JP2002091227A - Temperature controller for fixing device, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature controller for a fixing device capable of shortening warming-up time and preventing the overshoot of the fixing device. SOLUTION: When the temperature of a heat roller at the time of supplying power is equal to or under fixed temperature (T1), full wave power is supplied to the heater of the heat roller until the temperature of the heat roller attains specified temperature (T2), and half wave power is supplied to the heater of the heat roller after the temperature of the heat roller attains the specified temperature (T2). When the temperature of the heat roller at the time of supplying the power exceeds the fixed temperature (T1), the full wave power is supplied to the heater of the heat roller until the temperature of the heat roller becomes temperature (T3) lower than the specified temperature (T2), and the half wave power is supplied to the heater of the heat roller after the temperature of the heat roller attains the temperature (T3) lower than the specified temperature (T2). Thus, the temperature control of the fixing device is accurately performed.

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 a copying machine, a printer, and a facsimile, and more particularly, to a temperature control device for a fixing device, which is a main component of the image forming apparatus.

[0002]

2. Description of the Related Art Generally, a copying machine as an image forming apparatus transfers a toner image of a photoreceptor onto a transfer material such as paper by a transfer charger, and then transfers the transfer material between a heat roller and a pressure roller of a fixing device. Then, the toner image transferred to the transfer material is heated and pressed to be permanently fixed to the transfer material. Here, the heat roller of the fixing device has a surface layer of rubber or resin formed on the surface of the roller core, a heater as a heat source is housed inside the roller core, and the heat of the heater causes the roller core and the surface layer of rubber or resin to be heated. Is to be heated. Therefore, when the thickness of the heat roller is reduced, heat is rapidly conducted to the surface of the heat roller, and the heat responsiveness of the heat roller is improved, and the time from when a copy signal is input to when a copy operation is started is started. The warm-up time can be reduced. On the other hand, when the thickness of the heat roller is reduced as described above, overshoot increases when the surface temperature of the heat roller is increased to a predetermined fixing temperature. Or the temperature rises inside the copying machine. Therefore, conventionally, the thickness of the heat roller has been set to a thickness that does not cause a large overshoot.

[0003]

However, when the thickness of the heat roller is increased, the thermal responsiveness of the heat roller deteriorates, and it becomes difficult to control the temperature of the heat roller accurately. In addition, when the thickness of the heat roller is increased, the heat capacity of the heat roller becomes large, and it takes time for the heat of the heater to be conducted to the surface of the heat roller, so that the warm-up time becomes long.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art by accurately controlling the temperature of a fixing device so that overshooting does not occur even with a thin heat roller. And

[0005]

According to a first aspect of the present invention, there is provided an AC power supply for supplying power to a heater of a fixing unit, a temperature detecting unit for detecting a temperature of the fixing unit, and a detecting signal of the temperature detecting unit. Control means for outputting a control signal based on the control signal; and full-wave / half-wave driving means for outputting power from the AC power source to the heater in one of full-wave and half-wave based on the control signal from the control means. And a temperature control device for a fixing device having the following. If the temperature of the fixing device at the time of power-on is equal to or lower than a predetermined temperature (T1), the control unit supplies full-wave power until the temperature of the fixing device reaches a predetermined temperature (T2). After the fixing device reaches a predetermined temperature (T2), it outputs a control signal for supplying half-wave power.
Further, when the temperature of the fixing device at the time of turning on the power is higher than the predetermined temperature (T1), the control unit may determine that the temperature of the fixing device is lower than the predetermined temperature (T2) (T3).
Output a control signal for supplying half-wave power.

According to the present invention having the above-described structure, the fixing device is rapidly heated with full-wave power until the temperature is lower than the temperature suitable for fixing (the temperature not reaching T2 or T3), and the fixing is performed. After reaching a temperature (T2 or T3) close to a suitable temperature, the fixing device is heated relatively slowly with half-wave power to accurately control the temperature of the fixing device and prevent overshoot from occurring.

According to a second aspect of the present invention, there is provided a zero-cross detecting means for detecting a zero-cross timing of the phase of the AC power supply, and a switching means for turning on / off the power supply to the heater based on a control signal from the control means. Is provided in the temperature control device of the fixing device according to claim 1. The control means turns on the switching means based on the zero-cross detection signal from the zero-cross detection means to energize the heater.

