JPH02298980A - Image forming device - Google Patents

Abstract

PURPOSE:To improve fixing performance by making a warmup only by the heating means for a heating roller and making the quantity of copies per unit time small until specific fixation temperature is reached. CONSTITUTION:For the warmup after the power source is turned on, only the fixing heater lamp 44 of a fixing device 28 is turned on and the operation is completed when a thermistor 48 detects the heat roller 41 reaching the target fixation temperature of 190 deg.C. Then when a print button is pressed for the 1st time, the lamp 44 is turned on and a main motor is driven to rotate the roller 41 and a pressure roller 45; and the number of copies to be taken per unit time is made smaller than usual until the surface temperature of the roller 41 rises above 190 deg.C and the contact time of the rollers 41 and 45 is made relatively long to uniform a temperature distribution. Then the operation is returned to normal operation after the surface temperature rises above 190 deg.C, and thus the excellent fixing performance is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus, and particularly to an image forming apparatus that is designed to ensure quietness during warming up after turning on the power, and good fixing performance during the so-called first copying operation in the morning. 6 ``Prior art'' Heat roll fixing is a common fixing method for fixing toner images transferred onto copy paper. A fixing means that maintains a roller and a pressure roller in a non-rotating state6 and rotates both rollers together for a certain period of time when the surface temperature of a heating roller reaches a predetermined temperature is disclosed in Japanese Patent Publication No. 61-3.
No. 1462.

This fixing means was developed to speed up the rise in surface temperature of the roller during warm-up and to perform the subsequent fixing well.

Further, a fixing means that reduces the copying speed when the surface temperature of the fixing roller drops below a predetermined temperature during continuous copying is also known from Japanese Patent Laid-Open No. 143067/1983.

This fixing means is designed to perform the copying operation without interrupting even if the fixing temperature drops below a predetermined temperature during continuous copying.

``Problem to be Solved by the Invention'' However, in the former fixing means described above, when the surface temperature of the heating roller rises to a predetermined temperature during warming-up after the power is turned on, from that point on, the fixing means rotates together with the pressure roller. Due to heat conduction from the heating roller to the pressure roller, when the surface temperature of both rollers reaches the fixing target temperature, the rotation of both rollers is stopped and warming-up is completed. When not in use, the so-called preliminary rotation of both rollers may suddenly start, surprising the user. In addition, the sound of the rotation of both rollers during the copying standby period causes a psychological burden on the user and causes inconvenience in use-E, such as increasing irritation.

The latter fixing means prevents the continuous copying operation from being interrupted due to a drop in the fixing temperature, and ensures quietness during warming up, and also during the first copying in the morning after warming up is completed.
This was not a solution for ensuring good fixing properties.

The present invention has been made with attention to the above-mentioned points, and provides an image forming apparatus that can ensure quietness during warming up after turning on the power, and can also ensure good fixing performance during so-called first copying in the morning. The purpose is to

"Means for Solving the Problems" The specific means for achieving the above object includes a heating roller having a built-in heating stage, a pressure roller that rotates in contact with the heating roller that is rotationally driven, and a heating roller that rotates in contact with the heating roller that is driven to rotate. In an image forming apparatus equipped with a fixing means including a temperature detection means for detecting the temperature of a roller and a temperature control means for controlling the heating means based on a temperature detection signal, both rollers of the fixing means are rotated when the power switch is turned on. Warming-up is performed by driving only the heating means without driving the heating means, which is completed when the temperature detection means detects a predetermined temperature, and when the first copy start command signal is input after the completion of the warming-up, the fixing means The heating means, the pressure roller, and the heating roller are both driven, and until the temperature detection means detects a predetermined fixing target temperature, the number of copies per unit time is reduced compared to normal copying operation. The present invention is characterized in that a copying control means is provided for performing the copying operation and returning to the normal number of copies after detecting the fixing target temperature.

