JP2011180315A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent toner-melting due to a temperature rise in an apparatus, and achieve a highly efficient printing operation. <P>SOLUTION: The image forming apparatus includes an image forming means configured to form a toner image on a photoreceptor by an electrophotographic process. The image forming apparatus also includes: a thermistor 114 configured to detect the temperature in the apparatus; a temperature comparison means 120 configured to compare the detected temperature in the apparatus and the toner-melting starting temperature previously set as a threshold; and a process speed determination means 130 configured to determine the electrophotographic process speed based on the comparison result. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus including an image forming unit that forms an image with toner on a photoreceptor by an electrophotographic process.

  In recent years, as the demand for colorizing documents and creating them quickly increases, the colorization and speeding up of laser beam printers are rapidly progressing. As an example of a color printer, yellow (Y), cyan (C), magenta (M), and black (K) toners are used, and an image forming unit for each color is provided, and a toner image formed by each image forming unit is used. There is known a tandem color image forming apparatus that forms a color image by transferring an image onto an intermediate transfer member.

  In the tandem image forming apparatus, a plurality of image forming units independently form different toner images on each photoconductor, and the toner images on these photoconductors are transferred onto an intermediate transfer member in a multiple transfer manner. It is configured. Conventionally, in order to stabilize an image, a gradation pattern as a toner image is formed on an intermediate transfer member according to a predetermined condition, and the toner adhesion amount of the gradation pattern is measured by an image detection means constituted by an optical reflection density sensor. The development capability can be detected, and if the development capability is lower than the target, toner is supplied to the developing device. Conversely, if the development capability is higher than the target, the image is intentionally The toner is consumed to reduce the developing power, and the image forming conditions including the charging potential, the developing bias potential, and the potential due to exposure are controlled so that the target toner adhesion amount is obtained.

  In Patent Document 1, even if the temperature, humidity, or surface potential of the photoconductor changes to change the photosensitivity of the photoconductor, it is formed on the photoconductor drum in order to always obtain a constant gradation characteristic for the original. The adhesion amount of the reference toner image is detected by the AIDC sensor, and the image reproduction density is adjusted so as to keep the reproduction density of the reference toner image formed on the photosensitive drum constant based on the detection value of the AIDC sensor. Also, the temperature and humidity around the photosensitive drum are detected, or the surface potential, exposure potential, and residual potential of the photosensitive drum are detected, and the sensitivity characteristics of the photosensitive member are predicted or detected based on the detection results. In this document, the exposure amount, the developing bias potential or the surface potential of the photosensitive drum, and the γ correction table are corrected from the surface potential, the exposure potential, and the residual potential of the photosensitive drum.

  Patent Document 2 discloses a copying speed switching control device for a copying machine having multiple copying speeds, and a copying speed setting means for setting the copying speed to be switchable by an operation input, and detecting the temperature in the copying machine. The internal temperature detecting means and the copying speed are controlled to the setting speed of the copying speed setting means, and the temperature detected by the internal temperature detecting means is predetermined when the copying machine is operating at the copying speed on the high speed side of the multi-stage. And a speed control means for switching the copying speed to the low speed side while continuing the close-up operation when the value is reached.

  However, in the conventional image forming apparatus, the toner in the developing device, the toner bottle, the sub hopper, and the cleaned waste toner may be melted due to an increase in the temperature inside the apparatus. There is a problem in that the load on the part increases and the motor stops, or the path through which the toner is transported becomes hard and the image forming apparatus is destroyed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of preventing a toner from being melted due to an increase in an in-machine temperature and performing an efficient printing operation.

  According to a first aspect of the present invention, there is provided an image forming apparatus including an image forming unit that forms an image with toner on a photosensitive member by an electrophotographic process, a temperature detecting unit that detects a temperature in the machine, and the detected temperature in the machine in advance. An image forming apparatus comprising: a temperature comparing unit that compares a melting start temperature of toner set as a threshold; and a process speed determining unit that determines a process speed of electrophotography based on the comparison result. .

