JP2007328189A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent transfer failure even if a resistance corresponding to the maximum voltage of a power source is determined in the stage of the design of the resistance value of a transfer section. <P>SOLUTION: A controller 30 determines whether the resistance value of a secondary transfer mechanism 80 detected by a resistance detector 70 is greater than a threshold value a, stored in a storage, or not. If it is greater than the threshold value (a), an instruction to generate an image signal for a color image is restrained. This threshold (a) may be a resistance value corresponding to a voltage at which a monochrome or color toner image can be satisfactorily transferred. Thus, the reception of the instruction to generate the image signal for the color image is restricted. When the temperature in the apparatus is increased by rotating a secondary transfer roll 82 and both the rolls of a fixing mechanism 90 and then a resistance value equal to or lower than the threshold (a) is detected by the resistance detector 70, the controller 30 cancels the restraint of the instruction to generate the image signal for the color image. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image.

2. Description of the Related Art A so-called electrophotographic image forming apparatus includes an apparatus that transfers a toner image formed on a photosensitive drum onto a recording material using an electrostatic force. Some image forming apparatuses of this type realize good transfer by controlling electrostatic force according to the transfer environment. For example, the image forming apparatus disclosed in Patent Document 1 prevents the occurrence of transfer defects by controlling the output of the corotron according to the temperature and humidity in the apparatus. Further, the image forming apparatus disclosed in Patent Document 2 realizes good transfer by controlling the voltage applied to the transfer unit according to the resistance value of the transfer unit and generating an appropriate electrostatic field in the transfer unit. ing.
Japanese Patent Laid-Open No. 06-250532 JP 09-080924 A

By the way, in the image forming apparatus that performs transfer using electrostatic force disclosed in the above patent document, the transfer tolerance (transfer latitude) of the voltage applied to the transfer portion increases as the resistance of the transfer portion increases. Is preferable. This transfer allowable range is a value indicating a voltage range in which good transfer can be performed with respect to the application of voltage to the transfer portion.
FIG. 5 is a diagram illustrating the relationship between the resistance value (Rsys) of the secondary transfer mechanism including the transfer portion and the transfer allowable range. The vertical axis shown in FIG. 5 is the transfer output voltage indicating the voltage applied to the transfer portion, and the horizontal axis is the resistance value (Rsys) of the secondary transfer mechanism. The unit of the transfer output voltage is V, the unit of the resistance value of the secondary transfer mechanism is MΩ, and M is a value of 1,000,000 times. The resistance value of the secondary transfer mechanism varies within a certain range due to environmental changes such as temperature and humidity. (1) shown in FIG. 5 shows the range of the resistance value of the secondary transfer mechanism including the conventional transfer unit, and (2) shown in FIG. 5 shows the secondary transfer mechanism including the transfer unit having a higher resistance than the conventional transfer unit. The resistance value range is shown.
For example, when the resistance value of the secondary transfer mechanism is about 50 MΩ included in (1), it can be seen that the allowable transfer range is about 2000V to 2300V. When the resistance value of the secondary transfer mechanism is about 250 MΩ included in (2), the transfer allowable range is about 4500 V to 6000 V, and it can be seen that the transfer allowable range is wider than when the resistance is about 50 MΩ.

However, the transfer portion has a property that its resistance increases as it is used. FIG. 6 is a diagram illustrating the relationship between the number of printed sheets (that is, the number of times the transfer unit is used) and the resistance value of the transfer unit. The vertical axis shown in FIG. 6 is the resistance value of the transfer portion, and the horizontal axis is the number of prints. The unit of the resistance value of the transfer portion is LogΩ, the unit of the number of printed sheets is K sheets, and K is a value of 1000 times.
As shown in FIG. 6, the resistance value of the transfer portion increases to about 9.87 LogΩ after printing 250,000 sheets even if it is about 8.3 LogΩ before use. As the resistance increases, the voltage required for transfer also increases, and if the voltage required for transfer exceeds the maximum voltage of the power supply, transfer failure may occur. Therefore, conventionally, when designing the resistance value of the transfer portion provided in the apparatus, the resistance has to be lower than the resistance corresponding to the maximum voltage of the power supply.
The present invention has been made in view of such circumstances, and provides an image forming apparatus that does not cause a transfer defect even when a resistance corresponding to the maximum voltage of a power source is used when designing a resistance value of a transfer portion. With the goal.

