JPH1195606A - Toner image fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner image fixing device capable of preventing the flickering from occurring. SOLUTION: In this laser printer, a photo triac coupler 95 (PH95) is turned on when the temp. (A) falls down to ta, and this on-state continues until the temp. reaches tb. During this time, a current to a heater for fixing is passed, hence the above temp. rises. When the temp. reaches tb, the PH95 is turned off, and the off-state continues until the temp. falls down to ta. The similar control is repeated by turning-on the PH95 again, when the temp. falls down to ta. Moreover, at the time of starting to energize by turning-on the PH95 again, a discontinuous current in a pulse state as shown by (B) is passed. Then, the rush current of the heater for fixing is also parted in the pulse state, and the frequency of the voltage falls due to the rush current becomes high (C). In accordance with the voltage fall, the intensity of illuminating light is also changes with a high frequency that hardly makes humans feel unpleasant, and the flickering can be prevented satisfactorily from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a toner image fixing device for heating a toner image formed on a recording medium and fixing the toner image on the recording medium.

[0002]

2. Description of the Related Art Conventionally, a toner image formed on a recording medium is heated by generating heat in accordance with energization.
There has been proposed a toner image fixing device including a heating unit for fixing the recording medium on the recording medium, and an energizing unit for intermittently energizing the heating unit to adjust the temperature of the heating unit. This type of fixing device is used in, for example, a copying machine or a laser printer that forms a toner image by an electrophotographic method, and heats and fixes toner transferred from a photosensitive drum or the like onto a recording medium such as copy paper. Further, in this type of fixing device, it is considered that a heater made of, for example, a halogen lamp or the like is used as a heating means, and a triac or the like is used so that the surface of a heating roller including the lamp has a desired temperature. It has also been considered to control the energization of the lamp via the.

FIG. 6 is a time chart showing an example of the control. In the control illustrated in FIG. 6, the temperature (A) near the lamp is detected by a thermistor or the like, and the lamp is turned ON / OFF (B) so that the temperature fluctuates between the minimum value ta and the maximum value tb. Is switched. That is,
As shown in FIG. 6, when the temperature drops to ta, the lamp is turned off.
N, and the ON state is continued until the temperature rises and reaches tb. When the temperature reaches tb, the lamp is turned off,
The OFF state is continued until the temperature drops to ta. When the temperature drops to ta, the lamp is turned on again and the same control is repeated.

[0004]

However, in this case,
As illustrated in FIG. 6C, immediately after the lamp is turned on to start energizing the lamp, a large current called an inrush current flows through the lamp. In a case where a copying machine or the like is used in an office or the like using a common power supply with the lighting equipment, the power supply voltage of the lighting equipment decreases every time the inrush current flows. When this voltage drop occurs at a frequency of, for example, about 8.8 Hz, humans feel the most unpleasant as flickering of illumination light (flicker). In recent years, the use of large lamps of about 10 KW as lamps as heating means has been increasing, and it is an urgent task to suppress the generation of flicker due to inrush current.

Accordingly, it is an object of the present invention to provide a toner image fixing device capable of favorably suppressing the occurrence of flicker.

[0006]

Means for Solving the Problems and Effects of the Invention According to the first aspect of the present invention, which has been made to achieve the above object, a toner image formed on a recording medium is heated by generating heat in accordance with energization. A toner image fixing device comprising: a heating unit for fixing on the recording medium; and an energizing unit for intermittently energizing the heating unit to adjust the temperature of the heating unit. When power is supplied to the heating means, pulse-shaped discontinuous power supply is performed at the start of the power supply, and thereafter, continuous power supply is performed.

As described above, in the present invention, when the energizing means energizes the heating means, pulse-like discontinuous energizing is performed at the start of energization. For this reason, the rush current is also divided into pulses, and the frequency of voltage drop due to the rush current increases. Therefore, the intensity of the illumination light also changes at a high frequency that does not make a person feel uncomfortable, and the occurrence of flicker can be favorably suppressed.

