JPS5814871A - Heating and fixing device of electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To prevent a fixing roller from being damaged due to a toner which has adhered to the fixing roller and has coagulated, by constituting a titled device so that the fixing roller is rotated and driven when the temperature of the fixing roller has exceeded a softening point of the toner. CONSTITUTION:When an electric power supply switch 59 is turned on at the time t1, the temperature of a heating roller is raised by a heater 33, and at the time t2 when it has reached a temperature H3 which exceeds the softening point H1 of a toner and also is within a range lower than a temperature H2 suitable for heat fixing, a controlling circuit 61 drives a rotation of a main motor 56. As a result, a heating roller and a pressure roller are rotated and driven. Subsequently, after a temperature of the heating roller has reached the temperature H2 which is suitable for heat fixing, the heating roller is rotated and driven at a speed suitable for fixing, only when a printing button 60 is pushed and a copying operation is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat fixing device that heats and fixes a toner image on copy paper E in electrophotographic copying by guiding it to a fixing roller.

In the prior art, when the electrophotographic copying machine is powered on, the fixing roller is driven to rotate at a relatively high speed suitable for fixing. In such prior art, before the power is turned on, toner remains and solidifies on the fixing roller ball due to the same copying operation, and this toner causes the pair of fixing rollers to adhere to each other. There is. By rotating the fixing roller at the same time as the power is turned on, the fixing roller reaches the softening temperature or melting temperature of the toner rJfl
The VC fixing roller will be driven. Otherwise, the toner that has adhered to and solidified on the fixing roller will damage the roller. In order to remove the toner from the fixing roller E and prevent copy paper from wrapping around the fixing roller, there is a heating fixing device that is provided with a peeling plate that comes into sliding contact with the surface of the fixing roller. By the time the toner that has adhered and solidified on the roller surface and the peeling plate softens and melts, the fixing roller is driven to rotate, so the peeling plate rotates together with the fixing roller! IIIJ As a result, the angle between the peeling plate and the fixing port surface 7 deviates from the proper angle, causing damage to the peeling plate and the fixing roller.

In addition, if the toner that has solidified on the surface of the fixing roller adheres to the peeling plate, an abnormal sound will occur when the fixing roller starts rotating, and even when the scaffolding/roller is rotating, there will be no contact with the surface of the fixing roller. The toner hits the peeling plate and makes an abnormal noise. Since the fixing roller rotates at a speed suitable for fixing, it is noisy.

In other prior art, after the electrophotographic copying machine is powered on, the fixing roller is rotated at a relatively high speed suitable for fixing only after the surface of the fixing roller reaches a temperature suitable for fixing. In such prior art, once the fusing roller is heated to a temperature suitable for fusing, the fusing roller continues to be rotated at a relatively high speed suitable for fusing, which may cause damage to the fusing roller. But it's still noisy.

An object of the present invention is to prevent damage to the fixing roller caused by toner adhering to the fixing roller, and to maintain good fixing performance by making the temperature of the surface of the fixing roller uniform over the entire surface during fixing. It is an object of the present invention to provide a heat fixing device C for an electrophotographic copying machine which achieves the above-mentioned effects and further prevents the generation of noise.

FIG. 1 is a simplified vertical sectional view of an electrophotographic copying machine according to an embodiment of the present invention. The paper sheets 4, 5-1 in the cassettes 2, 3 mounted on the side of the machine body 1 are selectively fed one by one from the cassette 2.3 by the paper feed roller 6.7, and then transferred to the transport rollers 8, 9 and 10. A document 12 is brought into close contact with a horizontal transparent plate 11 provided at the top of the machine body 1 by means of a retaining cover 13. exposure lamp li
I9i and the paper 12 are irradiated through the transparent plate 11.

The Hull image is formed on the photosensitive drum 21 via the reflecting mirror 1 (i, 17, in-mirror lens 19, and reflecting mirror 20 of the optical device 15). In order to do this, reflector 22j23
is provided. During slit exposure, the exposure lamp 14 and the reflecting mirrors 1 (i, 22, 23 move in the exposure movement direction 24 from the rest position shown by the solid line to the position 25 shown by the imaginary line, and after the exposure is completed, It moves in the opposite direction of the exposure movement direction 24 and returns to the original rest position.

As the exposure lamp 14 and the reflecting mirrors 1'6, 22, and 23 move, the reflecting mirror 17 also moves, and the exposure lamp 1'
4 and reflector 16, 22, 23 are in position 25, reflector 17 is in position 26, shown in phantom.

Photosensitive drums 21, t charged by a discharge device 27
By forming the original image on the photosensitive drum 21, an electrostatic image is formed on the surface of the photosensitive drum 21. This electrostatic image is developed into a toner image by the developing device 28. This toner image is transferred to the conveying roller 10 by the action of the discharge device 29.
The image is transferred to copy sheets 4 and 5 that are conveyed from there. The copy sheets 4 and 5 on which the toner images have been transferred are reliably peeled off from the photosensitive drum 21 by the peeling claw 30 and the peeling roller 31.
The image is transported to a heat fixing device 32. The heat fixing device 32 includes a heat roller 34 having a built-in heater 33, and a pressure roller 35 that is in pressure contact with the heat roller 34.