An image forming apparatus according to a preferred aspect of the present invention receives an image signal for instructing drawing of an image and forms a single-color or multiple-color toner image on an image carrier in accordance with the supplied image signal. And a transfer means for transferring the toner image to a recording material by applying an electric field generated by application of a voltage from the voltage source to the image holding member on which the toner image is formed, and the transfer A resistance detection means for detecting the resistance of the means; an instruction means for instructing generation of an image signal of a single color or a plurality of colors; and an image signal of the indicated image is generated and supplied to the image forming means A signal supply means for forming a toner image of a single color or a plurality of colors according to the image signal, and an image signal of an image of a plurality of colors by the instruction means when the detected resistance is greater than a predetermined threshold value And a restriction means for restricting the instruction to generate.
In this aspect, the voltage source may supply an ideal power corresponding to the resistance detected by the resistance detection unit to the transfer unit.

An image forming apparatus according to another aspect is provided with an image forming unit that receives supply of an image signal instructing drawing of an image and forms a single color or a plurality of color toner images on an image holding body in accordance with the supplied image signal. A transfer means for transferring the toner image onto a recording material by causing an electric field generated by application of a voltage from the voltage source to act on the image carrier on which the toner image is formed; and the transfer means First temperature detecting means for detecting the temperature of the image, instruction means for instructing generation of an image signal of a single color or a plurality of colors, and generating an image signal of the instructed image and supplying the image signal to the image forming means Accordingly, when the temperature detected by the first temperature detection unit is smaller than a predetermined threshold value, the signal supply unit that forms a single color or a plurality of color toner images according to the image signal, the instruction unit And a restriction means for restricting an indication of the generation of the image signals for several color images.
In this aspect, the image forming apparatus further includes a fixing unit that fixes the toner image transferred to the recording material, and a second temperature detection unit that detects a temperature of the fixing unit, and the restriction unit includes the first temperature detection unit. When the temperature detected by the means and the temperature detected by the second temperature detection means are smaller than a predetermined threshold value, the instruction means for generating image signals of a plurality of colors by the instruction means may be restricted.

  In these embodiments, the image holding member includes a photosensitive drum that forms a toner image on its peripheral surface through a xerographic process including charging, exposure, and development by the image forming unit, and a periphery of the photosensitive drum. An intermediate transfer belt for transferring the toner image formed on the surface to the belt surface of the belt, and the transfer means applies a voltage having a polarity opposite to that of the toner image formed on the intermediate transfer belt from the voltage source. You may have a secondary transfer roll to receive and a backup roll which pinches | interposes the said intermediate transfer belt with the secondary transfer roll.

  According to the present invention, transfer defects do not occur even when the resistance is designed according to the maximum voltage of the power supply in the resistance value design of the transfer portion.

<First Embodiment>
(Constitution)
The configuration of the image forming apparatus 100 according to the first embodiment will be described with reference to FIG. As shown in FIG. 1, the image forming apparatus 100 includes a user interface (hereinafter referred to as “UI10”), a scanning unit 20, a controller 30 that controls each unit, an image forming engine 40, an intermediate transfer belt 50, and a paper tray 60. , A resistance detector 70, a secondary transfer mechanism 80, and a fixing mechanism 90. Hereinafter, each of these parts will be described.

The UI 10 has both a liquid crystal display for displaying various types of information and an operator for instructing various settings. The liquid crystal display displays, for example, a screen that prompts input of an instruction to generate a monochrome or color image signal.
The scanning unit 20 includes a CCD (Charge Coupled Device), a light source, and the like, reads an image of a document, and corresponds to the image in red (hereinafter referred to as “R”), green (hereinafter referred to as “G”), An image signal of blue (hereinafter referred to as “B”) raster data is supplied to the controller 30.