[Function] According to the above-mentioned specific means, warming-up after the power is turned on is performed by driving only the heating means built in the heating roller without rotating the heating and pressure roller, and the first warm-up after warming-up is completed. When a copying start command signal is input, the heating means of the fixing means and both the pressure roller and the heating roller are driven, and until the temperature detection means detects a predetermined fixing target temperature, the temperature is increased per unit time. The copying operation is performed by reducing the number of copies compared to the normal case, and after the fixing target temperature is detected, the copying operation is performed to return to the normal number of copies.

[Embodiment J] An embodiment of the present invention will be described with reference to the accompanying drawings in an embodiment using a copying machine as an image forming apparatus.

FIG. 1 shows a schematic sectional view of a copying machine which is an image forming apparatus according to the present invention.

The copying mechanism of the copying machine main body 1 is similar to that of a conventional electrophotographic copying machine. A photoreceptor drum 2 that can be rotated in a counterclockwise direction is disposed in the center of the copying machine body 1, and a main eraser lamp 3. Charger 6, developing device y17. Transfer charger8. Transfer paper separation charger9. Blade-type cleaner devices 10 and the like are sequentially installed. The photoreceptor drum 2 is a drum provided with a photoreceptor (for example, selenium) on its surface, and upon each copying, it is irradiated with light by an eraser lamp 3 and charged by passing through a charger 6, and then is charged as described below. The main motor M1 receives image exposure from the optical system.The main motor M1 drives the photosensitive drum 2 and the like.

The optical system is arranged below the document platen glass 11 so as to be able to scan the document image. The optical system includes a light source 12, a first mirror 13. 2nd mirror]4. Third mirror 15. Projection lens 1
6. It is composed of a fourth mirror 17. The original image is captured by each mirror 13, 14, 15, as indicated by a dashed line 18.
1.7, it reaches the photosensitive drum 2.

On the left side of the copying machine main body 1, an automatic paper feed cassette 20a is arranged in the upper paper feed slot, an automatic paper feed cassette 20b is arranged in the lower paper feed slot, and a manual paper feed section 21 is arranged in the second part. .

Automatic paper feed cassette 20a.

The copy paper in 20b or the manual paper feed section 21 is selectively fed into the copying machine main body 1 by the respective paper feed rollers 22 and 23, passes through each pair of transport rollers 24 and 25, and is in a pressed state at a certain timing. It is conveyed to rollers 26, where it is temporarily on standby.

At the time of transfer, the copy paper fed by the timing roller 26 comes into close contact with the photoreceptor drum 2 in the transfer section, and the toner image is transferred by the corona discharge of the transfer charger 8, and then the toner image is transferred by the corona discharge of the separation charger 9 and the copy paper is The paper is separated from the photosensitive drum 2 by its own stiffness. Next, the copy paper is sucked onto a conveyor belt 27 equipped with an air suction means (not shown) and conveyed to the right as the belt 27 rotates clockwise. The toner image is melted and fixed by passing through a fixing device 28 consisting of a toner image. and,
It passes through a pair of discharge rollers 29 and reaches a tray 30 outside the copying machine main body 1.
Alternatively, it is discharged to a T-combiner or the like (not shown).

FIG. 2 is an enlarged side view of the fixing device 28.

Reference numeral 41 denotes an upper fixing roller which is a heating roller. A Teflon coating layer 43 is formed on the outer periphery of a metal hollow rotating shaft 42 in order to improve release properties, and a fixing heater lamp is provided inside the hollow rotating shaft 42. 44 is installed inside the heating means. 45 is a lower fixing roller which is a pressure roller,
A silicone rubber coating 14 is placed around the outer periphery of the metal hollow rotating shaft 46.
7 is applied, and spring elasticity is applied to the shaft support portions at both ends to bring them into pressure contact with the upper fixing roller 41 to improve fixing performance.

Reference numeral 48 denotes a fixing thermistor installed to detect the surface temperature of the upper fixing roller 41, which is a force 1 heat roller.

