JPH09204115A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To consecutively form images, even if the images for hundreds of paper sheets are formed and further, to increase an image forming speed by supplying surplus power to a fixing means with a power supplying means, as heating energy. SOLUTION: The power of the power supplying means 5 is supplied to a read means 1, a toner image forming member 2, a fixing member 4 and a post- processing means 3 by the power supplying means 5. This power supplying means 5 is connected to a 100V, 15A commercial power source, composed of a power distributing part, 5a for distributing the power of the commercial power source to the read means 1, the toner image forming member 2, the fixing member 4 and the post-processing means 3 and a power control part 5b for controlling the distribution of the power by the power distributing part, 5a in accordance with the operating state of an image forming device and integrally arranged with an image forming means. In such a constitution, the surplus power is supplied to the fixing means by the power supplying means 5, as the heating energy. Thus, the drop of the temp. of the fixing means can be suppressed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laser printer,
The present invention relates to an electrophotographic image forming apparatus such as a copying machine, and more particularly, to an improvement in an image forming apparatus that transfers a toner image onto a recording material and then heats and fixes the recording material.

Heretofore, the electrophotographic image forming apparatus has been an analog image forming apparatus.
Then, the analog type image forming apparatus is, for example,
A photosensitive drum that is rotatably held, a charging corotron that is arranged facing the photosensitive drum and is applied with a high voltage, and an exposing unit that scans an original with light and exposes the photosensitive drum with the reflected light. Developing means for applying a developing voltage to a developing roll rotatably arranged facing the photoconductor drum to develop the electrostatic latent image to form a toner image, and a developing means facing the photoconductor drum. And a fixing means for fixing the toner image to the recording material by heating and pressurizing the recording material by transferring the toner image to the recording material when a high voltage is applied.

In the analog type image forming apparatus, a high voltage is applied to the charging corotron while rotating the photosensitive drum to charge the photosensitive drum to a uniform potential, and the original is rotated while rotating the photosensitive drum. To scan the surface of the photosensitive drum with light to form an electrostatic latent image on the photosensitive drum. While rotating the photosensitive drum and the developing roll, a developing voltage is applied to form a toner image on the photosensitive drum. While rotating, a high voltage is applied to the transfer corotroton to transfer the toner image to the recording material, and the fixing means heats and presses the recording material to fix the toner image on the recording material. To form an image.

Therefore, in the above-mentioned analog type image forming apparatus, a series of operations from the reading of the original image to the formation of the image on the recording material must be performed in synchronization.

Further, in the above-mentioned image forming apparatus, the fixing means has a heating roll in which a heater is arranged, and a pressure roll arranged in pressure contact with the heating roll. In general, the recording material is heated and pressurized by passing through the recording material to fix the toner image on the recording material. The upper limit temperature and the lower limit temperature of the heating roll are set, and when the temperature falls below the lower limit temperature, the heater is switched on and the heating roll is heated to the upper limit temperature. It is designed to be set within the temperature range.

[0006]

2. Description of the Related Art In the image forming apparatus described above, all the energy required to form an image is supplied as electric power from a single commercial power source, and the electric power is used to drive the photosensitive drum or to rotate the photosensitive drum. It is necessary to convey the recording material, apply a high voltage to the charging corotron and the transfer corotron, and supply heating energy to the fixing means.

Therefore, in the above analog type image forming apparatus, the operation from the reading of the original image to the formation of the image on the recording material is performed in synchronization, and when the fixing means operates, other means and Since the members also need to be operated, it is necessary to divide the electric power supplied from the commercial power source to determine the allocation, and the maximum heating energy that can be supplied to the fixing means from the 100 V, 15 A commercial power source is 700 to 800 W. It was about.

In particular, an image forming apparatus has an automatic document conveying means for sequentially conveying a plurality of originals to an original reading position, and a post-processing means for sorting a recording material on which an image has been formed and stapling each part. In the apparatus, the energy required for the operation of these means also needs to be supplied from the commercial power source, and the heating energy that can be supplied to the fixing means must be further reduced.

Further, in Japanese Patent Application Laid-Open No. 60-191277, in an image forming apparatus having an exposing means, a large rush current flows when the document scanning carriage of the exposing means is accelerated or decelerated, and the rush current causes a power overflow. Therefore, a technique for cutting the heating energy supplied to the fixing unit during acceleration / deceleration of the document scanning carriage is disclosed. However, even in this case, if the heating energy that can be supplied to the fixing unit is further reduced. I had no choice.

