JPH09190129A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evade a defective fixing action when an AC power source voltage is lowered by lowering a paper carrying speed with a earring driving means when it is judged by a power source voltage monitoring means that the AC power source voltage is lowered from a prescribed value. SOLUTION: When it is judged by a microcontroller 30 that the power source voltage of an external AC power source 43 is equal to or over the prescribed value, selectors 28 and 29 are instructed so as to select the clock outputs of oscillators 23 and 25. When it is judged by the controller 30 that the power source voltage of the power source 43 is lower than the prescribed value, the selectors 28 and 29 are instructed so as to select the clock outputs of oscillators 24 and 26. That means, the oscillators 23 and 25 are selected when the power source voltage is normal and the oscillators 24 and 26 are selected when the power source voltage is low. In such a way, a laser scanner motor 41 and a main motor 42 are rotated by the low number of revolution in comparison with a normal time when the power source voltage is low.

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 copying machine or an electrophotographic printer including a fixing device for fixing a toner image on a recording sheet and improving the fixing property of the toner.

[0002]

2. Description of the Related Art Recently, a so-called ceramic heater having a thick film resistor printed on a ceramic substrate is used for fixing a toner image formed on a recording paper in a copying machine or a printer using an electrophotographic process. An anchor has been developed. The Joule heat generated in the thick film resistance portion of the ceramic heater is transferred to the recording paper via the rotating heat resistant film. The characteristic of this fixing device is that it has a small heat capacity,
Since the heat generated in the heater portion is efficiently transferred to the recording paper, it is possible to raise the heating temperature in a very short time. Since the heating response is good, it is not necessary to preheat the toner to fix it on the recording paper, and the power consumption of the apparatus can be reduced.

Triacs and solid state relays (hereinafter abbreviated as SSR) are often used as elements for controlling electric power supply to the ceramic heater, as in the conventional fixing roller. These turn on the voltage received from the external AC power supply.
It is turned on / off to control the electric power to be supplied to the heater. The thick film resistance portion of the ceramic heater can be treated as a substantially linear element, and the current flowing through the heater is proportional to the voltage applied to the heater.

On the other hand, a halogen heater is often used in a fixing device which has been used for a long time. This halogen heater is a non-linear element, and the current flowing through the heater is approximately proportional to the 1/2 power of the voltage applied to the heater.

[0005]

The fixing device using this ceramic heater has a good heating response but has a drawback due to its linear element. The voltage of the AC power source from the outside changes greatly depending on the power transmission situation of the power company and the voltage drop in the distribution line. For example, in Japan, the general indoor voltage is 1
Although it is rated at 00V, the power outlet may drop to 90V due to the loss of the distribution line.

In such a case, in the image forming apparatus connected to the distribution line, the electric power that can be supplied to the internal ceramic heater is as follows, compared to the rated voltage. (90/100) ² × 100 = 81% On the other hand, the electric power that can be supplied to the conventional halogen heater is as follows, compared to the rated voltage. (90/100) ^1/2 x (90/100) x 100 = 8
5%

When the AC power supply voltage drops as described above, the maximum electric power that can be supplied to the ceramic heater becomes smaller than that of the halogen heater. Further, when it is attempted to secure the maximum supply power equal to or more than a predetermined value when the AC power supply voltage drops, the value of the current flowing through the ceramic heater at the rated voltage may increase as compared with the case of the halogen heater. ON / O to ceramic heater with high current value
If FF control is attempted, flicker (so-called flicker of light) may occur in an illumination device connected to the same distribution line as the image forming apparatus including the fixing device.

[0008]

The present invention solves the above-mentioned problems by adopting the structure described below.

Toner image generating means for generating a toner image on the recording paper at a predetermined paper conveying speed, and the recording paper on the surface of which the toner image has been generated by the toner image generating means come into contact with a predetermined pressure and at the contact portion. Heating means for fixing the toner image on the recording paper at the paper conveying speed by heating, and electric power received from an external AC power source are transmitted to the heating means to keep the temperature of the contact portion at a desired temperature. Image provided with temperature control means, power supply voltage monitoring means for monitoring the voltage of the AC power supply, and conveyance drive means mechanically connected to the toner image generation means and the heating means and capable of varying the paper conveyance speed In the forming apparatus, when the power supply voltage monitoring means determines that the AC power supply voltage has dropped below a predetermined value, the paper feed speed is lowered by the feed drive means. By Rukoto avoids fixing failure of the AC supply voltage at a decline.