When the copy paper after the transfer passes between the heat roller 34 and the pressure roller 35, the toner is thermally melted and fixed. The copy paper 4.degree. 5, which has been completely fixed, is discharged onto a tray 38 provided on the side of the machine body 1 via a conveyance roller 36 and a paper discharge roller 37. The surface of the photosensitive drum 21 after the transfer is made normal by the cleaning device 39.

FIG. 2 is a side view of a heat fixing device 32 according to the present invention;
FIG. 3 is a perspective view of a portion thereof. The heat fixing device 32 is installed on the side from the body of the electrophotographic copying machine (on the back side of the paper in FIG. 2).
can be pulled out.

FIG. 4 is a cross-sectional view taken along a cut plane including the axes of the heat roller 34 and the pressure roller 35.

The frame body 42 of the heat fixing device 320 is provided with a pair of heat roller 34 and a pressure roller 35 that are parallel to each other and have horizontal axes. The heat roller 34 and the heat fixing device 32 are rotatably supported by the frame 42 of the heat fixing device 32. The heater 33 is inserted into the heat roller 34 as described above. A pressure roller 35 is pivotally supported by a lever 46. One end of the lever 46 is pivoted to the frame 42 by a pin 48. This lever 46
The other end is biased by a spring f'' by a spring 49 so that the pressure roller 35 comes into pressure contact with the heat roller 34. The copy paper transport path is indicated by reference numeral 50 in FIG. The copy paper is guided in the direction of arrow 51 between a pair of heat rollers 34 and pressure rollers 35. A toner image corresponding to the original is formed on the copy paper guided by the VC between the heat roller 34 and the pressure roller 35.

A peeling plate 52 is provided on the downstream side of the heat roller 34 for removing toner adhering to the heat roller 34 and peeling off copy paper wrapped around the heat roller 34.

A sprocket wheel 54 is attached to one end of the heat roller 34.
is fixed. The sprocket wheel 54 is rotationally driven by a main motor 56 via a chain 55. The main motor 56 is energized during copying after the electrophotographic copying machine is powered on and when the heat roller 34 is at a temperature between H3 and H2 as described later. The sprocket wheel 54 is driven by the main motor 56, so that the heat roller 34 rotates in the direction of the arrow 57 at a speed suitable for heat fixing. I'm going to be jino.

A temperature detection element 58 such as a thermistor is in contact with one row of the outer peripheral surface of the heat roller 34 at the center in the axial direction.

This temperature detection element 58 detects the temperature of the surface of the heat roller 34.

Referring to FIG. 5, a block diagram for driving and controlling the main motor 56 is shown. The output from the power switch 59 of the electrophotographic copying machine, the output from the temperature detection element 58, and the print button 60 that is suppressed during printing.
The output from is given to the control circuit 61. Control circuit 61 controls main motor 56 in response to outputs from power switch 59, temperature detection element 58, and print button 60, as described in connection with FIG. 6 below.

The fan 62 prevents the temperature inside the machine body 1 from rising abnormally by E due to the heat from the exposure lamp 14 and the heat fixing device 32.

The !IvJ force from the main motor 5''6 is applied directly to the rotation of the heat roller 34 and the photosensitive drum 2] as described above, and is also applied to the exposure lamp 14 and the reflecting mirrors 16, 22 . . . via the electromagnetic clutch. 23 movements respectively.

Referring to FIG. 6, the temperature H of the surface of the heat roller 34 detected by the temperature detection element 58 changes over time. When the power switch 59 is turned on at time t1, the heater 33 is energized. As a result, the temperature H of the heat roller 34 rises. In this way, the temperature H of the heat roller 34 is adjusted to the softening point H1 of the toner (for example, 170°C).
Temperature H2 (for example, 1
Time t2 when the temperature H3 in the range below 80°C is reached.
In this case, the control circuit 61 drives the main motor 56 to rotate. As a result, the heat roller 34 and the pressure roller 35 following it are rotationally driven at a speed suitable for fixing. By rotationally driving the heat roller 34 at time t2, heat from the heat roller 34 is conducted to the pressure roller 35. As a result, the temperature of the heat roller 34 decreases during the period from time t2 to time t3. At time t3,
The temperature of the heat roller 34 and the pressure roller 35 both rise by 1, and at time t4, the temperature H2Vc suitable for heat fixing is reached.
Become. In this way, the heat roller 34 and the pressure roller 35 are rotationally driven at a speed suitable for heat fixing from time t2 to t4. 11 (at 4, the rotation of the heat roller 34 is stopped. Therefore, according to the experiment of the present inventor, from time t4 to
During t5, the temperature of the heat roller 34 is temporarily K −4
Although the temperature increases by 1, the temperature of the heat roller 34 is kept constant at the temperature H2 suitable for thermal fixing after time t5 by the action of the control circuit 61. Between times t4 and t5, the temperature of the VC heat roller 34 is temporarily lower than the temperature H2.
By increasing the temperature, the temperature around the heat roller 34 in the heat fixing device 32 is rapidly increased.

