JP2000075719A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To notify a user using a device first of the presence of a pressurization releasing means and surely set the pressurizing force released at the start of use by detecting the presence of a recording material by a recording material detecting means when a sheet member is supported by a recording guide member. SOLUTION: A fixing device 11 has a recording material detecting means (sensor lever 21) for detecting the passing or stay of a sheet. The lever part 21 of the sensor lever 21 is arranged near about the center of the sheet width, and when the lever 21b is pressed by the sheet to rotate a shaft 21c, a flag 21a blocks the light receiving part of a discharge sensor 22 mounted on an image forming device to detect the presence of the sheet. Therefore, an instruction film can be held in the state where a discharge guide 19 is closed, and the discharge sensor 22 is laid in the state of continuously obstructing the light because the lever part 21b is pushed up by the instruction film. Accordingly, the stay of the sheet is detected to form an image formation impossible state, and the sheet carrying in pressurized state can be thus prevented.

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 printer or a copying machine having a fixing device for fixing a toner image on a recording material by applying heat and pressure.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus employing an electrophotographic system, an image carrier for forming an electrostatic latent image on a surface thereof, a pre-exposure means for removing charges on the surface of the image carrier, and an image carrier Primary charging means for charging the surface of the substrate to a desired potential, exposure means for exposing the charged image carrier to form an electrostatic latent image, and developing the electrostatic latent image on the image carrier with a developer. A developing device for visualizing the image, a transfer device for transferring the toner image on the image carrier developed by the developing device to a recording material, and fusing and fixing the toner image transferred to the recording material by a heated and pressed fixing roller. A roller fixing device or the like is arranged at a predetermined position, and an image is recorded on a recording material by each image forming process such as charging, exposure, development, transfer, and fixing. Recording paper, OHP sheets, and the like are used as recording materials.

The roller fixing device is provided with a heater inside, and is heated and rotatably held by a housing or the like of the roller fixing device, and is pressed against the surface of the fixing roller by pressing means such as a spring member. A pressure roller that is in contact with and pressurized, and the recording material onto which the unfixed toner image has been transferred passes through a nip portion that is a pressure contact portion between the fixing roller and the pressure roller. The toner on the recording material is melted and fixed by the heat of the pressure roller and the pressing force of the pressure roller, and an image is recorded on the recording material.

Further, since the fixing roller and the pressure roller are pressed against each other at a predetermined pressure in a normal state, the pressure roller may be deformed by the pressure. In order to prevent this, at the time of shipping the image forming apparatus or when the apparatus is not used for a long period of time, a resin spacer or the like is provided between the shafts of both rollers, or by operating a lever previously provided in the apparatus. The two rollers are configured to be kept separated by an operating pressure releasing means.

[0005]

However, when a resin spacer or the like is provided between the shafts of both rollers, or when both rollers are kept out of contact with each other by a pressure releasing means provided in advance in the apparatus. In addition, it is possible to operate the apparatus main body without contact. In particular, many accidents occur when a user unpacks a shipped device and does not know the existence of the pressure releasing means to operate the apparatus main body and pass paper without contacting both rollers.
Passing the paper in this state not only does not fix the toner image on the recording material, but also causes offset of the unfixed toner to the roller, winding of the recording material around the roller, and the like, resulting in a catastrophic failure of the fixing device. Cause.

[0006] Therefore, an object of the present invention is to inform a user who uses the apparatus for the first time of the existence of the pressurizing release means and to surely set the pressing force released at the start of use to a pressurized state. .

[0007]

In order to solve the above-mentioned problems, an image forming apparatus according to the present invention comprises a fixing roller, a pressure roller which can be separated from and connected to the fixing roller, and A fixing device that includes a pressing unit that presses against the fixing roller, a heating unit that heats the fixing roller or the pressing roller, and a pressure release that can release a pressing force of the pressing unit and maintain a pressure released state Means, a recording material detecting means for detecting passage or residual of the recording material, and an openable and closable recording material guide member disposed in the vicinity of the recording material detecting means. A sheet-like member indicating a method of changing the pressurized state is separately supported by the recording material guide member, and when the sheet-like member is supported by the recording material guide member, the recording material detecting means is provided. Characterized in that a state has been detected wood.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a back surface of the image forming apparatus according to the present embodiment, FIG. 2 is a side view illustrating a fixing device of the image forming device, FIG. 3 is a side view illustrating a sheet passing state of the fixing device, and FIG. FIG. 5 is a side view of the fixing device, showing a pressure release state, FIG. 5 is a side view of the fixing device, FIG. 6 is a side view showing a release state of the fixing device, FIG. 8 is a partial top view of the fixing device, FIG. 9 is a partial top view of the fixing device, and FIG. 10 is a schematic configuration diagram of the image forming apparatus.