Further, the toner image generating means modulates a laser beam according to an image signal, a laser scanning means for irradiating a rotary reflecting plate with the laser beam output by the laser modulating means, and the laser scanning. The charged rotating photosensitive means that is irradiated with the scanning laser light output by the means, and the charged image formed by irradiating the charged rotating photosensitive means with the scanning laser light is converted into a toner image. In the case where the image forming apparatus is an electrophotographic printer including a laser beam scan, the image forming apparatus includes a developing unit and a transfer unit that transfers the toner image formed by the developing unit onto a sheet. When it is determined by the electric voltage monitoring means that the AC power supply voltage has dropped below a predetermined value, the paper feed speed is lowered by the feed drive means. In both cases, the laser modulation frequency of the laser modulation unit and the laser peak light amount of the laser modulation unit are reduced, and further, the laser scanning speed of the laser scanning unit is reduced, thereby reducing the image transfer rate due to the reduction of the paper conveyance speed. It is possible to avoid distortion (shrinkage) in the transport direction and increase in image density.

Toner image generating means for generating a toner image on the recording paper at a predetermined paper conveying speed, and the recording paper on the surface of which the toner image has been generated by the toner image generating means are in contact with each other with a predetermined pressure and at the contact portion. Heating means for fixing the toner image on the recording paper at the paper conveying speed by heating, and electric power received from an external AC power source are transmitted to the heating means to keep the temperature of the contact portion at a desired temperature. Temperature control means, power supply voltage monitoring means for monitoring the voltage of the AC power supply, conveyance drive means mechanically connected to the toner image generating means and the heating means, and capable of varying the paper conveyance speed, and the recording paper. In the image forming apparatus provided with the paper size detecting means for detecting the size of the paper, the size detected by the paper size detecting means is larger than the predetermined size, and When the AC power supply voltage is judged to have decreased below a predetermined value by serial power supply voltage monitoring unit, by reducing the paper conveyance speed by the conveyance drive unit,
Only in the case of large size paper which consumes a large amount of heat, it is possible to avoid the fixing failure when the AC power supply voltage drops due to the decrease in the paper transport speed.

Toner image generating means for generating a toner image on the recording paper at a predetermined paper conveyance speed, and the recording paper on the surface of which the toner image has been generated by the toner image generating means are brought into contact with a predetermined pressure and at the contact portion. Heating means for fixing the toner image on the recording paper at the paper conveying speed by heating, and electric power received from an external AC power source are transmitted to the heating means to keep the temperature of the contact portion at a desired temperature. Temperature control means, power supply voltage monitoring means for monitoring the voltage of the AC power supply, conveyance drive means mechanically connected to the toner image generating means and the heating means, and capable of varying the paper conveyance speed, and the recording paper. In the image forming apparatus provided with the paper thickness information input means for inputting the thickness of the paper thickness information, the paper thickness information input by the paper thickness information input means is larger than a predetermined thickness, and When the AC power supply voltage is judged to have decreased below a predetermined value by serial power supply voltage monitoring unit, by reducing the paper conveyance speed by the conveyance drive unit,
Only thick paper that consumes a large amount of heat consumes a
C Avoid defective fixing when the power supply voltage drops.

[0013]

【Example】

(Example 1) Example 1 of the present invention will be described below. FIG.
FIG. 1 is a schematic or mechanical configuration diagram when applied to a laser beam printer as a first embodiment. In addition, this FIG.
Is almost the same as the configuration of a known laser beam printer which has been used conventionally. FIG. 1 is an electrical configuration diagram of the first embodiment, and is a diagram most representative of the features of the first embodiment.

