JP3109178B2 - Image forming device - Google Patents

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, and more particularly to an image forming apparatus for transferring a toner image formed on an electrostatic latent image carrier by electrophotography onto paper.

[0002]

2. Description of the Related Art Conventionally, in this type of image forming apparatus,
As a fixing device for heating and fixing toner on paper, there is provided a fixing device in which one fixing (heating) roller can be brought into contact with and separated from the other fixing (heating) roller. In this type of fixing device, to prevent deformation of the fixing roller and to prevent paper jam (jam), the fixing roller is pressed only during the image forming operation. That is, the fixing roller is pressed together with the start of the image forming operation, and is released upon completion of the image forming operation or detection of a jam.

In a copier equipped with this type of fixing device, in order to shorten the time required for making a first copy, the paper transport system including the fixing roller is driven at the same time as receiving a copy start signal, and the fixing roller is driven. It is preferable to start the crimping operation. However, if the driving of the transport system and the pressing of the fixing roller are started at the same time, a problem may occur at the time of resetting the jam processing. That is, when the jam paper is taken out and the reset key is turned on, the fixing roller starts rotating at a point in time when the pressing of the fixing roller is not completed. If the reset key is turned on after forgetting to take out the paper in the fixing device, there is a possibility that the copy paper on which the unfixed toner is loaded is transported to the downstream side, and the transport rollers and the guide plate are stained with the unfixed toner. In addition, the operator's hand that carelessly touches the paper is stained.

[0004]

Object, structure and operation of the present invention
Provided is an image forming apparatus that achieves high-speed image forming processing, and that conveys a sheet to a downstream side in a state where toner is securely fixed even when the sheet is forgotten when resetting a jam processing. It is in. In order to achieve the above object, an image forming apparatus according to the present invention includes a first driving unit for bringing a fixed fixing roller into and out of contact, and a second driving unit for driving at least a conveyance system for conveying a sheet in a fixing device. and means, when receiving an image formation start signal immediately while driving the second transport system by operating the driving means, when receiving a reset signal after a paper jam processing, the fixing roller by operating the first driving means After starting crimping of
Operating the second driving means after completion of crimping, characterized in that a that control means drive the conveying system.

In the above configuration, the image forming start signal
At the time of receipt of the signal, the transport system is driven immediately, so that the transport of the sheet can be started, and the image forming process is speeded up (in particular, the first copy time is shortened). on the other hand,
If a paper jam occurs and the jammed paper is removed and a reset signal is received , the conveyance system is driven after the fixing roller is pressed, so if the paper left in the fixing device remains, This sheet is conveyed downstream of the fixing device with the toner fixed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus according to the present invention will be described below with reference to the accompanying drawings. In the embodiments described below, the present invention is applied to an analog type electrophotographic copying machine using visible light. In FIG. 1, in this copying machine, a photosensitive drum 1 is installed at a substantially central portion so as to be rotatable in the direction of arrow a, and a charging charger 2, a developing device 3, a transfer charger 4, a paper separating charger 5, A cleaning device 6 for residual toner and an erase lamp 7 for residual charge are provided. The original is placed on an original platen glass 10 with the image facing downward, and is exposed on the photosensitive drum 1 by an optical system 11. Note that the image forming process is well known, and a description thereof will be omitted.

The paper is stored in an upper automatic paper feed tray 20 or a lower automatic paper feed tray 25 provided on the left side of the copying machine. The sheets are separated and fed one by one by 22 and 27. The fed paper is a roller group 30, 3
Once stopped by the timing roller 35 after 1 and 32,
The toner image is conveyed to the transfer section in synchronization with the toner image formed on the photosensitive drum 1, and the toner image is transferred. The sheet is separated from the photosensitive drum 1 at the same time as the transfer proceeds, and sent to the fixing device 40 by the transport belt 36. Fixing device 4
Reference numeral 0 denotes a heating roller 41 and a pressure roller 44 provided with an elastic material on its surface, and fuses and fixes toner particles on paper. The sheet on which the toner is fixed is discharged to a tray 72 outside the apparatus through a discharge roller 71.

[0008] As an option, this copying machine has
An automatic document feeder can be mounted on the main body, or a sorter can be mounted in place of the tray 72. Next, the fixing device 40 will be described in detail with reference to FIGS. The fixing device 40 includes a heating roller 41 having a built-in heat lamp 42 and a pressure roller 44 having a built-in heat lamp 45. The heat lamp 42 is turned on and off so that the surface of the heating roller 41 maintains an optimal temperature for fixing toner while the main power of the copying machine is turned on. Such temperature control is performed based on temperature detection by a thermistor 43 provided close to the surface of the heating roller 41. On the other hand, the heat lamp 45 is an auxiliary heating means that is turned on and off so as to maintain the surface of the pressure roller 44 at a predetermined temperature during standby for a copying operation. Such temperature control is performed based on temperature detection by a thermistor 46 provided close to the surface of the pressure roller 44.

