JP2000292997A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent wasting of electrical power by shortening the starting time of a fixing means before an image can be output. SOLUTION: In this image forming device, an electrostatic latent image is formed on the surface of an electrophotographic photoreceptor 1 that is uniformly electrified by an electrifying device 2 by carrying out an image exposure corresponding to an input image signal, this electrostatic latent image is developed to be a toner image by a developing device 4, the toner image is transferred to a transfer material 6 by a transfer electrifying device 5 and an image is output by having the toner image on the transfer material 6 thermally fixed by a fixing device 8. In this case, a temperature detection device 15 detecting temperature of the fixing device 8 and a temperature control device 16 controlling the temperature of the fixing device 8 to be a specified temperature are provided and furthermore, a fixing control device 17 to selectively control an image processing method such as resolution of an output image according to the temperature detected by the temperature detection device 15 is provided.

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 or a printer for forming an image on a transfer material using an electrophotographic method.

[0002]

2. Description of the Related Art As a conventional image forming apparatus, for example,
On the surface of the electrophotographic photosensitive member uniformly charged by the charging means,
Forming an electrostatic latent image by performing image exposure corresponding to the input image signal, developing the electrostatic latent image into a toner image by a developing unit,
There is an image forming apparatus such as an electrophotographic copying machine or a printer which outputs the image by transferring the toner image to a transfer material by a transfer unit and fixing the toner image on the transfer material by a fixing unit.

FIG. 7 shows the structure of a fixing means in such a conventional image forming apparatus. This fixing means rotates a heating roller 111 having a heater 110 therein and a pressure roller 112 having a surface layer formed of a rubber layer by pressing against each other, and holding and transferring a transfer material 106 between the rollers 111 and 112. At the same time
The toner 114 on the transfer material 106 is melted at the surface temperature of the heating roller 111, and a toner image is fixed on the transfer material 106.

[0004] Further, the detection of the surface temperature of the heating roller 111 is performed by a temperature detecting device 1 which is brought into contact with the surface of the heating roller 111.
Perform by 15. Further, a predetermined control temperature is set in advance by the temperature control device 116. And the temperature control device
116 is the heating roller 11 detected by the temperature detecting device 115
The surface temperature of the heating roller 111 is compared with the set control temperature.If the surface temperature of the heating roller 111 is lower than the set control temperature, the heater 110 is energized, and the heating roller 111 is turned on. If the surface temperature is higher than the set control temperature, the power supply to the heater 110 is stopped.

In a conventional image forming apparatus, a main power supply (not shown) of the image forming apparatus is turned on / off so that the image forming operation can be executed as soon as an execution instruction of the image forming operation is input. The fixing unit is kept in a standby state in synchronization.

[0006]

However, in the above-described conventional example, the fixing operation is such that the toner 114 is melted by being heated by the heating roller 111 and the toner 114 is further melted.
The toner image is fixed on the transfer material 106 by the pressure from 12. At this time, the toners 114 function to fuse and fuse with each other to enhance the fixing power. Therefore,
An image in which the toner 114 is united in one place tends to have better fixability than an image in which the toners 114 are independent one by one.

Thus, it can be said that fixing is easier when the resolution is low than when the resolution is good. Also, if the resolution is the same, it can be said that the gradation property per dot is easier to fix when it is binary, than when it is multi-valued. Furthermore, when compared in terms of image density, it can be said that a dark image is easier to fix than a light image.

In the conventional image forming apparatus, the temperature of the fixing unit is raised to a predetermined temperature from a state in which the fixing unit is cooled, for example, in the morning. Since the raising time needs to be longer than necessary and the temperature of the fixing means needs to be increased, the time until image output becomes possible (hereinafter referred to as a wait time) is increased. It wastes power.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and an object of the present invention is to provide an image forming apparatus capable of shortening a wait time and preventing waste of power. Is what you do.