In the present invention having the above-described structure, the timing of energizing the heater of the fixing unit is adjusted to the timing of the zero crossing of the AC power supply, so that the value of the inrush current can be reduced. It is possible to suppress a voltage drop when energizing the heater of the fixing device.

According to a third aspect of the present invention, there is provided an image forming apparatus for transferring a toner image on a photosensitive member to a transfer material by a transfer charger and heating and fixing the toner image on the transfer material by a fixing device. The fixing device is controlled by the temperature control device of the fixing device according to claim 1 or 2.

As described above, the image forming apparatus of the present invention
A temperature control device for the fixing device according to claim 1 or 2,
Since overshoot can be effectively prevented, the occurrence of offset due to overshoot can be prevented, and the rise in the internal temperature of the image forming apparatus main body can be prevented, so that high-quality image formation can be achieved.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Overall Configuration of Copying Machine) FIG. 1 shows an example of an image forming apparatus according to the present invention. The image forming apparatus shown in FIG. 1 is a copying machine having a reader unit (image reading unit) and a printing unit (image forming unit), and FIG. 1 is a longitudinal sectional view showing a schematic configuration thereof.

First, an overall configuration of the copying machine 10 will be described with reference to FIG.

A copying machine 10 shown in FIG. 1 includes a copying machine main body 11 constituting an entire framework.
A reader unit 12 for reading the image surfaces (image information) G of the originals D1 and D2 is provided at the upper part of the apparatus, and a transfer of paper or the like is performed at a lower part of the copying machine main body 11 in accordance with the image information read by the reader unit 12. A printing unit 13 for forming a toner image on the material P is provided.

The former reader unit 12 is provided with a document D1.
, A transparent platen 14 placed with its image surface G facing down, an openable and closable document pressing plate 15 for bringing the image surface G of the document D1 into close contact with the upper surface of the platen 14, and a document on the platen 14 A scanning unit 18 having a light source 16 for irradiating the image plane G of D1 with light from below and a first reflecting mirror 17, and second and third reflecting mirrors for further reflecting the reflected light from the first reflecting mirror 17 20 and 21, a lens unit 22 that forms an image of light from the third reflection mirror 21, and a CCD 23 to which light from the lens unit 22 is incident. The scanning unit 18 is configured to scan the image surface G of the document D1 with the light source 16 while moving to the right from the home position HP shown in FIG. 1, and to return to the home position HP after the scanning is completed. I have.
The above is a configuration for performing the so-called fixed reading in which the document D1 is fixed and the scanning unit 18 is moved to read the image surface G.

The reader unit 12 further moves the document D2, and fixes the scanning unit 18 to read the document surface G.
4 is also provided. The automatic document feed mechanism 24 transports the document D2 on the paper feed table 25 leftward toward the scanning unit 18 disposed at the home position HP, and a paper feed table 25 that supports the leading end side of the document D2 from below. Paper feed roller pair 2
6 and a pair of paper discharge rollers 27 for carrying out the document D2 read by the scanning unit 18 to the left from the scanning unit 18. The automatic document feed mechanism 24 conveys the document D2 to the left in FIG. 1 by the above-described paper feed roller pair 26 and paper discharge roller pair 27, and after reading the document D2,
The second rear end of the second apparatus is sandwiched by a pair of paper discharge rollers 27 and discharged so as to hang down to the left side of the second apparatus main body. Here, the document D2 is pulled by a person to cause the discharge roller pair 27 to move.
Easily pulled out of

The above-mentioned fixed reading and drift reading are used, for example, in that a document D1 such as a bound book is placed on a platen 14 to perform fixed reading, while a cut sheet-shaped document is read. D <b> 2 is placed on the paper feed table 25 to perform the flow reading.

