JPH0996971A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent unsatisfactory transfer of a toner image to a recording material, which occurs in the image before a fixed time elapses after a power source is turned on, by providing a means for controlling a heating means in order to adjust the temperature of a transfer means. SOLUTION: The heater 50 is provided beneath a transfer unit 23, that is, in such a place where the transfer unit 23 is positioned so that heat emitted from the heater 50 is convected and conducted in a copying machine. Also, the heater 50 is connected to the temperature control means 51, and the paper- transfer bias roller 23a is controlled by the control means 51 so as to be kept at temperatures in a fixed range determined in advance. Therefore, because the paper-transfer bias roller 23a is kept at the temperatures in the fixed range even in a case the temperature of the inside of the copying machine is low, as when a power source is turned on, unsatisfactory transfer which results from a copying operation with the transfer bias roller 23a having a low temperature is 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 copying machine, a facsimile, and a printer.
A latent image carrier on which a toner image is formed, an intermediate transfer member on which the toner image formed on the surface of the image carrier is transferred, and the toner image transferred on the intermediate transfer member on a recording material. The present invention relates to an image forming apparatus including a transfer unit for transferring.

[0002]

2. Description of the Related Art For example, a toner image formed of charged toner particles formed on a latent image carrier such as a photosensitive drum is once transferred onto the surface of an intermediate transfer member such as an intermediate transfer belt, and this intermediate transfer is performed. 2. Description of the Related Art There is known an image forming apparatus that transfers a toner image on the body surface to a recording material such as transfer paper to form an image. Such an image forming apparatus is widely used for a color image forming apparatus such as a color copying machine that forms a color image by superposing a plurality of toner images of different colors on the surface of an intermediate transfer body. In the image forming apparatus, the transfer of the toner image from the intermediate transfer belt to the recording material is performed by applying a charge having a polarity opposite to the polarity of the charged toner particles forming the toner image to the recording material by the transfer means. It is realized by electrostatically moving the toner particles to the recording material.

[0003]

However, as a result of the research conducted by the inventors, in such an image forming apparatus, an image defect is likely to occur in an image formed before a certain period of time has elapsed since the main power supply was turned on. It became clear. Specifically, a toner image transfer defect occurs at an end portion in a direction perpendicular to the recording material conveyance direction.

The present invention has been made in view of the above points, and an object of the present invention is to form the main power source found by the inventors before turning on a main power source for a certain period of time. An object of the present invention is to provide an image forming apparatus capable of forming a good image by eliminating a transfer failure of a toner image generated on an image onto a recording material.

[0005]

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention comprises a latent image carrier on the surface of which a toner image composed of charged toner particles is formed, and the image carrier. A toner image formed on the surface of the intermediate transfer body by supplying an electric charge having a polarity opposite to that of the charged toner particles to an intermediate transfer body onto which the toner image formed on the surface is transferred and the recording material. An image forming apparatus comprising: a transfer unit configured to transfer a recording medium to the recording material; a heating unit configured to heat the transfer unit; and a temperature control configured to control the heating unit in order to adjust a temperature of the transfer unit. Means and are provided.

The image forming apparatus according to the first aspect of the present invention has been invented by the inventors after repeatedly researching the cause of the above-mentioned transfer failure and considering the result. Therefore, first, the cause of occurrence of a transfer failure that occurs until a certain time elapses after turning on the main power source will be described.

The cause of such a transfer failure is that the temperature in the image device is lower than that after a lapse of a fixed time until the main power is turned on and a fixed time elapses. The transfer member may also have a relatively low temperature. In this case, the electric resistance value of the transfer member is higher than that after a certain period of time has passed since the main power supply was turned on, and when a constant voltage is applied to the transfer member, the latent image is transferred from the transfer member via the intermediate transfer member. The amount of current flowing to the image carrier will be insufficient. This allows
The amount of toner forming the toner image transferred to the recording material is smaller than the amount of toner to be originally transferred, and the above-mentioned transfer failure occurs. When such a change in the resistance value of the transfer member is ignored, not only the transfer failure as described above may occur but also the separation of the recording material from the latent image carrier may occur.

In the image forming apparatus according to the first aspect, which is intended to solve the transfer failure due to such a cause, the temperature control means controls the heating means for heating the transfer apparatus to adjust the temperature of the transfer apparatus. Therefore, even if the temperature inside the apparatus is low immediately after the main power supply is turned on, the temperature of the transfer apparatus becomes a temperature at which good transfer can be performed. Therefore, the transfer failure caused by the low temperature of the transfer device can be eliminated.