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the temperature comparing means compares the internal temperature during the printing operation with the threshold value.

  According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the temperature comparing unit compares the in-machine degree during which the printing operation is stopped with the threshold value.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the process speed determining means determines the process speed of electrophotography when the in-machine temperature is higher than the threshold value. It is characterized by setting slower than the standard speed.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the process speed determining means is set so that a process speed of electrophotography is slower than a standard speed. If the in-machine temperature is lower than the threshold, the electrophotographic process speed is set to a standard speed.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the first aspect, when the process speed is changed, the process speed determining means interlocks the image forming conditions of the fixing temperature, the image forming potential, and the toner density. It is characterized by changing.

  According to a seventh aspect of the present invention, in the image forming apparatus according to the first aspect, the process speed determining means sets the electrophotographic process speed to be lower than the standard speed or the in-machine temperature when the in-machine temperature is higher than the threshold. It is possible to select to stop the printing operation until is lower than the threshold value.

  According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, when the process speed is changed by the process speed control determining means, the change is based on the amount of process change. And a process speed correcting means for correcting image forming conditions including a charging potential at a standard speed, a developing bias potential, and an exposure amount with a coefficient determined in this manner.

  According to a ninth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to seventh aspects, wherein a pattern forming unit that forms a gradation pattern on a photoconductor as a toner image; An image density detecting means for measuring density, and an image forming condition control means for controlling a charging potential, a developing bias voltage, and an image forming potential as image forming conditions, and when the process speed determining means switches the process speed, A process speed correction unit that generates a gradation pattern by the gradation pattern generation unit, detects a density of the gradation pattern by the image density detection unit, and corrects an image forming condition based on a detection result of the image density detection unit It is characterized by providing.

  According to the image forming apparatus of the present invention, since the process speed of the image forming apparatus is adjusted based on the in-machine temperature, the setting of the fixing temperature is lowered or the number of rotations of the motor is lowered to match the in-machine temperature. Since the amount of heat generated in the machine can be reduced, the toner can be prevented from melting and an image having no abnormality can be output stably.

1 is a schematic diagram illustrating a main part of an image forming apparatus according to an embodiment. 1 is a schematic diagram illustrating an image forming unit of an image forming apparatus according to an embodiment. It is a graph which shows the relationship of the temperature in the ambient temperature vessel in a different process speed. FIG. 3 is a block diagram illustrating a control system of the image forming apparatus according to the first embodiment. It is a block diagram which shows the control system of the image forming apparatus which concerns on a 2nd Example.

  The present invention relates to an image forming apparatus having an image forming means for forming an image with a toner on a photoreceptor by an electrophotographic process, a temperature detecting means for detecting the temperature in the apparatus, and the detected in-machine temperature as a threshold value in advance. An image forming apparatus comprising: a temperature comparison unit that compares the melting start temperature of the toner, and a process speed determination unit that determines a process speed of electrophotography based on the comparison result.

  In the image forming apparatus of the present invention, the temperature comparison unit can compare the temperature inside the apparatus during a printing operation with the threshold value.

  Further, in the image forming apparatus of the present invention, the temperature comparison unit can compare the in-machine degree when the printing operation is stopped and the threshold value.

  In the image forming apparatus according to the present invention, the process speed determining unit may set the electrophotographic process speed slower than the standard speed when the in-machine temperature is higher than the threshold value.

  In the image forming apparatus of the present invention, the process speed determining means is a case where the process speed of electrophotography is set slower than the standard speed, and when the in-machine temperature is lower than the threshold, the process speed of electrophotography is standardized. Can be set to speed.

  In the image forming apparatus of the present invention, when the process speed is changed, the process speed determining unit can change the image forming conditions of the fixing temperature, the image forming potential, and the toner density in conjunction with each other.