The heating roller 41 has both ends of a shaft member rotatably attached to a main body frame via bearings (not shown), and is driven to rotate in a direction indicated by an arrow f at a predetermined timing by a conveyance system driving motor M2 (see FIG. 5). Is done. The pressure roller 44 is held by a holder 48 via bearings 47 provided at both ends of a shaft member. The holder 48 is rotatably supported in a vertical direction (arrows b and b 'directions) with a support shaft 49 as a fulcrum, and the pressing roller 44 comes into contact with and separates from the heating roller 41 based on the vertical movement. In a state where the pressure roller 44 is pressed against the heating roller 41, when the heating roller 41 is rotationally driven, the pressure roller 44 is driven to rotate accordingly.

To drive the holder 48, a motor M
1 is installed. A worm gear 51 fixed to the output shaft of the motor M1 meshes with a worm wheel 52, and a gear 53 fixed coaxially with the worm wheel 52 meshes with a gear 54. A cam 56 is fixed to a support shaft 55 of the gear 54. When the motor M1 is turned on, it rotates in one direction, and rotates and drives the gear 54 and the cam 56 in a state where the gear 54 and the cam 56 are decelerated in the direction of arrow c.

On the other hand, another holder 60 has a support shaft 61.
The holder 60 and the holder 48 are connected by a tension coil spring 63 and are urged in directions approaching each other. Further, the collar 62 attached to the holder 60 is in contact with the outer peripheral surface of the cam 56. As shown in FIG.
2 is in contact with the small-diameter portion 56a of the cam 56, the holder 60 rotates in the direction of arrow d ', and the tension coil spring 63 moves in the direction of arrow e'. In this state, the pressure roller 44 has been released from the pressure roller 44 being pressed against the heating roller 41. Cam 5
6 is rotated about 180 ° in the direction of arrow c, FIG.
As shown in (b), the collar 62 is connected to the large-diameter portion 5 of the cam 56.
6b, the holder 60 rotates in the direction of arrow d, and the tension coil spring 63 is pulled in the direction of arrow e. In response, the holder 48 also rotates in the direction of arrow b, and the pressure roller 44 heats. It is pressed against the roller 41.

In order to control the above-mentioned crimping / releasing operation, a disk 57 is fixed to the support shaft 55 of the cam 56, and a sensor SE10 is installed near the disk 57. Edge portions 57a and 57b are formed on the disc 57 at intervals of approximately 180 °, and the cam 56 rotates in the direction of the arrow c, as shown in FIG.
As shown in FIG. 4, when the edge 57a passes through the optical axis of the sensor SE10, the sensor SE10 is turned off, and as shown in FIG.
E10 turns off.

In the state shown in FIGS. 3A and 4A, when the drive motor M1 is turned on, the cam 56 and the disk 57 rotate in the direction of arrow c. As a result, the collar 62 is pushed up by the cam 56, and the holder 48 is moved upward in the direction of the arrow b by the spring force of the tension coil spring 63 as described above, so that the pressure roller 44 is pressed against the heating roller 41. When the edge portion 57b of the cam 57 blocks the optical axis of the sensor SE10 (see FIG. 4B), the sensor SE10
Is turned off, and based on this, the drive motor M1 is turned off. At this time, the cam 56 and the holders 60 and 48 are in the state shown in FIGS.
1 is kept in a state of being pressed.

Next, when the drive motor M1 is turned on, the cam 56 and the disc 57 further rotate in the direction of arrow c. Thus, the small diameter portion 56a of the cam 56 faces the collar 62, the holder 60 rotates in the direction of arrow d ', and the tension coil spring 63 moves in the direction of arrow e'. With this,
The pressure roller 44 rotates together with the holder 48 in the direction of the arrow b ′, and the pressure of the pressure roller 44 against the heating roller 41 is released. Then, when the edge 57a of the cam 57 passes through the optical axis of the sensor SE10 (see FIG. 4A), the sensor SE10 is turned on, and based on this, the drive motor M1 is turned off.

FIG. 5 shows a control circuit of the copying machine. This control circuit is configured around the CPU 90, and the motor M
1 and M2 are turned on via D / A converters 91 and 92,
Controlled off. The CPU 90 has a sensor SE10.
ON and OFF signals from the thermistors 43 and 4
6 is input via the A / D converter 93. Further, CPU 90 receives ON signals from a copy start key 94 and a jam reset key 95 on an operation panel (not shown) provided in the copying machine.