Therefore, in the above-mentioned analog type image forming apparatus, since only the heating energy of a fixed value of about 700 to 800 W or less can be supplied to the fixing means, for example, several hundreds of sheets can be produced in a low environmental temperature. When images are continuously formed, that is, when the temperature of the recording material conveyed to the fixing means is low and a large number of recording materials are conveyed continuously to the fixing means, in other words, the unit time The amount of heat taken from the fixing means is extremely large, and
When the heat is continuously taken from the fixing means for a long time, sufficient heating energy for controlling the temperature of the fixing means within a predetermined temperature range cannot be supplied to the fixing means.

Further, in the above-mentioned image forming apparatus, since only the heating energy of a fixed value of about 700 to 800 W or less can be supplied to the fixing means, the number of images that can be formed per unit time is increased to increase the image forming apparatus. Even if an attempt was made to increase the speed, the speed could only be increased to about 20 to 30 per minute.

In the last few years, a digital image forming apparatus for reading an original image with a reading means having a CCD sensor or the like and then processing the image to form a digital image on a recording material has been developed. Although being developed, even in this digital image forming apparatus, the fixing unit has 700 to 800
Only heating energy equal to or lower than a constant value of about W was supplied.

[0013]

Therefore, the present invention can form images continuously even when hundreds of images are formed, and can improve the image forming speed of the image forming apparatus. It is an object to develop an image forming apparatus that can be used.

[0014]

That is, the present invention is an image forming apparatus having fixing means for heating a recording material on which a toner image is formed to form an image on the recording material, by fixing excess power. The image forming apparatus is provided with a power supply means for supplying the means as heating energy.

In the present invention, the surplus power means the power originally allocated to be used for other than the heating energy of the fixing means, and more specifically, the power that can be supplied by the commercial power and the actual image. The electric power is the difference from the electric power used by the image forming apparatus, and its magnitude varies depending on the operating state of the image forming apparatus. For example, in an image forming apparatus having a reading unit for reading a document, the electric power allocated to the reading unit is not used and becomes surplus power when the document is not read. Further, in the image forming apparatus having the post-processing means, the electric power allocated to the post-processing means is not used and becomes surplus electric power when the post-processing is not performed. Further, in the image forming apparatus, the electric power allocated to the image forming means such as the photosensitive drum driving means member is not used at the time of startup thereof and becomes an excessive electric power. It should be noted that when the heating of the fixing means is started at the time of starting the apparatus or returning from the energy saving mode for interrupting the heating, the operations of the reading means and the post-processing means are prohibited to positively surplus the power. It may be used as electric power.

The power supply unit may be any unit that can supply the surplus power to the fixing unit as heating energy. For example, in an image forming apparatus having a reading unit, the document is not read while the original is not read. The electric power allocated to the reading unit may be supplied to the fixing unit as heating energy.

A specific structure for supplying the surplus power to the fixing means as heating energy is, for example,
When the electric power allocated to the reading means is supplied to the fixing means as heating energy, a switching circuit for supplying electric power to either one of the reading means and the heater of the fixing means is provided, and the switching circuit is used for the reading means. Should be switched depending on whether or not the
When the reading unit is used, switching is performed so as to supply power to the reading unit, and when the reading unit is not used, switching is performed so as to supply power to the heater of the fixing unit).

Further, in the image forming apparatus having the reading means, it is preferable to provide the image information storage means for storing the image information of the document together with the power supply means.

Then, in the image forming apparatus, when the reading of the document is completed, the electric power for the reading means is supplied to the fixing means as heating energy and an image is formed based on the stored information of the image information storage means. As a result, high heating energy can be supplied to the fixing unit when the second and subsequent images are formed.

Further, in the above image forming apparatus, the original is read and the image information is stored in the image information storage means even when the fixing means is heated and started up when the apparatus is started up or when returning from an energy saving mode for interrupting heating. When the reading of the document is completed, the power for the reading unit can be supplied to the fixing unit as heating energy and the image can be formed based on the stored information of the image information storing unit by storing High heating energy can be supplied to the fixing unit even in the image formation of the first copy.