An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the heating means is operable even when the main switch of the apparatus main body is turned off. It is what

In the image forming apparatus according to claim 2,
Even if the main switch of the apparatus main body is turned off and the main power supply is turned off, the heating means can be operated. Therefore, when the main switch is turned on, the transfer member is heated at an earlier timing than in the image forming apparatus in which the heating unit is driven, and the transfer member is properly heated at the time when the image formation is started. As a result, the transfer failure can be solved better.

An image forming apparatus according to a third aspect of the present invention is the image forming apparatus according to the first aspect, which has a temperature sensor for detecting the temperature inside the apparatus, and the temperature control means detects the temperature sensor. The temperature of the transfer means is adjusted according to the temperature in the apparatus.

In the image forming apparatus according to claim 3,
Since the temperature control means controls the temperature of the transfer device according to the temperature in the device detected by the temperature sensor, the temperature of the transfer device can be adjusted better. Therefore, the transfer failure due to the low temperature of the transfer member can be better resolved.

An image forming apparatus according to a fourth aspect is the image forming apparatus according to the third aspect, wherein the temperature detected by the temperature sensor and the temperature of the transfer means have a correlation. It is characterized in that it is provided at a position.

According to the image forming apparatus of claim 4,
The temperature of the transfer device is controlled based on the temperature in the device detected by the temperature sensor provided at a position where the temperature in the device detected by the temperature sensor and the temperature in the transfer device have a correlation. Therefore, the temperature of the transfer device is adjusted better. Therefore, the transfer failure due to the low temperature of the transfer member can be better resolved.

An image forming apparatus according to a fifth aspect is the image forming apparatus according to the first aspect, characterized in that the heating means is provided below the transfer means. In the image forming apparatus according to the fifth aspect, since the transfer device is heated by the heating device provided below the transfer device, the transfer device is heated more than when the heating device is provided at another position. You will be able to do it quickly and efficiently.

An image forming apparatus according to a sixth aspect of the present invention is the image forming apparatus according to the first aspect, wherein the transfer means is provided in a direction in which heat generated by the heating means is convected and conducted. Is. In the image forming apparatus according to claim 6, since the heating means is provided so that the transfer device is positioned in a direction in which heat generated by the heating means is convected and conducted, a comparison is made with the case where the heating means is provided at another position. As a result, the transfer device can be heated quickly and efficiently.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] A first embodiment in which the present invention is applied to a color copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. First, regarding an example of a copying machine which is an image forming apparatus to which the present invention can be applied, FIG. 2 is a schematic configuration diagram of the copying machine, and an explanatory diagram showing an enlarged view of the periphery of a photoconductor / intermediate transfer belt in the copying machine. This will be described with reference to FIG.

A color image reading unit (hereinafter referred to as a color scanner) 1 provided in this copying machine forms an image of an original 3 on a color sensor 7 via an illumination lamp 4, a mirror group 5 and a lens 6. , The color image information of the document is, for example, blue (Blue, hereinafter B), green (Gree
n, hereinafter referred to as G) and red (Red, hereinafter referred to as R) color-separated light are read and converted into electrical image signals.
Then, on the basis of the B, G, and R color-separated image signal intensity levels obtained by the color scanner 1, color conversion processing is performed by an image processing unit (not shown), and black (hereinafter, referred to as Bk
), Cyan (Cyan, hereafter C), magenta (Magenta, hereafter M), yellow (Yellow,
Color image data (hereinafter referred to as Y) is obtained. This is visualized with Bk, C, M, and Y by a color image recording unit (hereinafter referred to as a color printer) 2 described below, and the toner images thus obtained are superimposed to form a four-color full-color image. Form.

The writing optical unit 8 of the color printer 2 converts the color image data from the color scanner 1 into an optical signal and performs optical writing corresponding to the original image, and the photosensitive member 9 as a latent image carrier is statically written. Form a latent image. The photoconductor 9 rotates counterclockwise as indicated by the arrow, and around it, a photoconductor cleaning unit (including a pre-cleaning static eliminator) 10, a static elimination lamp 11, a charger 12,
A potential sensor 13, a Bk developing unit 14, a C developing unit 15, an M developing unit 16, a Y developing unit 17, an optical sensor 18 for detecting a development density pattern, an intermediate transfer belt 19 as an intermediate transfer member, and the like are arranged.