(Image Forming Apparatus) An image forming apparatus 1 shown in FIG. 10 is an electrophotographic copying machine, which forms an image on a recording material in accordance with an image signal sent from a computer (not shown). The image carrier 2 of the image forming apparatus 1 is uniformly charged by the charging unit 3, and the laser oscillator 4 irradiates the image carrier 2 with light according to an image signal. An electrostatic latent image is formed on a portion of the image carrier 2 irradiated with the light beam, and is developed by a developing device 5 with toner as a developer to be a visible image.

The cassette 6 is loaded with recording sheets such as recording paper and OHP sheets.
Is fed and separated one by one by the registration roller pair 8.
After the skew has been corrected, the image reaches the image carrier 2. The toner image carried on the image carrier 2 is transferred to a transfer unit 9.
Is transferred to a sheet, and is conveyed to a fixing device 11 by a conveyor belt 10. The fixing device 11 melts and fixes the toner image by applying heat and pressure to the sheet. After the image is fixed, the sheet is discharged outside the apparatus by the discharge roller pair 12. The toner remaining on the image carrier 2 after transferring the toner image onto the sheet is removed by a cleaning device 13.
And the image carrier 2 is again subjected to image formation.

A fixing device 11 shown in FIG. 2 is detachably attached to a predetermined position of the image forming apparatus 1 and has a fixing roller.
The fixing device 11 includes a heating unit 14 for heating the heating unit 15, a pressure roller 16, and a pressure arm 17 that is rotatably attached to the fixing device 11. The fixing roller 14 is rotatably provided in the image forming apparatus 1, and the pressure roller 16 is rotatably attached to the pressure arm 17. The pressure arm 17 can swing about a fulcrum 17a, and presses the pressure roller 16 against the fixing roller 14 by the pressing force of a swing spring 17b (see FIG. 6).

A pressure arm is provided above the swing spring 17b.
A pressure release lever 18 as pressure release means is provided via 17. The pressure release lever 18 is rotatably mounted around a shaft 18b, and makes the cam 18a contact the pressure arm 17. When the cam 18a pushes down the pressure arm 17 by pushing up the pressure release lever 18 as shown in FIG. 6, the fixing roller 14 of the pressure roller 16 separates and the pressing force can be released. Pressure release lever as shown
By pressing down 18, the pressurizing arm 17 is opened and a pressing force is applied.

A discharge guide 19, which is a recording material guide member for guiding the sheet S, is provided downstream of the fixing roller 14 and the pressure roller 16. The discharge guide 19 has a discharge roller 19a for guiding a sheet at a leading end thereof, is rotatably attached to the fixing device 11 by a rotation shaft 19b, and is urged and brought into contact with the fixing device 11 by a discharge spring 20. Positioned.

Further, the fixing device 11 is provided with a sensor lever 21 which is a recording material detecting means for detecting passage or retention of the sheet S. The sensor lever 21 is rotatably attached to the fixing device 11 about a shaft 21c, and has a lever portion 21b protruding into the sheet conveyance path and a flag 21a. As shown in FIG. 8, the lever portion 21b is disposed near the center of the sheet width, and the lever portion 21b is pushed by the sheet S as shown in FIG.
When the rotating member 21c rotates, the flag 21a blocks the light receiving portion of the discharge sensor 22 attached to the image forming apparatus 1 and detects the presence of the sheet.

In the above configuration, for example, when there is a possibility that the apparatus will not be used for a long period of time, such as when the product is shipped from a factory, the pressure releasing lever 18 is used to prevent the fixing roller 14 and the pressure roller 16 from being deformed by the pressing force. Is operated to maintain the pressure release state as shown in FIG. At this time, the instruction film 23 which is a sheet-like member in which a pressing method (a method of releasing the pressure releasing means) is described in advance is discharged as shown in FIG.
Is set so as to be sandwiched in the transport path.

As shown in FIG. 8, the indication film 23 is provided with a holding hole 23a, while the discharge guide 19 is provided with a notch 19c for attaching the indication film. Further, a notch 23b is provided at a position downstream of the holding hole 23a of the instruction film 23 in the pulling direction and corresponding to the lever 21b.

Therefore, when the discharge guide 19 is closed, the indicator film 23 can be held, and at the same time, the indicator film 23 pushes up the lever portion 21b.
Reference numeral 22 indicates a state where the light is continuously shielded. As a result, the image forming apparatus 1 detects that the sheet is stagnant, disables the image formation, and can prevent the sheet from being conveyed in the pressure release state.