In FIG. 2, reference numeral 1 is a laser beam printer main body (hereinafter abbreviated as LBP), 2 is a photosensitive drum that rotates in the direction of the arrow in the drawing, and 3 is a charging for charging the surface of the photosensitive drum 2 with an electrostatic charge. Reference numeral 20 denotes a polyhedral mirror that reflects the modulated laser light while rotating it. Reference numeral 17 denotes an optical lens that allows the laser scanning light reflected by the polyhedral mirror 20 to pass therethrough. The laser scanning light output from the polyhedral mirror 20 is condensed by the A portion of the photosensitive drum 2, and the laser scanning speed at the A portion. Has a role of making the uniform. Reference numeral 16 denotes a folding mirror that reflects the laser scanning light that has passed through the optical lens 17 and irradiates the photosensitive drum 2 with the laser scanning light.

The surface of the photosensitive drum 2 charged by the charger 3 receives the laser scanning light modulated at the A portion,
As a result, a charge image (hereinafter abbreviated as a latent image) is formed on the surface of the photosensitive drum 2. A developing device 5 contains a developing material (toner) inside. The latent image formed on the surface of the photoconductor drum 2 is converted into a toner image by the developing device 5.
Converted in part. Reference numeral 14 is a paper tray on which a plurality of paper sheets are stacked. A paper feed roller 9 feeds the uppermost paper 13 stacked on the paper tray 14 and conveys it to the registration roller 10. With the registration roller 10 stopped, the sheet fed by the sheet feeding roller 9 strikes the registration roller 10. Then, the registration roller 10 rotates at a predetermined timing to convey the sheet toward the transfer charger 6.

The toner image on the surface of the photosensitive drum 2 formed in the B section is transferred by the transfer charger 6 onto the sheet conveyed by the registration roller 10 in the C section. The timing of starting the rotation of the registration rollers 10 is determined so that the transfer position on the sheet is adjusted to a desired position. The sheet on which the toner has been transferred by the transfer charger 6 passes through the fixing belt 12 via the conveyor belt 11. A ceramic heater is included inside the fixing device 12, and the toner image is fixed on the paper by the ceramic heater 12. Then, the fixed sheets are stacked on the ejection tray 15 attached to the outside of the LBP 1. A waste toner bottle 7 collects the remaining toner that could not be transferred to the sheet at the C portion. Reference numeral 8 is a lamp for clearing the electric charge left on the surface of the photosensitive drum 2. The function and operation of each device in FIG. 2 have been briefly described above. This description is the same as the operation of the known LBP.

In FIG. 1, reference numeral 30 is a microcontroller, which controls all the sequences of LBP1. 50
Is a microcontroller control bus, and all devices around the microcontroller control bus 50 are connected via the microcontroller control bus 50. Further, the microcontroller control bus 50 includes a data bus for the microcontroller 30 to send and receive data, an address bus indicating the address of the data, and a control bus for determining the synchronization timing of the data exchange. 31 is a random access memory (hereinafter referred to as RAM
And is connected to the microcontroller control bus 50. The RAM 31 also has a role of temporarily storing data calculated by the microcontroller 30 or newly generated. The ROM 32 is a read only memory (hereinafter abbreviated as ROM), and stores a program executed by the microcontroller control bus 50.

Reference numeral 49 is an external information processing device, and data obtained from the external information processing device 49 is input / output buffer 48.
Is input to The microcontroller 30 is a ROM 32
The data input to the input / output buffer 48 is received via the microcontroller control bus 50 in accordance with the program stored in, and the received data is temporarily stored in the RAM 31. The received data includes character information and graphic information. The microcontroller 30 converts the character information and the graphic information into binary information that is bit-mapped according to a program stored in the ROM 32,
The binary information is also stored in the RAM 31.

After the microcontroller 30 receives the data for one page and finishes converting the data into binary data which has been bit-mapped, the microcontroller 3
0 starts the printing sequence related to electrophotography. The microcontroller 30 instructs the motor controllers 39 and 40 via the microcontroller control bus 50 to rotate the motor. The scanner reference clock 56 is input to the motor controller 39, and the main motor reference clock is input to the motor controller 40. The motor controllers 39 and 40 rotate the laser scanner motor 41 and the main motor 42 at rotation speeds proportional to the clock frequencies of the scanner reference clock 56 and the main motor reference clock 57, respectively.