On the other hand, as shown in FIG. 1, sensors SE1 to SE1 for detecting a sheet being conveyed are provided in a sheet path in the copying machine main body.
SE4 is installed. The detection signals from the sensors SE1 to SE4 are input to the CPU 90, and are used for controlling paper passing, and the occurrence of a jam is detected by a combination with a timer. In the above configuration, at the time of the copy operation, as shown in FIG.
Is turned on to start copying, the motor M
1, M2 is turned on, and the pressure roller 44 is
And the paper transport system including the rollers 41 and 44 is driven. Then, the motor M
2 is turned off. The motor M1 is once turned on and the roller 4
It is turned off after releasing the crimping of 1,44.

If a jam occurs during copying, the copying operation is interrupted, the motor M1 is turned on for a predetermined time, and the pressure bonding of the rollers 41 and 44 is released. Thereafter, when the jam paper is removed and the jam reset key 95 is turned on, FIG.
As shown in (b), first, the motor M1 is turned on, and the pressure roller 44 is pressed against the heating roller 41. Motor M2 simultaneously with the crimping completion is turned on, the transport system is pre-rotated by a time t _1. At least the rollers 41 and 44 may be rotationally driven in this preliminary rotation. When pre-rotation time t ₁ has elapsed, motor M1 again releases the crimping is turned on a predetermined time rollers 41 and 44.

When a jam occurs, for example, at the position where the sensor SE1 or SE2 is installed, the operator may remove only the jammed paper and forget to remove the preceding paper stopped in the fixing device 40 and turn on the reset key 95. . In such a case, the rollers 41 and 44 are rotated after being pressed, so that the paper left in the fixing device 40 is conveyed to the discharge roller 71 in a state where the toner is fixed. Therefore, the discharge roller 71 or a guide plate (not shown) is not stained with the unfixed toner.

On the other hand, the control at the time of jam reset is shown in FIG.
In addition to the operation shown in FIG. 6B, the operation may be performed at the timing shown in FIG. That is, when the jam reset key 95 is turned on, the motor M1 is turned on and the pressure roller 44 is pressed against the heating roller 41. At the same time the on key 95, the timer is started which is set slightly longer t ₂ than crimping operation time, the transfer system by turning on the motor M2 when the timer terminates (at least the roller 41, 44) the time t ₁
Just pre-rotate. After the end of the preliminary rotation, the motor M
1 is turned on for a predetermined time to release the pressure contact between the rollers 41 and 44.

Next, the control procedure of the copying machine will be described with reference to FIGS.
This will be described with reference to the flowchart of FIG. In the following control, on-edge means that switches, sensors, signals, and the like are switched from an off state to an on state, and off-edge means that switches, sensors, signals, and the like are switched from an on state to an off state. means.

FIG. 7 shows a main routine of the CPU 90. When the main power is turned on and the CPU 90 is reset and the program starts, at step S1, R
Performs initial settings for clearing AM, resetting various registers, and setting various devices to an initial state. Next, the subroutines of steps S2 to S6 are sequentially called to perform necessary processing. At step S7, one of the main routines is executed.
It is determined whether or not the cycle has been completed.
Return to 2.

In step S2, input / output signals to and from the operation panel relating to copy control and input / output signals to the display are processed, as well as input of signals from sensors and switches in the copying machine and output of control signals to various devices. In step S3, the fixing roller and the transport system are controlled.
This will be described in detail with reference to the flowchart of FIG. In step S4, the copy operation is controlled, that is, paper feed, transport, charging, exposure, development, transfer, jam detection, and the like are processed. In step S5, ON / OFF of the heat lamps 42 and 45 is controlled so that the fixing roller maintains a predetermined surface temperature.
In step S6, data exchange with another CPU, that is, a CPU that controls the optical system 11, and a CPU that controls an automatic document feeder and a sorter that are installed as options are processed.

FIGS. 8 to 11 show a subroutine for controlling the fixing roller and the transport system, which is executed in step S3. Here, the count value of the state counter is checked in step S10, and the following processing is performed according to the value. State counter determines whether In the initial time is reset to "0", the table temperature temperature measurement T of the pressure roller 44 in the step S11 this time is equal to the reference temperature T _1. If T = T ₁ is set to "1", the state counter at step S12. If the temperature T has not reached the reference temperature T _1, is set to "7", the state counter in step S13, performs a warm-up.

