JPH01296270A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the fault of images and to reduce power consumption during copying when the temperature of a photosensitive body drum is below an initial set temperature in a waiting state by heating a heater and raising the temperature of the photosensitive body drum until it reaches the initial set temperature. CONSTITUTION:A thermistor detects the temperature of the photosensitive body drum 7 and an initial temperature is determined in an initial temperature set circuit 44 by means of an outside air temperature sensor 45. Both values are compared in a heater control circuit 43. A main processor detects whether the drum 7 is in an image forming state or not. When the compared result of the control circuit 43 shows that the temperature detected by the thermistor 40 is below the initial set temperature, it is decided that the processor 48 is not in the image forming state. The control means 43 heats the heater 41 through a heat circuit 42 so that it reaches the initial set temperature. As a result, the occurrence of the fault of the images is eliminated and the power consumption during copying can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an image forming apparatus using electrophotographic technology.

(Prior art) Currently, in image forming apparatuses using electrophotographic technology, the temperature range in which images can be formed on the photoreceptor drum is determined, so the temperature of the photoreceptor drum is increased using a heater (first detection means). A method is used in which the temperature of the photoreceptor drum is set within a temperature range in which image formation is possible. First, for example,
As described in Publication No. 2-170980, a predetermined temperature is set in advance, and when the temperature of the photoreceptor drum is below the predetermined temperature, the heater is activated and the predetermined temperature and the photoreceptor drum temperature become equal. It is a method of heating up to Among these methods, there are methods in which the photoreceptor drum is not heated during the copying operation and the photoreceptor drum can be copied only after reaching a predetermined temperature, and methods in which the photoreceptor drum can be heated even during the copying operation.

In the former method, even if the drum temperature falls below the above-mentioned predetermined temperature during a copying operation in a low-temperature environment, the photoreceptor drum cannot be heated until one copying operation is completed, and the photoreceptor drum temperature does not increase. Image defects are more likely to occur due to a decrease in image quality.

In the latter method, since the heater is operated during the copying operation, the power consumption during copying is large and the current capacity cannot be kept low.

(Problems to be Solved by the Invention) As described above, in conventional image forming apparatuses, it is possible to prevent image defects and reduce power consumption during copying by controlling the temperature of the photoreceptor drum within a predetermined range. The drawback was that there was no device to keep it low.

In order to eliminate the above drawbacks, the present invention provides an image forming apparatus that prevents image defects from occurring and reduces power consumption during copying.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above problems, in the present invention, an image forming apparatus includes: a photoreceptor carrying an electrostatic latent image; a casing in which the photoreceptor is housed; The surface temperature of the photoreceptor is maintained at an optimal level based on a first detection means for detecting the temperature of the body, a second detection means for detecting the temperature outside the housing, and a detected value of the second detection means. an initial temperature setting means for setting an initial temperature; a comparison means for comparing a set value of the initial temperature setting means with a detection value of the first detection means; and an image forming state in which an image is formed using the photoreceptor as a medium. a detection means for detecting whether or not an image is being formed; and the detection means detects that the image forming state is not present, and the comparison means determines that the detected value of the first detection means is lower than the set value of the initial setting means. The present invention is characterized by comprising a heating means that heats the photoreceptor only when it is determined that the photoconductor is heated.

(Function) The initial setting temperature of the photoreceptor drum of the image forming apparatus is determined by the external environmental temperature, and the temperature of the photoreceptor drum is raised to the initial setting temperature. Furthermore, the temperature of the photoconductor drum is compared with the initial setting temperature, and if the main body of the apparatus is in standby mode and the temperature of the photoconductor drum is less than the initial setting temperature, the heater is activated and the photoconductor is heated to the initial setting temperature. The temperature of the drum is increased.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic cross-sectional view of a copying machine as an image forming apparatus according to an embodiment of the present invention. A document table 2 is provided on the upper surface of the copying machine main body 1 (hereinafter referred to as the main body 1), and an upper paper feed cassette section 3 and an upper paper feed cassette section 4 are provided on the right side of the main body. The upper paper feed cassette 3 and the upper paper feed cassette 4□ are installed. The cassette cover of the upper paper feed cassette 3 serves as a manual paper feed tray 5 for manually feeding copy sheets P1 as appropriate, and is referred to as a manual paper feed section 5. The copy paper taken out by each paper feed section is sent to a pair of registration rollers 19. A paper ejection tray 6 is attached to the left side of the main body. Next, the internal structure of the main body l will be explained. A photosensitive drum 7 is disposed approximately at the center of the main body. Around the photosensitive drum 7, a charging charger 8, an optical system 9, a developing device 10, a transfer charger 11, a stripping charger 12, a cleaning device 13, a static elimination lamp 14, etc. are arranged in order. There is. A copy paper transport path 17 is formed below the photosensitive drum 7 to guide the copy papers P 1 P 2 and P 3 from the paper stop switch 18 to the paper discharge tray 6 . Around the copy paper conveyance path 17, from the upstream side, there are a paper stop switch 18, a pair of registration rollers 19, a transfer charger 11, a peeling charger 12, a fixing device 20, a paper discharge device 21, a paper discharge switch SW, and a paper discharge device. Tray 6
are arranged in sequence. The fixing device 20 includes a heat roller 201 and a pressure roller 202. The heat roller 20 and the pressure roller 20□ are provided above and below the copy paper strip feeding path 17. The heat roller 2o and the pressure roller 202 rotate to sandwich the copy paper and convey the toner image on the copy paper downstream while passing through the heating chamber. The paper ejection device 21 is provided with two rollers and a paper ejection switch SW. The copy paper is held between the two rollers and discharged, and at this time the paper discharge switch SW is turned on.