  The controller 30 controls each part of the image forming apparatus 100 in accordance with instructions input to the UI 10. More specifically, when an image signal generation instruction is input to the UI 10, the controller 30 causes the scanning unit 20 to read a document image. When image signals of R, G, and B raster data are supplied from the scanning unit 20, the color space of these image signals is converted to yellow (hereinafter referred to as “Y”), magenta (hereinafter referred to as “M”). ”, Cyan (hereinafter referred to as“ C ”), and black (hereinafter referred to as“ K ”) image signals. In addition, the controller 30 includes a storage unit, and the storage unit stores a threshold value a (details will be described later) serving as a reference as to whether or not to restrict an instruction to generate an image signal of a color image by the UI 10.

  When the image forming engine 40 is supplied with Y, M, C, and K image signals from the controller 30, the image forming engine 40 forms a monochrome or color toner image on the intermediate transfer belt 50 in accordance with the image signals. More specifically, the image forming engine 40 is provided for each of Y, M, C, and K toner colors. Each of the image forming engines 40 includes a photosensitive drum, a charging unit, an exposure unit, a developing unit, and a primary transfer roll, and performs an image forming process including charging, exposure, and development.

An overview of how these units are driven is as follows. First, the charging unit uniformly charges the circumferential surface of the photosensitive drum that circulates at a predetermined speed, and then the exposure unit scans the circumferential surface while scanning the laser. By irradiating light, an electrostatic latent image indicating an image signal supplied from the controller 30 is formed. Further, the electrostatic latent image is developed as a toner image by spraying charged toner in the developing unit. Thereby, a toner image is formed on the peripheral surface of the photosensitive drum. A voltage having a polarity opposite to the charging polarity of the toner is applied to each primary transfer roll provided inside the intermediate transfer belt 50 facing the respective photosensitive drums and extending substantially linearly. As a result, the toner images on the respective photoconductive drums are sequentially electrostatically attracted to the intermediate transfer belt 50, so that the toner images are formed on the intermediate transfer belt 50.
The intermediate transfer belt 50 is circulated and driven at a predetermined speed in the direction A shown in the drawing by various rolls. A toner image superimposed by the image forming engine 40 is formed on the belt surface of the intermediate transfer belt 50.

  The paper tray 60 stores a plurality of sheets cut into a predetermined size such as A4. The accommodated sheets are picked one by one from the sheet tray 60 and are sequentially conveyed on a sheet conveyance path connected to the sheet discharge port via the secondary transfer mechanism 80 and the fixing mechanism 90.

  The secondary transfer mechanism 80 is a transfer unit that causes an electrostatic field generated by applying a voltage to act on the intermediate transfer belt 50 on which the toner image is formed, thereby transferring the toner image onto a sheet. The secondary transfer mechanism 80 includes a power supply 81 for applying a voltage, a secondary transfer roll 82 for receiving a voltage having a polarity opposite to that of the toner image formed on the intermediate transfer belt 50 from the power supply 81, and the secondary transfer roll 82. A backup roll 83 that sandwiches the intermediate transfer belt 50, a support roller 84 provided between the secondary transfer roll 82 and the fixing mechanism 90, and an endless second belt spanned between the secondary transfer roll 82 and the support roller 84. A next transfer belt 85 is provided.

  More specifically, the secondary transfer roll 82 is made of a semiconductive material having a surface resistance higher than usual, and the surface on which the toner image of the intermediate transfer belt 50 is formed via the paper supplied from the paper tray 60. Press to touch. The backup roll 83 is disposed to face the secondary transfer roll 82 and is grounded. When a voltage having a polarity opposite to that of the toner image is applied from the power supply 81, the secondary transfer roll 82 generates an electrostatic field having a polarity opposite to that of the toner image on the intermediate transfer belt 50. The backup roll 83 is pressed against the secondary transfer roll 82 from the back surface of the surface on which the toner image of the intermediate transfer belt 50 is formed. As a result, the toner image on the intermediate transfer belt 50 is transferred to the paper supplied from the paper tray 60, and the paper on which the toner image has been transferred is conveyed from the secondary transfer belt 85 to the fixing mechanism 90.

