JPH02198479A - Thermal fixing device - Google Patents

Abstract

PURPOSE:To prevent the early deterioration of a cleaning pad by bringing the cleaning pad into contact with a heat roller during the energization to a heater and parting the cleaning pad from the heat roller while the heater is not energized. CONSTITUTION:The cleaning pad 76 provided freely attachably and detachably to and from the heat roller 31a and a driving means consisting of cleaning pad retaining members 78 which drive the cleaning pad 76 to attach and detach the cleaning pad to and from the heat roller 31a by responding to the energization and non-energization of the heater 67 and an electromagnet 75 are provided. The cleaning pad 76 is brought into pressurized contact with the heat roller 31a only when the heater 67 is energized. The cleaning pad 76 parts from the heat roller 31a when the energization to the heater 67 is held stopped. The early deterioration of the cleaning pad 76 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a heat fixing device used in an electrophotographic apparatus such as a laser printer or a copying machine.

[Prior Art] Conventionally, this type of heat fixing device is as shown in FIG.
The cleaning pad 12 is always held in a depressed state by a spring member 13 against a heat roller 11 provided with a heater.

[Problems to be Solved by the Invention] As described above, the conventional heat fixing device has a problem in that the cleaning pad deteriorates quickly because the cleaning pad is always in contact with the heat roller.

Further, if the temperature of the heat roller becomes abnormally high due to poor heater control or the like, there are problems such as burning of the cleaning pad onto the surface of the heat roller and, in some cases, smoke generation.

Therefore, an object of the present invention is to provide a heat fixing device that can prevent early deterioration of the cleaning pad by bringing the cleaning bat into contact with the heat roller when the heater is energized, and separating the cleaning pad from the heat roller when the heater is not energized. be.

The present invention also provides a heat fixing device that can separate the cleaning pad from the heat roller when the heating temperature of the heat roller by the heater reaches an abnormal temperature, thereby preventing the cleaning pad from burning onto the heat roller or emitting smoke in some cases. This is what we are trying to provide.

[Means for Solving the Problem] The invention according to claim (1) provides a thermal fixing device for thermally fixing a transfer paper onto which an image has been transferred via a heat roller provided with a heater. The cleaning pad is provided with a cleaning pad that is movable toward and away from the heat roller, and a driving means for driving the cleaning pad toward and away from the heat roller in response to energization and de-energization of the heater.

In addition, the invention described in claim (2) includes a cleaning pad that can be moved toward and away from the heat roller, an abnormal temperature detector that detects an abnormal temperature rise caused by the heater, and an abnormal temperature detector that detects an abnormal temperature rise caused by the heater, and a sensor that responds to energization or de-energization of the heater. The cleaning pad is provided with driving means for driving the cleaning bat towards and away from the heat roller, and also for moving the cleaning pad away from the heat roller when an abnormal temperature is detected by an abnormal temperature detector.

[Function] In the present invention having such a configuration, the cleaning pad is pressed against the heat roller by the driving means only when the heater is energized, and the cleaning pad is separated from the heat roller when the heater is not energized.

Further, when the temperature of the heat roller rises abnormally due to defective heater control or the like, the cleaning pad is forcibly separated from the heat roller by the abnormal temperature detection output.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. In this embodiment, the present invention will be described as applied to a laser printer.

FIG. 1 shows the overall structure of a laser printer, in which a photosensitive drum 22 whose surface is formed of a photosensitive member made of a photoconductive material is provided in the center of a printer body 21. As shown in FIG.

This photosensitive drum 22 is driven to rotate in one direction, and around this photosensitive drum 22, according to an electrophotographic process, there is a charging charger 23 constituting a charging section, and a laser beam is applied to the photosensitive member charged by this charging charger 23. A laser scanner unit 24 that records image information by irradiating a beam and forms an electrostatic latent image, a developer 25 that develops the formed electrostatic latent image into a toner image, and a transfer unit that transfers the toner image onto paper. A charger 26, a cleaning device 27 for removing toner from the photosensitive drum 22, and a charge removal lamp 28 for removing charge from the photosensitive drum 22 are provided in this order.