[0010]

According to a first aspect of the present invention, an image corresponding to an input image signal is formed on a surface of an electrophotographic photosensitive member uniformly charged by a charging means. Exposure is performed to form an electrostatic latent image, the electrostatic latent image is developed into a toner image by a developing unit, the toner image is transferred to a transfer material by a transfer unit, and the toner image on the transfer material is thermally fixed. In an image forming apparatus that outputs an image by performing thermal fixing with a unit, a temperature detecting unit that detects a temperature of the thermal fixing unit;
A temperature control unit that controls the temperature of the heat fixing unit to be maintained at a predetermined temperature based on the temperature detected by the temperature detection unit, and further outputs an output according to the temperature detected by the temperature detection unit. It has a control means for selecting and controlling an image processing method such as an image resolution.

According to a second aspect of the present invention for achieving the same object, an image exposure corresponding to an input image signal is performed on the surface of an electrophotographic photosensitive member uniformly charged by charging means. An electrostatic latent image is formed, the electrostatic latent image is developed into a toner image by a developing unit, the toner image is transferred to a transfer material by a transfer unit, and the toner image on the transfer material is thermally fixed by a heat fixing unit. A temperature detecting means for detecting a temperature of the heat fixing means, and maintaining the temperature of the heat fixing means at a predetermined temperature based on the temperature detected by the temperature detecting means. Control means and a selector for selecting an image processing mode, and image processing such as resolution of an image output according to the temperature detected by the temperature detecting means and the image processing mode selected by the selector. Method Characterized in that a control means for selecting control.

Based on the above configuration, by selectively controlling the image processing method such as the resolution of the image in accordance with the temperature detected by the fixing unit, it is possible to shorten the start-up time of the fixing unit before image output becomes possible. Power consumption can be prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an image forming apparatus to which the present invention is applied will be described in detail with reference to the drawings. In the following embodiments, an image forming apparatus such as a copying machine or a printer that forms an image on a transfer material by using an electrophotographic method is exemplified.

First Embodiment First, an image forming apparatus according to a first embodiment of the present invention will be described in detail with reference to FIGS.

FIG. 1 is a schematic configuration diagram showing a main configuration of an image forming apparatus according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a rotating drum-shaped electrophotographic photosensitive member,
The surface is uniformly charged by the primary charging device 2. Then, an image signal (for example, an input original image or the like) is formed on the surface of the electrophotographic photosensitive member 1 uniformly charged by the primary charging device 2.
By irradiating the image exposure 3 corresponding to the above, an electrostatic latent image is formed. After the electrostatic latent image is developed into a toner image by the developing device 4, the toner image is transferred to a transfer material 6 such as copy paper by the transfer charging device 5. The transfer material 6 onto which the toner image has been transferred is sent to a fixing device 8 via a guide 7, and after the toner image is fixed by the fixing device 8, is discharged as an output image.

FIG. 2 is a configuration diagram showing a schematic configuration of the fixing device 8. As shown in FIG. 2, the fixing device 8 rotates by pressing a heating roller 11 having a heater 10 therein and a pressure roller 12 having a surface layer formed of a rubber layer in pressure contact with each other.
At the same time as the transfer material 6 is nipped and conveyed between 11 and 12, the toner 14 on the transfer material 6 is melted at the surface temperature of the heating roller 11 and a toner image is fixed on the transfer material 6.

The surface temperature of the heating roller 11 is detected by
This is performed by the temperature detecting device 15 which is in contact with the surface of the heating roller 11. Further, a predetermined control temperature is set in advance by the temperature control device 16. Then, the temperature control device 16 compares the surface temperature of the heating roller 11 detected by the temperature detection device 15 with the set control temperature, and the surface temperature of the heating roller 11 is set. If the temperature is lower than the control temperature, the heater 10 is energized.If the surface temperature of the heating roller 11 is higher than the set control temperature, the heater 10 is energized.
Stop supplying power to 10.