  The resistance detector 70 detects the resistance value of the secondary transfer mechanism 80. In this resistance detector 70, no paper is supplied to the secondary transfer mechanism 80, and the backup roll 83 is pressed against the secondary transfer roll 82 from the back surface of the surface on which the toner image of the intermediate transfer belt 50 is formed. In this state, the resistance value of the secondary transfer mechanism 80 is detected. More specifically, the resistance detector 70 passes from the secondary transfer roll 82 to the secondary transfer belt 85, the intermediate transfer belt 50, and the backup roll 83 when the power supply 81 applies a voltage to the secondary transfer roll 82. The current flowing to the ground is measured, and the resistance is obtained from the applied voltage and the measured current. Since the resistance of the secondary transfer roll 82 is much higher than the resistance of each of the intermediate transfer belt 50, the secondary transfer belt 85, and the backup roll 83, the resistance value of the secondary transfer mechanism 80 is substantially the secondary transfer. The resistance value of the roll 82 can be considered.

  The fixing mechanism 90 fixes the toner image transferred to the recording material. The fixing mechanism 90 forms a contact portion by bringing the peripheral surfaces of a heating roll having a heat source therein and a pressure roll into contact with each other. When the heating roll is heated and the sheet on which the toner image has been transferred by the secondary transfer mechanism 80 is carried into the contact portion, the toner image is subjected to the heating action by the heating roll and the pressing action by the pressure roll. To settle.

(Operation)
Next, the operation of the image forming apparatus 100 according to the first embodiment will be described. When the apparatus is turned on, the controller 30 instructs each roll in the apparatus to cycle up in preparation for drawing a monochrome image, including both the secondary transfer roll 82 and the fixing mechanism 90. The roll of each part instructed to cycle up starts to rotate under the control of the controller 30. The controller 30 rotates the rolls of the respective parts for a certain period of time, and then stops the rotation and puts the apparatus into a standby state. Thus, preparation for drawing a monochrome image is completed. Subsequently, the resistance detector 70 detects the resistance value of the secondary transfer mechanism 80 and supplies a signal indicating the detected resistance value to the controller 30. The controller 30 determines whether or not the resistance value indicated by the supplied signal is greater than the threshold value a stored in the storage unit.

  The threshold value a may be set based on a measurement result that summarizes the relationship between the voltage required to transfer each of the monochrome and color toner images satisfactorily and the resistance value of the secondary transfer mechanism 80. FIG. 2 is a diagram showing the measurement results compiled by the inventors. The vertical axis shown in FIG. 2 is a transfer output voltage indicating the voltage applied to the secondary transfer roll 82, and the horizontal axis shown in FIG. 2 is the resistance value (Rsys) of the secondary transfer mechanism 80. The unit of the transfer output voltage is V, and the unit of the resistance value of the secondary transfer mechanism 80 is MΩ.

  Referring to the figure, it can be seen that when the resistance value of the secondary transfer mechanism 80 is constant, the voltage required for transferring the color toner image is higher than the voltage required for transferring the monochrome toner image. For example, when the resistance value of the secondary transfer mechanism 80 is 600 MΩ, the voltage necessary for transferring the monochrome toner image is 5000 V, but the voltage necessary for transferring the color toner image is 8000 V. However, when the maximum output voltage of the power supply 81 is 6000 V, the power supply 81 cannot supply a voltage (8000 V) necessary for transferring the color toner image to the secondary transfer roll 82. For this reason, the secondary transfer roll 82 cannot generate an electrostatic field as long as good transfer is performed, which may result in transfer failure. Therefore, the upper limit value of the resistance capable of generating an electrostatic field capable of satisfactorily transferring color and monochrome toner images at the maximum output voltage of the power supply 81 is set as the threshold value a. For example, when the maximum output voltage of the power supply 81 is 6000 V, the threshold value a may be set to 300 MΩ as shown in FIG.

  In FIG. 1, if the resistance value detected by the resistance detector 70 is equal to or less than the threshold value a, the controller 30 causes the UI 10 to display a screen that prompts the user to input a monochrome or color image signal generation instruction. When the UI 10 instructs the generation of either a monochrome or color image signal, the controller 30 causes the scanning unit 20 to read the document image. The scanning unit 20 reads an image of a set original, generates RGB color image signals corresponding to the image, and transmits the image signals to the controller 30. The controller 30 supplies the image signals for each color of YMCK obtained by converting the color space of the image signal transmitted from the scan unit 20 to the image forming engine 40 corresponding to each color. When the image signals are supplied, each image forming engine 40 is driven according to a series of image forming processes of charging, exposure, development, and transfer to form a toner image on the intermediate transfer belt 50. Subsequently, the secondary transfer mechanism 80 transfers the toner image onto the paper supplied from the paper tray 60, and the fixing mechanism 90 fixes the transferred toner image on the paper. As a result, a good image can be formed regardless of whether generation of a monochrome or color image signal is instructed.