  In the image forming apparatus of the present invention, when the in-machine temperature is higher than the threshold value, the process speed determining unit sets the electrophotographic process speed to be lower than the standard speed or the in-machine temperature becomes lower than the threshold value. It is possible to select to stop the printing operation until.

  Further, in the image forming apparatus according to the present invention, when the process speed is changed by the process speed control determining means, the charging potential, the developing bias potential, and the exposure at the standard speed with a coefficient determined based on the amount of the process change. A process speed correcting means for correcting an image forming condition including the amount can be provided.

  In the image forming apparatus according to the present invention, a pattern forming unit that forms a gradation pattern as a toner image on the photosensitive member, an image density detection unit that measures the density of the gradation pattern, and a charging potential that is an image forming condition Image forming condition control means for controlling the development bias voltage and the image forming potential, and when the process speed determining means switches the process speed, the gradation pattern creating means creates a gradation pattern, and the image density A process speed correction unit that detects the density of the gradation pattern by the detection unit and corrects the image forming conditions based on the detection result of the image density detection unit can be provided.

  In the following, an embodiment of the image forming apparatus will be described. FIG. 1 is a schematic diagram showing a main part of the image forming apparatus. The image forming apparatus 100 includes an intermediate transfer member 101, a first image forming unit 102, a second image forming unit 103, a third image forming unit 104, and a fourth image forming unit 105. Each image forming unit 102 to 105 corresponds to each color of yellow, magenta, cyan, and black. In addition to the primary transfer units 106 to 109, the image forming apparatus 100 includes final image carriers such as an image detection unit 110 that detects the toner density on the intermediate transfer member, a secondary transfer unit 111, and a paper 112. In the image forming apparatus 100, a thermistor 114 as temperature detecting means for measuring the temperature inside the apparatus is disposed. The thermistor 114 is set at a location where the in-machine temperature increases.

  FIG. 2 is a schematic diagram illustrating an image forming unit of the image forming apparatus. Since the image forming units 102 to 105 as image forming means have the same configuration, the illustrated image forming unit 102 will be described. The image forming unit 102 includes a photoconductor 202, a charger 201 that uniformly charges the photoconductor 202, an exposure unit 203 that generates laser light 204 that exposes the photoconductor 202, a developing device 205, a photoconductor cleaner 206, and an erase 207. Prepare.

  In this image forming unit 102, the photosensitive member 202 is uniformly charged by the charger 201, and then a discharge potential is formed by the laser light applied to the photosensitive member 202 according to the image data from the exposure unit 203, thereby forming a latent image. It is formed. Thereafter, the latent image formed on the photosensitive member 202 is developed with toner between the development potential and the discharge potential by the developing unit 205 to form a toner image. Next, the toner image formed on the photosensitive member 202 is transferred onto the intermediate transfer member 101 by the primary transfer unit 108, and the photosensitive member 202 is finally charged by being uniformly irradiated with light by the eraser 207. The site is discharged.

  Similarly, in the image forming units 103 to 105 having different color toners, toner images are formed on the respective photoreceptors 202, and the toner images of the respective colors are transferred onto the intermediate transfer member 101 by the primary transfer units 107 to 109. After being transferred from the intermediate transfer member 101 to the paper 112 by the secondary transfer device 111, it is fixed by the fixing device 113, and a series of printing processes is completed.

  On the other hand, the residual toner remaining on the photosensitive member 202 without being transferred to the intermediate transfer member 101 is collected by the photosensitive member cleaner 206.

  At this time, the rotation speed and conveyance speed of the conveyance path of the photosensitive member 202, the developing device 205, the intermediate transfer member 101, the fixing device 113, and the paper 112 are determined according to the electrophotographic process speed, respectively.

  Next, the thermal characteristics of the toner will be described. The toner has a glass transition point, and when the temperature exceeds the glass transition point, the toner starts to melt. In recent years, development of toner that melts at a low temperature is progressing due to energy-saving design in consideration of the environment, and the glass transition point has also been lowered.