The laser scanner motor 41 rotates the polyhedral mirror 30 described with reference to FIG. 1, and the main motor 42 also has the photosensitive drum 2, the developing device 5, the paper feed roller 9, the registration roller 10, and the conveyor belt also described with reference to FIG. The driving force is transmitted to 11 and the fixing device 12. 56 and 57 are signals output from the selectors 28 and 29, respectively. The selector 28 selects the clock signal received from the oscillators 23 and 24 and transmits one of them to the motor controller 39 as the scanner reference clock 56. Similarly, the selector 29 selects the clock signals received from the oscillators 25 and 26 and transmits one of them to the motor controller 40 as the main motor reference clock 57. The clock selection of those selectors 28 and 29 is R
It is performed by the microcontroller 30 via the microcontroller control bus 50 according to the program of the OM32.

An external AC power source 43 supplies the original power for operating the LBP1, and its voltage waveform is input to the power source voltage detection circuit 44. The output of the power supply voltage detection circuit 44 is input to the AD converter 45. AD
Converter 45 converts the analog voltage received from power supply voltage detection circuit 44 into digital data. The micro controller 30 executes the AD converter 45 via the micro controller control bus 50 according to the program of the ROM 32.
Can be read, and as a result, the power supply voltage of the external AC power supply 43 can be known.

If the microcontroller 30 is an external AC
When it is determined that the power supply voltage of the power supply is equal to or higher than a predetermined value (for example, 90V), the microcontroller 30 determines that the selector 28
And 29 to select the clock outputs of the oscillators 23 and 25. Where 23, 24, 25, 26
Clock frequencies of f23, f24, f25,
When f26 is set, it is set in advance so that the following relationships are established between the clock frequencies. f24 = k × f23 (1) f26 = k × f25 (2) However, k is a value between 0 and 1. ... (3) For example, k = 0.8 is selected.

Further, the microcontroller 30 is an external AC
When it is determined that the power supply voltage of the power supply 43 is lower than a predetermined value (for example, 90V), the microcontroller 30 causes the selector 2 to operate.
Instruct 8 and 29 to select the clock output of oscillators 24 and 26. That is, the oscillators 23 and 25 are selected when the power supply voltage is normal, and the oscillators 24 and 26 are selected when the power supply voltage is low. In this way, when the power supply voltage is low, the laser scanner motor 41 and the main motor 42 are rotated at a lower rotation speed than in the normal state.

Reference numeral 27 denotes a selector, which outputs a clock (hereinafter referred to as an image clock) 55 that serves as a reference for laser modulation. 27 selects one of the clock signals of the oscillators 21 and 22 and outputs it as an image clock 55 to the FIFO 33. The microcontroller 30 selects the image clock according to the program stored in the ROM 32. Here, when the clock frequencies of the oscillators 21 and 22 are f21 and f22, respectively, it is set in advance so that the following relationship is established between the clock frequencies. f22 = k × f21 (4) Note that this k is the same as the value shown in (3).

When the microcontroller 30 determines that the power supply voltage is equal to or higher than a predetermined value (for example, 90V), that is, the power supply voltage is normal, it causes the output clock of the oscillator 21 to be selected as the image clock 55. When it is determined that the power supply voltage is lower than a predetermined value (for example, 90V), the output clock of the oscillator 22 is selected as the image clock 55.

The FIFO 33 is a first-in first-out memory (hereinafter abbreviated as “FIFO”), and sequentially stores the image data received from the microcontroller 30. The microcontroller 30 stores the bitmap data in the RAM 31 already stored in the FI.
Move to FO33. The FIFO 33 synchronizes with the horizontal synchronizing signal 58 and the image clock 55 input from the beam position detector 35 and outputs the sequential data already received from the microcontroller 30 as parallel data in the order of reception. The output data of the FIFO 33 is input to the shift register 34. The shift register 34 converts the received data into a serial image signal in synchronization with the horizontal synchronizing signal 58 and the image clock 55. The serial image signal output from the shift register 34 is input to the laser driver 36. The laser driver 36 ON / OFF modulates the semiconductor laser 37 according to the image signal received from the shift register 34. That O
The laser driver 36 drives the semiconductor laser 37 so that the amount of laser light at N hours is proportional to the analog signal received from the DA converter 38. The DA converter 38 is
It converts the data received from the microcontroller 30 via the microcontroller control bus 50 into analog signals. Thereby, the microcontroller 30 can instruct the laser light amount when the semiconductor laser 37 is turned on.