  On the other hand, when the resistance value detected by the resistance detector 70 is larger than the threshold value a, the controller 30 restricts an instruction to generate an image signal of a color image. More specifically, the controller 30 causes the UI 10 to display a message indicating that a color image is not drawn. As a result, the acceptance of the instruction to generate the color image signal is rejected. Then, the controller 30 rotates the secondary transfer roll 82 and the fixing mechanism 90 apart from each other. Then, the temperature in the apparatus rises due to the heat generated by the rotation of both the secondary transfer roll 82 and the fixing mechanism 90 and the heat generated from the heating roll of the fixing mechanism 90.

  FIG. 3 is a diagram showing the relationship between the temperature in the image forming apparatus and the resistance value of the secondary transfer mechanism 80 compiled by the inventors. The vertical axis shown in FIG. 3 is the resistance value (Rsys) of the secondary transfer mechanism 80, and the horizontal axis shown in FIG. 3 is the temperature in the apparatus. The unit of resistance value of the secondary transfer mechanism 80 is MΩ, and the unit of temperature in the apparatus is degree. Referring to FIG. 3, it is understood that the resistance value of the secondary transfer mechanism 80 is 300 MΩ to 400 MΩ when the temperature in the apparatus after power-on is about 13 degrees. When the threshold value a is 300 MΩ, the controller 30 determines that the detected resistance value is larger than the threshold value a, and restricts the instruction to generate the image signal of the color image.

When the controller 30 rotates the secondary transfer roll 82 and both rolls of the fixing mechanism 90 apart from each other and the temperature in the apparatus increases, the resistance value of the secondary transfer mechanism 80 decreases. Referring to FIG. 3, when the temperature in the apparatus rises from about 13 degrees after the power is turned on to about 17 degrees, the resistance value of the secondary transfer mechanism 80 that is 300 MΩ to 400 MΩ after the power is turned on is 130 MΩ. It can be seen that it drops to ˜170 MΩ. Since the resistance detector 70 detects the resistance value of the secondary transfer mechanism 80 at predetermined time intervals, as soon as a resistance value equal to or less than the threshold value a is supplied from the resistance detector 70, the controller 30 causes the secondary transfer roll to The rotation of both rolls 82 and the fixing mechanism 90 is stopped, and the restriction on the instruction to generate the image signal of the color image is released. More specifically, the message displayed on the UI 10 that the color image is not drawn is deleted. Thereby, the acceptance of the instruction to generate the image signal of the color image is not rejected.
Thereafter, the operation when an instruction to generate an image signal of either a monochrome image or a color image is input to the UI 10 is the same as the operation when the resistance value is equal to or less than the threshold value a, and thus description thereof is omitted.

Second Embodiment
(Constitution)
Next, the configuration of the image forming apparatus 200 according to the second embodiment will be described with reference to FIG. The configuration of the second embodiment differs from the configuration of the first embodiment described above in that a temperature detector 71 is provided instead of the resistance detector 70 that is a component of the first embodiment, and the controller 30 The storage unit stores a threshold value b (details will be described later) in advance. Since the other hardware configuration is the same as that of the first embodiment, the same reference numerals are given and description thereof is omitted.
The temperature detector 71 is provided in the vicinity of the secondary transfer roll 82, detects the temperature in the apparatus around the secondary transfer mechanism 80, and supplies a signal indicating the detected temperature to the controller 30.

(Operation)
Next, the operation of the image forming apparatus 200 according to the second embodiment will be described. When the power of the apparatus is turned on, the controller 30 prepares to draw a monochrome image by cycling up each roll in the apparatus, similarly to the operation after the power is turned on in the first embodiment.
Subsequently, the temperature detector 71 detects the temperature in the apparatus around the secondary transfer mechanism 80 and supplies a signal indicating the detected temperature to the controller 30. The controller 30 determines whether or not the temperature indicated by the supplied signal is smaller than a predetermined threshold value b stored in the storage unit.