[0008] Further, if such a pulse-shaped energization is performed for a long period of time, the heating means cannot be efficiently heated.
Therefore, the energizing means of the present invention switches to continuous energization after performing pulsed energization at the start of energization. Since the inrush current is generated in a very short time at the start of energization, even after continuous energization, flicker becomes a small factor. Further, by switching to the continuous energization in this way, it is possible to minimize the influence of the pulsed energization as noise on the electronic device.
Therefore, according to the present invention, it is possible to satisfactorily suppress the generation of flicker, enable efficient heating, and satisfactorily prevent the influence of energization from affecting the electronic device.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, it is also possible to determine whether the heating unit is performing the fixing while the image is being formed or is not performing the fixing but is in a standby state where the temperature needs to be maintained. The power supply unit may further include a determination unit configured to make a determination, wherein the power supply unit changes the power supply mode at the time of the power supply start between the time of the image formation and the time of the standby based on the determination result of the determination unit.

The required total amount of power to the heating means differs between the time of image formation in which the heating means is performing the fixing and the standby time in which the fixing is not performed but the temperature needs to be maintained.
If the total energization amount differs, the optimal energization mode for suppressing flicker also changes. Therefore, in the present invention, the determination unit determines whether to perform image formation or standby, and based on the determination result, changes the power supply mode when the power supply unit starts power supply between image formation and standby time. For this reason, in the present invention, in addition to the effect of the invention described in claim 1, there is an effect that flicker can be more favorably suppressed irrespective of the time of image formation or standby.

According to a third aspect of the present invention, in addition to the configuration of the second aspect, the energizing means changes at least one of an ON time, an OFF time, and a pulse number of the pulse as the energizing mode. It is characterized by doing. In the present invention, the energizing means changes at least one of the ON time, the OFF time, and the number of pulses of the pulse as the energizing mode according to the second aspect. The on-time, off-time and the number of pulses of the above-mentioned pulses are factors that have a great influence on flicker suppression. In the present invention, at least one of these factors is changed by the energizing unit depending on whether the image is being formed or is in a standby state. For this reason, in addition to the effect of the invention described in claim 2, there is an effect that flicker can be more effectively suppressed.

According to a fourth aspect of the present invention, in addition to the configuration according to any one of the first to third aspects, a storage means for storing an energization mode of the energization means at the start of the energization is further provided. And The state of occurrence of flicker also changes depending on the type of power supply of a copying machine or the like equipped with the fixing device, for example, voltage, frequency, indoor wiring conditions, and the like. In addition, the flicker permitted in a copying machine or the like also varies depending on the regulations of each country. Therefore, it is desirable to change the energizing mode of the energizing means at the start of energizing according to the regulations of the country where the fixing device is used and the mode of the power supply. In the present invention, the energization mode of the energization unit at the start of energization is stored in the storage unit. For this reason, it is possible to rewrite the energization mode stored in the storage means or replace it with a storage means storing an appropriate energization style in accordance with the regulations of the export destination country and the power supply style. By doing so, flicker can be appropriately suppressed in accordance with the regulations of each country and the type of power supply.

Therefore, according to the present invention, in addition to the effects of the invention according to any one of claims 1 to 3, an effect that flicker can be more appropriately suppressed according to the regulations of each country and the type of power supply. Occurs. According to a fifth aspect of the present invention, in addition to the configuration of any one of the first to third aspects, the heating means is a lamp.

When the heating means is constituted by a lamp, the rush current increases, and suppression of flicker is a particularly important problem. In the present invention, since the invention according to any one of claims 1 to 3 is applied to a fixing device in which a heating unit is configured by a lamp, the effect of the invention is more remarkably exhibited.