As shown in FIG. 3, each developing unit 1 is
Reference numerals 4, 15, 16, and 17 denote developing sleeves (14a, 15a, 16a, and 17a) that rotate by bringing the ears of the developer into contact with the surface of the photoconductor 9 to develop the electrostatic latent image, and the developer. Rotating development paddle (14 for pumping and stirring)
b, 15b, 16b, 17b), and a toner concentration sensor (14c, 15c, 16c, 17c) for the developer.

The copying operation of the copying machine described above (hereinafter,
The outline of the copying operation) will be described by taking the case where the order of the developing operations (color image forming order) is Bk, C, M, and Y as an example (however, the image forming order is not limited to this). is not). When the copying operation is started, the color scanner 1 starts reading Bk image data at a predetermined timing, and optical writing by a laser beam and latent image formation are started based on the image data (hereinafter, referred to as Bk image data). The electrostatic latent image is referred to as a Bk latent image.For C, M, and Y, a C latent image, an M latent image, and a Y latent image, respectively.
Called latent image). Then, in order to enable development from the tip of the Bk latent image, the developing sleeve 14a is provided before the tip of the latent image reaches the developing position of the Bk developing unit 14.
Starts to rotate, and the Bk developing unit 14 starts developing the Bk latent image with Bk toner. After that, the Bk developing unit 14 continues the developing operation of the Bk latent image area, and stops the operation when the trailing edge of the latent image passes the Bk developing position. The above operation needs to be completed at least before the leading edge of the C latent image by the next C image data arrives.

B formed on the photoconductor 9 by the above operation
The k toner image is transferred onto the surface of the intermediate transfer belt 19 that is driven at the same speed as the photosensitive member (hereinafter, the toner image transfer from the photosensitive member to the intermediate transfer belt is referred to as belt transfer). This belt transfer is performed with the transfer bias rollers 20a and 20b in a state where the photoconductor 9 and the intermediate transfer belt 19 are in contact with each other.
It is realized by applying a predetermined bias voltage to. The Bk toner image, the C toner image, the M toner image, and the Y toner image, which are sequentially formed on the photoconductor 9, are superimposed on the intermediate transfer belt 19 while being sequentially aligned on the same surface, and four colors are formed. An overlapping belt transfer image is formed. Then, this belt transfer image is subsequently bulk-transferred onto the transfer paper. The intermediate transfer belt unit and the transfer unit serving as a transfer unit, in which such operations are performed, will be described later.

On the side of the photoreceptor 9, the Bk process is followed by the C process. That is, the color scanner 1 is set at a predetermined timing.
C reading of C image data is started, and C latent image formation is performed by laser light writing based on this image data. Then, in order to enable development from the tip of the C latent image, the developing sleeve 15a starts rotating before the tip of the latent image reaches the developing position of the C developing unit 15, and the C developing unit 15 Starts developing the C latent image with C toner. After that, the C developing unit 15
The developing operation of the latent image area is continued, and when the trailing edge of the latent image passes the C developing position, the operation is stopped. The above operation also needs to be completed at least before the leading edge of the M latent image by the next M image data arrives.

In each of the steps M and Y, the image data reading, latent image forming and developing operations are performed in the same manner as the steps Bk and C described above, and therefore the description thereof is omitted. .

Next, the above-mentioned intermediate transfer belt unit will be described. The intermediate transfer belt 19 is driven by the drive roller 2
1, the transfer bias rollers 20a and 20b, and the driven roller group are stretched and driven by a drive motor (not shown). Further, the belt cleaning unit 22 provided in this unit is composed of a brush roller 22a, a rubber blade 22b, a contact / separation mechanism 22c from the belt, and the like. While transferring the 4th color image on the belt,
The contact / separation mechanism 22c keeps the belt separated from the belt surface.

The above-mentioned paper transfer unit 23 is composed of a paper transfer bias roller 23a, a roller cleaning blade 23b, and a mechanism 23c for contacting and separating from the belt. The bias roller 23a is normally separated from the surface of the belt 19, but a timing is set when the superimposed images of four colors formed on the surface of the intermediate transfer belt 19 are collectively transferred to the transfer paper 24 as a recording material. Contact and separation mechanism 2
It is pressed by 3c and a predetermined bias voltage is applied to the roller 23a to transfer it to the paper. The transfer paper 24 is
By the paper feed roller 25 and the registration roller 26, the leading end portion of the four-color superimposed image on the surface of the intermediate transfer belt is fed at the timing of reaching the paper transfer position.