When the power supply voltage is equal to or higher than a predetermined value (for example, 90 V), that is, when the power supply voltage is normal, the microcontroller 30 sets the laser light amount when the semiconductor laser 37 is ON to P1. When it is determined that the power supply voltage is lower than a predetermined value (for example, 90V), the laser light amount when the semiconductor laser 37 is ON is set to P2. The microcontroller 30 sets the laser light amount so that the relationship between P1 and P2 satisfies the following expression. P2 = k × P1 (5) Note that this k is the same as the value shown in (3).

In this way, when the power supply voltage is low,
The semiconductor laser is modulated at a lower laser light amount than in the normal state that satisfies the expression (5) and at a lower frequency than in the normal state that satisfies the expression (4). The beam position detector 35 is arranged on the scanning line of the laser beam reflected by the rotating polyhedron 30 and passing through the optical lens, and detects the scanning reference position of the laser beam. Then, the output of the beam position detector 35 is treated as a horizontal synchronizing signal as described above.

As described above, when the power supply voltage is low (eg, below 90 V), the laser scanning frequency (laser scanner rotation speed) is k times (eg, 0.8 times) lower than the normal voltage. , And a low laser peak light quantity (laser light quantity when ON) of k times (for example, 0.8 times) and a laser modulation frequency of k times (for example, 0.8 times), the modulation scanning laser beam is applied to the photosensitive drum 2. Is irradiated on the surface of.
Then, as described with reference to FIG. 2, a latent image is formed on the surface of the photosensitive drum 2, and the latent image is modulated into a toner image by the developing device 5. Then, the toner image is transferred onto the paper by the transfer charger 6, and the paper on which the toner image is transferred is fixed by the fixing device 12.

Since the processes from latent image formation to fixing are driven by the main motor 42, when the power supply voltage is low (for example, below 90 V), k times (for example, 0.8 times) the normal voltage is applied. ) Image formation at low electrophotographic process speeds. If the power supply voltage is low,
While the sheet conveyance is k times (eg 0.8 times) lower, the laser scanning frequency and the laser peak light amount are also k times (eg 0.8 times) lower and k times (eg 0.8 times) laser modulation frequency. The vertical and horizontal distortion of the image on the paper and the change in the image density are eliminated as compared with the case where the power supply voltage is normal.

The charging device 3, the developing device 5, and the transfer charging device 6 are driven by the high voltage generator 46, and the driving command is issued by the microcontroller 30 via the microcontroller control bus 50. Further, various sensors and actuators 47 perform the feeding of the sheets stacked on the sheet tray 14 by the sheet feeding rollers 9, the driving of the sheets by the registration rollers, the detection of the presence or absence of sheet conveyance, etc. The control is performed by a micro controller. This is done by the microcontroller 30 via the bus 50.

Further, the temperature control in the fixing unit 12 is performed by the heater driving circuit 51, the ceramic heater 52, the AD converter,
This is performed by the temperature detection circuit 54 and the like. The microcontroller 30 gives a heater ON / OFF instruction to the heater drive circuit 51 via the microcontroller control bus 50. The heater driving circuit 51 drives the ceramic heater 52 according to the received instruction. The temperature detection circuit 54 is attached near the fixing unit of the fixing unit 12 and detects the temperature of the fixing unit. The output of the temperature detection circuit 54 is input to the AD converter 53, which converts the temperature of the fixing unit into digital data and gives the data to the microcontroller 30 via the microcontroller control bus 50. Microcontroller 30 is ROM3
According to the program stored in 2, the heater is turned on / off so that the data received from the AD converter 53 becomes a constant value (that is, the temperature of the fixing unit becomes constant).

When the power supply voltage is low, the paper conveying speed becomes k times slower as described above, so that the amount of heat taken to the paper in the fixing unit 12 per unit time is reduced to about k times. As a result, it is possible to compensate for the decrease in the maximum power supply by the heater due to the low power supply voltage.

The resistance of the heater can be increased by supplementing the power supplied to the heater when the power supply voltage drops. As a result, when the power supply voltage becomes high, the current flowing through the heater (that is, corresponding to the current flowing through the power supply) can be suppressed low. This turns the heater on / off
When this is done, flicker on other lighting equipment is reduced.