According to a sixth aspect of the present invention, in addition to the configuration of any one of the first to third aspects, the apparatus further comprises a temperature detecting means for detecting the temperature of the heating means or the vicinity thereof. . In the present invention, by the temperature detecting means,
The temperature at or near the heating means can be detected. For this reason, if the temperature detected by the temperature detecting means is reflected in the temperature adjustment by the energizing means, the temperature of the heating means or the vicinity thereof can be adjusted more accurately. Then, the toner can be more favorably fixed on the recording medium. Therefore, in the present invention, in addition to the effect of the invention according to any one of the first to third aspects, an effect that the temperature of the heating means can be more accurately adjusted and the fixing can be performed more favorably occurs. .

[0016]

Next, an embodiment in which the present invention is embodied in a fixing device for a laser printer will be described. FIG. 1 is a perspective view of main components of a laser printer as an image forming apparatus, and FIG. 2 is a schematic side sectional view of the laser printer.

As shown in FIG. 1, a main body case 1 made of synthetic resin in a laser printer has a main frame 1a.
And a main cover 1b that covers the outer surface of the main frame 1a on four sides (front and rear and left and right sides). The main frame 1a and the main cover 1b are integrally formed by injection molding or the like.

A scanner unit 2 as an exposure unit, a process unit 3 as a transfer unit, a fixing unit 4 as a toner image fixing device, and a paper feeding unit 5 are mounted on the main frame 1a from above. .
The drive system unit 6 including the main motor 84 (see FIG. 3) and the gear train is located in the storage recess 1d between the left inner surface of the main cover 1b in FIG. 1 and the left side of the main frame 1a adjacent thereto. It is inserted and fixed from below the main body case 1. Further, the top cover 7 as a synthetic resin body cover for covering the upper surfaces of the main frame 1a and the main cover body 1b has a hole 7a through which an operation panel 1c projecting upward to the right side of the main frame 1a. Hole 7 for penetrating the base of paper feed unit 5
b is perforated. The base of the paper discharge tray 8 is provided with brackets 9 (see FIG.
(Only one is shown) so as to be able to swing up and down. When not used, the paper discharge tray 8 can be folded over the top surface of the top cover 7 to cover it.

In the feeder unit case 5a of the paper feeding unit 5, recording papers P as recording media are set in a stacked state. As shown in FIG. 2, the leading end side of the recording paper P is pressed toward the paper feed roller 11 by the support plate 10 with the biasing spring 10a in the feeder case 5a. For this reason, the power is transmitted from the drive system unit 6 and the paper feed roller 11 and the separation pad 12 that rotate and rotate,
The recording paper P can be separated one by one and sent to a pair of upper and lower registration rollers 13 and 14.

The process unit 3 includes a registration roller 1
The separated recording paper P fed at 3 and 14
An image is formed on the surface of the substrate with toner. Further, the fixing unit 4 heats the recording paper P on which the toner image is formed by sandwiching the recording paper P between the heating roller 15 and the pressing roller 16 to fix the toner image on the recording paper P. A paper discharge unit including a paper discharge roller 17 and a pinch roller 18 disposed downstream in the case of the fixing unit 4 discharges the recording paper P on which the toner image has been fixed to the paper discharge tray 8. The section from the paper feed roller 11 to the paper discharge section is a recording medium transport route. The paper feeding unit 5 is provided with a manual insertion slot 5b that opens diagonally upward, and the recording paper for printing on a recording paper different from the recording paper P in the feeder unit case 5a is used as the recording medium. It can be inserted into the transport route.

An upper support plate 2a of the scanner unit 2 is provided with a bottom plate of the main frame 1a at a position below the process unit 3 which is disposed substantially at the center of the main frame 1a having an open top in the main body case 1 in plan view. It is fixed to a stay part integrally formed on the upper surface side of the part with screws or the like.
In the scanner unit 2 as an exposure unit, a laser emitting unit (not shown), a polygon mirror 20, a lens 21, a reflecting mirror 22, and the like are arranged on the lower surface side of the synthetic resin upper support plate 2a. A laser beam passes through a glass plate 24 covering a horizontally long scanner hole formed in the upper support plate 2a so as to extend along the axis of the photosensitive drum 23 as a photosensitive member, and to the outer peripheral surface of the photosensitive drum 23 in the process unit 3. It is configured to irradiate and expose.