The printing section 13 is disposed substantially at the center in the vertical direction on the left side in FIG.
And a cylindrical photoreceptor (hereinafter, referred to as “photoreceptor drum”) 30. The photoreceptor drum 30 is rotatably supported by the copying machine main body 11 in the direction of the arrow (clockwise in FIG. 1), and its primary charger 31 and the exposing device 32 are arranged around the photoreceptor drum 30 substantially in the rotational direction. , Developing device 33,
A transfer charger 34 and a cleaning device 35 are provided. Further, along a transport path 36 (shown by a two-dot chain line in FIG. 1) of a transfer material P such as paper to be image-formed, from the upstream side to the downstream side (from substantially lower to upper in FIG. 1), Paper feed cassette 37, paper feed roller 38, transport roller pair 40, registration roller pair 41, transport guide 42,
A fixing device 43, a paper discharge roller pair 44, and a paper discharge space 45 are provided.

The photosensitive drum 30 is rotated at a predetermined process speed (peripheral speed) in the direction of the arrow by a stepping motor as a driving means (motor) as described later.

In the present embodiment, a scorotron-type corona charger is used as the primary charger 31. The primary charger 31 is configured to uniformly charge the surface of the photosensitive drum 30 to a predetermined polarity and potential by applying a charging bias from a charging bias application power supply (not shown).

The exposing device 32 has a laser oscillator, a polygon mirror and the like (neither is shown), and forms an electrostatic latent image on the surface of the photosensitive drum 30. Document D1 (or D2) read by reader unit 12 described above
The image information is subjected to appropriate processing such as A / D conversion, density correction, shading correction and the like by an image processing unit (not shown) provided in the printing unit 13 and then input to a laser oscillator as an image signal. You. The laser oscillator controls the charged photosensitive drum 3 via a polygon mirror or the like with a laser beam that is turned on / off based on the image signal.
The surface 0 is exposed, and the charge on the exposed portion is removed to form an electrostatic latent image.

The developing unit 33 conveys the developer carried on the surface thereof to the developing position opposite to the surface of the photosensitive drum 30 by rotating the developer carried on the surface in a direction indicated by an arrow (counterclockwise). And a developing roller 47. The developing roller 47 has a developing bias application power supply (not shown).
As a result, a developing bias is applied, whereby the toner in the developer adheres to the electrostatic latent image on the surface of the photosensitive drum 30, and the electrostatic latent image is developed as a toner image.

The transfer charger 34 is formed by a roller-shaped member disposed so as to face the surface of the photosensitive drum 30. To the transfer charger 34, a transfer bias having a polarity opposite to that of the toner image on the photosensitive drum 30 is applied by a transfer bias application power supply (not shown), whereby the toner on the photosensitive drum 30 is applied to the surface of the transfer material P. This is for transferring an image. Here, the transfer material P to which the toner image is transferred
Is fed from a paper feed cassette 37, fed by a paper feed roller 38, transported by a transport roller pair 40, temporarily stopped by a registration roller pair 41, and then The sheet is fed from the pair of registration rollers 41 so as to be synchronized with the image.

At the time of the above-mentioned transfer, the cleaning device 35
A cleaning blade 48 is in contact with the surface of the photosensitive drum 30 to remove residual toner remaining on the surface of the photosensitive drum 30 without being transferred to the transfer material P.

On the downstream side of the transfer charger 34, a transport guide 4 for guiding the transfer material P after the transfer of the toner image to the fixing device 43 is provided.
2 are provided.

The fixing device 43 includes a heater 5 disposed inside.
0 heat roller 51 and the heat roller 5
1 has a pressure roller 52 for pressing the transfer material P, and heats and presses the transferred transfer material P, which carries an unfixed toner image on the surface, and fixes the toner image on the surface of the transfer material P. It is made to let.

The paper discharge roller pair 44 discharges the transfer material P after fixing the toner image to a paper discharge space 45 as a completed product. The paper discharge space 45 is defined inside the copying machine body 11.

