JP3165702B2 - Image forming device - Google Patents

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 such as an electrophotographic apparatus and an electrostatic recording apparatus, and more particularly to an image forming apparatus having a heating and fixing means.

[0002]

2. Description of the Related Art In an image forming apparatus such as a laser beam printer and a copying machine, a heat fixing device, particularly a heat roller fixing device, is widely used for fixing a visible image on a recording material.

[0003] In such an image forming apparatus, a warm-up time is required from when a power supply is turned on to a heating element typified by a heating roller until the heating element reaches a fixing temperature.

Therefore, in order to reduce the wait time during which image formation is prohibited, it has been practiced to enable image formation at a temperature lower than the fixing temperature.

This will be described by taking a laser beam printer as an example.

FIG. 10 is a diagram showing the control of the heating roller from when the power is turned on until the heating roller reaches the fixing temperature to obtain the first print (hereinafter referred to as a first print time).

[0007] The printer control unit monitors the heating roller temperature by a thermistor or the like temperature detector as well as on the heater of the heat roller when the power source is turned on, the spirit of the ready signal is a print operation can start reaches a predetermined temperature T _R (/ RDY) is valid (hereinafter referred to as “truw”). The image signal generator starts receiving the ready signal and, if print code data exists, starts developing the code data into dot data and sends a print signal (/ PRNT) to the printer controller. The printer control unit enters the fixing temperature control mode the temperature is raised further to the fixing temperature T _C turns on the heater starts the paper feeding operation and receives a print signal. If there is no print code data, the print signal remains invalid (hereinafter referred to as false) and the apparatus enters a standby temperature control mode at a predetermined temperature T _S. And the ready temperature T _R is a standby temperature T _S and the same temperature,
The temperature is set at a temperature about 10 degrees lower than the fixing temperature T _{C, and} the temperature control is performed so that the temperature reaches the fixing temperature with a sufficient margin from the start of the printing operation until the recording material reaches the fixing device.

[0008]

BRIEF Problems to Solved] However, in the fixing device heating process of power after turning According to this control method, according to the temperature T _R of the fuser initial temperature and manufacturing variations in which the Toruu a ready signal Considering the influence of the temperature rise characteristics and the slow rise of the heating roller when the power is turned on after leaving it for a long time in a low temperature state, fix it with sufficient margin in the shortest time from the start of printing until the recording material reaches the fixing unit. Since the temperature is set high enough to reach the fixing temperature, the first print time has not been sufficiently reduced.

[0009]

According to the present invention, there is provided a polygon mirror for rotating a laser beam modulated in accordance with an image signal while rotating at a set number of rotations, and for forming an image on a recording material. A fixing unit that is controlled to a fixing temperature when heating and fixing and is controlled to a standby temperature during standby .
In an image forming apparatus capable of setting a plurality of set rotation speeds of a polygon mirror, a standby temperature is determined according to a temperature rise rate of the fixing unit measured when the fixing unit is raised to a standby temperature and a set rotation speed of the polygon mirror. Is set again.

[0010]

Embodiments of the present invention will be described below.

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention.

Reference numeral 101 denotes a printer engine which receives an image signal developed into dot data from an image signal generator 102 and prints it on a recording medium.

Reference numeral 103 denotes a CPU, which is a printer control unit 10.
4 together with the control of the printer engine.

The photosensitive drum 105 is uniformly charged by the charging roller 11, and the surface of the semiconductor laser 1 is controlled by an image signal.
The laser beam that drives the 06
07 to scan to obtain a latent image.

The latent image on the photosensitive drum 105 is developed by the developing sleeve 12 with toner powder.

Reference numeral 109 denotes a heat fixing roller serving as a heating member, in which a heater 109 is provided, and an AC driver 11 is provided.
2 and further to the CPU 103. Reference numeral 14 denotes a pressure roller that is in pressure contact with the heat fixing roller.

A thermistor 111 is disposed in contact with the surface of the heat fixing roller 109, and an output signal of the thermistor 111 is input to the CPU 103 as a digital amount by an A / D converter 113. CPU103 to the AC driver on / off and closed-loop control so that the surface temperature of the heat fixing roller becomes a predetermined fixing temperature T _C by these configurations.

At the time of printing, the sheet 108 is fed by a feed roller 115, abutted by a registration roller 114, and re-fed to the registration roller 114 in synchronization with a vertical synchronization signal / SYNC of an image signal, and a drum obtained by an electrophotographic process. The leading end is aligned with the upper toner image, transferred to a sheet by a transfer roller 13, fixed by a heat fixing roller, and discharged to a discharge tray 110 to obtain a print.

FIG. 2 is a flow chart for explaining a control sequence of the printer engine from power-on to obtaining the first print, showing a reference example for understanding the present embodiment in the above configuration. . Also, FIG.
3 is a graph illustrating temperature control of the surface of a heat fixing roller when the control sequence of FIG. 2 is executed.