As shown in FIG.
Is a photosensitive drum 23 and a transfer roller 2 in contact with the upper surface thereof.
5, a scorotron-type charger 26 disposed below the photosensitive drum 23, a developing device having a developing roller 27 and a supply roller 28 disposed upstream of the photosensitive drum 23 in the sheet feeding direction, and further disposed upstream thereof Developer (toner) supply unit, ie, detachable toner cartridge 2
9, a cleaning roller 30 disposed downstream of the photosensitive drum 23, and a discharge lamp 30a disposed downstream of the cleaning roller 30.

A charger 26 is provided on the outer peripheral surface of the photosensitive drum 23.
An electrostatic latent image is formed by scanning a laser beam from the scanner unit 2 on the charged photosensitive layer. Developer (toner) in the toner cartridge 29
Is released by being stirred by the stirrer 31 and then carried on the outer peripheral surface of the developing roller 27 via the supply roller 28, and the thickness of the toner layer is regulated by the blade 32. The electrostatic latent image on the photosensitive drum 23 is visualized by the developer adhering from the developing roller 27. The image (toner image) formed by the developer is transferred to a recording sheet P passing between the transfer roller 25 and the photosensitive drum 23 to which a transfer bias having a potential opposite to the potential of the photosensitive drum 23 is applied to form a toner image. I do. Then, after the toner remaining on the photosensitive drum 23 is temporarily collected by the cleaning roller 30, the toner is returned to the photosensitive drum 23 at a predetermined timing, and is collected by the developing roller 27 into the process unit 3.

The upper support plate 2a of the scanner unit 2
Is provided with a toner sensor 33 protruding upward, and a toner sensor 33 composed of a pair of a light emitting unit and a light receiving unit faces the lower surface recess of the toner cartridge 29 in the process unit 3, and the presence or absence of toner in the toner cartridge 29. Can be detected.

The process unit 3 is made into a cartridge by being incorporated in a case 34 made of synthetic resin.
The process unit 3 formed into a cartridge is detachably mounted on the main frame 1a. A storage portion 3 for storing the cooling fan 35 is provided on the lower surface side of the continuous portion between the front portion of the main frame 1a and the front portion of the main cover body 1b.
6 and a ventilation duct 37 extending in the left-right direction perpendicular to the direction in which the recording paper P passes, are formed so as to communicate with each other. Then, the upper surface plate portion 37a of the ventilation duct 37 is formed in a V-shape with a downward section, and the upper surface plate portion 37a is located between the process unit 3 and the fixing unit 4 to generate the heat generated by the heating roller 15 in the fixing unit 4. Heat generated by process unit 3
To prevent direct transmission to the side.

The cooling air generated by the cooling fan 35 passes through the inside of the ventilation duct 37 and along the lower surface of one side of the main frame 1a, and the power supply unit 39 (see FIG. 2) at the rear and the main motor of the drive system unit 6 On the other hand, the cooling air is blown out from a plurality of slit holes opened on the side of the process unit 3 in the upper surface plate portion 37a, and the cooling air passes through between the process unit 3 and the fixing unit 4 and rises. The air is exhausted from the apparatus through a plurality of exhaust holes 40 formed in the cover 7.

Next, the control unit 70 provided inside the right side of the main frame 1a will be described. FIG.
3 is a block diagram showing the control unit 70 and a configuration related to the control unit 70. FIG. The control unit 70
CPU 71 and RO storing various control programs
M72, a RAM 73 provided with various memories such as a reception buffer for receiving and storing transmission data transmitted from an external data transmission device PC such as a personal computer or a host computer, and timing for writing / reading reception data to / from the reception buffer Control circuit (TC) 74 for generating a timing signal for printing, and an interface (I / F) 7 for receiving transmitted print data.
5, a video interface (V.I / F) 76 having a scan buffer and sequentially outputting print information converted to bit image data to the DC controller circuit 82
And a sensor interface (S · I) that receives detection signals from the toner sensor 33, the paper feed sensor 51 provided in the vicinity of the downstream of the paper feed roller 11, and other sensors.
/ F) 77, and a panel interface (P / I / F) 78 for selecting various control modes from the operation panel section 1c and receiving the switched signals. These are provided to the CPU 71 via the bus 81, respectively. It is connected.