  The setting method of the threshold value b will be described in detail. The resistance value of the secondary transfer mechanism 80 can generate an electrostatic field that can satisfactorily transfer color and monochrome toner images at the maximum output voltage of the power supply 81. The temperature in the apparatus corresponding to the upper limit value is set as the threshold value b. That is, when the upper limit value of the resistance is 300 MΩ, 17 degrees corresponding to the resistance value group having the resistance value of 300 MΩ or less in FIG. 3 may be set as the threshold value b.

  In FIG. 4, if the temperature indicated by the signal supplied from the temperature detector 71 is equal to or higher than the threshold value b, the controller 30 causes the secondary transfer mechanism 80 to achieve good color and monochrome toner images at the maximum output voltage of the power supply 81. It is assumed that a transferable electrostatic field can be generated, and an instruction to generate a monochrome or color image signal from the UI 10 is accepted. On the other hand, if the temperature indicated by the supplied signal is lower than the threshold value b, the secondary transfer mechanism 80 generates an electrostatic field that can satisfactorily transfer color and monochrome toner images at the maximum output voltage of the power supply 81. The controller 30 constrains the generation instruction of the image signal of the color image by the UI 10.

  The operation when the temperature indicated by the supplied signal is equal to or higher than the threshold value b is the same as the operation when the signal indicated by the resistance value supplied by the resistance detector 70 in the first embodiment is equal to or lower than the threshold value a. It is the same. The operation when the signal indicating the supplied temperature is smaller than the threshold value b is the same as the operation when the signal indicating the resistance value supplied by the resistance detector 70 in the first embodiment is larger than the threshold value a. It is. Therefore, a description of each of those further operations is omitted.

<Other embodiments>
The present invention can be modified in various ways.
In the first embodiment, when the power supply 81 applies a voltage to the secondary transfer roll 82, the resistance detector 70 moves the secondary transfer belt 85, the intermediate transfer belt 50, and the backup roll 83 from the secondary transfer roll 82. The current flowing through the ground is measured, and the resistance is obtained from the applied voltage and the measured current. However, the resistance value may be obtained by other methods. For example, when the power supply 81 passes a current from the secondary transfer roll 82 to the ground through the secondary transfer belt 85, the intermediate transfer belt 50, and the backup roll 83, the voltage applied to each of those parts is measured. The resistance may be obtained in accordance with the applied current and the applied voltage. In the above embodiment, the resistance detector 70 detects the resistance of the entire secondary transfer mechanism 80, but may detect the resistance of only the secondary transfer roll 82.

  In the second embodiment, the temperature detector 71 is provided in the vicinity of the secondary transfer roll 82 and detects the temperature of the secondary transfer mechanism 80. However, the temperature detector 71 detects the temperature so as to contact the surface of the secondary transfer roll 82. A device 71 may be provided to detect the surface temperature of the secondary transfer roll 82. Further, a temperature detector 71 is provided in each of the secondary transfer mechanism 80 and the fixing mechanism 90, detects the temperatures of the secondary transfer mechanism 80 and the fixing mechanism 90, and supplies a signal indicating the temperatures to the controller 30. May be. In that case, the controller 30 determines whether or not the signal indicating each supplied temperature is smaller than the threshold value b.

  In the first embodiment, when the value detected by the resistance detector 70 is larger than the threshold value a, and in the second embodiment, when the value detected by the temperature detector 71 is smaller than the threshold value b, the controller 30 Although the secondary transfer roll 82 and the fixing mechanism 90 are separated and rotated, only the secondary transfer roll 82 may be separated and rotated.

  In the above-described embodiment, the secondary transfer mechanism 80 transfers the toner image onto the paper by the power supply 81 applying a voltage having a reverse polarity to the toner image formed on the intermediate transfer belt 50 to the secondary transfer roll 82. However, the transfer method to the paper is not limited to this. For example, by applying a voltage having the same polarity as that of the toner image formed on the intermediate transfer belt 50 to the backup roll 83 and applying a voltage having a polarity opposite to that of the toner image to the secondary transfer roll 82, the intermediate transfer belt can be obtained. It is also possible to generate an electrostatic field that transfers the toner image formed on the sheet 50 to the sheet and transfer the toner image to the sheet.