In this embodiment, the temperature TR at which the printing operation is possible or started after power is turned on (hereinafter referred to as ready) is variably set so that the time from the fixing temperature reaching timing to the fixing start timing is minimized or eliminated. I have.

[0021] When the power-on is performed by a ready signal to false (201), setting the temperature T _R to be the ready the fixing temperature T _C and the same temperature (202). Next, the initial temperature of the fixing roller is read (203), and the temperature register T _n is read.
Is cleared to 0 (205), the energization of the heater is started (206), and the timer in the CPU is started. The temperature of the thermistor is read (208). When the temperature reaches the ready temperature, the ready is set to true (216). In the process of reaching the ready temperature, the processing of 211 or less is performed at regular time intervals Δt (210, 214). In processes 211 and 212, A =
An operation of (T _{n + 1} −T _n ) / Δt is performed to determine the rate of temperature rise A of the fixing device per time Δt. Next, T _R = T _C − (A ×
t _W1 ), the minimum time t _W1 from the start of sheet feeding to the start of fixing (when image development time <sheet feeding time is satisfied), the fixing temperature T _C , and the fixing unit temperature rise rate A obtained earlier. the the ready temperature T _R to reset determined by linear approximation (21
3). Update the register t _n for timer processing (21
4) The current temperature is stored in the register _Tn , and the process returns to the process 208 to repeat the process. By repeating this process until the temperature reaches the ready temperature, avoid the effects of nonlinearity at low temperatures due to thermistor temperature characteristics, which is a problem in the process of rising characteristics, and finally calculate results in a temperature region with good linearity Control can be performed with higher accuracy.

[0022] the ready temperature reaches the control enters the temperature control mode in the case the fixing temperature T _C which is determined print signal whether there is a print signal at 217 as well as the the ready Moving to 216 Toruu (219), if no Standby temperature T
The temperature control mode in _S is entered (218). With these controls, the optimum ready temperature can always be set irrespective of the initial temperature state of the fixing device, and the time from the fixing temperature reaching timing to the fixing start timing can be minimized.

In this embodiment, since the ready temperature is corrected based on the output of the thermistor for controlling the temperature of the heat fixing roller, it is not necessary to provide a special sensor for detecting the environment.

FIG. 4 is a flowchart for explaining another reference example. FIG. 5 is a graph illustrating temperature control of another reference example. The hardware configuration is the same as in the previous reference example.

In this embodiment, the average value of three measurements including the results of the past two measurements is not used as a method of determining the fixing device temperature rise rate A, but rather is temporarily determined by the influence of noise or the like. This prevents the temperature rise rate A from becoming high and the ready temperature from being set low, causing the ready signal to become false and starting printing. By setting the standby temperature TS to the same temperature as the ready temperature TR, the standby temperature can be kept low without extending the printing time.

Hereinafter, description will be given with reference to FIG. 401 to 4
In the same manner as in the above-described reference example, initialization processing, heater ON, and timer start are performed in step 06, and it is checked whether the ready temperature has been reached in steps 407 and 408. Temperature TS
Is set to the same temperature as the ready temperature TR. If there is a print signal, the temperature is adjusted to the fixing temperature TC (421). If there is no print signal, the temperature is adjusted to the standby temperature TS (421). Until the temperature reaches the ready temperature, the temperature is detected at intervals of Δt in the processing of 409 to 417, and the temperature rise rate at that time is calculated (410, 411). The average value A of An-2 is calculated and the ready temperature T
R is calculated and set (413). Reference numerals 414 to 417 perform a process of updating register data.

As described above, by adopting the control means, it is possible to prevent the temperature rise rate A from being temporarily increased due to the influence of noise and the like, and the ready temperature from being set low to prevent the ready signal from becoming false and starting printing. It is in the thing.
Moreover, in which so can be kept low without standby temperature to prolong that the printing time for setting the standby temperature T _S to the ready temperature T _R and the same temperature.
As a result, there is an advantage that power consumption during standby can be reduced, and measures for increasing the temperature inside the print can be reduced.

[Embodiment] FIG. 6 is a flowchart for explaining control of an embodiment of the present invention. The graph explaining the hardware configuration and the temperature control is the same as the reference example.

This embodiment is different from the above-mentioned reference example in that
The time tW1 from the start of sheet feeding to the start of fixing, which is used in the calculation of the ready temperature, is not constant but variable according to the operating conditions of the printer. That is, the laser scanning time is made variable by switching the resolution of the printer, and when the rising time of the polygon mirror is different, the time from paper feeding to the start of fixing is changed according to the rising time.

Hereinafter, control portions characteristic of the present embodiment will be described with reference to FIG. In step 606, the initial value is set to a long value when it takes a long time to start the polygon motor with high resolution. And 61 before the ready temperature setting
In the processing of steps 4, 615, and 616, the time from paper feeding to the start of fixing is set to t _W1 according to the set value of the rotation speed of the polygon motor.
Is switched.

