JPH06161175A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain a copying possible state in a short time at the rising time of a device or even at the switching time from a preheating mode by copying at the action speed in accordance with a surface temperature on condition that the surface temperature of a heating roller has reached the fixable temperature. CONSTITUTION:An image forming device is provided with a temperature detecting means 17 for detecting the surface temperature of a heating roller 15, and copying is started when the surface temperature of the roller 15 reaches the temperature exceeding the fixable surface temperature so as to make constant speed copying possible. At this time, a control means 6 turns a fuser lamp 14 on/off to maintain the surface temperature of the roller 15 in a specified temperature range. The control means 6 also drives a scanning optical system 2, a photosensitive body 3, copying paper conveyor mechanism 4, a fixing element 5, and the like at the specified low speed, and controls the action timing of a charger 7, a developing apparatus 8, a transfer element 9, a cleaner 10 according to the action speed. The stand-by time from power input to the start of copying can be thereby shortened without causing the increase of power source capacity of the fixing element 5 and without shortening the service life of the lamp and a switching element.

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 for heating and fixing, and more particularly to an image forming apparatus in which the waiting time from turning on the power source to the first copying is shortened.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine using a xerographic system, heat is applied to a powder toner forming an image transferred on a copy sheet by heat to melt and fix the powder toner. In such an image forming apparatus that performs heat fixing, a waiting time is required until the fixing device rises to a predetermined temperature and heat fixing becomes possible after the power is turned on and before the first copying is performed. I had to. In order to reduce the waiting time, a method of increasing the electric power capacity of the fixing device to supply a larger amount of heat in a short time, a material of the fixing device having good heat conduction, or the like is adopted. However, according to the former method, the power consumption of the entire device increases, and there is a fear that the capacity (15 A) of a general power outlet may be exceeded. According to the latter method, the fixing device warms up quickly but cools down quickly, and in order to keep the fixing device at a constant temperature, the surface temperature of the fixing device is detected and the power is frequently turned on / off.
Since the F control is performed and a rush current flows through the heater of the fuser lamp every time the power is turned on, there is a disadvantage that the life of the lamp heater, the switch, and the switch element is shortened. Further, in JP-A-60-123878, it is possible to prevent incomplete fixing when the power supply voltage is reduced to about 90% or less of the rated value, the balance between the power supplied to the fixing device and the amount of heat released is lost. Therefore, it has been proposed to reduce the copying speed of the apparatus, but no consideration is given to shortening the standby time when the power is turned on.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and does not increase the power supply capacity of the fixing device and shortens the life of the fuser lamp and the switch element. The purpose is to shorten the waiting time from power-on to the start of copying.

[0004]

In order to perform heat fixing, attention is paid to the fact that heat energy of a predetermined amount of heat or more at a predetermined temperature or more is applied to the powder toner, and until the copying becomes possible at a normal copying speed. Without waiting, the copying operation is executed from the time when the temperature of the fixing device reaches a predetermined temperature at a copying speed at which fixing can be performed at that temperature.

[0005]

The present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing the overall configuration of an image forming apparatus according to the present invention,
FIG. 2 is a curve diagram showing a heating state of the fixing device. In FIG. 1, the image forming apparatus 1 includes a scanning optical system 2, a rotating photoconductor 3, a copy sheet transport mechanism 4, a fixing unit 5, and a control unit 6. A charging device 7, a toner developing device 8, a transfer device 9 and a cleaner 10 are arranged around the photoconductor 3, and the transport mechanism 4 includes a paper cassette 11 and a paper feed roller 1.
2. Consists of a transport roller 13 and is configured to feed the copy sheet to the transfer portion in synchronization with the toner image formed on the photoconductor 3. The fixing device 9 includes a heat roll 15 having a fuser lamp 14 therein, a pressure roll 16 provided to face the heat roll 16, and a temperature detecting means 17 for detecting the surface temperature of the heat roll 16. The toner image transferred onto the copy sheet is fused and fixed by heat. The control signal regarding the heater temperature from the control unit 6 is the heater lighting control unit 18
The control signal relating to the speed of the drive system is output to the drive system control unit 19. Operation panel 2 of image forming apparatus 1
0 is provided with means for inputting information and commands necessary for copying such as a power switch, a switch for setting a document size and a copy paper size, a copy number setting switch, and a start switch. The control unit 6 outputs a control signal to the drive system control unit 19 based on the information and commands input from the operation panel 20, and the scanning optical system 2, the photoconductor 3, the conveyance mechanism 4, and the fixing device of the image forming apparatus 1. 5 is driven at a predetermined speed and timing, and the operation of various means and devices such as the charging device 7, the developing device 8, the transfer device 9 and the cleaner 10 is controlled by another control signal. The control unit 6 further outputs a control signal for maintaining the heat roll 15 of the fixing device 5 at a predetermined temperature according to the operating state of the apparatus to the heater lighting control unit 18 to control the temperature of the heater.