Further, as shown in FIG. 2, the fixing device 8 according to this embodiment has a fixing control device 17 for controlling the fixing device 8.
The fixing control device 17 includes the temperature detection device
According to the surface temperature of the heating roller 11 detected by 15, the resolution of the output image, which is one of the image processing methods, is selectively controlled. In this embodiment, the resolution mode of the normal image is set to 400 dpi.

FIG. 3 is a comparison graph showing the relationship between the same image and the fixability of the image when the same image is output at different resolutions (100 dpi, 200 dpi, and 400 dpi in this embodiment). In FIG. 3, the vertical axis indicates the fixing property of the image, and the horizontal axis indicates the resolution of the image. The comparison conditions are all the same except for the difference in the mode (resolution). Here, the fixability indicates a rate of decrease in density before and after the image is rubbed after fixing. Therefore, in FIG. 3, it can be said that the smaller the numerical value of the fixing property, the better the image is fixed. That is, it can be understood from FIG. 3 that an image having a higher fixing property is inferior to an image having a lower resolution than an image having a lower resolution.

From this, as the resolution increases, the size of one pixel decreases. Therefore, as the resolution increases, the toner 14 is less likely to bond with each other when the toner 14 is heated and melted by the surface temperature of the heating roller 11 of the fixing device 8. That is, it can be said that the fixing property is inferior.

Next, the control operation of the start-up time of the fixing device 8 in the image forming apparatus according to the present embodiment will be described.

In this embodiment, in order to satisfy the fixability of a normal image having a resolution of 400 dpi in a normal environment (17 ° C.), the temperature control temperature of the heating roller 11 of the fixing device 8 needs to be 200 ° C. There is. FIG. 4 is a diagram illustrating the relationship between the temperature of the heating roller 11 and the time during the start-up time of the fixing device 8. From FIG. 4, it can be seen that a rise time of 90 seconds is required to increase the temperature regulation temperature of the heating roller 11 from normal temperature to 200 ° C.

Further, Table 1 shows the temperatures of the heat roller 11 and the temperatures that can be fixed when the image resolution is set to 200 dpi and when the image resolution is set to 100 dpi in order to obtain the same fixability as that when the resolution is 400 dpi. Represents the time required to start up. From Table 1, in order to obtain the same fixing property as that of the case of the resolution of 400 dpi, a resolution of 20
In the case of 0 dpi, the startup time of the fixing device 8 requires 75 seconds. When the resolution is set to 100 dpi, the start-up time of the fixing device 8 is 67 seconds.

[0024]

[Table 1]

That is, the start-up time of the fixing device 8 for a normal image having a resolution of 400 dpi requires 90 seconds in a normal temperature environment (17 ° C.). Can be started up to 75 seconds in a normal temperature environment (17 ° C.) to shorten the startup time. Further, in the mode of the resolution of 100 dpi, the start-up time of the fixing device 8 can be reduced to 67 seconds in a normal temperature environment (17 ° C.).

FIG. 5 is a flowchart showing a start-up control procedure of the fixing device 8 in the image forming apparatus according to the present embodiment. First, in step S21, a heating roller
It detects whether the temperature of 11 is 70 degreeC or more. If the detected temperature is 70 ° C. or higher, the process proceeds to step S22, and the resolution is set to 400 dpi from the first sheet. From FIG. 4, it can be seen that it takes 70 seconds to make the temperature of the heating roller 11 reach 200 ° C. at 70 ° C. If the temperature is equal to or lower than 70 ° C., the process proceeds to step S23 to detect whether the temperature is equal to or higher than 20 ° C. Where 20
If the temperature is not lower than ℃, the process proceeds to step S24, where the resolution of the first sheet is set to 200 dpi, and the resolution from the second consecutive sheet is 400 dpi.
Set to. On the other hand, if the temperature is lower than 20 ° C., step S55
Go to and set the resolution of the first sheet to 100 dpi.
The resolution of the first sheet is set to 200 dpi, and the third consecutive sheet is set to 400 dpi.