In this embodiment, tW1 is switched based on the set value of the number of revolutions of the polygon motor. However, the switching control may be performed based on a signal indicating the number of revolutions such as a tack signal in a straight line. TW1 may be switched by detecting a parameter that changes the time until the start of fixing. In short, by dynamically changing the time tW1 from the sheet feeding to the start of fixing, the temperature of the fixing unit and the timing of the print sequence are optimized, and the optimum rise time is obtained under any conditions. is there.

[Other Reference Examples] FIGS. 7 and 8 are flow charts for explaining control of another reference example. FIG. 9 is a graph showing the temperature control of this embodiment. The hardware configuration is the same as in the first reference example. In this reference example, the temperature rise characteristic of the fixing roller is continuously measured after the temperature reaches the ready temperature, and when the fixing temperature arrival time is later than the expected value at the ready time, the transmission of the vertical synchronization request signal (/ VSREQ) is delayed by the delay time. This delays the vertical synchronizing signal (/ VSYNC), delays refeeding from the registration roller, and delays the fixing start timing. With this control, even if the temperature rise of the fixing roller is delayed halfway due to fluctuations in the power supply voltage or the like, the fixing start timing is delayed, so that the timing of reaching the fixing temperature and the unfixed defect can be prevented.

Hereinafter, a description will be given with reference to FIGS. The control until the ready temperature is reached is the same as in the embodiment. However, 7
At 22, the estimated time to reach the fixing temperature is recorded in the register tC1. When the temperature reaches the ready temperature, the control is shifted to 728, and 0 is substituted into the delay time register td, and a series of operations of the print sequence are performed in 728 to 732. 737 to 74
In the process (3), the fixing temperature reaching time tC2 is calculated from the current rising characteristic of the fixing roller temperature and the time, and 744 is calculated.
The delay time td is calculated by adding the delay time tC2 to tC1 to the delay time td. If it is detected at 734 that the timing is the vertical synchronization request timing, the timing is delayed by the timer by the delay time td previously obtained and transmitted to the image signal generator (746). By these controls, even if the temperature rise of the fixing roller is delayed halfway, the fixing start timing can be delayed by the delay time.

The embodiment described above is only an example. In order to determine the ready time, it is not necessary to determine the ready time by linear approximation, and an approximate expression is established based on the characteristics of the fixing roller temperature detecting sensor and the characteristics of the fixing roller itself. This may be performed, and the method of calculating the time t _W1 may be obtained using the same set values and sensors.

In short, a special hardware configuration is provided by providing dynamic parameter setting means for monitoring the temperature of the temperature sensor for the temperature control for the temperature rise of the fixing unit every moment when the power is turned on and calculating and setting the ready temperature from the rising characteristic. The timing of the temperature rise of the fixing unit and the timing of the print sequence are optimized without adding the above, so that the optimum rise time can be obtained under any conditions.

Although the embodiment of the present invention has been described with reference to an image forming apparatus having a heat roller fixing device, other heat fixing methods having a heating element maintained at a constant temperature can be used as a fixing method.

[0037]

As described above, according to the present invention, the ready temperature is properly corrected even if the temperature rise characteristics of the heating element of the fixing unit are changed due to environmental fluctuations, jam processing, and the like. Poor fixing can be prevented.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating a control sequence according to a reference example of the present invention.

FIG. 3 is a diagram showing a temperature change of a heating body according to a reference example of the present invention.

FIG. 4 is a flowchart showing a control sequence according to another reference example of the present invention.

FIG. 5 is a diagram showing a temperature change of a heating body according to another reference example of the present invention.

FIG. 6 is a flowchart showing a control sequence according to the embodiment of the present invention.

FIG. 7 is a flowchart showing a control sequence according to another reference example of the present invention.

FIG. 8 is a flowchart showing a control sequence according to another reference example of the present invention.

FIG. 9 is a diagram showing a temperature change of a heating body according to another reference example of the present invention.

FIG. 10 is a diagram showing a temperature change of a conventional heat roller.

[Explanation of symbols]

 103 CPU 105 Photosensitive drum 107 Polygon motor 109 Heat roller 111 Thermistor

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/00 303 G03G 21/00 370-540 B41J 2/44 G03G 15/20-15/20 111

Claims (1)

(57) [Claims] A polygon mirror for deflecting a laser beam modulated according to an image signal while rotating at a set number of rotations;
Yes and a fixing means controlled to the standby temperature during standby is controlled to a fixing temperature when heat fixing an image on a recording material
In the image forming apparatus capable of setting a plurality of set rotation speeds of the polygon mirror, a temperature rise rate of the fixing unit measured when the fixing unit is raised to a standby temperature, and a set rotation speed of the polygon mirror are determined. An image forming apparatus, wherein a standby temperature is reset.