Example 2 Example 2 of the present invention will be described below. The laser beam printer is applied to the second embodiment as well, and its schematic or mechanical configuration diagram is FIG. FIG. 3 is an electrical configuration diagram of the second embodiment, and is a diagram most representing the characteristics of the second embodiment. 3 is different from FIG. 1 in that the paper size detector 55 and the AD
That is, the converter 56 is added. The other devices have the same numbers as in FIG.

In the first embodiment, when the power supply voltage drops,
The laser scanning frequency (laser scanner rotation speed), laser modulation frequency, laser light amount, and main motor rotation speed are reduced. In the second embodiment, the power supply voltage drops and the output of the paper size detector 55 causes the microcontroller 30
When it recognizes that the paper to be printed is larger than the specified value,
The laser scanning frequency (laser scanner rotation speed), laser modulation frequency, laser light amount, and main motor rotation speed are reduced.

The paper size detector 55 is the paper feed tray 14
The width in the laser scanning direction of the paper attached to the paper feed tray 14 is detected. For example, paper feed tray 1
A lateral regulating plate of the paper is provided on the side of 4, and a slide variable resistor mechanically interlocking with the regulating plate is attached. The operator places the paper on the paper feed tray 14 and adjusts the position of the regulation plate to the position where the paper is placed. By detecting the resistance value of the slide variable resistor, the paper size detector 55 can convert the paper width into an electric signal. The output of the paper size detector 55 is AD
It is input to the converter 56, and the analog signal corresponding to the paper width is converted into digital data. The microcontroller 30 can detect the width of the currently set paper by reading the digital data via the microcontroller control bus 50.

If the paper size (width) detected by the microcontroller 30 by the AD converter 56 is not less than a predetermined value,
Further, when the AD converter 45 determines that the power supply voltage is lower than a predetermined value (for example, 90V), the oscillators 22, 24, and 26 are selected by the means described in the first embodiment. Otherwise, the microcontroller 30 has the oscillator 21,
Select 23 and 25. Oscillators 21, 22, 23, 2
Between 4, 25, and 26, (1) described in Example 1,
It is set in advance so that the relationships (2), (3), (4), and (5) hold.

When the paper size (width) thus detected is equal to or larger than the predetermined value and the AD converter 45 determines that the power supply voltage is lower than the predetermined value (for example, 90 V), the laser scanning frequency (laser scanner rotation speed). To k times (for example, 0.8 times), the laser modulation frequency to k (for example, 0.8 times), the laser light amount to k (for example, 0.8 times),
And the number of rotations of the main motor is increased by k times (for example, 0.8 times).

When the paper size (width) is large, the amount of heat per unit time taken by the fixing cup 12 becomes large, so that the insufficient supply of electric power to the fixing cup 12 when the power supply voltage drops is compensated for by the paper conveyance speed reduction. be able to. At this time, similarly to the first embodiment, no distortion in the vertical and horizontal directions of the image or a change in density occurs. When the paper size (width) is equal to or smaller than the predetermined value, the paper conveyance speed is not decreased even when the power supply voltage is decreased, and the printing speed is not decreased.

Example 3 Example 3 of the present invention will be described below. The laser beam printer is also applied to the third embodiment, and its schematic or mechanical configuration diagram is FIG. FIG. 4 is an electrical configuration diagram of the third embodiment, and is a diagram most representing the characteristics of the third embodiment. 4 is different from FIG. 1 in that a control panel 57 and an input / output buffer 58 are added. The other devices have the same numbers as in FIG.

In the first embodiment, when the power supply voltage drops,
The laser scanning frequency (laser scanner rotation speed), laser modulation frequency, laser light amount, and main motor rotation speed are reduced. In the third embodiment, when the microcontroller 30 recognizes that the power supply voltage is low and the paper is thicker than a predetermined value, the laser scanning frequency (laser scanner rotation speed), laser modulation frequency, laser light amount, and main motor rotation speed are set. Lower.