Then, near the front entrance of the transfer charger 26, the transfer paper stored in the paper feed section 29 is transferred to the transfer charger 26.
A pickup roller 30 is provided for feeding and transporting paper toward the paper 6 at a predetermined timing. Further, behind the transfer charger 26, a thermal fixing device 31 for thermally fixing the image on the transfer paper and a paper discharge roller 32 for discharging the fixed image on the transfer paper are provided in this order. The heat fixing device 31
There is a heat roller 3 heated by a heater to be described later.
1a and the conveyance roller 31b are arranged facing each other and in contact with each other.

Furthermore, a transport motor 33 that drives the transport section, photosensitive drum 22, and heat fixing device 31, a cooling fan 34, and a printer main body 2
an ink lock switch 35 that detects the opening of the casing 1;
A DC power supply 36 is provided respectively.

As shown in FIG. 2, the laser scanner unit 24 includes a laser diode control circuit 42 that drives a laser diode structure 41, a start sensor 43 consisting of a PIN diode, etc. that detects the start position of a laser beam, and a polygon that rotates a polygon mirror. A polygon motor drive circuit 45 that drives and controls the motor 44, and a PLL control circuit 46 that controls the rotational speed of the motor 44 by this drive circuit 45.
has been established.

FIG. 3 is a block diagram showing the circuit configuration, where 51 is a CPU (central processing unit) that constitutes the main body of the control section, and 52 is this C.
A ROM (read only memory) is provided with program data and various tables for the PU 51 to control each part, and a RAM (53) stores image information and various processing data sent from an external host computer.
54 is the I10 port.

These are connected by a pass line 55.

The I10 port 54 includes a motor drive circuit 56 for driving and controlling the transport motor 33, a high voltage power supply circuit 57 for supplying high voltage to the laser scanner unit 24, the charger 23 and the transfer charger 26, and a high voltage power supply circuit 57 for supplying high voltage to the developer 25. A toner sensor circuit 60 that controls the provided toner empty sensor 58 and toner full sensor 59.
, an operation unit 61, and a paper sensor 6 that detects paper jams.
2.63, 64, the fan 34, and an interface 65 for receiving image information from the host computer are connected, respectively.

The interlock switch 35 is inserted into a 24V supply line connected from the DC power supply 36 to the motor drive circuit 56, laser scanner 24, high voltage power supply circuit 57, and fan 34, and the casing of the printer main body 21 is opened. It is designed to detect this and shut off this supply line.

Said CPU51, ROM52, RAM5B and I10
+5V is supplied to the port 54 from the DC power supply 36.

The DC power supply 36 is connected to a commercial AC power supply via a noise filter 66.

Further, the commercial AC power input through the noise filter 66 is also supplied to the fixing device drive circuit shown in FIG.

The fixing device drive circuit includes a heater 67 for heating the heat roller 31a, a temperature fuse 68, and a primary winding 6 of a transformer 69 between the output lines from the noise filter 66.
A series circuit of the output section of the 9p1 heater control circuit 70 is connected.

The input terminal of a full-wave rectifier diode bridge 71 is connected to the secondary winding 69s of the transformer 69. A ceramic capacitor 73 and an electrolytic capacitor 74 are connected to the output terminal of the diode bridge 71 via a switch 72 that operates in conjunction with the interlock switch 35. Note that the switch 35 is connected to the printer main body 2.
It is designed to turn off when the first case is opened.

An electromagnetic magnet 75 is connected to both ends of the electrolytic capacitor 74.
is connected.

The heater control circuit 70 short-circuits its output section when a heater control signal is input from the CPU 51.

FIG. 5 shows the configuration of the main parts of the heat fixing device 31, in which a cleaning pad 76 is provided so as to be able to freely approach and separate from the upper surface of the heat roller 31a, and the cleaning pad 76 is always held by a spring 77. It is urged upward, that is, in a direction away from the heat roller 31a.