Ejection of the copying device is detected by turning on the paper ejection switch SW. Further, each of the above-mentioned paper feed sections is provided as a pre-process of the copy paper conveyance path 17. The lower paper feed cassette section 3 is configured with the following device as means for supplying the copy paper P2 stored in the upper paper feed cassette 3 to the copy paper transport path. The pickup roller 5, the paper feed roller 312, the separation roller 313, etc. from the one closest to the upper paper feed cassette 31.

The lower paper feed cassette section 4 is configured with the following device as means for supplying the copy paper P3 stored in the lower paper feed cassette 41 to the copy paper transport path 17.

The pickup roller 6, the paper feed roller 314, the separation roller 315, etc. are arranged in order from the one closest to the lower paper feed cassette 41. The manual paper feed section 5 feeds the copy sheets P1 stacked on the manual paper feed table 5 to the paper feed roller 31 of the overprint paper cassette section 3.
□ and the separation roller 313, and is composed of a feed roller 311 and the like.

The optical system 9 described above includes an exposure lamp 26 whose back part is surrounded by a reflector 25, mirrors M1 to M6, and a lens 28.
It has a configuration with.

Inside the main body 1, an upper frame and a lower frame (not shown) are pivotally supported at one end via a support shaft (not shown), and the other ends of both frames can be opened at a predetermined angle, for example, about 30 degrees. It is composed of

Inside the upper frame, around the photoreceptor drum 7, a charging device 8, an optical system 9, an exposure lamp 26, a developing device 10.
It has a configuration in which various devices such as a cleaning device 13 and a static elimination lamp 14 are provided. Furthermore, a document table 2, a lower paper feed cassette section 3, and a manual paper feed section 5 are attached to the upper frame to constitute an upper unit IA.

The lower frame has a lower paper feed cassette section 4 and a transfer charger 1.
1. Mechanisms such as a peeling charger 12, a fixing device 20, a paper discharge device 21, and a paper discharge tray 6 are provided by appropriate means, and constitute a lower unit IB.

After the front cover of the main body 1 is rotated and removed, it can be opened and closed approximately along the copy paper conveyance path 17 via a housing opening/closing device (not shown).

If the casing is openable and closable along the copy paper transport path 17, the various rollers interposed therein can be easily replaced.

The operation of the apparatus configured as described above will be explained below.

The photoreceptor drum 7 is moved by a drive mechanism (not shown) as indicated by the arrow a in the drawing.
direction in synchronization with the optical system 9.

During operation, the temperature of the surface of the photosensitive drum 7 that carries a toner image is controlled within a predetermined range. This control device will be explained later. When the operation starts, the photosensitive drum 7 is uniformly charged by the charging device 8. Next, the exposure lamp 26 uniformly irradiates the original with light. The optical system 9 forms a projected image of the document using scattered light onto the photosensitive drum 7, thereby forming an electrostatic latent image. The developing device 10 develops the electrostatic latent image on the photoreceptor drum 7 with toner. The toner image formed on the photosensitive drum 7 as described above is sent onto the transfer charger 11.

On the other hand, copy sheets P1, P, or P3 (hereinafter referred to as copy sheets P) supplied by the paper feed section are conveyed onto the transfer charger 11 by rotation of a pair of registration rollers 19. The rotation of the pair of registration rollers 19 is sequentially controlled as the paper stop switch 18 is turned on. This sequence control is for synchronizing the toner image on the photosensitive drum 7 and the copy paper P so that they overlap.