Here, the drive control of the intermediate transfer belt 19 will be described. As a method of driving the intermediate transfer belt 19, the following three methods can be considered as an operation method after the belt transfer of the Bk toner image of the first color is completed to the end, and one of these methods or one of the copy speeds is considered. The intermediate transfer belt 19 is driven by efficiently combining a plurality of these methods according to the copy size from the surface.

(1) First, a constant speed forward movement method will be described as a first method. In this method, even after the Bk toner image is transferred onto the belt, it continues to move at a constant speed, and the Bk image front end position on the surface of the belt 19 is again at the belt transfer position of the contact portion with the photoconductor 9. When it reaches, the image is formed on the side of the photoconductor 9 with a timing so that the front end portion of the next C toner image is exactly at that position. As a result, the C image is accurately aligned with the Bk image and is transferred onto the intermediate transfer belt 19 in a superposed manner.
Further, thereafter, the same operation is performed to proceed to the M and Y image process, and a belt transfer image of four colors is obtained. Furthermore, 4
Following the Y toner image belt transfer process of the color, the four color superposed toner images on the belt surface are collectively transferred onto the transfer paper 24 as described above while moving forward.

(2) Next, a skip forward method will be described as a second method. In this method, when the belt transfer of the Bk toner image is completed, the belt 19 is separated from the surface of the photoconductor 9 and is skipped at high speed in the forward movement direction as it is, and after moving a predetermined amount, the initial forward movement speed is restored. Thereafter, the belt 19 is brought into contact with the photoconductor 9 again. When the front end position of the Bk image on the surface of the belt 19 reaches the belt transfer position again, an image is formed on the photosensitive member 9 side with timing so that the front end of the next C toner image is exactly at that position. It As a result, the C image is accurately aligned with the Bk image and transferred onto the belt in a superimposed manner. Also,
After this, the same operation is performed to proceed to the M and Y image process.
Obtain a belt transfer image with color overlap. And Y of the fourth color
Subsequent to the toner image belt transfer step, the four-color superimposed toner images on the surface of the belt 19 are collectively transferred onto the transfer paper 24 at the same forward speed.

(3) Next, a reciprocating (quick return) system will be described as a third system. In this method, when the belt transfer of the Bk toner image is completed, the belt 19 is separated from the surface of the photoconductor 9, and the forward movement is stopped, and at the same time, the belt is returned in the opposite direction at a high speed. In the return, the leading end position of the Bk image on the surface of the belt 19 passes through the position corresponding to the belt transfer in the opposite direction, and after moving a preset distance, it is stopped and put in the standby state. Next, when the front end of the C toner image on the photoconductor 9 reaches a predetermined position before the belt transfer position, the intermediate transfer belt 1
Start 9 again in the forward direction. Further, the belt 19 is brought into contact with the surface of the photoconductor 9 again. Also in this case, the C image is transferred under the condition that the C image is accurately overlapped with the Bk image on the surface of the belt 19. Further, thereafter, the same operation is performed to proceed to the Y and M image processes to obtain a belt transfer image of four-color overlapping. Further, following the belt transfer process for the Y toner image of the fourth color, the four-color superimposed toner image on the surface of the belt 19 is transferred to the transfer paper 2 without moving back at the same speed.
Transfer to 4 at once.

The transfer paper 24 on which the four-color superposed toner images have been collectively transferred from the intermediate transfer belt surface as described above is conveyed to the fixing device 28 by the paper conveying unit 27, and the fixing device is controlled to a predetermined temperature. After the toner image is melted and fixed by the fixing roller 28a and the pressure roller 28b, the transfer paper 24 is carried out to the copy tray 29 and a full color copy image is formed.

The photosensitive member 9 after the belt transfer is the photosensitive member cleaning unit 10 (pre-cleaning static eliminator 10).
The surface is cleaned by a, the brush roller 10b, and the rubber blade 10c), and the surface is discharged by the discharge lamp 11. Further, the cleaning unit 2 in which the intermediate transfer belt 19 after the toner image is transferred onto the transfer paper 24 is pressed against the surface by the contact / separation mechanism 22c.
It is cleaned by 2.

The operation of copying on the first sheet of transfer paper has been described above. However, when repeatedly copying on a plurality of sheets of transfer paper (repeat copy), the operation of the color scanner 1 and the photosensitive member. The image forming operation on the first sheet
(Fourth color) After the image process, 2
Proceed to the Bk (first color) image step for the first sheet. Further, in the intermediate transfer belt 19, after the first four-color superimposed image is collectively transferred onto the transfer paper, the surface thereof is cleaned by the cleaning unit 22, and in the cleaned area, the second Bk image is transferred. The toner image is transferred onto the belt. After that, the same image forming operation as that for the first sheet is performed.