1 is a configuration of an image forming apparatus 100 (first embodiment). 6 is a diagram illustrating a relationship between a transfer output voltage and a resistance value of the secondary transfer mechanism 80. FIG. FIG. 6 is a diagram showing the relationship between the temperature in the apparatus and the resistance value of the secondary transfer mechanism 80. This is a configuration of the image forming apparatus 200 (second embodiment). FIG. 6 is a diagram illustrating a relationship between a resistance value of the secondary transfer mechanism 80 and a transfer allowable range. It is a figure which shows the relationship between the number of printed sheets and the resistance value of a transfer part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... UI, 20 ... Scan part, 30 ... Controller, 40 ... Image formation engine, 50 ... Intermediate transfer belt, 60 ... Paper tray, 70 ... Resistance detector, 71 ... Temperature detector, 80 ... Secondary transfer mechanism, 81 DESCRIPTION OF SYMBOLS Power supply, 82 ... Secondary transfer roll, 83 ... Backup roll, 84 ... Support roller, 85 ... Secondary transfer belt, 90 ... Fixing mechanism, 100, 200 ... Image forming apparatus.

Claims (5)

Image forming means for receiving an image signal for instructing image drawing and forming a toner image of a single color or a plurality of colors on an image carrier in accordance with the supplied image signal;
A voltage source;
Transfer means for transferring the toner image to a recording material by causing an electric field generated by application of a voltage from the voltage source to act on the image carrier on which the toner image is formed;
Resistance detection means for detecting the resistance of the transfer means;
Instruction means for instructing generation of an image signal of a single color or a plurality of colors;
A signal supply unit that generates an image signal of the instructed image and supplies the image signal to the image forming unit, thereby forming a toner image of a single color or a plurality of colors according to the image signal;
An image forming apparatus comprising: a restricting unit that restricts an instruction to generate image signals of a plurality of colors by the instruction unit when the detected resistance is greater than a predetermined threshold value. The image forming apparatus according to claim 1.
The voltage source is
An image forming apparatus that supplies ideal power corresponding to the resistance detected by the resistance detection unit to the transfer unit. Image forming means for receiving an image signal for instructing image drawing and forming a toner image of a single color or a plurality of colors on an image carrier in accordance with the supplied image signal;
A voltage source;
Transfer means for transferring the toner image to a recording material by causing an electric field generated by application of a voltage from the voltage source to act on the image carrier on which the toner image is formed;
First temperature detecting means for detecting the temperature of the transfer means;
Instruction means for instructing generation of an image signal of a single color or a plurality of colors;
A signal supply unit that generates an image signal of the instructed image and supplies the image signal to the image forming unit, thereby forming a toner image of a single color or a plurality of colors according to the image signal;
An image forming apparatus comprising: a restriction unit that restricts an instruction to generate an image signal of a plurality of color images by the instruction unit when the temperature detected by the first temperature detection unit is lower than a predetermined threshold value. The image forming apparatus according to claim 3.
Fixing means for fixing the toner image transferred to the recording material;
And a second temperature detecting means for detecting the temperature of the fixing means,
The constraint means is
When the temperature detected by the first temperature detection unit and the temperature detected by the second temperature detection unit are smaller than a predetermined threshold, the instruction unit generates an instruction to generate an image signal of a plurality of colors. Image forming apparatus. The image forming apparatus according to claim 1, wherein:
The image carrier is
A photosensitive drum that forms a toner image on its peripheral surface through a xerographic process including charging, exposure, and development by the image forming unit;
An intermediate transfer belt for transferring a toner image formed on the peripheral surface of the photosensitive drum to its belt surface;
The transfer means includes
An image forming apparatus comprising: a secondary transfer roll that receives, from the voltage source, a voltage having a reverse polarity to a toner image formed on the intermediate transfer belt; and a backup roll that sandwiches the intermediate transfer belt together with the secondary transfer roll.

Images