In the copying machine 10 having the above-described configuration, when forming an image, first, the photosensitive drum 30 is driven to rotate in the direction of the arrow by the driving means, and the surface thereof is
The primary charger 31 uniformly charges to a predetermined polarity and potential. An electrostatic latent image corresponding to the image information is formed on the surface of the charged photosensitive drum 30 by irradiation of laser light from an exposure device 32 that operates according to the image information of the document D1 (or D2) read by the reader unit 12. It is formed. The electrostatic latent image is developed with a toner by a developing device 33 as a toner image. The toner image formed on the surface of the photosensitive drum 30 is transferred to the transfer material P conveyed at a predetermined timing by the pair of registration rollers 41 and the like. Transferred to the surface. Photoconductor drum 30 after transfer of toner image
The remaining toner remaining on the surface is removed by the cleaning device 35 and used for the next image formation. On the other hand, the transfer material P after the transfer of the toner image is transported to the fixing device 43 along the transport guide 42, where the toner image is fixed on the surface by receiving heat and pressure. The transfer material P after the toner image is fixed is discharged to the paper discharge space 45 by the discharge roller pair 44 in a posture in which the image surface (the surface on which the toner image is fixed) faces downward, that is, in a so-called face-down state. Thus, the image forming (printing) by the copying machine 10 is completed.

(Temperature Control Device of Fixing Unit) Copying Machine 1
At 0, the fixing process is a step of determining the final image, which has a great effect on the image quality, and it is necessary to accurately control the temperature of the heat roller 51 of the fixing device 43.

FIG. 2 is a control block diagram of the temperature control device 60 of the fixing unit. The fixing device temperature control device 60 shown in this figure includes an AC power supply 61 for supplying power to the heater 50 of the heat roller 51 of the fixing device 43, and a zero-cross detecting means 62 for detecting a zero cross of the power output from the AC power supply 61.
And a full-wave / half-wave driving means 63 for outputting the electric power output from the AC power supply 61 to the heater 50 as a full-wave or a half-wave, and energizing states of the full-wave / half-wave driving means 63 and the heater 50. Switching means 64 for turning on and off;
Temperature detecting means 65 for detecting the surface temperature of the laser beam, and full-wave / half-wave driving means 63 and switching means 6 based on detection signals from temperature detecting means 65 and zero-cross detecting means 62
And control means 66 for outputting a control signal to the control unit 4. In the heat roller 51, the outer periphery of the roller core 51a has a surface material 51b such as Teflon (registered trademark) or silicone rubber.
Covered by The CPU that controls the operation of the entire copying machine 10 also functions as the control unit 66 of the fixing device 43.

FIG. 3 is a flow chart showing a control state of the temperature control device 60 of the fixing device. As shown in this figure, when the power of the copying machine body 11 is turned on (when the copy switch is turned on), the temperature of the heat roller 51 of the fixing device 43 is detected by the temperature detecting means 65, and the detection signal is input to the control means 66. You. When the control means 66 determines that the temperature of the heat roller 51 is 100 ° C. (T1) or less (S
1) A control signal is output to the full-wave / half-wave driving means 63, and full-wave power is output from the full-wave / half-wave driving means 63 (S2). Further, the control unit 66 turns on the switching unit 64 based on the zero-cross detection signal of the zero-cross detection unit 62, and energizes the heater 50 of the heat roller 51 at the timing of the zero-cross (power supply voltage is 0 V). This makes it possible to keep the rush current value low and the voltage drop low.

When the heat roller 51 is supplied with full-wave power,
When the temperature reaches 50 ° C. (T2) (S3), a control signal is output from the control means 66 to the full-wave / half-wave driving means 63, and the mode is switched to half-wave driving. Power is output (S4). Thereafter, the heat roller 51
Heats up with half-wave power.

When the temperature of the heat roller 51 reaches 185.degree. C. (S5), the control means 66 turns on / off the switching means 64 to output a control signal so as to keep the temperature of the heat roller 51 constant at 185.degree. Output (S6). At this time, half-wave power is output from the full-wave / half-wave driving means 63.

The temperature control state of the fixing device 43 as described above is represented as shown in FIG. That is, in FIG.
Corresponds to S1 to S3, and corresponds to S4 to S6.
Corresponding to In this stage, the full-wave power as shown in FIG. 6A is supplied to the heat roller 51. In this stage, half-wave power as shown in FIG. 6B is supplied to the heat roller 51.