The toner image on the photoreceptor drum 7 is transferred onto the copy paper P supplied onto the transfer charger 11 by the transfer charger 11 . The copy paper P onto which the toner image has been transferred is peeled off from the photosensitive drum 7 by a peeling charger 12 and guided to a fixing device 20 . A toner image is melted and fixed on the copy paper P by a fixing device 20, and the copy paper P is guided to a paper discharge device 21. Then, the copy paper P is discharged to the paper discharge tray 6 by the paper discharge device 21. At this time, the paper ejection switch SW is turned on once to detect the ejection of the copy paper P.

On the other hand, after the toner image on the photoreceptor drum 7 is transferred to the copy paper P, residual toner remaining on the photoreceptor drum 7 is cleaned by a cleaning device 13. Furthermore, the afterimage of the charge on the photosensitive drum 7 is erased by the static elimination lamp 14, and the photosensitive drum 7 is prepared for the next copying operation.

The above series of operations is achieved by the microcomputer driving control objects such as motor lamps and heaters in a fixed sequence in response to operation switches, detection switches provided at appropriate locations, and other signal output signals. .

Next, the control system for the surface temperature of the photosensitive drum 7 mentioned above will be explained with reference to FIG. FIG. 1 is a block diagram of a control system for controlling the surface temperature of the photosensitive drum 7. As shown in FIG.

The above-mentioned photoreceptor drum 7 is provided with a thermistor 40 so as to be in sliding contact with the surface of the photoreceptor drum 7. The thermistor 40 is provided at either end of the photosensitive drum 7 where no image is formed on the surface thereof. A heater 41 for heating the photoreceptor drum 7 is fixed and provided inside the photoreceptor drum 7 . A heater heating circuit 42 for driving the heater 41 is connected to the heater 41 . An output part of a heater control circuit 43 that controls turning on and off of the heater heating circuit 42 is connected to an input part of the heater heating circuit 42 .

The input section of the heater control circuit 43 is the thermistor 4 described above.
Initial temperature setting circuit 4 for determining 0 and initial setting temperature
The four output sections are connected separately. The input section of the initial temperature setting circuit 44 is connected to a ? An outside air temperature sensor 45 that detects FjL degrees is connected. The outside temperature sensor 45 is provided, for example, on the right side in FIG.

This is to more appropriately set the drum temperature by detecting the environmental temperature around the copy paper P, which affects the surface temperature of the photosensitive drum 7.

An input section of the heater control circuit 43 is connected to one of the output terminals of a main processor 48 that controls the entire copying machine. Here, the main processor 48 is used as a detection means for detecting whether or not the main body 1 is in an image forming state. This detection operation will be explained in detail later. Another output terminal of the main processor 48 is connected to an input section of a driver 46 for driving a motor. An input section of a drum motor 47 that rotationally drives the photosensitive drum 7 is connected to an output section of the driver 46 .

The input terminal of the main processor includes an output section of an operation panel 49 provided with keys for starting copying, setting the number of copies, etc., an output section of the above-mentioned paper ejection switch SW, and detecting the toner concentration in the above-mentioned developing device 10. The output section of an auto toner sensor 50 is connected thereto.

The operation of this control system is as follows.

The outside temperature T detected by the outside temperature sensor 45 is input to the initial temperature setting circuit 44 as a voltage value. Further, the drum temperature T detected by the thermistor 40 is input to the heater control circuit 43 as a voltage value. Outside temperature sensor 4
5, the detected value of the outside temperature T input into the initial temperature setting circuit 44 is set to the drum set temperature T according to the magnitude of the signal.
Output as 1. The outside air temperature T and the drum set temperature T1 have a relationship as shown in FIG. That is, when the outside temperature T is in a region (T≦T-) below a certain temperature T- (for example, 28° C.), the lower the outside temperature T is, the higher the drum set temperature T1 becomes.

However, the area where the outside temperature T is higher than the temperature T''(T>T'')
, regardless of the outside temperature T, the drum set temperature T
becomes a constant temperature T- (for example, 28°C). Theoretically, when the outside air temperature T is in a region higher than the temperature T', it is preferable that the higher the outside air temperature T is, the higher the drum set temperature T is.

To achieve this, it is necessary to provide a separate cooling device. In this embodiment, from the viewpoint of simplifying the apparatus, the drum set temperature T1 is set to the temperature T' as the upper limit as described above, and cooling is not performed. Even in such a case, as will be described later, according to experiments conducted by the present inventors, problems such as abnormal drum surface temperature do not occur.