By the way, the fixing means may be any one capable of heating a recording material on which a toner image is formed to form an image on the recording material. For example, heating with a heater provided therein. It can be configured by a roll and a pressure roll arranged in pressure contact with the heating roll. Also,
It suffices that the temperature of the heating roll is controlled within a predetermined temperature range, for example, the upper limit temperature and the lower limit temperature are set, and when the temperature falls below the control temperature, the heater is switched on until the upper limit temperature is reached. It may be controlled to be heated, or may be controlled to be heated with an appropriate amount of heating energy according to the environmental temperature and the operating state. Then, preferably, by calculating the amount of heat taken from the heating roll to the recording material based on the number of image formation, etc., and by supplying heating energy corresponding thereto to the heater, the number of times of switching of the heater can be reduced, Generation of a large inrush current due to the switching can be limited, and the stability of the image forming operation can be improved. As a control method of the heating energy amount, even if a plurality of heaters are provided and ON / OFF of each heater is independently controlled,
A heater is provided and the ON time ratio of the heater (= O
N hours / (ON time + OFF time) may be controlled. Then, as a method of realizing the latter control, there is a method of controlling by so-called cycle stealing, in which an AC voltage is applied to the heater and the AC voltage is thinned out every predetermined cycle.

In the image forming apparatus of the present invention, since the surplus power is supplied to the fixing means by the power supply means as heating energy, the heating energy is increased to suppress the temperature drop of the fixing means. be able to.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] FIG. 1 shows an image forming apparatus according to a first embodiment of the present invention. The image forming apparatus includes a reading unit 1 that reads an original image, an image forming unit that forms an image on a sheet (recording material) based on the image information, and a sheet on which the image is formed is stapled for each set. And post-processing means 3 for doing so.

The reading means 1 includes a platen 1a on which a document is placed, an automatic document feeding member 1b for sequentially transporting a plurality of documents on the platen 1a, and a light source for irradiating the document on the platen 1a with light. 1c, a CCD sensor 1d for reading the light reflected by the original, and a CCD for the light reflected by the original
Mirror 1e to be incident on the sensor 1d, and the exposure light source 1
It has a scanning drive motor for moving the c and the mirror 1e to scan the original.

The image forming means is the CCD sensor 1 described above.
An image information storage memory 2a for storing digital image information read by a, a photosensitive drum 2b rotatably held, and a charging corotroscope which is arranged so as to face the photosensitive drum 2b and to which a high voltage is applied. 2c and a laser exposure member 2d that forms an electrostatic latent image by exposing the photosensitive drum 2b according to the image information from the image information storage memory 2a.
A developing member 2e for applying a developing voltage to a developing roll rotatably arranged opposite to the photosensitive drum 2b to develop the electrostatic latent image to form a toner image, and the photosensitive drum. 2b, a transfer corotroton 2f arranged to face the toner image onto the paper by applying a high voltage, a fixing member 4 for heating and pressurizing the paper to fix the toner image on the paper, and a paper tray 2h. A sheet conveying member 2i that conveys a sheet to the fixing member 2g.

In the following description, all the image forming means except the fixing member 4 will be referred to as the toner image forming member 2.

The post-processing means 3 includes a pair of carry-in rollers 3a for drawing in the paper discharged from the image forming means, a plurality of post-processing trays 3b for accommodating the sheets to be stapled for each section, and a section. It has a discharge tray 3c for accommodating sheets which are not stapled and a post-processing sheet conveying member 3d for conveying sheets from the carry-in rollers 3a to these trays 3b, 3c.

As shown in FIG. 2, the fixing member 4 has a cylindrical heating roll 4a, a pressure roll 4b arranged in pressure contact with the heating roll 4a, and the heating roll 4a.
One heater 4c provided inside, a temperature sensor 4d that detects the temperature of the heating roll 4a, and a temperature control member 4e that controls the heating power supplied to the heater 4c according to the output of the temperature sensor 4d. Consists of.

The reading means 1, the toner image forming member 2, the fixing member 4 and the post-processing means 3 are supplied with electric power by an electric power supply means 5. As shown in FIG. 2, the power supply means 5 is connected to a commercial power source of 100 V and 15 A and distributes the power to the reading means, the toner image forming member, the fixing member and the post-processing means.
a and a power control unit 5b that controls the distribution of power by the power distribution member 5a according to the operating state of the image forming apparatus, and is disposed integrally with the image forming means as shown in FIG. . The power control unit 5b, in the state where the power switch 6 is turned on, responds to the ON history of the start switch 7 and the reading operation of the reading means 1 in the normal startup mode, the reading startup mode, the standby mode, and the reading mode. There are five mode states: formation mode and formation mode.