As described above, by controlling the selection of the resolution of the output image in accordance with the temperature detected by the fixing device 8,
The time until image output becomes possible (the time required to start up the fixing device 8) can be reduced (from 90 seconds to 75 seconds in this embodiment), and as a result, waste of power can be prevented. Can be. Note that only the initial one job has a resolution of 20
It may be 0dpi.

[Second Embodiment] Next, an image forming apparatus according to a second embodiment of the present invention will be described in detail. still,
Since the configurations of the image forming apparatus and the fixing device are substantially the same as those of the first embodiment, detailed description thereof will be omitted.

In the image forming apparatus according to the present embodiment, the operator can select an image processing mode from two modes for a photograph and a character by a selector (not shown). The fixing control device 17 selectively controls the resolution and gradation of an output image, which is one of image processing methods, according to the temperature detected by the temperature detection device 15 and the image processing mode selected by the selector. I do.

In this embodiment, the resolution of the normal image in each mode is set to binary 400 dpi for characters and to multi-value 400 dpi for photographs. In addition, the multi-value for a photograph is set to 256 gradations. Further, in the present embodiment, description will be given for a photograph. In the photo mode, in order to perform image processing with emphasis on halftone reproduction, in the present embodiment, multi-valued 600 dpi control of 256 gradations is performed. Therefore, since the bonding force between the toners 14 per dot is inferior to the case of binary, the fixability tends to be deteriorated.

Here, the control operation of the start-up time of the fixing device 8 in the image forming apparatus according to the present embodiment will be described.

In the present embodiment, in order to satisfy the fixability of a binary image of 400 dpi in the character mode in the normal environment (17 ° C.), the temperature control temperature of the heating roller 11 of the fixing device 8 is set to 200.
℃. However, in this embodiment, there is a photograph mode. In this case, the temperature regulation temperature of the heating roller 11 of the fixing device 8 needs to be 205 ° C. in order to satisfy the fixing property.

FIG. 4 shows the relationship between the temperature of the heating roller 11 and the time when the fixing device 8 is started, as described above. From FIG. 4, the temperature control temperature of the heating roller 11 is changed from the normal temperature.
It can be seen that a rise time of 95 seconds is required to reach 205 ° C. Therefore, the wait time of the image forming apparatus according to the present embodiment (the time until image output is enabled)
Requires 95 seconds.

Further, Table 2 shows that the binary 400dpi and the multi-value 400dpi
The relationship between pi and the temperature of the heat roller 11 that can be fixed at each of multiple values of 300 dpi and the time required to start up to that temperature is shown. From Table 2, in order to obtain the same fixing performance as that of the binary 400 dpi, a multi-valued 400 dpi
In the case of pi, the startup time of the fixing device 8 needs 95 seconds. When the multi-value is set to 300 dpi, the start-up time of the fixing device 8 is required to be 85 seconds.

[0035]

[Table 2]

That is, the start-up time of the fixing device 8 for a multi-valued 400 dpi photographic image requires 95 seconds in a normal temperature environment (17 ° C.). Start up time is normal temperature environment (17
(° C.) to 85 seconds, reducing the startup time.

FIG. 6 is a flowchart showing a start-up control procedure of the fixing device 8 in the image forming apparatus according to the present embodiment. First, in step S31, it is detected whether the mode is the text mode or the photo mode. Here, in the case of the character mode, the process proceeds to steps S32 and S33 and the temperature of the heating roller 11 is set to 70
It detects whether it is over ℃. If the detected temperature is equal to or higher than 70 ° C., the process proceeds to step S34, and the resolution is set to a binary value of 400 dpi from the first sheet. From FIG. 4, it can be seen that it takes 70 seconds to make the temperature of the heating roller reach 200 ° C. at 70 ° C. If the temperature is not higher than 70 ° C., step S35
And set the resolution of the first sheet to 200 dpi,
Set the resolution from the first sheet to 400 dpi.