When the state counter is "1", that is,
If the warm-up of the fixing device 40 has been completed, it is determined in step S14 whether or not the copy start key 94 is on-edge, and the state counter holds "1" until it is determined that it is on-edge. If the key 94 is on-edge, the motor M1 is turned on in step S15, and
At 16, the motor M2 is turned on. Thus, the pressing of the pressing roller 44 against the heating roller 41 is started, and the transport system is driven to rotate. Next, the state counter is set to "2" in step S17.

When the state counter is "2", that is,
When the copying operation is started and the pressing of the rollers 41 and 44 is started, it is determined in a step S18 whether or not the sensor SE10 is off-edge. When the sensor SE10 is turned off, the motor M1 is turned off in step S19. Thus, the pressing of the pressure roller 44 to the heating roller 41 is completed. Next, the state counter is set to "3" in step S20.

When the state counter is "3", that is,
When the copying operation is started and the pressure bonding of the rollers 41 and 44 is completed, it is determined in step S21 whether or not the copying operation is completed, and if completed, the motor M1 is turned on in step S22 and the motor M2 is turned off in step S23. . Accordingly, the pressing of the pressure roller 44 against the heating roller 41 starts to be released, and the rotation of the transport system is stopped. Next, in step S24, the state counter is set to "4".
Set to. On the other hand, if a copy operation is being performed, step S
It is determined at 25 whether or not a jam has occurred. If no jam has occurred, the state counter holds "3". If a jam occurs, the motor M1 is turned on in step S26, and the motor M2 is turned off in step S27. With this, while the pressure release of the rollers 41 and 44 is started,
The rotation drive of the transport system is stopped. Next, step S28
Sets the state counter to "5".

When the state counter is "4", that is,
When the copy operation is completed and the pressure release of the rollers 41 and 44 is started, it is determined in a step S29 whether or not the sensor SE10 is on-edge. The state counter keeps “4” until it is determined that an ON edge has occurred. If the sensor SE10 is turned on, the motor M1 is turned off in step S30, and the state counter is set to 1 in step S31. With this, the pressure bonding of the rollers 41 and 44 is released,
The fixing device 40 waits for the next copy operation.

When the state counter is "5", that is,
When a jam occurs during the copying operation and the pressure release of the rollers 41 and 44 is started, the sensor SE1 is determined in step S32.
It is determined whether 0 is an on-edge. When the sensor SE10 is turned on, the motor M1 is turned off in step S33, and the state counter is set to "6" in step S31. This releases the pressure bonding of the rollers 41 and 44, and the operator removes the jammed paper and the paper stopped in the transport path.

When the state counter is "6", that is,
When the jam processing ends, it is determined in a step S35 whether or not the jam reset key 95 is on-edge. Key 95
Is on edge, the state counter is set to "7" in step S36. State counter is "7"
In other words, when the jam reset signal is input or when the rollers 41 and 44 need to warm up (NO in step S11), the measured surface temperature T of the pressure roller 44 is changed to the reference temperature T _{1 in} step S37. Is determined as equal to or not. If T = T ₁ to turn on the motor M1 at step S38, the set to "8", the state counter at step S39. With this, the pressure bonding of the rollers 41 and 44 is started. On the other hand, the temperature T has not reached the reference temperature T _1, the state counter holds the "7", to continue the warm-up. The warm-up temperature control is performed in step S5 of the main routine.

When the state counter is "8", that is,
When the warm-up is completed and the pressing of the rollers 41 and 42 is started, it is determined in a step S40 whether or not the sensor SE10 is on-edge. If sensor SE10 is the on-edge and turns off the motor M1 to stop the crimping operation of the pressure roller 44 in step S41, a timer is started t ₁ at step S42. Next, in step S43, the motor M2 is turned on, and the transport system is rotationally driven.
In step 4, the state counter is set to "9". Thus, the transport system starts the preliminary rotation shown in FIG.

If the operator forgets to remove the paper stopped in the fixing device 40 and turns on the jam reset key 95 during the paper jam processing, the paper is
The toner is conveyed to the downstream side by the rollers 1 and 44, but since the pressure bonding of the rollers 41 and 44 is completed before the conveyance operation, the toner on the sheet reaches the discharge roller 71 in a fixed state. In other words, the sheet on which the unfixed toner is loaded is not conveyed downstream of the rollers 41 and 44.

When the state counter is "9", that is,
When the preliminary rotation of the roller 41 and 44 is started, it determines whether a jam has occurred in step S45, if there is no occurrence of a jam, after confirming the termination of the timer t ₁ in step S46, step S47 To turn off the motor M2,
It resets the timer t ₁ at step S48. This completes the preliminary rotation of the transport system. Further, step S
The motor M1 is turned on at 49, and the state counter is set to "4" at step S50. With this, roller 4
When the release of the crimping of the sensors 1 and 44 is started, and thereafter the on-edge of the sensor SE10 is confirmed in step S29, the motor M1
Is turned off, and the fixing device 40 waits for the next copy operation.