Therefore, after time t5, it is ensured that the temperature H of the heat roller 34 is stably maintained at the temperature H2 suitable for thermal fixing.

The main motor 56 is driven only when the temperature H of the heat roller (4) becomes equal to or higher than the softening point H1 of the toner.
4 and the pressure roller 35 rotate. At this time, heat roller 3
Since the toner that may have adhered to the heat roller 4 and the pressure roller 35 has been softened, the heat roller 34 and the pressure roller 35 will not be damaged, and the peeling plate 52 will not be damaged.

The temperature H3 is set so that the time from time t2 to t4 is as short as possible, so that the heat roller 34 and the pressure roller 3
5 is the temperature H2 suitable for heat fixing with the lowest possible rotation speed
The value is selected such that the temperature becomes uniform over the entire surfaces of the heat roller 34 and the pressure roller 35 at time t4 when . By selecting the times t2 to t4 to be as short as possible as described in t above, the generation of noise is reduced and the amount of power consumed by the main motor 56 is reduced.

When the print button 60 is pressed at time t6 and a copying operation is performed, the time t during the copying 9J is
The main motor 56 is driven during the period from 6 to t7. Therefore, the power from the main motor 56 is transmitted to the photosensitive drum 21, and the photosensitive drum 21 rotates.
The light is transmitted to the exposure lamp 14 and the reflecting mirrors 16.17, 22.23 (II).
moves to perform slit exposure. Main motor 5
6, the press roller 34 and the pressure roller 35 are constantly rotating. Therefore, when the transferred copy paper passes the heat roller 34 and the pressure roller 35, the heat roller 34 and the pressure roller 35 are rotated. The surface has a uniform temperature H2 distribution suitable for heat fixing. Therefore, good fixing is achieved.

In another embodiment of the invention, temperature sensing element 58 is l'E
It may be provided on the roller 35. The set roller in the claims of I of I includes the heat roller 34 and/or
The concept should be interpreted as including the folding or pressure roller 35.

According to the above-mentioned theory, when the temperature H of the fixed A1' roller is lower than the temperature suitable for heat fixing, the temperature H of the fixing roller is higher than the softening point H1 of the toner. When the fixing roller rotates 1<UJ, the fixing roller and the like are prevented from being damaged by toner that has adhered to and solidified on the fixing roller. After the temperature H of the fusing roller reaches the temperature H2V suitable for thermal fixing, the fusing roller is rotated only during copying. Therefore, the generation of noise is suppressed, and the power consumption is also reduced. Consumption is reduced.The fixing roller is rotationally driven at a speed suitable for thermal fixing, and therefore the configuration for driving the fixing roller can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a simplified sectional view of an electrophotographic copying machine including a heat fixing device 32 according to an embodiment of the present invention, FIG. 2 is a side view of the heat fixing device 32 according to an embodiment of the present invention, and FIG. 4 is a perspective view of a part of the heat fixing device 32, FIG. 4 is a cross-sectional view taken along a cut plane including the axes of the heat roller 34 and the pressure roller 35, and FIG. 5 is a block diagram related to the main motor 56. , FIG. 6 is a graph showing the temperature of the heat rod 234 detected by the temperature detection element 58 over time. 32... Heat fixing device, 33... Heater, 34...
・Heat 0-ra, 35...pressure roller, 55...chain, 56...main motor, 58...temperature detection element,
59...Power switch, 60...Print button Agent, Kei Nishi, Part 2, Figure 3, Procedural Amendment December 4, 1981 Commissioner of the Patent Office, F'J':, (, :. ■, Indication of the case Patent application 1983-114938 2. Name of the invention Heat fixing device for electrophotographic copying machine 3, Person making the amendment Relationship to the case Applicant address 1-2-28 Tamatsukuri, Higashi-ku, Osaka Name (615
) Mita Kokuri Co., Ltd. Representative 3 1) +ia Kei 4, Agent Address Shinkoyaku Building 5, 1-13-38 Nishihonmachi, Nishi-ku, Osaka City, 5th floor, 1156th floor, date of amendment order November 24, 1156 (Shipping date) 6 , the specification to be amended and drawing 7, the content of the amendment, the full-type written specification (no change in content), and the appropriate drawings (no change in content) should be attached as separate sheets. that's all

Claims (1)

[Claims] In a heat fixing device of an electrophotographic copying machine that guides copy paper with a toner image on its surface to a fixing roller having a temperature suitable for fixing and fixes it, a temperature detection element is provided to detect the temperature H of the fixing roller, and the power is turned on. Afterwards, the fixing roller is heated by a heater, and in response to the output from the temperature detection element, the temperature H of the fixing roller is set to a temperature H3 which is in the range of the toner softening point H1 or higher and lower than the temperature H2 suitable for thermal fixing. When the fixing roller is rotated at a speed suitable for fixing,
A heat fixing device for an electrophotographic copying machine, characterized in that when the temperature H of the fixing roller reaches a temperature H2 suitable for heat fixing, the fixing roller is driven to rotate at a speed suitable for fixing only during copying.