Further, the electromagnetic magnet 75 is fixed to the inside of the upper surface of the housing of the heat fixing device 31, and the cleaning bat 7
A cleaning pad pressing member 78 is provided above the housing 6 so as to be slidable left and right along the inner side of the upper surface of the housing.

The cleaning pad holding member 78 has one end connected to the plunger of the electromagnetic magnet 75 and the other end fixed to the inner side surface of the housing via a spring 79. When the electromagnetic magnet 75 operates, the spring 79
It is pulled to the right in the figure against the force of.

Several recesses 76a are formed above the cleaning pad 76, and several protrusions 78a each having a roller at the tip are formed below the cleaning pad pressing member 78 in correspondence with the recesses 76a. There is.

The protruding portion 78a is located within the recess 76a of the cleaning pad 76 when the electromagnet 75 is not operating, and when the electromagnet 75 is operating and the cleaning pad holding member 78 slides to the right, it is positioned on one side of the recess 76a. It is designed to come into contact with a smooth slope formed on the ground.

In this embodiment with such a configuration, the electromagnetic magnet 75 does not operate when the power is turned off.
At this time, the protruding portion 78a of the cleaning pad pressing member 78 is located within the recess 76a of the cleaning pad 76, so that the cleaning pad 76 is biased by the spring 77 and is spaced apart from the heat roller 31a.

When the power is turned on in this state and a heater control signal is input to the heater control circuit 70, power supply to the heater 67 is started and the heat roller 31a is heated. Further, a voltage is generated in the secondary winding 69s of the transformer 69, the electrolytic capacitor 74 is charged by the output of the full-wave rectifier diode bridge 71, and the electromagnetic magnet 75 is operated.

Thus, the cleaning pad pressing member 78 is pulled to the right in the figure by the electromagnetic magnet 75. As a result, the roller of the protrusion 78a comes into contact with the slope of the recess 76a and moves smoothly along the slope. Since the lower end position of the protruding portion 78a is fixed, the cleaning pad 76 comes to descend. and protrusion 7
At the position where the roller 8a comes out of the recess 76a, the cleaning pad 76 comes into pressure contact with the upper surface of the heat roller 31a, as shown in FIG.

When the heater 67 starts to be energized in this way, the cleaning pad 76 comes into contact with the heat roller 31al.

When the temperature of the heat roller 31H reaches a certain set temperature, the input to the heater control signal is stopped, and the power supply to the heater 67 is stopped. Thereafter, the heater 67 is repeatedly energized and de-energized, and the temperature of the heat roller 31a is maintained substantially constant. When the heater 67 is not energized, the cleaning pad 76 is separated from the heat roller 31a.

In this way, since the cleaning pad 76 is brought into contact with the heat roller 31a only when the heater 67 is energized, early deterioration of the cleaning pad 76 can be prevented.

Then, when the thermal fixing device 31 reaches the set temperature state, the printer becomes capable of printing. In this printing operation, the photosensitive drum 22 first rotates, and the photosensitive member is charged by the charger 23.
charged by. Information is then written onto the charged photoreceptor by a laser beam from the laser scanner unit 24, forming an electrostatic latent image. Toner supplied from the developing device 25 is attached to this electrostatic latent image, and the image is further moved to a transfer section.

On the other hand, the transfer paper stored in the paper feed section 29 is sent to the conveyance path by the pickup roller 30 at a predetermined timing. When this paper is conveyed to the transfer charger 26, a toner image is transferred from the photoreceptor of the photoreceptor drum 22. Then, the paper is further thermally fixed by the thermal fixing device 31, and is discharged by the paper discharge roller 32, thereby completing printing.

In addition, the control of the heater 67 may be defective, and even if the set temperature is reached, the power supply to the heater 67 is not stopped and the heat roller 31H
If an accident occurs in which the temperature of the transformer 6 rises abnormally, the temperature fuse 68 will be blown, and the
No voltage is output to the secondary winding 69s of 9, and the operation of the electromagnetic magnet 75 is stopped. However, the cleaning pad 76 is the cleaning pad 76.
The suppressed state of the cleaning pad 76 is released and the cleaning pad 76 is separated from the heat roller 31a.