When the instruction film 23 is removed from the fixing device 11 after the pressing operation is performed according to the instruction, as shown in FIG. 5, the discharge guide 19 is moved to the rotation shaft 19b in the same manner as in the case where a normal sheet stays. Rotate to the center and open. Then, the holding hole 23a of the instruction film 23 which has been held can be easily separated by pulling the instruction film 23 upward (in the direction of arrow A) from the notch 23b of the discharge guide 19.

Even if the user forcibly pulls out the indicating film 23 without opening the discharge guide 19, the notch 23b of the indicating film 23 can be pulled out as shown in FIG. It is. This notch 23
Due to the spread of b, the side 23c of the holding hole 23a on the upstream side in the withdrawing direction is deformed and retracts with respect to the lever portion 21b. As described above, since the lever portion 21b of the sensor lever 21 and the notch 23b of the indicator film 23 are arranged at corresponding positions, the indicator film 23 comes into contact with the lever portion 21b together with the deformation of the side 23c. There is no fear. So the instruction film
Even when 23 is forcibly pulled out, deformation and breakage of the sensor lever 21 can be prevented.

[0020]

As described above, the image forming apparatus according to the present invention has a state in which a sheet-like member indicating a method of changing the pressure releasing means of the fixing roller and the pressure roller is held in the fixing device. Is configured such that the recording material detecting means operates, so that the apparatus main body cannot form an image unless the sheet-like member is removed. Therefore, when removing this, the user can be informed of the existence and operation method of the pressure release means, and the accident that occurs when the apparatus body is operated with both rollers not in contact with each other is prevented beforehand. can do.

Further, if a material such as a recording paper or a PET film used as a recording material is used for the sheet-like member, it can be constructed at a low cost, and a load is applied to the recording material guide member and the recording material detecting means. , The existing recording material detecting means can be used.
Therefore, the cost and size of the apparatus can be reduced, and the quality can be improved by reducing the causes of defects by simplifying the mechanism.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a back surface of an image forming apparatus according to an embodiment.

FIG. 2 is a side view illustrating a fixing device of the image forming apparatus.

FIG. 3 is a side view illustrating a sheet passing state of the fixing device.

FIG. 4 is a side view illustrating a pressure release state of the fixing device.

FIG. 5 is a side view of the fixing device.

FIG. 6 is a side view illustrating a pressure release state of the fixing device.

FIG. 7 is a side view illustrating a pressing state of the fixing device.

FIG. 8 is a partial top view of the fixing device.

FIG. 9 is a partial top view of the fixing device.

FIG. 10 is a schematic configuration diagram of an image forming apparatus.

[Explanation of symbols]

 S ... Sheet 1 ... Image forming apparatus 2 ... Image carrier 3 ... Charging means 4 ... Laser oscillator 5 ... Developing apparatus 6 ... Cassette 7 ... Feed roller pair 8 ... Registration roller pair 9 ... Transfer means 10 ... Conveyer belt 11 ... Fixing Means 12: Discharge roller pair 13: Cleaning device 14: Fixing roller 15: Heater 16: Pressure roller 17: Pressure arm 17b: Swing spring 18: Pressure release lever 18a: Cam 18b: Shaft 19: Discharge guide 19a: Discharge roller 19b Rotating shaft 19c Notch 20 Discharge spring 21 Sensor lever 21a Flag 21b Lever 21c Shaft 22 Discharge sensor 23 Indicator film 23a Holding hole 23b Notch 23c Edge

Claims (3)

[Claims] 1. A fixing roller, a pressure roller that can be separated from and brought into contact with the fixing roller, a pressure unit that presses the pressure roller against the fixing roller, and a heating unit that heats the fixing roller or the pressure roller. A pressure release unit capable of releasing the pressure of the pressure unit to maintain the pressure release state, a recording material detection unit for detecting the presence or absence of a recording material, and the recording material detection unit And an openable and closable recording material guide member disposed in the vicinity of the recording material guide member, wherein the recording material guide member supports a sheet-like member so as to be separable, and the sheet-like member is supported by the recording material guide member. The image forming apparatus is characterized in that when the recording is performed, the recording material detecting unit detects that the recording material is present. 2. The image forming apparatus according to claim 1, wherein a cutout portion is provided at a position downstream of the sheet-like member in the pulling-out direction and corresponding to the recording material detecting means. 3. The image forming apparatus according to claim 1, wherein at least a method of changing a pressurized state and a pressurized state is described on the sheet member.