Next, the case of the photograph mode will be described. In the case of the photo mode, the process proceeds to steps S36 and S37, where the heating roller 11
Detects whether the temperature is 60 ° C or higher. Here, if the detected temperature is 60 ° C. or higher, the process proceeds to step S38, where the
Set to 400dpi. If the temperature is not higher than 60 ° C., the process proceeds to step S39, where the resolution of the first sheet is set to multi-valued 300 dpi, and the resolution from the second successive sheet is set to multi-valued 400 dpi.

As described above, by controlling the resolution of the output image in accordance with the temperature detected by the fixing device 8 and the image processing mode by the selector, the time until the image can be output (the time required for the fixing device 8) It is possible to reduce the time required for the start-up (from 95 seconds to 85 seconds in the present embodiment). As in the present embodiment, even when the image processing method is various such as the character mode or the photo mode, the wait time can be reduced by controlling the image processing method according to the temperature of the fixing device 8. As a result, waste of power can be prevented.

In the above-described embodiments, a printer is exemplified as an image forming apparatus. However, the present invention is not limited to this. For example, other image forming apparatuses such as a copying machine and a facsimile apparatus may be used. The same effects can be obtained by applying the present invention to the image forming apparatus.

[0041]

As described above, according to the present invention,
Since the temperature of the fixing unit is detected and the image processing method such as the resolution of the image is selectively controlled in accordance with the detected temperature, the startup time of the fixing unit before image output becomes possible can be reduced. As a result, power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a schematic configuration of an image forming apparatus according to a first embodiment.

FIG. 2 is a configuration diagram illustrating a schematic configuration of a fixing device in the image forming apparatus according to the first embodiment.

FIG. 3 is a graph showing a relationship between resolution and fixability in each mode in the image forming apparatus according to the first embodiment.

FIG. 4 is a graph showing a relationship between a temperature of a heating roller and a time when the fixing device is started up.

FIG. 5 is a flowchart illustrating a control procedure of a resolution of image processing according to a temperature of a fixing device in the image forming apparatus according to the first embodiment.

FIG. 6 is a flowchart illustrating a control procedure of a resolution of image processing according to a temperature of a fixing device in the image forming apparatus according to the second embodiment.

FIG. 7 is a configuration diagram illustrating a schematic configuration of a fixing device in a conventional image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrophotographic photosensitive member 2 ... Primary charging device 3 ... Image exposure 4 ... Developing device 5 ... Transfer charging device 6 ... Transfer material 7 ... Guide 8 ... Fixing device 10 ... Heater 11 ... Heating roller 12 ... Pressing roller 14 ... Toner 15… Temperature detector 16… Temperature controller 17… Fixing controller

Claims (2)

[Claims] 1. An electrostatic latent image is formed on a surface of an electrophotographic photosensitive member uniformly charged by a charging unit by performing image exposure corresponding to an input image signal, and the electrostatic latent image is formed by a developing unit. Developing the toner image on a transfer material by a transfer unit, and thermally fixing the toner image on the transfer material by a heat fixing unit to output an image. Temperature detecting means for detecting the temperature of the heat fixing means, and temperature control means for controlling the temperature of the heat fixing means to be maintained at a predetermined temperature based on the temperature detected by the temperature detecting means, and further comprising: An image forming apparatus comprising: a control unit that selectively controls an image processing method such as a resolution of an image to be output according to a temperature detected by a detection unit. 2. An electrostatic latent image is formed on a surface of an electrophotographic photosensitive member uniformly charged by a charging unit by performing image exposure corresponding to an input image signal, and the electrostatic latent image is developed by a developing unit. Developing the toner image on a transfer material by a transfer unit, and thermally fixing the toner image on the transfer material by a heat fixing unit to output an image. Temperature detecting means for detecting the temperature of the image forming apparatus, temperature controlling means for controlling the temperature of the heat fixing means to be maintained at a predetermined temperature based on the temperature detected by the temperature detecting means, and a selector for selecting an image processing mode. And control means for selecting and controlling an image processing method such as a resolution of an image to be output in accordance with the temperature detected by the temperature detecting means and the image processing mode selected by the selector. Image forming apparatus.