In the normal start-up mode, as shown in FIG. 3, supply of electric power to the reading means 1, the toner image forming member 2 and the post-processing means 3 is prohibited, and electric power is supplied only to the fixing member 4. In this case, the power distribution unit 5a can supply the fixing member 4 with the power allocated to the reading unit 1, the toner image forming member 2, and the post-processing unit 3. Then, in the embodiment of the present invention, the maximum heating power in the normal start-up mode is set to 1100 W, and the temperature control member 4 e sets all of the heating maximum power to the heater 4.
c.

The reading start-up mode is a mode in which the supply of electric power to the toner image forming member 2 and the post-processing means 3 is prohibited, and the electric power is supplied to the reading means 1 and the fixing member 4. In this case, the electric power is distributed. The section 5 a can supply the electric power allocated to the toner image forming member 2 and the post-processing unit 3 to the fixing member 4. Then, in the embodiment of the present invention, the maximum heating power in the reading start-up mode is set to 1100 W, and the temperature control member 4e supplies all of the heating maximum power to the heater 4c.

The standby mode is a mode in which the supply of electric power to the reading unit 1, the toner image forming member 2 and the post-processing unit 3 is prohibited and electric power is supplied to the fixing member 4, and in this case, the electric power distribution unit 5a. Can supply the fixing member 4 with the electric power allocated to the reading unit 1, the toner image forming member 2, and the post-processing unit 3. In the embodiment of the present invention, the maximum heating power in the standby mode is set to 2
When the temperature detected by the temperature sensor 4d falls below the lower limit temperature T _L , the temperature control member 4e supplies all of the heating maximum power to the heater 4c, and the detected temperature exceeds the upper limit temperature T _H. The supply of the heating power to the heater 4c is stopped.

The reading and forming mode is a mode in which electric power is supplied to the reading means 1, the toner image forming member 2, the fixing member 4 and the post-processing means 3, and the maximum electric power for heating is set to 800W. Then, in the embodiment of the present invention, in the read formation mode, the temperature control member 4e supplies all of the heating maximum power to the heater 4c when the temperature detected by the temperature sensor 4d falls below the lower limit temperature _TL , the detected temperature to stop the supply of the heating power to the heater 4c Once above the maximum temperature T _H.

The formation mode is a mode in which the supply of electric power to the reading means 1 is prohibited and the electric power is supplied to the toner image forming member 2, the fixing member 4 and the post-processing means 3. In this case,
The power distribution unit 5a can supply the power allocated to the reading unit 1 to the fixing member 4. Then, in the embodiment of the present invention, the maximum heating power in the formation mode is set to 800 W, and the temperature control member 4e causes the temperature sensor 4d to detect the temperature and the lower limit temperature T _L when the mode is switched. And the amount of heat absorbed by the paper is calculated based on the number of images formed in this mode, and the detection temperature of the heating roll 4a becomes the lower limit temperature T _L when the formation of all images is completed. Then, the heating power to the heater 4c is adjusted. Specifically, the temperature control member 4e
Applies an AC voltage to the heater 4c and thins out the AC voltage wave at predetermined time intervals to turn on the ON time ratio (=
The heating power is controlled by controlling the ON time / (ON time + OFF time). By the above control, the number of times the heater 4c is switched can be reduced, the generation of a large inrush current due to the switching can be limited, and the stability of the image forming operation can be improved.

As shown in FIG. 4, the power control section 5b operates when the power switch 6 is turned on (S
1, S2), it is determined whether or not the start switch 7 has already been pressed (S3), and if it has been pressed, the reading start-up mode is selected (S5), while if it has not been pressed, it is normal. A startup mode is selected (S4). Then, the power control unit 5b confirms at regular time intervals whether or not the device has started up (S6), and if it has not started up, determines whether or not the start switch 7 has already been pressed. Then, the above mode selection is repeated (S3). The start-up of the above device is determined by whether or not the temperature of the heating roll 4a has become _{equal to} or higher than the lower limit temperature T _L.