The transfer paper cassettes 30, 31, 32,
Reference numeral 33 stores transfer papers of various sizes, which are fed and conveyed in the direction of the registration rollers 26 from the storage cassette of the size paper designated by the operation panel (not shown) at a certain timing. Reference numeral 34 denotes a manual paper feed tray for OHP paper and thick paper.

The full-color copy mode for forming a four-color full-color image has been described above, but the three-color copy mode for forming an image composed of three-color toners or the image composed of two-color toners is formed. In the case of the two-color copy mode for doing so, the same operation as described above may be performed for the designated color and the number of times. In the case of the monochromatic copy mode consisting of only a single toner, until the predetermined number of sheets is completed, only the developing unit of that color is in the developing operation (agent stand) state, and the intermediate transfer belt 1
9 may be driven in the forward direction at a constant speed while being in contact with the surface of the photoconductor 9, and the copying operation may be performed while the belt cleaner 22 is also in contact with the belt 19. (Hereinafter, margin)

In the copying machine configured and operated as described above, the heater 50 as a heating means for heating the transfer unit 23 as a transfer means is provided. FIG.
FIG. 4 is an explanatory view showing the function of the heater. As shown in FIG. 1, the heater 50 is provided under the transfer unit 23, that is, at a position where the heat generated by the heater is convected / conducted in the copying machine. Further, the heater 50 is the temperature control means 5
The temperature control means 51 controls the temperature of the paper transfer bias roller 23a to be kept within a predetermined width. As a result, even when the temperature inside the copying machine is low, such as when the power is turned on, the paper transfer bias roller 23a is kept at a constant temperature, and the copying operation is performed while the temperature of the roller is low. Therefore, the transfer failure due to the above-mentioned process is prevented. In FIG. 1, a paper transfer power supply 52 that applies a voltage to the paper transfer bias roller 23 a and a power supply 53 that applies a voltage to the transfer bias roller 20 are shown.

The reason why good transfer is realized even in a low temperature environment by heating the transfer bias roller 23a will be described below. FIG.
FIG. 4 is a graph showing the relationship between the temperature of the transfer bias roller 23a and the resistance value of the roller. And, ∘ shows the relationship when the temperature inside the copier is 10 ° C and the humidity inside the copier is 15%, and □ shows the relationship when the same temperature is 20 ° C and the humidity is 10%. Is shown. As can be seen from this graph, even if the environment inside the apparatus is low temperature (temperature 10 ° C, humidity 15%, see characteristic line indicated by ◯), the transfer bias roller 23
If a is heated to a temperature of about 30 ° C, the resistance value of the roller is set to a value similar to that when the environment inside the device is high temperature (temperature 20 ° C, humidity 10%, □). be able to. Therefore, when the transfer bias roller 23a is heated, the transfer failure due to the increase in the resistance value of the roller due to the low temperature inside the apparatus or the like is eliminated, and good copying is performed. is there.

Further, FIG. 5 shows the transfer bias roller 23a.
FIG. 6 is an explanatory diagram showing changes in the transfer bias required for sheet transfer when the sheet is heated. In FIG. 5, the horizontal axis shows the environment inside the copying machine, and the vertical axis shows the transfer bias required for transfer under each environment. A characteristic line a in FIG. 5 indicates that the environment inside the device is low temperature and high humidity (temperature 10
C, humidity 15%, refer to the characteristic line indicated by ◯ in FIG. 4), and shows the range of the transfer bias required when the transfer bias roller 23a is not heated. Further, the characteristic line b shows the required transfer bias value when the transfer bias roller 23a is heated in the same environment. The characteristic line c indicates the required transfer when the environment in the apparatus is high temperature and low humidity (temperature 20 ° C., humidity 10%, see □ in FIG. 4) and the transfer bias roller 23a is not heated. The range of bias is shown. From FIG. 5 described above, even if the environment in the apparatus is low, if the transfer bias roller 23a is heated, the transfer bias to be applied to the transfer bias roller 23a in order to achieve good transfer is not changed. It can be seen that the value can be the same as that at the high temperature. Therefore, by heating the transfer bias roller 23a, it is not necessary to apply a high bias voltage to the roller in order to achieve good transfer even if the temperature inside the apparatus is low.

Further, in this copying machine, it is desirable that the heater 50 as the heating means be operable even when the main switch of the copying machine is turned off. Hereinafter, a specific description will be given.