Reference numerals 49 and 50 indicate separation claws provided to prevent the copy paper from wrapping around the upper and lower fixing rollers 41 and 45.

FIG. 3 is a schematic control circuit diagram of the device of this embodiment,
/D converter built-in CPU has ACloo outlet.
When connected to the power supply of V, the power supply starts with the DC5V power of the power supply circuit 61 regardless of whether the power switch 62 is on or off. When the power switch 62 is turned on,
63 to the main switch 7 of the switch matrix 64
0 is turned on. 71 is a print button for inputting a copying operation start command. The switch matrix 64 includes various display sections 65, and the switch matrix 64
Inputs from the various switches constituting the CPU are time-divisionally input to the CPU using a decoder 66.

The temperature signal detected by the fixing thermistor 48 is input to the analog port of the CPU, A/D converted, and processed as temperature data, and information regarding the control of the copying machine is input to the other input ports.

Each output port of the CPU is connected to the main motor Ml of the copying machine main body 1, the electrostatic charger 6, and the transfer charger 8.
．． Drive switching transistors (not shown) are connected to the heater lamp 44 of the fixing device 28, the developing device clutch that drives the developing device 7, the paper feed rollers 22 and 23 clutch, and the timing roller 26 clutch. Other outputs are sent out as control information for peripheral circuits.

FIG. 4 is a flowchart showing an outline of the main routine of the CPU that controls the entire copying machine.

Before explaining the flowchart, the terms on-edge and off-edge will be defined.

On-edge is defined as when the state of a switch, sensor, signal, etc. changes from an off state to an on state.

Off-edge is defined as an off-edge when the state of a switch, sensor, signal, etc. changes from an on state to an off state.

When the CPU is reset and the program starts, step Sl (hereinafter abbreviated as step) clears the RAM, initializes CI (CI) U, sets various registers, etc., and performs initial settings to put the copier into the initial mode. .

In S2, an internal timer built into the CPU and preset with 1 routine time in the initial setting is started, and in each step from <83 to S6, the key, switch turning, temperature adjustment routine, and copy operation routine are started. , and other processing routines are sequentially called, and when all the subroutine processing is completed, the first routine is terminated after waiting for the end of the internal timer set first (87).

The time length of this l routine is used to count the various timers used in each subroutine.The various timer values can be used to judge the end of the timer depending on how many times this one routine has been counted. can.

FIG. 5 is a flowchart showing the temperature adjustment routine.

First, in step 5200, it is determined whether or not the power switch 62 is in the on state. If it is in the off state, the answer is No and the flag F2
is set to "1", and the flag Fl is reset to "0" at 5220. The flag F2 is a flag for storing that the power switch 62 is turned off, and the flag F1 is set to 1-mining up and the target fixing temperature is 19.
This flag indicates that the temperature control state is 0° C. (hereinafter referred to as temperature control state).

Next, the process advances to 5250, where the fixing heater lamp 44 is turned off and this subroutine ends.

In this case, even when the power is off, the CPU is backed up by a 5V DC power source, as explained in the control circuit above.

If the power switch 62 is in the on state at step 3200, the answer is YES and the process proceeds to step 8230, where it is determined whether the detected temperature TU of the fixing thermistor 48 is the fixing target temperature 190° C. or higher, and if it is 190° C. or higher, the answer is YES. At 8240, the flag F1 is set to "1", and at 5250, the fixing heater lamp 44 is turned off. Also, the TU is 190 in the above 5230
If the temperature is lower than .degree. C., the process proceeds to 8260, where the fixing heater lamp 44 is turned on, and this subroutine ends.

FIG. 6 is a flowchart showing the copy operation routine.

First, in 8300, it is determined whether the flag F1 is set to "1" or not, and if F1=0, that is, the power switch 62 is off, or the warming-up is completed with the power switch 62 on. Since this is not the case, return and end this subroutine.