The DC controller circuit 82 includes a paper-feeding-side transport mechanism including the paper-supplying roller 11, registration rollers 13 and 14, the photosensitive drum 23, and the like. And pinch roller 18
Motor 84 for driving the discharge-side transport mechanism section made of
Drive circuit 87, a drive circuit 89 for a laser diode 85 constituting the laser emitting section, a drive circuit 90 for a scanner motor 86 for driving the polygon mirror 20, and a halogen lamp in the heating roller 15. And a high-voltage substrate 92 for generating a high-voltage electric field on the photosensitive drum 23, the transfer roller 25, the charger 26, the developing roller 27, and the cleaning roller 30, and further turning on the neutralizing lamp 30a. And are respectively connected.

In the ROM 72, in addition to various control programs as a normal laser printer, a font memory storing printing dot pattern data relating to a large number of characters such as characters and symbols, a reception data buffer provided in the RAM 73, A memory management program for managing the memory capacity and the head address of each memory such as a print image memory is stored in advance.

Next, the configuration of the drive circuit 91 and its peripherals will be described in detail with reference to FIG. As shown in FIG. 4, the drive circuit 91 is mainly composed of various elements such as a transistor 93, a phototriac coupler 95, and a triac 97, and various resistors described below. The DC controller circuit 82 includes a transistor 93
Is connected via a resistor 93a to switch the transistor 93. Transistor 93
Is connected to a light emitting diode 95a of a phototriac coupler 95 via a resistor 93b. Both ends of the triac 95b of the phototriac coupler 95 are connected to both ends of the triac 97 via resistors 97a and 97b, respectively. I have. Also, Triac 9
The gate of 7 is connected between the resistor 97a and the triac 95b, and when a current flows through the resistor 97a, a gate current corresponding to the voltage drop is supplied.

Between both ends of the triac 97, AC1
A 00V commercial power supply 101, a power switch 103, and the above-described fixing heater 15a are connected in series. Further, a low-voltage power supply 105 that outputs DC voltages of 5 V and 24 V is connected to both ends of a series circuit including the commercial power supply 101 and the power switch 103.

A thermistor 107 is provided near the fixing heater 15a. Thermistor 107
Has one end grounded via a resistor 109 and the other end connected to a 5 V DC power supply, and the potential between the thermistor 107 and the resistor 109 is input to the CPU 71 via an A / D converter (not shown). For this reason, the CPU 71
By reading the above potential, the temperature near the fixing heater 15a can be detected. Therefore, the CPU 71
Is based on the temperature near the fixing heater 15a, via the DC controller circuit 82 as follows:
3 is switched ON / OFF. When the power switch 103 is ON, the phototriac coupler 95 is turned ON when the transistor 93 is turned ON, and the resistor 97a is turned ON.
, And the triac 97 is turned on. Therefore, the ON / OFF of the transistor 93 is controlled by the triac 9
7, which switches between energization and non-energization of the fixing heater 15a. Since the triac 97 performs a zero-cross operation when it is off, the triac 97 is turned off at the maximum when it is off, with a delay of a half cycle of the power supply frequency. Furthermore,
When the phototriac coupler 95 has a zero-cross detection, the triac 97 is turned on at a maximum of a half cycle of the power supply frequency later than the transistor 93 is turned on.