Next, in FIG. 3, when the power of the copying machine main body 11 is turned on, the temperature of the heat roller 51 is 125 ° C. (T
3) (S11), a control signal is output from the control means 66 to the full-wave / half-wave driving means 63, and a half-wave power is output from the full-wave / half-wave driving means 63.
1 is heated by half-wave power (S4). After the temperature of the heat roller 51 reaches 185 ° C. (S5), the switching unit 64 is controlled to be turned on and off by the control unit 66.
The temperature of the heat roller 51 is kept constant at 185 ° C. (S6). The heating roller 51 is energized by turning on the switching means 64 by the control means 66 in synchronization with the zero-cross timing.

In FIG. 3, when the power of the copying machine main body 11 is turned on, the temperature of the heat roller 51 is 100 ° C. (T
1) and the temperature of the heat roller 51 is 1
When the temperature is not higher than 25 ° C. (T3) (S11), a control signal is output from the control means 66 to the full-wave / half-wave driving means 63, and a full-wave power is output from the full-wave / half-wave driving means 63. The temperature of the heat roller 51 is increased by the electric power of the wave (S12).
When the temperature of the heat roller 51 reaches 125 ° C. (T3) (S13), a control signal is output from the control unit 66 to the full-wave / half-wave driving unit 63, and the full-wave / half-wave driving unit 63 is output.
Output half-wave power, and the heat roller 51 is heated by the half-wave power (S4). After the temperature of the heat roller 51 reaches 185 ° C. (S5), the switching means 6
4 is controlled on / off by the control means 66 so that the temperature of the heat roller 51 is kept constant at 185 ° C. (S6). The heating roller 51 is energized by turning on the switching means 64 by the control means 66 in synchronization with the zero-cross timing.

FIG. 5 shows the control state from step 11 (S11) to step 6 (S6). That is, in FIG.
The step corresponding to S13 corresponds to S4 to S6. In this stage, the full-wave power as shown in FIG. 6A is supplied to the heat roller 51. Also, the stage of
Half-wave power as shown in FIG. 6B is supplied to the heat roller 51.

As described above, the temperature control device 60 of the fixing device according to the present embodiment, when the temperature of the heat roller 51 when the power of the copier body 11 is turned on is 100 ° C. (T1) or less, The heat roller 51 is heated with full-wave power until the temperature of the roller 51 reaches 150 ° C. (T2), and is heated with half-wave power after the temperature of the heat roller 51 reaches 150 ° C. (T2). When the temperature of the heat roller 51 exceeds 100 ° C. (T1) when the power of the copier body 11 is turned on, the temperature of the heat roller 51 is 125 ° C. (T3). Up to the heat roller 5 with full-wave power
1 is heated, and the temperature of the heat roller 51 is 125 ° C. (T3)
Is reached, the heat roller 51 is heated by half-wave power, and even if the thickness of the heat roller 51 is reduced,
The temperature of the heat roller 51 can be accurately controlled so that overshoot does not occur. As a result, the fixing device temperature control device 60 according to the present embodiment can not only shorten the warm-up time, but also can prevent high-temperature offset due to overshoot, and can form high-quality images. Will be possible.

Further, since the temperature control device 60 of the fixing device according to the present embodiment can effectively prevent overshoot as described above, it is possible to suppress an increase in the internal temperature of the copying machine body 11.

In this embodiment, the copying machine 10 has been exemplified as an image forming apparatus. However, the present invention is not limited to this, and is widely applied to a printer, a facsimile, and the like having a configuration in which a toner image is fixed on a transfer material P by a fixing device 43. can do.

[0041]

As described above, according to the present invention, when the temperature of the fixing device at the time of turning on the power is lower than the predetermined temperature (T1), the entire temperature is maintained until the temperature of the fixing device reaches the predetermined temperature (T2). The power of the wave is supplied to the heater of the fixing device, and after the temperature of the fixing device reaches a predetermined temperature (T2), half-wave power is supplied to the heater of the fixing device. When the temperature of the fixing device exceeds a predetermined temperature (T1), the full-wave power is supplied to the heater of the fixing device until the temperature of the fixing device is lower than the predetermined temperature (T2) (T3). After the temperature of the fixing device reaches a temperature (T3) lower than the predetermined temperature, half-wave power is supplied to the heater of the fixing device, so that the fixing device does not overshoot. Temperature control can be performed accurately. As a result, according to the present invention, not only the warming-up time can be shortened, but also high-temperature offset caused by overshoot can be prevented, and high-quality image formation can be performed. It is possible to suppress an increase in the internal temperature of the forming apparatus main body.