If flag F1 = 1, the copying can be started after the warming-up has been completed, and the process proceeds to step 5310, where it is determined whether the print button 71 is on edge (when the state of the switch changes from the off state to the on state). If it is on-edge, the answer is YES, and the process goes to 5320, where the main motor M1 is turned on and started, and the heating roller 41 of the fixing device 28 is heated.
Then, the pressure roller 45 is rotated and the fixing heater lamp 44 is turned on. Continued (Flag F2 is set to rl in S330)
Determine whether or not it is set to J. If F2=1, this indicates that the print button 71 is pressed for the first time after the power switch 62 is turned on, that is, in the morning. It is determined whether the temperature TU detected by the thermistor 48 is 190° C. or higher. N if lower than 190℃
After setting flag F3 to "1" at 5350 at O,
The process advances to 8360 to start a copying operation in a second copying mode, which will be described later. If the temperature is 190℃ or higher, YES, 537
Proceed to 0 and determine whether flag F3 is set to "1"; if F 3 = O, then N.

Then, proceed to 8360 and perform the copying operation in the second copy mode.If F3=1, proceed to 3380 with YES, reset the flags F2 and F3 to "0", and then proceed to 5390 to copy in the first copy mode described later. Start operation.

The flag F3 indicates that when the main motor is turned on and the heating roller 41 and pressure roller 45 start rotating after the power switch 62 is turned on and warming-up is completed, heat is transferred from the heating roller 41 to the pressure roller 45. Since the surface temperature of the heating roller 41 once drops to below 190°C due to conduction, this is confirmed and the normal copying operation (first copying mode) is performed only after it rises above 190°C again. It's a flag. That is, in the morning after the so-called warm-up is completed, while the surface temperature of the heating roller is lower than 190°C, and while the surface temperature of the heating roller is 190°C or higher and the flag F3 is set to rl.
If it is not set to J, the copying operation is performed in the second copying mode.

On the other hand, if the flag F2=0 in 5330, the current print button 71 is pressed after the power switch 62 is turned on.
This indicates that warming-up has already been completed and the copying operation has been performed in the first copying mode by the time the button is pressed, and the process immediately advances to 5390 to begin the copying operation in the first copying mode.

If the print button 71 is not on-edge at 5310, go to 5400, and if copying is currently in progress, determine whether or not the copying operation for the set number of sheets has been completed.If not, go to 5330-5390 with NO. Execute each step, and if the copying operation for the set number of sheets is completed, press YES to 8.
The process advances to 410 to end the copying operation.

Next, the first copy mode and the second copy mode will be explained.

The first copy mode is for copying using normal copying operations, and the second copy mode is for copying with a reduced number of copies per unit time compared to the first copy mode. .

One way to reduce the number of copies per unit time in the second copying mode is to make the system speed of the copying machine slower than the system speed in normal copying operations.

For example, the normal system speed of about 200 am/sec, which is the speed at which A4-sized copy paper is passed across when copying at the same size, is reduced to about 150 m+*/sec. In this second copy mode, the system speed is reduced through comprehensive adjustment of the scanning speed of the scanning system, the paper feeding interval, the amount of light emitted from the exposure lamp, and the like.

In addition, by using two types of paper feed interval timers, one for the first copy mode and one for the second copy mode, and increasing the paper feed interval in the second copy mode, the number of copies per unit time can be reduced. 1. For example, when A4 size copy paper is passed horizontally during full-size copying, the paper feeding interval in the first copy mode is set to 200-rings between the trailing edge of the copy paper and the leading edge of the next copy paper. Expand the 300 theory.