  FIG. 3 is a graph showing the relationship of the temperature in the ambient temperature chamber at different process speeds. If the horizontal axis is the ambient environment and the vertical axis is the in-machine temperature, it can be seen that as the process speed increases, the motor speed increases and the in-machine temperature rises.

  Next, control of the image forming apparatus according to this example will be described. First, the image forming apparatus according to the first embodiment will be described. The image forming apparatus according to this example changes the process speed based on the detected in-machine temperature. FIG. 4 is a block diagram illustrating a control system of the image forming apparatus according to the first embodiment. The control system of the image forming apparatus according to this example includes a temperature comparison unit 120 connected to the thermistor 114 and a process speed determination unit 130 that determines a process speed based on the output of the temperature comparison unit 120.

  The temperature comparison unit 120 is preliminarily input and set with the glass transition point of the toner to be used as a threshold, and the process speed determination unit 130 is input with the set speed of the image forming apparatus. The temperature comparison unit 120 and the process speed determination unit 130 are realized by executing a program with a microcomputer including a CPU, a RAM, a ROM, and the like. Then, the temperature comparison unit 120 compares the input value from the thermistor 114 with the threshold value and outputs the comparison result to the process speed determination unit 130. The process speed determining unit 130 determines a process speed based on the comparison result. The process speed is determined taking into account the current process speed. The process speed is determined based on a setting table stored in the ROM or RAM.

  For example, when continuously operated at a standard process speed, the in-machine temperature rises, and this is detected by the thermistor 114 at the site where the in-machine temperature is highest. Then, the temperature comparison means 120 compares this detected temperature with a threshold value and outputs the result to the process speed determination means 130. The temperature comparison unit 120 determines whether or not the continuous operation in the standard mode (high speed) is possible based on the comparison result and the speed setting. A moving speed control signal and a process control signal for reducing the linear speed and the process speed are generated, and the process speed is controlled to be switched to the low speed side. This prevents the in-machine temperature from exceeding a certain value T0 set lower than the glass transition point of the toner in terms of durability and image quality.

  The temperature comparison unit 120 can obtain the temperature in the machine during the printing operation or in the machine during the printing operation stop from the thermistor 114.

  The process speed determining means 130 is a case where the electrophotographic process speed is set slower than the standard speed, and when the in-machine temperature is lower than the threshold, the electrophotographic process speed is set to the standard speed. In addition, when the process speed is changed, the image forming conditions of the fixing temperature, the image forming potential, and the toner density can be changed in conjunction with each other.

  In addition, when the in-machine temperature is higher than the threshold, the process speed determination unit 130 sets the electrophotographic process speed to be slower than the standard speed or stops the printing operation until the in-machine temperature becomes lower than the threshold. Can also be made selectable.

  Next, control of the image forming apparatus according to the second embodiment will be described. The image forming apparatus according to this example is capable of smoothly changing the process speed. In the image forming apparatus according to this example, in addition to the temperature comparing unit 120 and the process speed determining unit 130, an image forming condition control unit 140 for adjusting the developing force, and a toner image having a predetermined pattern on the intermediate transfer member 101. Pattern forming means 150 for forming a tone pattern is provided.

  In the image forming apparatus according to this example, when the process speed determining unit 130 switches the process speed, the pattern forming unit 150 again forms the gradation pattern 160 that is a toner image on the intermediate transfer body 101 under a predetermined condition. Then, the developing ability is detected by detecting the toner adhesion amount of the gradation pattern 160 by the image detecting unit 110 including the light emitting unit 115 and the optical reflection density sensor 116. The image forming condition control unit 140 replenishes the developing device with toner when the developing ability is lower than the predetermined state, and conversely, when the developing ability is higher than the predetermined state, the image forming condition control unit 140 intentionally executes the image. For example, the gradation pattern 160 is formed to consume the toner and reduce the developing power. Then, an image forming condition including a charging potential, a developing bias potential, and a potential due to exposure is controlled so that a target toner adhesion amount is obtained. According to this example, it is possible to perform a smooth speed switching that provides stable image quality immediately after the speed switching.