In the fixing unit 4 configured as described above, the CPU 71 controls the temperature in the vicinity of the fixing heater 15a detected via the thermistor 107 between the maximum value tb and the minimum value ta, and Fixing is possible. That is, as shown in FIG.
a, the photo triac coupler 95 (PH9
5) is turned ON, and is kept ON until the temperature rises and reaches tb. During this time, the fixing heater 15a is energized, and the temperature rises. When the temperature reaches tb, the phototriac coupler 95 is turned off, and remains off until the temperature drops to ta. When the temperature drops to ta, the phototriac coupler 95 is turned on again and the same control is repeated.

When the CPU 71 turns on the phototriac coupler 95 and starts the above-mentioned energization, the CPU 71 shown in FIG.
As shown in (B), the phototriac coupler 9
5, a pulse-shaped discontinuous energization is performed. For this reason, FIG.
As shown in (C), the current (lamp current) supplied to the fixing heater 15a is also divided into pulses at the start of the supply of the current, and the following effects are produced.

At the start of energization of the lamp current, a large current called an inrush current flows. When the commercial power supply 101 is used as a common power supply for lighting equipment, the power supply voltage of the lighting equipment decreases every time the inrush current flows. When this voltage drop occurs at a frequency of, for example, about 8.8 Hz, humans feel the most unpleasant as flickering of illumination light (flicker). In the present laser printer, the above-described pulse-shaped energization is performed when the energization of the fixing heater 15a is started, so that flicker can be reduced as follows. That is, if discontinuous energization in a pulse shape is performed at the start of the energization, the inrush current is also divided into pulses, and the frequency of the voltage drop due to the inrush current increases. Therefore, the intensity of the illumination light also changes at a high frequency that does not make a person feel uncomfortable, and the occurrence of flicker can be favorably suppressed. In this laser printer, when the power supply frequency is 50 Hz, the ON time of the pulse is set to 10 msec as an appropriate energization mode for suppressing flicker.
c. The off time was around 20 msec., and the number of pulses was 3 pulses.

Further, the CPU 71 performs the above-described pulse-shaped energization at the start of energization (that is, about 9% from the start of energization).
(After 0 msec.), The phototriac coupler 95 is continuously turned on. For this reason, the lamp current is also switched to continuous energization. Since the inrush current is generated in a very short time (about 90 msec.) At the start of energization, even if energization is continuously performed to the fixing heater 15a, a factor of flicker is small. In addition, by switching to the continuous energization in this way, it is possible to minimize the influence of the pulsed energization as noise on the electronic device and efficiently heat the fixing heater 15a. Therefore, in the present laser printer, the occurrence of flicker can be suppressed well, the fixing heater 15a can be efficiently heated, and the effect of energization of the fixing heater 15a can be favorably applied to electronic devices. Can be prevented. Furthermore, in this laser printer, the thermistor 107
The power supply to the fixing heater 15a is controlled based on the temperature in the vicinity of the fixing heater 15a detected through the control unit, so that the temperature in the vicinity of the fixing heater 15a is more accurately adjusted to improve the fixing. It can be carried out.

In the present laser printer, the on-time of the pulse is about 10 msec., The off-time is about 20 msec., And the number of pulses is 3 pulses. Can be changed to For example, the required fixing heater 15 may be used when the image is formed while the fixing unit 4 is performing the fixing, and when the fixing unit 4 does not perform the fixing but needs to keep the temperature.
The total energization amount to a is different. If the total energization amount differs, the optimal energization mode for suppressing flicker also changes. Therefore, based on the driving state of the process unit 3, the CPU 7
1 (determining means) to determine whether to form an image or to wait,
Based on the determination result, the power supply mode at the start of the power supply may be changed between the time of image formation and the time of standby. In this case, in addition to the above-described effects, there is an effect that flicker can be more effectively suppressed regardless of whether the image is being formed or the image is on standby.

Also, among the above-described energization modes, the on-time, off-time, and the number of pulses of the pulse are factors that greatly affect flicker suppression. Therefore, if at least one of these factors is changed depending on whether the image is being formed or the image is on standby, flicker can be more effectively suppressed.