FIG. 6 is an explanatory view schematically showing an electrical system in this copying machine. As shown in FIG. 6, electric power is supplied to the copying machine from an external power supply 61 via an outlet 60. The output supplied into the apparatus through the outlet 60 is supplied to the power supply board 63 and the control board 64 through the main switch 62 and used for driving various electric components in the copying machine. On the other hand, as shown in FIG. 6, electric power is supplied to the heater 50 from between the outlet 60 and the main switch 62 via the temperature control means 51. That is, the electrical system of this copying machine includes a power supply board 6 for supplying electric power to each electrical component.
3. A portion including the main switch 62 and the like for starting and stopping the supply of electric power to the substrate and a portion including the heater 50 and the like are arranged in parallel.

In the case of adopting the above-described configuration for the electrical system, if the outlet 60 is connected to the external power source 61, even if the main switch 62 is in the OFF state where it does not supply power to the power board 63 or the like. However, since the electric power is supplied to the heater 50, the heater 50 is kept in an operable state. Therefore, even immediately after the main switch 62 is turned on, it is possible to prevent the occurrence of transfer failure due to the low temperature inside the apparatus, and it is possible to form a good image. Hereinafter, this will be described. FIG. 7 is a graph showing the relationship between the time after the main switch 62 is turned on and the environmental temperature inside the copying machine. From this graph, set the main switch 62 to O
It can be seen that the temperature in the copying machine does not reach the saturation temperature immediately after N, but the temperature in the copying machine reaches the saturation temperature in about 75 minutes (see t1). On the other hand, the time from the turning on of the main switch 62 until the copying machine becomes ready for copying (rise time) is a constant temperature required for the fixing device 28 (see FIG. 2) to achieve good fixing. It is determined by time, and in this copying machine, it is about 7 to 8 minutes as indicated by t2. Therefore, when the main switch 62 is turned on,
This copying machine is in a copy-ready state after the lapse of 8 minutes and until the lapse of 75 minutes, but the environmental temperature does not reach the saturation temperature and the transfer by the transfer bias roller 23a is defective. It is in a state where it easily occurs.

Therefore, in this copying machine, as described above, the transfer bias roller 23a is heated by the heater 50 to prevent the transfer failure. However, even if such a configuration is adopted, when the power supply to the heater 50 is started only after the main switch 62 is turned on, the transfer bias roller 23a of the transfer bias roller 23a is started after the power supply is started. Since it usually takes a certain amount of time for the temperature to rise to the desired temperature, it is impossible to prevent transfer defects during this time. Therefore, in this copying machine, when the main switch 62 of the copying machine is turned off by configuring the electrical system in parallel with the part including the power supply board 63, the main switch 62 and the like and the part including the heater 50 and the like. Even in such a case, the heater 50 is set in an operable state so that the temperature of the transfer bias roller 23a at the time of turning on the main switch becomes a temperature sufficient for good transfer.

[Second Embodiment] A second embodiment in which the present invention is applied to a color copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. The copying machine according to the first embodiment has a temperature detection sensor for detecting the temperature inside the apparatus, and the temperature control unit 51 adjusts the temperature of the transfer bias roller 23a according to the temperature detected by the sensor. Although it is different from the copying machine according to the first embodiment, the other points are common to the copying machine according to the first embodiment. Therefore, only the temperature sensor will be described, and description of points common to the first embodiment will be omitted.

FIG. 8 is an explanatory view showing the main part of this copying machine. In addition, in FIG. 8, the members common to those of the first embodiment are designated by the same reference numerals as those of the first embodiment. As shown in FIG. 8, in this copying machine, a temperature sensor 70 is connected to the temperature control means 51. And
The temperature control means 51 turns on / off the supply of electric power from the external power source 61 to the heater 50 based on the temperature inside the apparatus detected by the temperature sensor 70, and the temperature of the transfer bias roller 23a falls within a predetermined range. Control to be within. As a result, the temperature of the transfer bias roller 23a is controlled well, and the transfer failure is less likely to occur, so that better copying is realized.

In this copying machine, if the temperature control means 51 is adapted to eliminate and correct the mounting location of the temperature sensor 70 in the apparatus and the variation in the temperature detection of the sensor, the temperature of the transfer bias roller 23a is corrected. Better control is achieved.