The drum set temperature T1 shown in FIG. 3 is output from the cut-off temperature setting circuit 44 and input to the heater control circuit 43.

In the heater control circuit 43, a voltage value corresponding to the drum setting lH degree T1 is compared with a voltage value corresponding to the drum temperature TD output from the thermistor 40. Even if the drum temperature TD is lower than the drum set temperature T as a result of this comparison, if the main body is in an image forming state, no drive signal is supplied from the heater control circuit 43 to the heater heating circuit .

Here, a case where the main body 1 is in an image forming operation and a case where the main body 1 is on standby for image forming will be explained using FIGS. 1 and 5.

When the main body 1 is powered on, the following state is assumed to be an image forming operation in progress.

The image forming operation of the main body 1 is started by turning on a copy key (not shown) after setting the number of copies, density, etc. using the keys on the operation panel 49. When the copy key is turned on, a copy start signal is supplied from the operation panel 49 to the main processor 48. Main processor 48 supplied with a copy start signal
sequentially supplies various signals to the heater control circuit 43, driver 46, and other devices (not shown) in the image forming process. Here, the main processor 48 is
An rHIGHJ level signal is supplied to the driver 46 to rotate the drum motor 47. Then, the driver 46 rotates the drum motor 47.

On the other hand, the main processor 48 supplies an rLOWJ level signal to the heater control circuit 43 so as not to drive the heater heating circuit 42 . Then, the heater control circuit 43
A drive signal is not supplied to the heater heating circuit 42 under any condition.

In this way, the image forming operation of the main body 1 is started, and the main processor 48 sends rLOW to the heater control circuit 43 until the number of copies set on the operation panel 49 is completed.
A J level signal is supplied.

In the image forming operation of the main body 1, the final copy of the number of copies set before the start of this copying operation is activated by the above-mentioned paper ejection switch SW.
It ends by inputting .

At the end of the set number of copies, press the eject switch S.
When W is turned on, the paper ejection switch SW supplies a signal at the l-HI GHJ level to the main processor 48.

The main processor 48, which is supplied with the rHIGHJ level signal from the paper ejection switch SW, outputs the auto toner sensor 50.
If a signal at the rLOWJ level is supplied from the heater control circuit 43, a signal at the rHIGHJ level is supplied to the heater control circuit 43, and a signal at the rLOWJ level is supplied to the driver 46. rLOWJ
The driver 46 supplied with the level signal stops driving the drum motor 47. The auto toner sensor 50 supplies a "LOW" level signal to the main processor 48 if the toner comparative density in the developing device 10 described above is in an appropriate state for image formation. However, when the specific toner density within the developing device 10 is not in an appropriate state for image formation and there is a toner shortage, a signal at the rHIGHJ level is supplied to the main processor 48 .

The main processor 48, which is supplied with the rHIGHJ level signal from the paper ejection switch SW, outputs the auto toner sensor 5.
If a signal from 0 to rHIGHJ level is supplied, toner is supplied into the developing device by a toner supply means (not shown), and rLO is supplied to the heater control circuit 43 until a signal at rLOWJ level is supplied from the auto toner sensor 50.
The WJ level signal continues to be supplied to the driver 46.The HIGHJ level signal is continuously supplied to the driver 46.The signal supplied from the auto toner sensor 50 to the main processor 48 is
After reaching the level, the process is as described above.

In this way, the image forming operation ends when the rHIGHJ level signal is supplied to the heater control circuit 43 and the rLOWJ level signal is supplied to the driver 46.

Comparing the two voltage values, if the main body 1 is on standby for image formation and the drum temperature T is lower than the drum set temperature T1 (TI>TD), the heater control circuit 43 drives the heat heating circuit 42. In order to
Supplies rHIGHJ level signal. The heater heating circuit 42 supplied with the rHIGHJ level signal from the heater control circuit 43 is driven and turns on the heater 41 . The photosensitive drum 7 is heated by turning on the heater 41, and the surface temperature is raised to the drum set temperature T1. If image formation is still in progress even if the temperature of the photosensitive drum 7 falls below a predetermined temperature, the heater 41 will not be turned on.

When the two voltage values are compared, if the drum temperature TD is equal to or higher than the drum set temperature T (T ≦T o ), the heater control circuit 43 sets rLOWJ to the heater heating circuit 42 regardless of whether image formation is in progress or not. Supply a level signal. The heater heating circuit 42 supplied with the LOWJ level signal from the heater control circuit 43 is not driven, and the heater 4
Turn off 1. Since the heater 41 is turned off, the photosensitive drum 7 is not heated.