Further, the state of occurrence of flicker also changes depending on the type of the power supply of the laser printer, for example, the voltage, the frequency, the state of indoor wiring, and the like. The flicker allowed for the laser printer also varies depending on the regulations of each country. Therefore, it is desirable to change the power supply mode at the start of the power supply according to the regulations of the country where the laser printer is used and the power supply mode. To achieve this goal,
The energization mode at the start of energization may be stored in storage means such as NVRAM. In this case, depending on the regulations of the export destination country and the power supply style, the power-on style stored in the NVRAM may be rewritten, or
It can be replaced with RAM. By doing so, flicker can be appropriately suppressed in accordance with the regulations of each country and the type of power supply.

In the above embodiment, the fixing heater 15a serves as a heating means, and the CPU 71 drives the driving circuit 91.
Corresponds to the energizing means, and the thermistor 107 corresponds to the temperature detecting means. In addition, the present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the gist of the present invention.
For example, in the above embodiment, the temperature near the fixing heater 15a is detected via the thermistor 107, but the impedance of the fixing heater 15a is calculated to detect the temperature of the fixing heater 15a itself. May be reflected in the energization control.

In the above embodiment, the fixing heater 15a composed of a halogen lamp is used as the heating means, but various configurations can be adopted as the heating means. However, when the heating means is formed of a lamp such as a halogen lamp, the rush current increases, and suppression of flicker is a particularly important problem. In the above embodiment, since the present invention is applied to the fixing unit 4 in which the heating means is configured by a lamp, the effect of the present invention appears more remarkably. Further, the present invention is not limited to a laser printer, but can be applied to a toner image fixing device formed by various mechanisms such as a copying machine.

[Brief description of the drawings]

FIG. 1 is a perspective view of main components of a laser printer according to an embodiment.

FIG. 2 is a schematic side sectional view of the laser printer.

FIG. 3 is a block diagram illustrating a control unit of the laser printer and a configuration related to the control unit.

FIG. 4 is a circuit diagram illustrating a configuration of a drive circuit connected to a control unit.

FIG. 5 is a time chart showing energization control by the drive circuit.

FIG. 6 is a time chart illustrating energization control in a conventional fixing device.

[Explanation of symbols]

2. Scanner unit 3. Process unit
4: fixing unit 5: paper feeding unit 6: drive system unit 15
... Heating roller 15a ... Fixing heater 70 ... Control unit
71 CPU 72 ROM 73 RAM 82 DC controller circuit 87, 89, 90, 91 Drive circuit 93 Transistor 95 Phototriac 97 Triac
101: Commercial power supply 107: Thermistor

Claims (6)

[Claims] 1. A toner image formed on a recording medium,
Heating means for heating by generating heat in response to energization to fix the recording medium, and energizing means for intermittently energizing the heating means to adjust the temperature of the heating means. In the toner image fixing device, when the energizing unit energizes the heating unit, a discontinuous energization in a pulse shape is performed at the start of the energization, and then a continuous energization is performed thereafter. apparatus. 2. The image forming apparatus according to claim 1, further comprising: a determination unit configured to determine whether the heating unit is performing image formation while the fixing is being performed or a standby state where the fixing is not performed but the temperature needs to be maintained. 2. The toner image fixing device according to claim 1, wherein an energization mode at the time of the energization start is changed between the image formation and the standby time based on a determination result of the determination unit. 3. The power supply device according to claim 3, wherein the power supply means comprises:
3. The toner image fixing device according to claim 2, wherein at least one of the on time, the off time, and the number of pulses of the pulse is changed. 4. The toner image fixing device according to claim 1, further comprising a storage unit configured to store an energization mode of the energization unit at the start of the energization. 5. The toner image fixing device according to claim 1, wherein said heating means is a lamp. 6. The toner image fixing device according to claim 1, further comprising a temperature detecting unit for detecting a temperature of the heating unit or a temperature in the vicinity thereof.