Further, unlike a device that detects the temperature of the transfer bias roller 23a itself and controls the temperature of the roller based on the detected value, the temperature inside the device is detected by the sensor 70 like this copying machine. However, in an apparatus that controls the temperature of the transfer bias roller 23a based on the detected value, the temperature is detected at a location where the temperature detected by the temperature sensor 70 and the temperature of the transfer bias roller 23a have a correlation. It is desirable to provide the sensor 70. Therefore, the inventors have confirmed where the temperature sensor 70 is provided in the apparatus so that the temperature detected by the sensor and the temperature of the transfer bias roller 23a have a correlation. Hereinafter, the results are shown.

FIG. 9 shows the temperature sensor 7 in the above confirmation.
It is explanatory drawing which shows the position which attached 0, and FIG.
6 is a graph showing the relationship between the temperature detected by the temperature sensor 70 provided at each position shown in and the temperature of the transfer bias roller 23a. In FIG. 9, position A, position B,
Position C indicates the position where the temperature sensor 70 is attached, A indicates the vicinity of the transfer paper cassette 31 (see FIG. 2), B indicates the upper position of the guide plate on which the transfer paper is guided, and C indicates cleaning. The positions in contact with the blade 23b are shown. The characteristic line a in FIG. 10 shows the relationship between the temperature of the transfer bias roller 23 a and the temperature detected by the temperature sensor 70 when the temperature sensor 70 is provided at the position A, and the characteristic line b shows the temperature sensor 70.
And the characteristic line c
Indicates the relationship when the temperature sensor 70 is provided at the position C.

8 and 9, when the temperature sensor 70 is provided at the position B, that is, the upper position of the guide plate for guiding the transfer paper, the temperature detected by the sensor and the transfer bias roller 23a. It can be seen that has the strongest correlation. Therefore, as shown in FIG.
Also in this copying machine, the temperature sensor 70 is provided near the position B.

In the copying machine according to the first embodiment and the copying machine according to the second embodiment described above, the heater 5 is used.
It is desirable to provide the heater 50 at a position where the heat generated from 0 is efficiently transmitted to the transfer bias roller 23a and the temperature of the roller rises in a short time. Therefore, the inventor et al.
It was confirmed whether the temperature of the transfer bias roller 23a rises in a short time if 0 is set. Hereinafter, the results are shown.

FIG. 11 is an explanatory view showing the position where the heater 50 is attached in the above confirmation, and FIG. 12 is a diagram showing the heating time by the heater and the transfer bias roller 23a when the heater 50 is provided at each position shown in FIG. It is a graph which shows the relationship with the temperature of. In FIG. 11, position D, position E, and position F indicate the positions where the heater 50 is attached, D is the lower position of the transfer unit 23, E is the side position of the transfer unit 23, and F is the transfer position. The upper part position of the unit 23 is shown, respectively. The characteristic line d in FIG. 12 shows the relationship between the heating time by the heater when the heater 50 is provided at the position D and the temperature of the transfer bias roller 23a, and the characteristic line e shows the case when the heater 50 is provided at the position E. The relationship and the characteristic line f show the relationship when the heater 50 is provided at the position F.

From FIGS. 11 and 12, it can be seen that the temperature of the transfer bias roller 23a rises in the shortest time when the heater 50 is provided at the position D, that is, at the lower position of the transfer unit 23. It should be noted that the position D is located in the direction where the heat generated by the heater 50 is most convective and conductive among the positions D, E, and F. Therefore, as shown in FIGS. 1 and 8, the heater 50 is provided at the position D also in the copying machine according to each embodiment.

[0052]

According to the invention of claim 1, even if the temperature in the apparatus is low immediately after the main power source is turned on, the temperature of the transfer apparatus becomes a temperature at which good transfer is performed. Therefore, the transfer failure due to the low temperature of the transfer device is eliminated, and good image formation is achieved. In the above description, the occurrence of an image defect when the transfer member is in the low temperature state has been described due to the temperature inside the apparatus being relatively low before the elapse of a certain time from turning on the main power. The present invention has a sufficient effect even when the transfer member is in a low temperature state due to other reasons. Therefore, the technical scope of the present invention is not limited to the image forming apparatus in which the transfer member is in the low temperature state immediately after the main power supply is turned on, and the image forming in which the transfer member is in the low temperature state is caused by other causes. It extends to devices.

According to the second aspect of the present invention, the transfer member is heated at an earlier timing than in the image forming apparatus in which the heating means is driven only when the main switch is turned on, so that the transfer failure is better. Therefore, better image formation is achieved.

According to the third aspect of the invention, the temperature of the transfer device is controlled according to the temperature inside the device, so that the temperature of the transfer device is adjusted better and the transfer member is at a low temperature. Since the transfer failure can be eliminated better, better image formation can be achieved.

