate wasteful energy consumption, and reduce internal R-temperature. A forming device is provided.

[Means for Solving the Problems] An example of a typical configuration of the means for achieving the object of the present invention includes an image information reading means for scanning and reading image information on a document, and a reading device for reading image information by the image information reading means. A developing means that visualizes the latent image formed on the image carrier through the exposure means based on the information, and a transfer material to which the developed image on the image carrier has been transferred is heated and pressurized to develop the unfixed image. In an image forming apparatus equipped with a pulse current heating type fixing means that heats and melts an image and fixes it on a transfer material, the image forming apparatus determines whether or not the image on the original is correct based on the read information from the image information reading means. An image forming apparatus comprising: a control means that stores information in chronological order in the scanning direction and energizes the fixing means only when an unfixed developed image on the document reaches a fixing position of the temperature constant means. It is in.

[Function] In the present invention configured as described above, the fixing means is energized only when the unfixed developed image on the transfer material passes through the fixing position.

[Embodiment] FIG. 1 shows a schematic configuration of an embodiment of an image forming apparatus according to the present invention.

Reference numeral 1 denotes a document reading device, which scans a document (not shown) placed on a document table 1a using a scanning illumination optical system (not shown) consisting of an internal light source, etc., and converts light reflected from the document into a CCD. It is read by an optical sensor (not shown) such as a line sensor and converted into an electrical signal. Reference numeral 2 denotes an area specifying device (digitizer), which sets the reading area of the document and outputs a signal. Reference numeral 3 denotes an image output device that forms an image based on signals from the document reading device 1 and the digitizer 2, and includes the fixing device 20 described above.

A control section 4 receives signals from the document reading device 1 and the digitizer 2, performs signal processing for sending commands to various sections, and performs various controls. Reference numeral 5 indicates image data that has been subjected to signal processing in the control unit 4.C An image writing device, for example, a racer, creates an electrostatic latent image on the photosensitive tram 6; A power source 10 supplies electric power, and a thermistor 10 detects the temperature of the heater and feeds it back to the control unit 4.

The heat generating surface 28 of the heating element 21 has a small heat capacity, and is supplied with power from the power source 7 in a pulsed manner, each time instantaneously increasing to 260°C.
The temperature rises to the front and back, and the heat fixes any unfixed toner on the transfer paper. Therefore, when the unfixed toner image comes to the fixing heater 80, it is possible to fix it by supplying power, and fixing can be performed with the least amount of power required.

In this embodiment, the timing of energization from the power source 7 to the heat generating surface 28 is controlled by the following two control methods.

(1) When reading a document with the document reading device 1, an area without an image is detected and power is not supplied to the heat generating surface 28 at the fixing timing of that area.

(2) Based on the data from the setting means 2a which specifies the document reading area by the digitizer 2, power is not supplied to the heat generating surface 28 at the timing when fixing outside the specified area.

The control sequence of the control unit 4 that executes the control method (1) is illustrated in the flowcharts of FIGS. 2 and 3. First, in manual image processing (lOo), numbers are assigned to image line data from 1 to n ma
2), the value indicating that there is an image in the manuscript on the data or 1
Please judge whether it is present or not across all lines +0
3) If there is data, set a flag F/n line fixing to turn on the heater at the timing when the image is carried on the transfer paper and fixed (104). Do it (105).

In parallel with this, in the fixing control (200), from when the leading edge of the transfer paper reaches the fixing position of the fixing device 20, the flag F/m line fixing that was set earlier is sequentially determined line by line (20+) ( 202) If set, subroutine processing is performed to supply power to the heater (203). This process is continued until m reaches nmax (204). Next, FIG. 4 shows a control sequence of the control section 4 that executes the control method (2).

In the image input process (300), reading area data (x+
, y+) - (X2, 3/2) is manually generated (30+). Here, y++y2 is the starting point and ending point of the area designation section in the document scanning direction, as shown in FIG. Then, from the 1st line to the (y+1) line, set the flag F/n line fixation (302) (303)
, y1 line to y2 line, a flag F/n line fixation is set (304) (305) (306). The fixing control performed in parallel with this is the same as the flowchart in FIG.

[Effects of the Invention] As explained above, pulse heat fixing can be controlled only in the area necessary and sufficient to fix the unfixed developed image on the transfer material using the information from the image reading means and the area specifying means. This has made it possible to minimize power consumption and lower cabin temperature. Additionally, the time required for energizing the heating element of the fixing device is minimized, thereby increasing durability.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of an image forming apparatus according to the present invention, FIG. 2 is a flowchart of image input data processing of the control section, FIG. 3 is a flowchart of fixing control of the control section, and FIG. 4 5 is a flowchart of image input data processing when the control unit uses the digitizer, FIG. 5 is a diagram showing the position of document reading area designation, and FIG. 6 is a schematic diagram of the fixing device. 1... Original reading device 2... Original reading area specifying device 3... Image output device 4... Signal processing/control unit 5.
...Laser writing device 6...Photosensitive tram 7...Heater power supply 20.
・Fusing device

Claims (1)

[Scope of Claims] 1. An image information reading device that scans and reads image information on a document, and a latent image formed on an image carrier through an exposure device based on the information read by the image information reading device. The image forming apparatus includes a developing means for forming an image, and a fixing means of a pulsed current heating type that heats and presses a transfer material onto which the developed image on the image carrier has been transferred, thereby heating and melting the unfixed developed image and fixing it to the transfer material. In an image forming apparatus, the presence or absence of an image on a document is stored in chronological order in the scanning direction based on the read information from the image information reading means, and the unfixed developed image on the document is located at the fixing position of the fixing means. An image forming apparatus comprising: a control means for energizing the fixing means only when the fixing means is reached. 2 Image information reading means for reading image information on a document, area specifying means for specifying an image reading area, and image carrying based on the read information from the image information reading means that has been specified and read by the area specifying means. A developing means for visualizing the latent image formed on the body through the exposure means, and a transfer material to which the developed image on the image bearing member has been transferred are heated and pressurized to heat and melt the unfixed developed image. In an image forming apparatus equipped with a pulsed current heating type fixing means for fixing onto a transfer material, when the transfer material passes through the fixing position of the fixing means based on image reading area information specified by the area specifying means, An image forming apparatus comprising a control means for energizing the fixing means only when an area corresponding to a designated area passes through.