The microcontroller 30 receives the data obtained from the control panel 57 via the input / output buffer 58 in accordance with the program stored in the ROM 32. The control panel 57 displays data received from the micro controller 30 to the operator as a message and passes key data input by the operator to the micro controller 30. The operator can set various modes (for example, select a print area or a character font) via the control panel 57. In the mode setting, the operator inputs the paper thickness information of the paper. For example, as the paper thickness information by key input,
Allow the operator to select two types, "thick" and "thin". When the operator inputs “thickness” as the paper thickness information into the control panel 57, the micro controller 30 sends the information from the control panel 57 to RO.
Receive according to the program stored in M32. When the microcontroller 30 recognizes "thickness" as the paper thickness information and the AD converter 45 determines that the power supply voltage is lower than a predetermined value (for example, 90V), the oscillators 22, 24, 26 are processed by the means described in the first embodiment. Select. Otherwise, the microcontroller 30 selects the oscillator 21, 23, 25. Oscillators 21, 22, 2
The numbers 3, 24, 25, and 26 are set in advance so that the relationships (1), (2), (3), (4), and (5) described in the first embodiment are established.

When the paper size (width) thus detected is equal to or greater than the predetermined value and the AD converter 45 determines that the power supply voltage is lower than the predetermined value (for example, 90 V), the laser scanning frequency (the number of revolutions of the laser scanner). To k times (for example, 0.8 times), the laser modulation frequency to k (for example, 0.8 times), the laser light amount to k (for example, 0.8 times),
And the number of rotations of the main motor is increased by k times (for example, 0.8 times).

When the paper is thick, the amount of heat per unit time taken by the fixing cup 12 is large, so that the insufficient supply of electric power to the fixing cup 12 when the power supply voltage drops can be compensated for by reducing the paper conveyance speed. At this time, similarly to the first embodiment, no distortion in the vertical and horizontal directions of the image or a change in density occurs. Further, when the paper is thin, the paper conveyance speed does not decrease even when the power supply voltage decreases, and the printing speed does not decrease.

[0046]

As described above, according to the present invention,
The effects described below can be obtained. (1) When the AC power supply voltage drops, the laser scanning frequency, the laser modulation frequency, the laser light amount, and the paper transport speed are reduced, so that the insufficient power supply to the heater due to the AC power supply voltage drop can be compensated. As a result, it is possible to increase the heater resistance, and it is possible to suppress an excessive current to the heater (that is, a current flowing to the AC power supply) when the AC power supply voltage becomes high.

(2) When the paper size is large and the AC power supply voltage drops, the laser scanning frequency, the laser modulation frequency, the laser light amount, and the paper transport speed are reduced to reduce the power supply to the heater due to the AC power supply voltage drop. Supply shortage can be compensated. As a result, it is possible to increase the heater resistance, and it is possible to suppress an excessive current to the heater (that is, a current flowing to the AC power supply) when the AC power supply voltage becomes high. In addition, if the paper size is not large, the paper transport speed is not decreased, and the printing speed is not decreased.

(3) When the paper is thick and the power supply voltage is lowered, the laser scanning frequency, the laser modulation frequency, the laser light amount, and the paper transport speed are lowered, so that the power supply to the heater is insufficient due to the AC power supply voltage drop. Can be supplemented. As a result, it is possible to increase the heater resistance, and it is possible to suppress an excessive current to the heater (that is, a current flowing to the AC power supply) when the AC power supply voltage becomes high. If the paper is not thick,
As a matter of course, the printing speed is not lowered because the paper conveying speed is not lowered.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing a schematic structure of Examples 1 to 3 of the present invention.

FIG. 3 is a block diagram showing an electrical configuration of a second embodiment of the present invention.

FIG. 4 is a block diagram showing an electrical configuration of a third embodiment of the present invention.