According to the fourth aspect of the present invention, based on the temperature in the apparatus detected by the temperature sensor provided at a position where the temperature in the apparatus detected by the temperature sensor and the temperature in the transfer apparatus have a correlation. By controlling the temperature of the transfer device by this, the transfer failure due to the low temperature of the transfer member can be eliminated better, so that better image formation can be achieved.

According to the fifth aspect of the present invention, the transfer device is heated by the heating means provided below the transfer means, and the heating of the transfer device is quicker than in the case where the heating means is provided at another position. In addition, since the transfer can be efficiently performed, the transfer failure due to the low temperature of the transfer member can be better resolved, and the better image formation can be performed.

According to the sixth aspect of the present invention, the transfer device is heated by the heating device provided so that the heat generated by the heating device is positioned in the direction where the heat is convected and conducted, and the heating device is moved to another position. As compared with the case where the transfer member is provided, the transfer device can be heated more quickly and efficiently, so that the transfer failure due to the low temperature of the transfer member can be better eliminated, and a better image formation can be achieved. Will be done.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a function of a heater provided in a color copying machine according to a first embodiment.

FIG. 2 is a schematic configuration diagram of the color copying machine.

FIG. 3 is an enlarged view showing a photosensitive member and an intermediate transfer belt of the color copying machine.

FIG. 4 is a graph showing the relationship between the temperature of a transfer bias roller and the resistance of the roller provided in the color copying machine.

FIG. 5 is an explanatory diagram showing a change in transfer bias to be applied to the transfer bias roller.

6 is an explanatory view showing an electrical system of the color copying machine according to FIG.

FIG. 7: The main switch in the color copying machine is turned off
6 is a graph showing the relationship between the elapsed time after N and the temperature of the transfer bias roller.

FIG. 8 is an explanatory diagram showing a main part at the time of color copying according to the second embodiment.

FIG. 9 is an explanatory view showing a position where a temperature sensor is attached.

FIG. 10 is a graph showing the relationship between the temperature inside the apparatus detected by a temperature sensor and the temperature of the transfer bias roller.

FIG. 11 is an explanatory view showing a position where a heater is attached.

FIG. 12 is a graph showing the relationship between the time after the heater starts driving and the temperature of the transfer bias roller.

[Explanation of symbols]

 1 Color Scanner 2 Color Image Recording Part 3 Original Document 4 Irradiation Lamp 5 Mirror Group 6 Lens 7 Color Sensor 8 Optical Unit 9 Photoreceptor (Latent Image Carrier) 10 Cleaning Unit 11 Electrification Lamp 12 Charger 13 Potential Sensor 14 Bk Development Unit 15 C developing unit 16 M developing unit 17 Y developing unit 18 optical sensor 19 intermediate transfer belt (intermediate transfer member) 20 transfer bias roller 21 drive roller 22 belt cleaning unit 23 paper transfer unit 23a transfer bias roller 24 transfer paper (recording material) 25 Paper feed roller 26 Registration roller 27 Paper transport unit 28 Fixer 50 Heater 51 Temperature control means 52 Paper transfer power supply 53 Power supply 60 Outlet 61 External power supply 62 Main switch 63 Power supply board 64 Control board 70 Temperature Capacitors

Claims (6)

[Claims] 1. A latent image carrier on the surface of which a toner image composed of charged toner particles is formed, and an intermediate transfer member on which the toner image formed on the surface of the image carrier is transferred. An image forming apparatus comprising: a transfer unit that supplies a charge having a polarity opposite to that of the charged toner particles to a material to transfer the toner image formed on the surface of the intermediate transfer member to the recording material. An image forming apparatus comprising: a heating unit that heats the transfer unit; and a temperature control unit that controls the heating unit to adjust the temperature of the transfer unit. 2. The image forming apparatus according to claim 1, wherein the heating unit is operable even when a main switch of the apparatus main body is turned off. 3. The image forming apparatus according to claim 1, further comprising a temperature sensor for detecting a temperature in the apparatus, wherein the temperature control unit transfers the transfer according to the temperature in the apparatus detected by the temperature sensor. An image forming apparatus, wherein the temperature of the means is adjusted. 4. The image forming apparatus according to claim 3, wherein the temperature sensor is provided at a position where a temperature detected by the sensor and a temperature of the transfer unit have a correlation. Forming equipment. 5. The image forming apparatus according to claim 1, wherein the heating unit is provided below the transfer unit. 6. The image forming apparatus according to claim 1, wherein the transfer unit is provided in a direction in which heat generated by the heating unit is convected and conducted.