Further, according to the present invention, the timing of supplying power to the heater of the fixing device is adjusted to the timing of zero crossing of the AC power supply, so that the value of the rush current can be reduced, and the voltage drop during power supply is reduced. Therefore, the temperature control of the fixing device can be more easily and accurately performed in combination with the effect of the overshoot described above.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus of the present invention.

FIG. 2 is a control block diagram of a fixing device temperature control device according to the present invention.

FIG. 3 is a flowchart illustrating a control state of a temperature control device for a fixing device according to the present invention.

FIG. 4 is a diagram illustrating a first state of a temperature change of the fixing device controlled by the temperature control device of the fixing device according to the present invention.

FIG. 5 is a diagram showing a second state of the temperature change of the fixing device controlled by the temperature control device of the fixing device according to the present invention.

FIG. 6 is a diagram showing a state of power output from full-wave / half-wave driving means. FIG. 6A is a diagram illustrating a state of a full wave, and FIG. 6B is a diagram illustrating a state of a half wave.

[Explanation of symbols]

Reference numeral 10: copying machine (image forming apparatus), 30: photoconductor drum (photoconductor), 34: transfer charger, 43: fixing device,
50: heater, 60: fixing device temperature controller, 61
…… AC power supply, 62 …… Zero cross detection means, 63 ……
Full-wave / half-wave drive means, 64 switching means, 65
... temperature detection means, 66 ... control means, P ... transfer material

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Yamamoto 1-2-28 Tamazo, Chuo-ku, Osaka-shi, Osaka Inside Kyocera Mita Co., Ltd. (72) Inventor Takakazu Morita 1-2-2 Tamazo, Chuo-ku, Osaka-shi, Osaka No. 28 Inside Kyocera Mita Co., Ltd. (72) Hiroshi Kinoshita 1-2-2 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka 28-28 Inside Kyocera Mita Co., Ltd. Ryoji Kanematsu 1-2-2 Tamatsukuri, Chuo-ku, Osaka, Osaka No. 28 Kyocera Mita Co., Ltd. F-term (reference) 2H033 AA24 AA30 AA41 BA30 CA01 CA07 CA28 CA30 CA32 CA47 CA48 3K058 AA04 AA12 BA18 CA07 CB04 CB06 5H323 AA36 BB05 CA08 CB02 DA01 EE01 FF01 HH02 KK05 MM18 MM18MM

Claims (3)

[Claims] An AC power supply for supplying power to a heater of the fixing device; a temperature detecting device for detecting a temperature of the fixing device; a control device for outputting a control signal based on a detection signal of the temperature detecting device; Full-wave / half-wave driving means for outputting electric power from the AC power supply to the heater in either full-wave or half-wave based on a control signal from the control means; When the temperature of the fixing device at the time is equal to or lower than the predetermined temperature (T1), the full-wave power is supplied until the temperature of the fixing device reaches the predetermined temperature (T2), and the fixing device is set to the predetermined temperature (T2). When the control unit outputs a control signal for supplying half-wave power after the arrival, the control unit determines that the temperature of the fixing unit is lower than the predetermined temperature (T1) when the power is turned on. Temperature (T) lower than predetermined temperature (T2) ) In the power of the half-wave outputs a control signal to be supplied, the temperature control device of the fixing device, characterized in that. 2. A zero-cross detecting means for detecting a zero-cross timing of a phase of the AC power supply, and energizing the heater based on a control signal from the control means.
And switching means for turning off the switching means based on a zero-crossing detection signal from the zero-crossing detection means, thereby energizing the heater.
A temperature control device for a fixing device as described in the above. 3. An image forming apparatus for transferring a toner image on a photoreceptor to a transfer material by a transfer charger and heating and fixing the toner image on the transfer material by a fixing device, wherein the fixing device is Item 1. An image forming apparatus controlled by the temperature control device of the fixing device according to Item 1 or 2.