[Explanation of reference numerals] 1 laser beam printer main body 2 photoconductor drum 3 charger 20 polyhedral mirror 17 optical lens 16 folding mirror 5 developer 14 paper tray 9 paper feed roller 10 registration roller 12 fixer 8 lamp 30 microcontroller 50 microcontroller Control bus 31 Random access memory 32 Read only memory 49 External information equipment 48 Input / output buffer 39 Motor controller 40 Motor controller 41 Laser scanner motor 51 Heater drive circuit 52 Ceramic heater 53 AD converter 54 Temperature detection circuit 55 Paper size detection circuit 56 AD converter 57 control panel 58 input / output buffer

Claims (7)

[Claims] 1. A toner image generating means for generating a toner image on a recording paper at a predetermined paper conveying speed, and a recording paper on the surface of which a toner image is generated by the toner image generating means comes into contact with and contacts with a predetermined pressure. Heating means for fixing the toner image on the recording paper at the paper conveying speed by heating the sheet at a portion, and electric power received from an external AC power source is transmitted to the heating means to set the temperature of the contact portion to a desired temperature. Temperature control means, power supply voltage monitoring means for monitoring the voltage of the AC power supply, and conveyance drive means mechanically connected to the toner image generation means and the heating means and capable of varying the paper conveyance speed. Image forming apparatus,
An image forming apparatus, wherein when the power supply voltage monitoring unit determines that the AC power supply voltage has dropped below a predetermined value, the transport driving unit reduces the paper transport speed. 2. The image forming apparatus according to claim 1, wherein
The toner image generation unit modulates a laser beam in accordance with an image signal, a laser scanning unit configured to irradiate a rotary reflection plate with the laser beam output from the laser modulation unit, and a laser scanning unit to output the laser beam. And a developing means for converting a charged image formed by irradiating the charged rotating photosensitive means with the scanning laser light into a toner image. An image forming apparatus comprising: a transfer unit configured to transfer the toner image formed by the developing unit onto a sheet; and the rotation photosensitive unit being mechanically driven by the transport driving unit. 3. The image forming apparatus according to claim 2,
When the power supply voltage monitoring unit determines that the AC power supply voltage has dropped below a predetermined value, the transport driving unit lowers the paper transport speed and the laser modulation frequency of the laser modulation unit is reduced. Forming equipment. 4. The image forming apparatus according to claim 2, wherein
When the power supply voltage monitoring unit determines that the AC power supply voltage has dropped below a predetermined value, the transport driving unit lowers the paper transport speed and the laser peak light amount of the laser modulation unit is reduced. Forming equipment. 5. The image forming apparatus according to claim 2,
An image characterized in that, when the power supply voltage monitoring means determines that the AC power supply voltage has dropped below a predetermined value, the transport drive means lowers the paper transport speed and the laser scanning speed of the laser scanning means. Forming equipment. 6. A toner image generating means for generating a toner image on a recording paper at a predetermined paper conveying speed, and a recording paper on which a toner image is generated on the surface by the toner image generating means, contacting and contacting with a predetermined pressure. Heating means for fixing the toner image on the recording paper at the paper conveying speed by heating the toner portion, and electric power received from an external AC power source is transmitted to the heating means to set the temperature of the contact portion to a desired temperature. Temperature control means, power supply voltage monitoring means for monitoring the voltage of the AC power supply, conveyance drive means mechanically connected to the toner image generating means and the heating means, and capable of varying the paper conveyance speed, In an image forming apparatus provided with a paper size detecting unit for detecting the size of the recording paper,
The size detected by the paper size detecting means is larger than a predetermined size, and the power source voltage monitoring means is used for AC.
An image forming apparatus, wherein when it is determined that the power supply voltage has dropped below a predetermined value, the paper feed speed is lowered by the feed drive means. 7. A toner image generating means for generating a toner image on a recording paper at a predetermined paper conveying speed, and a recording paper on the surface of which a toner image is generated by the toner image generating means are in contact with and contact with a predetermined pressure. Heating means for fixing the toner image on the recording paper at the paper conveying speed by heating the toner portion, and electric power received from an external AC power source is transmitted to the heating means to set the temperature of the contact portion to a desired temperature. Temperature control means, power supply voltage monitoring means for monitoring the voltage of the AC power supply, conveyance drive means mechanically connected to the toner image generating means and the heating means, and capable of varying the paper conveyance speed, In an image forming apparatus provided with a paper thickness information input unit for inputting the thickness of the recording paper, the paper thickness information input by the paper thickness information input unit is larger than a predetermined thickness, and AC by the power supply voltage monitoring means
An image forming apparatus, wherein when it is determined that the power supply voltage has dropped below a predetermined value, the paper feed speed is lowered by the feed drive means.