FIG. 5 shows the drum temperature TD in the copying machine of this embodiment.
This is a graph showing changes in . The solid line in FIG. 5 shows the change in drum temperature TD when the copying machine of this embodiment is used in a normal temperature environment.

The broken line in FIG. 4 shows the change in drum temperature T when the copying machine of this embodiment is used in a low temperature environment.

After the power is turned on, the outside air detected by the outside temperature sensor 45/2
Based on iT, the drum set temperature T1 is determined through the initial temperature setting port 44 as described above. Outside air under normal temperature environment and low temperature environment? Since the HT is different, the drum set temperature T1 is also different. In a low temperature environment, the drum set temperature T1
□, and in a normal temperature environment, the drum set temperature becomes T11.

As described above, the heater 41 is turned on and the photoreceptor drum 7 is heated until the drum temperature TD reaches the drum set temperature T1 corresponding to each outside temperature T. At this time, the state on the main unit is warming up. Drum temperature TD
becomes equal to the drum set temperature T1, the heater 4
1 is turned off. The main body 1 is now in a standby state ready for copying operations.

When the copying operation is started by inputting the copy key, the drum temperature T,
decreases. On the other hand, in a normal temperature environment, the drum temperature TD also rises because the machine body temperature rises with the copying operation. In each environment, the drum temperature T converges to a specific temperature during continuous copying, depending on the environmental temperature. This convergence temperature is related to the machine body temperature, the outside temperature T, the copy paper temperature, and the like.

In a low temperature environment, the drum set temperature at the start of copying is T.
The drum temperature T is set high as <T. Therefore, at the time of convergence, the drum temperature TD never falls below the lower limit of the copyable temperature.

As mentioned above, if the drum temperature T is below the drum set temperature T1 at the end of copying, the drum temperature T at the end of copying
, to the drum set temperature T1 again, the heater heating circuit 42 is controlled by a heater control circuit 43. At the end of copying, the outside air temperature T is detected by the outside air temperature sensor 41, the drum set temperature T1 is again determined by the initial 1m degree setting circuit 44, and the heater 41 is turned on as described above.

In this way, at the start of copying, the drum temperature TD is
It is controlled to be equal to the drum set temperature T1 according to the outside air temperature T.

The above-described configuration can be obtained by providing the outside temperature sensor 45 in a conventional device and improving the control software, so it can be easily modified and realized at low cost. Further, the image forming standby state is not limited to this embodiment.

Note that the present invention is not limited to the above embodiments. The reference temperature for determining the set temperature may be set as appropriate depending on the material of the photoreceptor drum.

The present invention is not limited to copying machines, but may be applied to any image forming apparatus that requires temperature control of a photoreceptor.

(Effects) As described in detail above, according to the present invention, the initial setting temperature of the photoreceptor drum is determined from the environmental temperature outside the image forming apparatus, and the heater is turned on only when the apparatus is in the standby state. Since the photoreceptor drum maintains the temperature at which it can form an image,
This has the effect of preventing image defects from occurring and reducing power consumption during copying.

[Brief explanation of the drawing]

1 to 5 show a practical example of the present invention. FIG. 1 is a block diagram showing a control system for the photoreceptor drum temperature, and FIG. Is the cross-sectional view of the photocopier, Figure 3, outside air? 1μ
4 is a flowchart to explain the image forming standby state, and FIG. 5 is a graph to explain the relationship between the photoreceptor drum temperature and the drum set temperature. 7... Photosensitive drum, 40... Thermistor (first detection means), 41... Heater (heating means), 42
... Heater heating circuit (heating means), 43 ... Heater control circuit (comparison means), 44 ... Initial temperature setting circuit (
initial temperature setting means), 45... outside temperature sensor (second detection means), 48... main processor (detection means)
Agent Patent Attorney Nori Ken Chika Yudo Yamashita - Figure 3 Figure 4

Claims (1)

[Scope of Claims] A photoreceptor carrying an electrostatic latent image, a housing in which the photoreceptor is housed, a first detection means for detecting the temperature of the photoreceptor, and a temperature outside the housing. an initial temperature setting means for setting an initial temperature of the surface temperature of the photoreceptor from a detection value of the second detection means; a comparison means for comparing the detection value of the detection means; a detection means for detecting whether or not an image is being formed using the photoreceptor as a medium; and a heating means for heating the photoreceptor only when the comparison means determines that the detected value of the first detection means is lower than the set value of the initial setting means. .