In this way, even if the temperature of the heat roller 31a rises abnormally, the cleaning pad 76 can be removed from the heat roller 31a.
Since the cleaning pad 76 can be separated from the heat roller 31H, accidents such as burning of the cleaning pad 76 on the heat roller 31H and smoke generation in some cases do not occur.

Furthermore, if the casing of the printer main body 21 is opened while the heater 67 is energized, the switch 72 is turned off and the energization to the electromagnetic magnet 75 is stopped. It can be separated from

Next, other embodiments of the present invention will be described with reference to the drawings. Note that the same parts as in the above embodiment are given the same reference numerals and detailed explanations will be omitted.

This is a recess 76a formed in the cleaning pad 76 as a cleaning pad pressing member as shown in FIG.
This embodiment also uses a member 80 having a protrusion 80a having approximately the same shape as the electromagnetic magnet 7.
When the cleaning pad pressing member 80 is pulled by the operation 5, the protrusion 80a moves on the smooth slope of the recess 76a as shown in FIG. 8, and the cleaning pad 76 can be pressed against the heat roller 31a. Therefore, in this embodiment, the same effects as in the previous embodiment can be obtained.

In the above embodiments, the driving means is made up of a cleaning pad pressing member and an electromagnetic magnet, but the driving means is not limited thereto.

Furthermore, although the above embodiment describes the application of the present invention to a heat fixing device of a laser printer, the present invention is not necessarily limited to this, and can be applied to various types of equipment that require heat fixing, such as copying machines. be.

[Effect of the invention] As detailed above, according to the invention described in claim (1),
It is possible to provide a thermal fixing device that can prevent early deterioration of the cleaning pad by bringing the cleaning pad into contact with the heat roller when the heater is energized and separating the cleaning pad from the heat roller when the heater is not energized.

Further, according to the invention described in claim (2), when the heating temperature of the heat roller by the heater reaches an abnormal temperature, the cleaning pad can be separated from the heat roller, and the cleaning pad may be burned to the heat roller or smoke may occur in some cases. Therefore, it is possible to provide a heat fixing device that can prevent such problems from occurring.

[Brief explanation of the drawing]

Figures 1 to 6 show an embodiment of the present invention, with Figure 1 showing the configuration of a laser printer, Figure 2 showing the configuration of a laser scanner unit, and Figure 3 showing the circuit configuration. 4 is a fixing device drive circuit diagram, FIGS. 5 and 6 are main part configuration diagrams of the heat fixing device, and FIGS. 7 and 8 are heat fixing devices showing other embodiments of the present invention. FIG. 9 is a diagram showing the configuration of the main parts of a conventional heat fixing device. 31... Heat fixing device, 31a... Heat roller, 6
7... Heater, 70... Heater control circuit,
75... Electromagnetic magnet, 76... Cleaning pad, 77... Spring, 78... Cleaning pad pressing member. Applicant's agent Patent attorney Takehiko Suzue 88ε

Claims (3)

[Claims] (1) In a thermal fixing device that thermally fixes a transfer paper onto which an image has been transferred via a heat roller provided with a heater, a cleaning pad is provided that is movable toward and away from the heat roller; A thermal fixing device comprising a driving means for driving the cleaning pad toward and away from the heat roller in response to energization and de-energization. (2) In a thermal fixing device that thermally fixes the transfer paper onto which an image has been transferred via a heat roller provided with a heater, there is a cleaning pad that is provided so as to be able to freely approach and separate from the heat roller, and an abnormality caused by the heater. An abnormal temperature detector detects a temperature rise, and the cleaning pad is driven toward and away from the heat roller in response to energization or de-energization of the heater, and the cleaning is performed by detecting abnormal temperature by the abnormal temperature detector. A heat fixing device comprising a drive means for separating the pad from the heat roller. (3) The driving means constantly urges the cleaning pad away from the heat roller by a spring force, drives a cleaning pad holding member by energizing an electromagnetic magnet, and resists the spring force by the operation of the pad holding member. The heat fixing device according to claim 1 or 2, wherein the cleaning pad is brought into pressure contact with a heat roller.