The state of the surface temperature of the heat roll 15 is shown in FIG.
Will be explained. The temperature at which fixing is possible at a normal operating speed is represented by T ₁ . This temperature is set to a temperature relatively higher than the surface temperature T ₂ (40 to 50 ° C.) of the heat roll capable of fixing so that the copying speed can be set high and the copying efficiency can be improved. When copying at the normal operation speed shown by the curve B, when the power is turned on, the fuser lamp 14 is turned on to heat the heat roll. Until the time t ₁ when the surface temperature of the heat roll reaches T ₁ , “please wait” is displayed on the operation panel 18 of the image forming apparatus, and copying is not started even if the start button is pressed. When the surface temperature of the heat roll reaches T ₁ , the display on the panel changes to “Ready to copy” and copying starts. At this time, the fuser lamp 14 is turned on at a ratio of, for example, 4: 1 to 1: 1.
It is turned off / maintained and maintained within a predetermined temperature range, and the fixing operation is executed.

The energy used for fixing in this situation is a rectangular area having four corners bs, be, t ₄ , and t ₁ . As described above, when copying is performed at the normal operation speed, it is necessary to wait from the power-on until time t ₁ . Therefore, when copying in the standby time reduction mode, the copying machine is operated at a low speed as shown by the curve A. That is, copying is started at time t ₃ when the surface temperature of the heat roll 15 reaches the temperature T ₃ at which constant-speed copying is possible, which exceeds the surface temperature T _{2 at} which fixing is possible. At this time, the control means 6 controls the fuser lamp 14
Is turned on / off to maintain the surface temperature of the heat roll 15 in a predetermined temperature range (for example, at a minimum of 80 to 90 ° C.), and the scanning optical system 2, the photoconductor 3, the copy sheet conveyance mechanism 4, and the fixing device 5. Etc. are driven at a predetermined low speed, and the operation timings of the charging device 7, the developing device 8, the transfer device 9, and the cleaner 10 are controlled in accordance with the operating speed. The energy used for fixing in this operating state is as, a
It is represented by the area of a rectangle having four corners e, t ₅ , and t ₃ , and the operation speed is controlled so that this area is approximately equal to the area of the rectangle represented by the case of the curve B. . When the first copying is completed, the copying machine enters the standby mode, and the fuser lamp 14 of the heat roll 15 is supplied with power for preheating, for example, for 3 seconds ON and 27 seconds OFF. The surface temperature of the heat roll at this time is maintained at the same temperature regardless of the operating speed and the operating temperature at the time of the first copying, so that the normal copying operation ns is executed at the next copying. In the preheating mode, the fuser lamp 14 is turned on / off at a lighting / extinguishing ratio of about 1:15 to lower the preheating temperature and stand by.

FIG. 3 is a flow chart regarding the operation speed control in the control section 6 of the present invention. When the copy mode is set (S1) and the start button is pressed (S2), the temperature detecting means 17 is used to fuse the fuser. Detect the temperature (S3),
It is judged whether or not the fixing temperature T ₂ is reached (S
4) When the temperature at which fixing is possible has not been reached, JOB
Is canceled and the waiting time is displayed (S41), and the process waits until the start button is pressed again. When the fuser temperature reaches the fixing temperature, the normal operating temperature T
_It is determined whether or not the temperature has reached ₁ , and when the temperature has reached T ₁ , a control signal for operating at a normal speed is issued to perform a copying operation (S6), and when the operation is completed, the JOB is ended (S6).
7). When the temperature has not reached the temperature T ₃ , the operating speed according to the temperature is calculated (S51), and a control signal for operating at the calculated speed is issued to perform the copying operation (S52). According to this control, the operating speed can be freely selected according to the temperature of the fixing device.

The above description has been made on the assumption that one copy is made at the start-up of the image forming apparatus. However, when the number of copies is a predetermined amount or more, this function is canceled and normal operation is possible. You may make it wait by displaying the waiting time until the temperature is reached. Further, when there are a plurality of originals, the first original may be operated at a low speed and the copying of the next page may be sequentially changed to the speed according to the temperature of the fixing device. As described above, if the drive system and the control system are digitally controlled when the measures are taken, it is possible to easily select the operation speed freely.

[0010]

As described above, according to the present invention, the temperature of the fixing device is monitored at the time of copying, and copying is performed at an operating speed corresponding to the speed when the temperature reaches the fixing-possible temperature. Even when the first imaging device is started up in the morning or when switching from the preheat mode such as after lunch break, it takes a long time (t
Copying can be done in a short time (t ₃ ) without waiting (up to ₁ ).

[Brief description of drawings]

FIG. 1 is a diagram showing a concept of a configuration of an image forming apparatus according to the present invention.

FIG. 2 is a curve diagram showing temperature characteristics when the image forming apparatus is started up.

FIG. 3 is a diagram showing a flow of operation speed control in the image forming apparatus according to the present invention.

[Explanation of symbols]

1 image forming apparatus, 2 scanning optical system, 3 photoconductor,
4 copy paper transport mechanism, 5 fixing device, 6 control means, 14 fuser lamps, 15 heat rolls, 17 temperature detection means.

Claims (1)

[Claims] 1. An image forming apparatus for heat fixing, comprising: a heat roll; a means for detecting the temperature of the heat roll; and an image at a speed according to the temperature of the heat roll when the temperature exceeds a fixable temperature. An image forming apparatus comprising: a control unit that operates the forming apparatus.