When the apparatus is started up, the power control section 5b determines whether or not the start switch 7 has already been pressed. If so, the power control section 5b enters a subroutine for forming an image while pressing the switch. If not, the standby mode is selected (S8).

Further, in the above subroutine, the power control section 5b judges whether or not the reading of the document is completed (S9), and if the reading is not completed, the reading formation mode is selected (S10). ) On the other hand, when the reading is completed, the forming mode is selected (S11). Then, the power control unit 5b checks at regular time intervals whether or not the image formation is completed (S12), and if not, whether or not the reading of the document is completed. When the judgment is made and the mode selection is repeated (S9), on the other hand, when it is completed, the process returns to the main routine and the standby mode is selected (S8).

Finally, in the standby mode (S8) state, the power control section 5b confirms whether or not the start switch 7 has already been pressed at regular time intervals, and switches between the subroutine and the standby mode. The selection is repeated (S7).

Then, in the embodiment of the present invention, two kinds of tests were conducted using the image forming apparatus.

In the first test, the image forming apparatus is already started up in a low temperature state, 50 originals are set on the reading means 1, and 20 copies of the same image as the originals are formed by the image forming means. That is, the image is formed, that is, a total of 1000 images are formed, and then stapled for each copy. As a result, in the image forming apparatus, as shown in FIG. 5, the reading formation mode is executed when the start switch 7 is pressed, the formation mode is executed when the reading of the document is completed, and in the formation mode, Since the surplus electric power of the image forming apparatus is supplied to the fixing member 4 as the electric power for heating, the heating roll 4a can be kept within a predetermined temperature range even when 1000 images are continuously formed in a low temperature state. did it.

In the second test, while the image forming apparatus is starting up in a low temperature state, 50 originals are set on the reading means 1 to form an image of 20 copies,
It is stapled for each copy. As a result, in the image forming apparatus, as shown in FIG. 6, if the start switch 7 is pressed during execution of the normal start-up mode, the read start-up mode is executed, and the read formation mode and the formation are performed. The modes are sequentially executed, and the surplus power of the image forming apparatus is supplied to the fixing member 4 as heating power in the above-described formation mode.
Even when 000 images were continuously formed, the heating roll 4a could be kept within the predetermined temperature range.

Therefore, in the image forming apparatus, hundreds of images can be continuously formed in a low temperature state,
Moreover, the image forming speed of the image forming apparatus can be improved.

[0043]

As described above, in the image forming apparatus of the present invention, since the surplus power is supplied to the fixing means as heating energy by the power supply means, the temperature drop of the fixing means of the fixing means can be suppressed. Even when several hundreds of images are formed, the images can be continuously formed, and the image forming speed of the image forming apparatus can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present application.

2 is an explanatory diagram of a power supply system of the image forming apparatus of FIG.

3 is an explanatory diagram of each mode of a power control unit of the image forming apparatus in FIG.

FIG. 4 is an operation flowchart of a power control unit of the image forming apparatus in FIG.

5 is an operation sequence in a first test of the image forming apparatus in FIG.

6 is an operation sequence in a second test of the image forming apparatus in FIG.

[Explanation of symbols]

1: reading means, 2a: image information storage memory (image information storage means), 4: fixing member (fixing means), 4a: heating roll, 4b: pressure roll, 4c: heater, 5: power supply means.

Claims (4)

[Claims] 1. An image forming apparatus having a fixing unit for heating a recording material having a toner image formed thereon to form an image on the recording target, in which electric power is supplied to the fixing unit as heating energy. An image forming apparatus comprising means. 2. A reading means for reading an image of a document and an image information storage means for storing the image information read by the reading means, wherein the power supply means is for the reading means when the reading of the document is completed. 2. The image forming apparatus according to claim 1, wherein the electric power is supplied as heating energy to the fixing unit. 3. A reading unit for reading an image of a document and an image information storage unit for storing the image information read by the reading unit, and the document is read even when the fixing unit is heated. The image forming apparatus according to claim 1, wherein the electric power supply unit supplies electric power for the reading unit to the fixing unit as heating energy when the reading of the document is completed. 4. The fixing unit has a heating roll inside which a heater is arranged and a pressure roll arranged in pressure contact with the heating roll, and the fixing roll is covered by the heating roll based on the number of images formed. The image forming apparatus according to claim 1, wherein the amount of heat taken by the recording material is calculated, and heating energy corresponding to the calculated amount of heat is supplied to the heater.