In the copy operation routine of the above embodiment, the warming-up when the power switch 62 is turned on t& is performed by turning on only the fixing heater lamp 44, which is the heating means, without rotating the heating roller 41 and pressure roller 45 of the fixing device 28. This is completed when the fixing thermistor 48 detects that the heating roller 41 has reached the fixing target temperature of 190° C., ensuring quietness during warming up. In the morning when the print button 71 is pressed for the first time, the fixing heater lamp 44 is turned on and the main motor M1 is driven to rotate the heating roller 41 and the pressure roller 45 in contact with the heating roller 41 to a temperature of 190° C. The surface temperature of the heating roller 41, which has fallen below 190℃ again
Until this happens, the number of copies per unit time is reduced compared to the normal copying operation, and the contact time between the heating roller 41 and the pressure roller 45 is relatively increased. By promoting heat conduction between the rollers to make the temperature distribution uniform, and returning to normal copying operation after the temperature rises to 190° C. or higher, good fixability of the copied image is ensured. During this time, the fixing heater lamp 44 built into the heating roller 41
is controlled on and off to maintain the fixing target temperature by a temperature adjustment operation routine.

It should be noted that the copying termination described in each of the above embodiments and the first.
Since the subroutines of the second copy mode are outside the scope of the present invention and their basic operations are well known, their explanations will be omitted.

[Effects of the Invention] As clarified in the explanation of the above-mentioned specific means and operation, the present invention performs warming-up after turning on the power by driving only the heating means of the fixing means. Also, warming up can be performed quietly without the pressure roller starting to rotate and surprising the user, and heat is conducted to the pressure roller that contacts the heating roller when it is not rotating. The time interval until the temperatures of both rollers become uniform can be shortened, and the time required to reach the fixing target temperature can be shortened. In addition, warming up after the power is turned on is performed by driving only the heating means built into the heating roller without rotating the heating and pressure roller, and when warming up is completed, f&M's first copy start command signal is input. The heating means of the fixing means and both the pressure roller and the heating roller are driven, and the number of copies per unit time is reduced compared to the normal case until the temperature detection means detects a predetermined fixing target temperature. After the fixing target temperature is detected, the copying operation returns to the normal number of copies, so if the temperature drops below the fixing target temperature, the heating roller The contact time with the pressure roller increases,
The speed of heat conduction between both rollers is relatively increased, and uniformity of temperature distribution can be promoted, and good fixing performance can be ensured from the first copying operation, even when copying is done first thing in the morning. Furthermore, since the operation of the copy control means is controlled based on the temperature detection signal, there are various effects such as further uniformity of temperature distribution between the heating roller and the pressure roller.

[Brief explanation of drawings]

The accompanying drawings illustrate embodiments of the present invention, in which FIG. 1 is a schematic sectional view of a copying machine main body which is an image forming apparatus, FIG. 2 is an enlarged sectional view of a fixing device, FIG. 3 is a schematic control circuit diagram, and FIG. 4 is a flowchart of the main routine, FIG. 5 is a flowchart of the temperature adjustment routine, and FIG. 6 is a flowchart of the copy operation routine. 28 .Fixing device 41 .Heating roller 4
5. Pressure roller 48. ,,fixed thermistor,
62 , source switch, 71 , print button. Figure 2

Claims (1)

[Scope of Claims] A heating roller having a built-in heating means, a pressure roller rotating in contact with the rotationally driven heating roller, a temperature detecting means for detecting the temperature of the heating roller, and a temperature detecting means for detecting the temperature of the heating roller. In an image forming apparatus equipped with a fixing means including a temperature control means for controlling a heating means, when a power switch is turned on, only the heating means is driven without rotationally driving both rollers of the fixing means, and the temperature detection means is set to a predetermined value. Performs a warm-up that is completed by temperature detection, and when the first copy start command signal is input after the completion of the warm-up, drives the heating means of the fixing means and both the pressure roller and the heating roller, Until the temperature detection means detects a predetermined fixing target temperature, the copying operation is performed with the number of copies per unit time being reduced compared to the normal case, and after the fixing target temperature is detected, the number of copies is returned to the normal number of copies and the copying operation is performed. An image forming apparatus characterized in that it is provided with a copy control means for performing the following operations.