  Next, a third embodiment will be described. The image forming apparatus according to this example includes a process speed correction unit in the image forming apparatus according to the first embodiment. The process speed correction means is preset with a coefficient corresponding to the amount of change in the process speed by the process speed determination means 130. When the process speed determination means 130 sets the process speed, the charging potential at the standard speed, the development bias potential, Correct the exposure. According to this example, it is possible to perform a smooth speed switching that provides stable image quality immediately after the speed switching.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 101 Intermediate transfer body 102 1st image formation part 103 2nd image formation part 104 3rd image formation part 105 4th image formation part 106-109 Temporary transfer machine 107-109 Transfer machine 108 Transfer machine 106-109 Primary Transfer machine 110 Image detection means 111 Secondary transfer machine 112 Paper 113 Fixing device 114 Thermistor (temperature detection means)
115 Light Emitting Unit 116 Optical Reflectance Density Sensor 120 Temperature Comparison Unit 130 Process Speed Determination Unit 140 Image Formation Condition Control Unit 150 Pattern Forming Unit 160 Gradation Pattern 201 Charger 202 Photoconductor 203 Exposure Unit 204 Laser Light 205 Developer 206 Photoconductor Cleaner 207 Erase

Japanese Patent Laid-Open No. 5-14729 JP-A-4-57066

Claims (9)

In an image forming apparatus provided with an image forming means for forming an image with toner on a photoreceptor by an electrophotographic process,
Temperature detection means for detecting the temperature inside the machine;
A temperature comparison unit that compares the detected in-machine temperature with a toner dissolution start temperature set in advance as a threshold; and a process speed determination unit that determines an electrophotographic process speed based on the comparison result. An image forming apparatus.   The image forming apparatus according to claim 1, wherein the temperature comparison unit compares an in-machine temperature during a printing operation with the threshold value.   The image forming apparatus according to claim 1, wherein the temperature comparison unit compares the threshold value with the threshold value when the printing operation is stopped.   4. The process speed determination unit according to claim 1, wherein when the in-machine temperature is higher than the threshold, the process speed of electrophotography is set slower than a standard speed. 5. Image forming apparatus.   The process speed determining means is a case where the process speed of electrophotography is set slower than the standard speed, and when the in-machine temperature is lower than the threshold, the process speed of electrophotography is set to the standard speed. The image forming apparatus according to any one of claims 1 to 3.   2. The image forming apparatus according to claim 1, wherein when the process speed is changed, the process speed determining unit changes the image forming conditions of the fixing temperature, the image forming potential, and the toner density in conjunction with each other.   When the in-machine temperature is higher than the threshold, the process speed determining means can select to set the electrophotographic process speed to be slower than the standard speed or to stop the printing operation until the in-machine temperature is lower than the threshold. The image forming apparatus according to claim 1, wherein:   When the process speed is changed by the process speed control determining means, the process speed corrects the image forming conditions including the charging potential at the standard speed, the developing bias potential, and the exposure amount by a coefficient determined based on the amount of the process change. The image forming apparatus according to claim 1, further comprising a correcting unit. Pattern forming means for forming a gradation pattern as a toner image on the photoreceptor, and image density detection means for measuring the density of the gradation pattern,
When the process speed determining means switches the process speed, a gradation pattern is created by the gradation pattern creating means, the density of the gradation pattern is detected by the image density detecting means, and the detection result of the image density detecting means is obtained. 8. The image forming apparatus according to claim 1, further comprising a process speed correcting unit that corrects the image forming condition based on the process speed correcting unit.