On the other hand, if it is determined in step S45 that a paper jam has occurred, for example, the paper that has been forgotten in the fixing device 40 is transported to the discharge roller 71, and if a paper jam is detected here, in step S51. The motor M1 is turned on, and the motor M2 is turned off in step S52. With this, while the pressure release of the rollers 41 and 44 is started,
The preliminary rotation of the transport system stops. Next, the state counter is set to "6" in step S53. Thereafter, the jam reset processing is executed again.

The image forming apparatus according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the invention. For example, instead of an analog copying machine, a digital copying machine using an image reading device equipped with a CCD and a laser beam scanning optical system, or a printer that reproduces an image signal from a computer on paper may be used.

In the above control procedure, the preliminary rotation of the fixing device 40 after the warm-up of the fixing unit 40 when the main power is turned on is controlled at the timing shown in FIG. 6B. Or the other timings. Further, the pressing roller 4
Various mechanisms other than those shown in FIG. 2 can be employed as a mechanism for bringing the heating roller 41 into and out of contact with the heating roller 41.

[0036]

As is apparent from the above description, according to the present invention, when the image forming start signal is received, the transport system is driven immediately. The paper can be conveyed, and the image forming process can be sped up, particularly the first copy time can be shortened. Also, when a reset signal after a paper jam is received, the conveyance system is driven after the fixing roller is pressed, so that even if the paper left behind remains in the fixing device, the paper on the paper may be removed. The toner is conveyed downstream of the fixing device in a fixed state, so that there is no possibility that the discharge roller and the guide plate are stained with unfixed toner. Further, the operator does not carelessly touch his hands with unfixed toner.

[Brief description of the drawings]

 The drawings show an embodiment of the image forming apparatus according to the present invention.

FIG. 1 is a schematic configuration diagram of a copying machine.

FIG. 2 is a front view illustrating a contact / separation mechanism of a fixing roller.

FIG. 3 is an explanatory diagram showing an operation of a holder based on rotation of a cam.

FIG. 4 is an explanatory diagram showing an operation of a cam rotation angle detection mechanism.

FIG. 5 is a block diagram showing a control circuit.

FIG. 6 is a chart illustrating timings of a contact / separation operation of a fixing roller and a rotation drive of a conveyance system.

FIG. 7 is a flowchart showing a main routine of the CPU.

FIG. 8 is a flowchart illustrating a subroutine for controlling a fixing roller and a transport system.

9 is a flowchart showing a subroutine for controlling the fixing roller and the transport system, and is a continuation of FIG. 8;

FIG. 10 is a flowchart showing a subroutine for controlling the fixing roller and the transport system, and is a continuation of FIG. 9;

11 is a flowchart showing a subroutine for controlling a fixing roller and a transport system, and is a continuation of FIG. 10;

[Explanation of symbols]

 40 fixing device 41 heating roller 44 pressure roller 48, 60 holder 62 cam 90 CPU 94 copy start key 95 jam reset key M1 pressure drive motor M2 transport motor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-51181 (JP, A) JP-A-2-176689 (JP, A) JP-A-5-53473 (JP, A) JP-A-56- 52784 (JP, A) JP-A-56-146169 (JP, A) JP-A-61-121074 (JP, A) JP-A-58-220166 (JP, A) JP-A-63-216074 (JP, A) JP-A-4-115280 (JP, A) JP-A 63-115160 (JP, U) JP-A 54-74541 (JP, U) JP-B 62-4714 (JP, B2) (58) (Int.Cl. ⁷ , DB name) G03G 21/14 G03G 15/00 518 G03G 15/20 102 G03G 15/20 107

Claims (2)

(57) [Claims] An image forming apparatus having a toner fixing device capable of bringing a pair of fixing rollers into and out of contact with each other, the image forming apparatus comprising: a first driving unit that moves the fixing roller into and out; and a transport system that transports a sheet at least in the fixing device. second drive means for driving, when receiving an image formation start signal immediately while driving the second transport system by operating the driving means, when receiving a reset signal after a paper jam processing, first drive means To start the pressure bonding of the fixing roller ,
After the completion, the second driving means is operated to drive the transport system.
Image forming apparatus characterized by the that control means, comprising a. 2. The image forming apparatus according to claim 1 , wherein
When the signal is received, the first drive is performed simultaneously with the second drive means.
Activating the moving means to start the pressing of the fixing roller
The image forming apparatus according to claim 1, wherein: