JP2002148995A - Heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating device which actualized heating processing at the printing speed that the device originally has and also actualizes the printing speed that the device originally has and the short preheat time (quick starting performance) for the device when a form of small size is not printed while preventing respective members from being damaged owing to a rise in the temperature of a paper-nonfeed part when a form of small size is printed, and an image forming device equipped with the heating device as a heat fixing device. SOLUTION: This device is equipped with a pressure rotary body which is heated directly or indirectly by a heating part, more than two paper discharge means which are selectively switched according to the width of the heated body, and a heat-conductive means with high heat conductivity which comes into contact with the pressure rotary body to make the heat of the pressure rotary body uniform; and a contacting/leaving control means makes the heat- conductive contacts and leave the pressure rotary body associatively with the switching operation of the paper discharging means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating apparatus for heating a material to be heated (hereinafter, referred to as paper) such as an envelope, a postcard, a sheet material, etc., to perform glossing, wrinkle removal, and the like. The present invention relates to an image forming apparatus using the above-mentioned heating device as a heating and fixing device for heating and fixing an unfixed image corresponding to the image information to the sheet.

[0002]

2. Description of the Related Art Conventionally, in a recording section of an image forming apparatus,
A heat roller system has been widely used as a heat fixing device for heating a sheet on which an unfixed image (toner image) is formed and fixing the unfixed image on the sheet.

In this heat roller method, as shown in FIG. 8, a metal heat roller 51 as a heating element which has a heat source H such as a halogen heater therein and is controlled at a predetermined fixing temperature.
A pressure roller 50 as an elastic pressure rotating body that comes into pressure contact with the roller has a basic configuration, and the pair of heat rollers 51 and the pressure roller 50 are rotated so that a pressure contact portion between both roller pairs (hereinafter, a fixing nip portion and a fixing nip portion). N), the sheet P is supplied from the recording unit A, and the sheet P is pinched and conveyed through the fixing nip N, so that the unfixed image T is transferred to the sheet P by the heat of the heat roller 51 and the pressure of the fixing nip N. Is to be established.

In the recording section A, reference numeral 10 denotes, for example, an electrophotographic rotary photosensitive drum as an image gripping member, on which a toner image T of target image information is formed by an image forming process device (not shown). Then, the toner image T is sequentially transferred to the surface of the sheet P introduced into a pressure contact portion (hereinafter, referred to as a transfer nip portion) n between the photosensitive drum 10 and the transfer roller 12, and is conveyed to a fixing portion.

In the above heat roller system, since the heat roller 51 has a large heat capacity, it takes a very long time (a wait time, a long time) to raise the surface of the heat roller 51 to a predetermined fixing temperature.
Warm-up time). In addition, in order to quickly execute the image output operation, the temperature of the heat roller surface must be controlled to a certain temperature even when the apparatus is not used, which causes a problem of increased power consumption. there were.

Japanese Patent Application Laid-Open Nos. 4-44075 to 4-4408 disclose heat-fixing devices that do not have such a problem.
No. 3, JP-A-4-204980 to JP-A-4-204980
There is a tension-free type film heating method disclosed in Japanese Patent No. 204984.

FIG. 9 is a schematic structural view showing an example of the film fixing type heat fixing device. In FIG. 9, 15
Is a trough-shaped guide member having a substantially semi-circular cross section, and a heating member fitting groove 15a is provided along the length of the guide member at a substantially central portion of an outer lower surface of the guide member 15, and a low-profile groove is provided in the groove. A heating element 16 having a linear heat capacity is fitted and supported.

The heating element 16 includes a heater substrate (a flat ceramic material such as alumina or aluminum nitride) having good thermal conductivity, a current-generating resistor (heating element) 16-b, and a thermistor as a temperature detecting element. 16-e, surface protective layer 1
6-d and the like. The thermistor 16-e is located substantially at the center in the longitudinal direction of the heating element 16, detects the temperature of the heating element 16 in the paper passing area, and uses a temperature control system (not shown) based on this detection signal to perform heating. The power supplied to the body 16 is controlled so that a predetermined temperature, that is, the temperature of the fixing nip portion N becomes a predetermined fixing temperature.

A cylindrical heat-resistant film 14 is loosely fitted to a guide member 15 for guiding the inner surface of the film provided with the heating element 16. The pressure roller 17 as a pressure rotating body is pressed between the pressure rollers. This pressure roller 1
Numeral 7 is an elastic roller provided with a rubber portion 17b on a stainless steel or aluminum core bar 17a, and silicone rubber is often used for the rubber portion 17b.

In some cases, a fluoro rubber latex layer or a fluoro resin layer 17c is provided on the surface of the rubber portion 17b in order to impart a releasing property to the toner. The length of the heating element 16-b is slightly longer than the maximum image area in order to secure the maximum printable image area. Further, a portion of the pressure roller 17 which is opposed to the heating element 16 and is in pressure contact with the heating element 16-b is at least a heating element 16-b.
The length is such that it does not become shorter than the length b.

In this heat fixing device, the cylindrical roller 14 is heated by the frictional force between the pressure roller 17 and the outer surface of the film, and the inner surface of the cylindrical film 14 is heated by driving the pressing roller 17 as a driving roller. The guide member 15 is driven to rotate while being in close contact with the downward surface of the body 16.

Therefore, in the film rotation driving state,
The paper P is introduced between the film 14 and the pressure roller 17, and the heat of the heating body 16 is given to the paper P via the film 14 in the process of passing through the fixing nip N, thereby heating the unfixed image T. Fixation is made.

At this time, the heating element 16 always heats the entire area irrespective of the size of the sheet P and the size of the image. Further, even in the fine control of the fixing temperature, the heating element 16 can perform only 0N or OFF, and is performed by a combination thereof.

[0014]

However, the above-mentioned prior art has the following problems.

When printing is performed by continuously passing small-sized paper (such as an envelope or a postcard) in the main scanning direction with respect to the maximum printable paper size of the image forming apparatus, the heating element 16 is always printed. Since all the possible areas are heated and fixed, there is no problem in the area where the paper P of the pressure roller 17 passes because the heat is removed by the paper P, but the area where the paper P does not pass is heated. The temperature is too high, and the non-sheet passing portion of the pressure roller melts, or problems such as breakage of the heating element and the film occur.

For example, the temperature of the heating element 16 is detected by the thermistor 16-e, and is controlled at 160 ° C. to 190 ° C. by a controller (not shown) based on the detection signal. The temperature of the pressure roller 17 rises only up to about 120 ° C. because the paper P loses heat.

However, for example, when small-sized paper P such as an envelope having a width of 105 mm and a length of 240 mm is continuously passed, the heat from the heating element 16 outside the paper passing region is
Therefore, it is accumulated on the pressure roller 17 and the film 14 and reaches 230 ° C. after continuous feeding of about 100 sheets. In the worst case, the pressure roller 17 and the film 14 are damaged.

This problem is particularly problematic in a heat fixing device using a heat roller as described above, since the heat roller itself has a large heat capacity, so that it is difficult to be actualized. Is remarkable due to its small size, which is a serious problem. For this reason, at present, a separate sensor for detecting the width of the paper is installed in the device.
Control is performed to reduce the number of prints per unit time to, for example, about 50%, that is, the interval between sheets is spread, and heat is diffused to suppress a rise in temperature, thereby preventing damage to a pressure roller, a film, and the like. . For this reason, there is a problem that the printing speed inherent in the apparatus cannot be realized in small-size paper printing.

Further, as a measure for transmitting the amount of heat of the pressure roller 17 in an area where the paper P does not pass to the area where the paper P passes, and as a measure for equalizing the temperature of the pressure roller 17, FIG.
As shown in FIG. 1, a heat transfer roller 23 is also proposed in which the heat transfer roller 23 is brought into contact with the pressure roller 17.

However, in order to make the temperature of the pressure roller 17 uniform, it is necessary to set the cross-sectional area of the heat transfer roller 23 to be large to some extent and to secure the heat transfer amount. In such a case, since the heat capacity of the heat transfer roller 23 also becomes large, even when an attempt is made to print paper P other than the small-size paper, the time until the temperature of the heat fixing device reaches the control temperature is extended as a result, There is a problem that the characteristics of the heat fixing device in which the heater temperature rises quickly as shown in FIG. 9 are lost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and a main object of the present invention is to prevent damage to each member due to an increase in the temperature of a non-sheet passing portion when printing on small-size paper. Prevents heat processing at the printing speed that the device originally has, and reduces the printing speed that the device originally has and the short remaining heat time of the device (quick start property) except when printing on small-size paper. It is an object to provide a heating device to be realized and an image forming apparatus including the heating device as a heat fixing device.

[0022]

According to the present invention, there is provided a heating apparatus and an image forming apparatus having the following constitution.

(1) A pressurizing rotator that is directly or indirectly heated by the heating unit, and a temperature detecting unit disposed on the heating unit within a minimum width region of the width of the heatable body that can be fed. Temperature control means for controlling the temperature of the heating section based on the temperature detected by the temperature detection means; two or more paper discharge means for selectively switching in accordance with the width size of the object to be heated; A heat transfer means having high thermal conductivity for contacting a rotating body to equalize the heat of the pressure rotating body; and interlocking with a switching operation of the paper discharging means, the heat transferring means is connected to the pressure rotating body. A heating device comprising: contact / separation control means for contacting / separating with respect to the heating device.

(2) There is provided a size detecting means for detecting a width size of the object to be heated, and a paper discharging means selecting state detecting means for detecting a selecting state of the paper discharging means (1). A heating device as described.

(3) The temperature of the pressurizing rotator which is directly or indirectly heated by the heating unit and the temperature of the pressurizing rotator which is detected within the minimum width region of the width of the heated object which can be fed. 1 temperature detecting means, temperature controlling means for controlling the temperature of the heating section based on the temperature detected by the first temperature detecting means,
Two or more sheet discharging means for selectively switching according to the width of the object to be heated, and heat transfer of high thermal conductivity for contacting the pressure rotator to uniform the heat of the pressure rotator Means, and a second temperature for detecting a temperature on the pressurizing rotator in a region outside a region through which the heated object having the smallest width passes and inside a region through which the heated object having the largest width passes. Detecting means, switching means for switching the paper feed timing based on the detection signal from the second temperature detecting means or switching the paper feed timing and the temperature control of the heating section, and interlocking with the switching operation of the paper discharging means, A heating device, comprising: a contact / separation control unit for bringing the heat transfer unit into and out of contact with the pressure rotating body.

(4) A first detecting means for detecting the temperature of the pressurizing rotator which is directly or indirectly heated by the heating unit and the temperature of the pressurizing rotator within a minimum width region of a width size of the heating target which can be passed. Temperature detection means, temperature control means for controlling the temperature of the heating section based on the temperature detected by the first temperature detection means, and selective switching corresponding to the width size of the object to be heated 2
The above-mentioned switching means, a heat transfer means having high thermal conductivity for contacting the pressurizing rotator to make the heat of the pressurizing rotator uniform, and an outer side of an area through which a heated object having a minimum width passes. A second temperature detecting means for detecting a temperature on the heating portion in a region inside a region through which the object to be heated having the largest width passes, and a sheet feeding unit based on a detection signal from the second temperature detecting unit Switching means for switching the timing or the paper feed timing and the temperature control of the heating unit; and contact / separation control means for bringing the heat transfer means into and out of contact with the pressure rotating body in conjunction with a switching operation of the paper discharge means. A heating device comprising:

(5) The paper discharging means comprises a face-up tray for discharging a material to be heated having a minimum width and a face-down tray for discharging a material to be heated having a maximum width. Any one of (1), (3), and (4), wherein the heat transfer member is brought into contact with the pressurizing rotating body in conjunction with the operation of setting the tray to the use state.
The heating device according to Item.

(6) The face-up tray has a conveyance guide for guiding the discharged material to the face-down tray when the face-up tray is stored in the apparatus and is not used. The heating device according to any one of (1), (3), and (4).

(7) The temperature on the pressure rotating body is detected in a region outside the region through which the heated object having the smallest width passes and inside the region through which the heated object having the largest width passes. The heating device according to (3), wherein the second temperature detecting means is covered with a heat-resistant member.

(8) The heat transfer means is made of aluminum or copper (1), (3), (4),
The heating device according to any one of (5).

(9) In the image forming apparatus having an image forming means for forming an unfixed image on the object to be heated and a heat fixing means for heating and fixing the unfixed image to the object to be heated, An image forming apparatus to which the heating device according to any one of (1) to (8) is applied.

[0032]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 is a sectional view in which a heating device according to a first embodiment of the present invention is applied to a heat fixing device of a tensionless type film heating system, and FIG. FIG. 3 is a schematic perspective view, and FIG. 3 shows an image forming apparatus (a laser beam printer using an electrophotographic process) to which the heat fixing device of the present embodiment is applied.

First, referring to FIG. 3, an image forming apparatus (hereinafter, referred to as an image forming apparatus)
Will be described. In FIG. 3, A is an apparatus main body, 10 is an electrophotographic photosensitive drum (hereinafter, referred to as a photosensitive drum) as an image carrier, and the photosensitive drum 10 has a predetermined peripheral speed (process speed) in a clockwise direction of an arrow. It is driven to rotate. The photosensitive drum 10 is temporarily and uniformly charged to a predetermined polarity and potential by a charging roller (not shown) during the rotation process.

The laser light L modulated according to the time-series electric digital pixel signal of the target image information is output from a laser scanning exposure device (laser beam scanner) 8 and reflected by a reflection mirror 9 to form a photosensitive drum. By irradiating the charged surface of the photosensitive drum 10, an electrostatic latent image corresponding to the target image information is formed on the peripheral surface of the photosensitive drum 10.

The electrostatic latent image is developed as a toner image by the developing device 11 and the toner image is
To a transfer nip portion n between the transfer roller 12 and the transfer roller 12. The sheet P, which has received the transfer of the toner image at the transfer nip portion n and passed through the transfer nip portion, is separated from the surface of the photosensitive drum 10 and guided to the transport guide 13 to enter the fixing portion F, where it is fixed as described later. The toner image is heated and fixed by passing through the nip portion N.

On the upstream side of the photosensitive drum 10, a registration sensor arm 44 for detecting the position of the leading edge of the sheet P and a photo interrupter 45 for detecting the movement of the registration sensor arm 44 are arranged. The scanning exposure with the laser light L is performed in synchronization with the electric signal output from the photo interrupter 45.

On the other hand, reference numeral 40 denotes a paper feed tray, on which a paper feed pressure plate 42 urged by a pressure spring 41 is arranged. The paper P on the paper feed tray 40 is separated by separation means (not shown) by the rotation of the paper feed roller 43 in response to a paper feed signal transmitted from the paper feed number control means 64, and is fed one by one.

The sheet P separated and fed from the sheet feed tray 40 and conveyed by the conveying roller pairs 5-a and 5-b is conveyed downstream along the guide 6, and thereafter, as described above, And a transfer roller 12 which is opposed to and in pressure contact with the transfer portion T, and the toner image on the photosensitive drum 10 side is sequentially transferred onto the feed sheet P.

The paper P on which the toner image has been transferred at the transfer section T is separated from the surface of the photosensitive drum 10 and introduced into a fixing section F along a guide 13, and the unfixed toner image is transferred to the fixing section F to be described later. Heat fixing is performed. A paper width detection sensor arm 46 as a paper width detection sensor and a photo interrupter 47 are arranged on the transport guide 13 between the transfer unit T and the fixing unit F. Paper width detection sensor arm 4
The photo interrupter 6 and the photo interrupter 47 are arranged at a position W mm away from the center of the sheet width as shown in FIG.

The paper width sensor arm 46 and the photo interrupter 47 make it possible to identify whether the width of the paper P to be printed is equal to or larger than twice the width W. Here, the value of W is set to 70 mm so that the paper P having a small width such as an envelope or a postcard does not cause the paper width detection sensor arm 46 to fall down. Therefore, it is possible to identify whether the width of the paper P is 140 mm or less or more.

Next, the details of the fixing section F will be described with reference to FIG. In FIG. 1, the fixing portion F of this embodiment has a heating element fitting groove 1 at a substantially central portion on the outer lower surface of a trough-shaped guide member 15 having a substantially semicircular cross section along the longitudinal direction of the guide member.
5a, a low-capacity linear heating element 16 is fitted and supported in the premise, and a guide member 15 with the heating element 16 is provided.
In this case, a cylindrical heat-resistant film 14 is loosely fitted outside, and the film 14 is sandwiched between the cylindrical heat-resistant film 14 and the heating body 16, and a pressure roller 17 as a pressure rotating body is pressed against the heating body 16.

The pressure roller 17 is formed of silicone rubber having high heat resistance, and is obtained by baking 30 μm of fluoro rubber latex on the surface layer 17-c. Fixing film 1
Reference numeral 4 shows a cylindrical polyimide film having a thickness of 45 μm, on which the outer surface is coated with PTFT to a thickness of 10 μm.
Further, the heating element 16 has a width of 6.5 mm and a length of 236 m.
A silver-palladium heating element resistance pattern is applied as a heating element layer 16-b by screen printing on an alumina substrate 16-a having a thickness of 0.6 mm and a thickness of 0.6 mm, followed by firing.

The thermistor 16-e is connected to the substrate 16-e.
On the other side of (a) (a substrate surface opposite to the side of the current-carrying heating element layer 16-b), it is attached near the longitudinal center of the substrate. The thermistor 16-e is a sensor for detecting the temperature of the heating element 16 in the paper passing area. The controller 61, which has received a detection signal from the sensor, controls the power control unit 62 to The power supplied to the heating element 16 is controlled such that the predetermined temperature, that is, the temperature of the fixing nip N reaches a predetermined fixing temperature (for example, 190 ° C.). For the control of the supply power, for example, phase control of an AC power supply or the like is used.

In the apparatus main assembly A, there are a paper discharge path (paper discharge port) as two paper discharge means, and a face as a first paper discharge path (paper discharge port) downstream of the fixing section F. There is an up tray 25 and a face down tray 34 as a second paper discharge path (paper discharge port).

The face-up tray 25 is attached so as to rotate around a tray rotation shaft 25-e provided in the apparatus main assembly A. The face-up tray 25 is positioned at the position shown in FIG. ) And two positions (face-down discharge) stored in the apparatus main assembly A shown in FIG.

The paper P discharged to the face-up tray 25 is discharged with its print surface facing upward, and the discharged paper P
Have the drawback that the order of the discharged pages is reversed, but the paper transport path can be relatively straight, so that wrinkles and curls can occur even on thick paper, envelopes, postcards, etc. Is relatively small. Therefore, it is mainly suitable for discharging relatively thick sheets P such as envelopes and postcards, and it is recommended that the user use the face-up tray 25 when using these sheets.

Since the face-down tray 34 as a second paper discharge path (paper discharge port) has an arc-shaped paper path having a relatively small curvature, the face-up tray 2
5 is not suitable for discharging thick paper P such as an envelope or a postcard, but the printed paper P is discharged with its print surface facing downward, and is stacked in a page order so that plain paper ( For example, it is suitable as a paper discharge tray for Letter size, A4 size paper>.

The face-up tray 25 has a paper transport guide portion 25-c which forms a transport path for the paper P when stored in the apparatus main body, and guides the paper P when the face town tray 34 is used. Then, it becomes a part of the transport path to the face-down tray 34.

The face-up tray 25 has a snap-fit portion 25-d associated with the apparatus main body A. When the face-up tray 25 is stored in the apparatus main body, the face-up tray 25 engages with the engaging claws 27 provided in the apparatus main body. In addition, the face-up tray 25 is stored in the apparatus main body (the position shown in FIG. 4) against the force of a tension spring (pressure spring) 19 described later.
To be restrained.

On the other hand, on the face-up tray 25, there is a tab 25-b.
The tab portion 25-b enters the photointerrupter 26 in the apparatus main body while the controller is stored in the apparatus main body.
6, it is possible to detect whether the face-up tray 25 is stored in the apparatus main body (the position shown in FIG. 4) or opened (the position shown in FIG. 3). . That is, the tab portion 25-b and the photo interrupter 26 function as a sensor that detects the open / closed state of the face-up tray 25.

Reference numeral 23 denotes a heat transfer roller (heat transfer means) formed of a material having good heat conductivity such as aluminum.
It is rotatably attached to one end of a link member 21 that rotates about zero. The link member 21 is a tension spring 1
9, the heat transfer roller 23 and the pressure roller 17 are urged by a predetermined force in a contact direction. Here, the tension spring 19 and the link unit 21 function as a sheet discharge control unit.

The face-up tray 25 has a projection 25-a. When the face-up tray 25 is stored in the apparatus main body, the projection 25-a connects the rotating shaft 20 of the link member 21. Thus, the heat transfer roller 23 is pressed against the side opposite to the heat transfer roller 23 against the urging force of the tension spring 19 to separate the heat transfer roller 23 from the pressure roller 17. That is, when the face-up tray 25 is open, the heat transfer roller 23 and the pressure roller 17 are in contact with each other, and when the face-up tray 25 is stored in the apparatus main body, the heat transfer roller 23 is
And the pressure roller 17 are in non-contact.

(Face Up Discharge) FIG. 3 shows a paper discharge state with the face up tray 25 opened (face up discharge). In this discharged state, the sheet P fixed by the fixing unit F passes between the post-fixing guides 22-a and 22-b, and is further transported by the transport roller pairs 24-a and 24-b. The paper is ejected on top. In this state, the tab 25-b is connected to the photo interrupter 2
6 is not blocked, and the main unit is face-up tray 2
Recognize that 5 is open.

Normally, special paper such as envelopes and postcards is so thick that its transport path is selected and used by the user to be discharged from the more straight face-up tray 25. In use,
As described above, the heat transfer roller 23 is brought into pressure contact with the pressure roller 17 by the urging force of the tension spring 19 in conjunction with the movement of the face-up tray 25, and is in contact therewith.

In this state, when small-size paper is passed,
Since the heat generated from the heating element 16 is not taken away by the paper P outside the paper passing area, the heat is mainly radiated outside the printing area of the pressure roller 17 having a large heat capacity. Since the heat transfer roller 23 is in contact with the pressure roller 17, heat is taken from the high temperature portion (outside the printing area) of the pressure roller 17, and the heat taken from the high temperature portion passes through the heat transfer roller 17. And transmitted to the low-temperature part (print area).

Therefore, heat is transmitted from the heat transfer roller 23 to the portion where the temperature of the pressure roller 17 is low, so that the temperature unevenness in the longitudinal direction of the pressure roller 17 is smaller than when the heat transfer roller 23 is not in contact. The temperature of the entire pressure roller 17 can be suppressed to a maximum of about 190 ° C. As a result, even at the time of continuous printing of small-size paper, printing can be performed at the highest printing speed of the apparatus main body.

It is recommended that plain paper of A4 size or letter size be discharged to the face-up tray 25 with the face-up tray 25 closed, that is, the face-up tray opened. When the plain paper is to be discharged onto the face-up tray, since the heat transfer roller 23 is in contact with the pressure roller 17, it takes a few extra seconds to reach the predetermined control temperature. After reaching the temperature, printing can be performed at the maximum speed of the apparatus main body.

(Face Down Discharge) Next, FIG. 4 shows a discharge state in which the face-up tray 25 is stored in the main body (face down discharge). In this state, since the protrusion 25-a of the face-up tray 25 pushes one end of the link member 21 as described above, the heat transfer roller 23 is separated from the pressure roller 17.

Here, the tab 25-b blocks the photo interrupter 26, and the apparatus main body recognizes that the face-up tray 25 is stored in the apparatus main body. In a state where the face-up tray 25 is stored in the apparatus main body, the sheet P fixed by the fixing unit F passes between the post-fixing guides 22-a and 22-b, and furthermore, the conveying roller pair 2
4-a and 24-b. Thereafter, the sheet passes between the conveyance guides 25-c provided on the face-up tray 25 and the conveyance guides 33-a and 33-b on the apparatus main body side.
The paper is discharged onto the face-down tray 34 by the paper discharge roller pairs 35-a and 35-b.

Normally, the paper discharged to the face down tray 34 is selected and used by the user as a paper discharge tray for normal size paper (for example, letter size, A4 size paper) because the order of printed pages is correctly stacked. You.

When printing on normal size paper in a state where the face-up tray 25 is stored in the apparatus main body, it can be recognized by the above-mentioned paper width size detection sensor. It is possible to control to print at the maximum speed.

On the other hand, the user forgets to open the face-up tray 25 even though printing small-sized paper such as envelopes and postcards, and continuously prints small-sized paper and discharges the paper onto the face-down tray 34. However, in this case, the sensor that detects the open / close state of the face-up tray 25 and the sensor that detects the paper width size detect them, and the controller 63 that has input the detection signal sends By controlling the number control means 64,
For example, by controlling the number of printed sheets per unit time to be about 50% of the maximum number of printed sheets originally possessed by the apparatus main body, it is possible to avoid a partial temperature rise of the pressure roller 17 and the film 15 and prevent damage. be able to.

In addition to controlling the paper feed timing, changing the temperature control of the heating element 16 is also effective in avoiding the temperature rise of the pressure roller 17 and the film 15. For example, when there is no paper in the fixing nip portion N (between papers) during continuous paper feeding, the power supply to the heating element 16 is stopped, or the control temperature is reduced from the normal 190 ° C. to, for example, 120 ° C.
By reducing the amount of heat supplied to the pressure roller between the sheets, it is possible to suppress a rise in the temperature of the pressure roller and the film as compared with a case where only the paper feed timing is controlled.

As described above, according to the present embodiment, the face-up tray 25 is opened, and the heat transfer roller 2 having good heat transfer properties is opened.
By bringing the pressure roller 3 into contact with the pressure roller 17, heat is taken from a high-temperature portion (non-sheet passing area) of the pressure roller 17, and the heat is transmitted to a portion where the temperature of the pressure roller 17 is low, thereby forming the pressure roller 17. The temperature unevenness in the longitudinal direction of the roller 17 is equalized as compared with the case where the heat transfer roller 23 is not in contact, and the maximum temperature of the pressure roller 17 can be suppressed to about 200 ° C.

As a result, abnormal temperature rise in the non-sheet passing portion due to continuous passing of the small-sized paper P is suppressed, and the fixing portion F including the pressure roller 17 is prevented from being damaged. In addition, this enables printing at the speed inherent in the apparatus main body even when printing on small-size paper, in the same manner as when printing on normal-size paper.

In this embodiment, an example has been described in which aluminum is used as the material of the heat transfer roller 23. However, other high heat conductive materials such as copper can be used.

Further, in this embodiment, an example of the heating device using the heating element 16 and the film 14 has been described. Among the heating devices using the heat roller as shown in FIG. It is also effective for a heating device using a thin heat roller.

In this embodiment, the paper width size detection sensor is provided between the transfer unit T and the fixing unit F. However, the paper width size detection sensor is provided on the paper feed tray or between the paper feed tray and the transfer unit. It may be provided between T.

Further, in an apparatus body having a paper feed cassette or the like as a paper feed tray, the paper width size can be similarly detected by detecting the set position of the width regulating member on the paper feed cassette.

In the case of an apparatus main body having a dedicated paper feed cassette according to the paper size and having means for detecting the type of the paper feed cassette, printing is performed by using the type information of the paper feed cassette instead of the width size detecting means. Speed control may be performed.

(Second Embodiment) In the first embodiment, a sensor for detecting the paper width size and a sensor for detecting the open / close state of the face-up tray 25 are provided in the apparatus main body. The example in which when the small size paper is passed, the number of prints per unit time is controlled to prevent the pressure roller 17 from being damaged due to a temperature rise.

In the second embodiment, as shown in FIG. 6, a pressure roller is used instead of a sensor for detecting the paper width size and a sensor for detecting the open / close state of the face-up tray 25 in the apparatus main body. A second thermistor 18 as a second temperature detection sensor was provided near the longitudinal end from the center of 17. Here, the surface of the second thermistor 18 is covered with a heat-resistant film 28 of polyimide or the like so that toner or the like is hardly attached thereto, and is pressed against the pressure roller 17 with a predetermined pressure (for example, 10 gf) by an elastic member (not shown). Has been abutted.

When small-size paper is passed when the paper is discharged to the face-down tray 34, the heating element 16
Is mainly generated by the pressure roller 1 having a large heat capacity.
When the temperature detected by the second thermistor 18 reaches, for example, 200 ° C. or more, the number of prints per unit time is reduced to, for example, 50% of the maximum printing speed originally possessed by the apparatus main body. By performing the control by the controller 65, further temperature rise is prevented,
Breakage of the pressure roller 17, the film 14, and the like can be avoided.

As shown in the first embodiment, it is also effective to change the temperature control of the heating element 16 together.
When the paper width size detection sensor and the open / closed state detection sensor of the face-up tray 25 as shown in the first embodiment are used, when printing on the paper P having a width equal to or less than a predetermined paper width and forgetting to open the face-up tray 25. Control is performed to reduce the printing speed per unit time only when printing is performed.However, even with small-size paper, the degree of temperature rise at the end of the pressure roller differs depending on the paper width size, paper length, and paper thickness. Come.

For this reason, in the first embodiment, among the recommended papers P, not only the paper P having the highest temperature rise at the end of the pressure roller 17 but also the paper P which is actually out of specification is erroneously operated by the user. Considering the possibility of printing, it was necessary to set the position of the paper width size detection sensor and the number of prints per unit time with a sufficient margin.

However, as in the second embodiment, when the second thermistor 18 is used as the second temperature detecting sensor, the temperature of a portion that may be damaged is directly measured, and the unit time is measured. Since the number of printed sheets per unit is controlled, even when the user erroneously prints out of specification paper P, it is possible to reliably prevent the temperature of the pressure roller 17 from excessively rising.

If the user desires to discharge a small width paper, such as a thin sheet of plain paper, to the face-down tray 34, the operation is performed from the start of printing until the temperature of the pressure roller exceeds 200 ° C. During this time, printing can be performed at the maximum speed of the apparatus main body.

Further, in this embodiment, an example is shown in which the thermistor 18 is arranged so as to be in contact with the pressure roller 17. However, the same effect can be expected even if the thermistor 18 is arranged near the pressure roller 17 without contact. it can.

(Third Embodiment) In the second embodiment, a second temperature detecting sensor 18 is provided near the longitudinal end of the pressure roller 17 so that small-size paper An example is shown in which the number of printed sheets per unit time is controlled based on the temperature detected by the temperature detection sensor 18 when paper is passed, thereby preventing the pressure roller 17 from being damaged due to a rise in temperature.

In the third embodiment, instead of disposing the temperature detection sensor 18 so as to be in contact with the pressure roller 17,
As shown in FIG. 7, a second thermistor 16 serving as a second temperature detection sensor is provided near a longitudinal end on the heating body 16.
−f is provided, and the number of prints per unit time is controlled based on the temperature detected by the second thermistor 16-f.

When the temperature detected by the thermistor 16-f reaches 220 ° C. or higher, the number of prints per unit time is reduced, or at the same time, the temperature is controlled by the controller 66 to further increase the temperature. This prevents the pressure roller 17 and the film 14 from being damaged.

In the present embodiment, the second thermistor 16-f
Is disposed on the surface of the heating body 16 opposite to the film 14, so that toner and the like adhere to the thermistor 16-f as compared with the case where the temperature of the pressure roller 17 is measured as shown in the second embodiment. Because there is no need to worry, reliability is improved.
Further, since there is no fear of abrasion of the pressure roller 17 and the film 14, the durability is improved as compared with the second embodiment.

[0084]

As described above, according to the first aspect of the present invention, the pressure rotating body directly or indirectly heated by the heating unit and the pressure rotating body selectively corresponding to the width size of the heated body. A plurality of paper discharging means for switching, and a heat transfer means having high thermal conductivity for contacting the pressurizing rotator to make heat of the pressurizing rotator uniform; The heat transfer means is configured to move toward and away from the pressurizing rotating body in conjunction with the switching operation, so that the heating device is damaged due to excessive temperature rise when small size paper is continuously passed. And printing can be performed at the printing speed originally possessed by the apparatus main body. Also, in this case, even when printing on normal-size paper such as A4 or letter, printing at the maximum speed inherent in the apparatus main body can be performed by switching the paper discharging means without sacrificing the temperature rising speed. This has the effect.

Further, according to the second aspect of the present invention, there is provided a size detecting means for detecting a width size of the object to be heated, and a discharging means status detecting means for detecting a selection state of the discharging means. With this configuration, the sheet feeding timing is controlled, for example, by controlling the number of processed sheets per unit time to be about 50% of the maximum processed sheet number, thereby avoiding a rise in the temperature of the components of the neglected main body. This has the effect that damage can be prevented.

According to the third aspect of the present invention, the pressurizing rotator heated directly or indirectly by the heating unit and the two or more pressure rotators selectively switched according to the width size of the object to be heated are provided. A switching means for detecting a temperature on the pressure rotating body in a region outside a region through which the heated object having the smallest width passes and inside a region through which the heated object having the largest width passes. Temperature detecting means, and means for switching between sheet feeding timing or sheet feeding timing and temperature control of the heating section based on a detection signal from the second temperature detecting means, and the contact / separation control means switches the sheet discharging means. In conjunction with the operation, the heat transfer member is configured to be brought into contact with and separated from the pressurizing rotating body, so that even if the user erroneously prints out of specification paper, the overheating of the pressurizing roller is ensured. Can be prevented. Also, if the user desires to discharge a sheet of paper having a small width but as thin as plain paper in the same manner as plain paper, if the user starts processing and waits until the temperature of the pressure roller reaches a predetermined temperature, Printing can be performed at the maximum speed of the apparatus main body, and heat is diffused by lowering the printing speed as in the related art, which has the effect of preventing damage to the pressurizing rotation.

Further, according to the fourth aspect of the present invention, the pressurizing rotator heated directly or indirectly by the heating unit, and two or more selective switching units corresponding to the width size of the object to be heated. Switching means, and a second temperature for detecting a temperature on the heating unit in an area outside a region where the object to be heated having the smallest width passes and an area inside an area where the object to be heated having the largest width passes. Detecting means, and means for switching the sheet feeding timing or the sheet feeding timing and the temperature control of the heating unit based on a detection signal from the second temperature detecting means,
The contact / separation control means is configured to move the heat transfer means toward and away from the pressurizing rotating body in conjunction with the switching operation of the sheet discharging means. By spreading the heat by lowering the printing speed as described above and preventing damage to the pressure rotation, the temperature can be detected without toner or the like adhering to the thermistor as the second temperature detecting means. Since there is no possibility of damaging the surface of the pressure roller, there is an effect that the reliability and durability of the apparatus are further improved.

According to the fifth aspect of the present invention, the paper discharging means includes a face-up tray for discharging a sheet having a minimum width and a face-down tray for discharging a sheet having a maximum width. Since the heat transfer means is configured to contact the pressurizing rotating body in conjunction with the operation of setting the face-up tray to a use state, a heating device for continuously feeding small-size paper is provided. Thus, there is an effect that printing can be performed at the printing speed originally possessed by the apparatus by preventing damage due to excessive temperature rise.

Further, according to the sixth aspect of the present invention, the face-up tray has the transport guide section for guiding the discharged sheet to the face-down tray when the face-up tray is stored in the apparatus and is not used. With such a configuration, there is an effect that the discharged paper can be smoothly guided to the face-down tray.

Further, according to the seventh aspect of the present invention, since the temperature detecting means provided at the end of the pressurizing rotator is covered with the heat-resistant member, there is no fear that toner or the like adheres. The reliability is improved. In addition, there is no fear of abrasion of the pressure roller and the film, and there is an effect that the durability is improved.

Further, according to the eighth aspect of the present invention, since the heat transfer means is made of aluminum or copper,
There is an effect that the heat transfer property is excellent, and the uniformity of the heat of the pressurizing rotating body can be quickly achieved.

According to the ninth aspect of the present invention, the image forming apparatus is configured so that the unfixed image formed on the sheet by the image forming means is heated and fixed by using the heating apparatus of the present invention. Therefore, there is an effect that an image forming apparatus that can always perform stable heat fixing regardless of the sheet size and can form a high-quality image can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment in which a heating device according to the present invention is a heat fixing device.

FIG. 2 is a perspective view showing a part of the heat fixing device in the first embodiment.

FIG. 3 is a cross-sectional view illustrating an example of an image forming apparatus to which the heat fixing device according to the first embodiment is applied.

FIG. 4 is a cross-sectional view illustrating the image forming apparatus when paper is discharged to a face-down tray.

FIG. 5 is a perspective view showing an arrangement of a width size detection sensor.

FIG. 6 is a perspective view showing a part of a heat fixing device according to a second embodiment.

FIG. 7 is a perspective view showing a part of a heating body in a third embodiment.

FIG. 8 is a schematic configuration diagram showing an image forming apparatus to which a conventional heat roller system is applied.

FIG. 9 is a schematic configuration diagram showing an image forming apparatus to which a conventional film heating method is applied.

FIG. 10 is a cross-sectional view showing a paper discharge unit of a conventional image forming apparatus.

[Explanation of symbols]

10 photosensitive drums, 14 films, 15 heating element support members, 16 heating elements, 17 pressure rollers, 2
3 ... heat transfer roller, 25 ... face-up tray, 3
4 ... Face down tray, 40 ... Paper feed tray, P
... paper, F ... fixing unit, T ... fixing unit.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G03G 21/14 H05B 3/00 335 H05B 3/00 335 365G 365 G03G 21/00 372 F term (reference) 2H027 DA12 DC00 DC10 DE04 DE09 EA12 ED17 ED19 ED25 EE02 2H033 AA03 AA23 AA25 BA26 BA31 BA32. AA34 AA65 BA18 CA23 CA28 CA45 CA61 CE13 DA05 GA03 GA06

Claims (9)

[Claims] A pressurizing rotator heated directly or indirectly by a heating unit; a temperature detecting unit disposed on the heating unit within a minimum width region of a width size of a heated object that can be fed; Temperature control means for controlling the temperature of the heating section based on the temperature detected by the temperature detection means, and two or more sheet discharge means for selectively switching according to the width size of the object to be heated;
The heat transfer means is contacted with the pressurizing rotator to make the heat of the pressurizing rotator uniform, and the heat transfer means is pressurized in conjunction with the switching operation of the paper discharging means. A heating device, comprising: a contact / separation control unit configured to contact / separate from a rotating body. 2. The apparatus according to claim 1, further comprising: a size detection unit configured to detect a width size of the object to be heated, and a discharge unit selection state detection unit configured to detect a selection state of the discharge unit. Heating equipment. 3. A pressurizing rotator heated directly or indirectly by a heating unit, and a first detecting means for detecting a temperature on the pressurizing rotator in a minimum width region of a width size of a heating target capable of passing paper. Temperature detection means, temperature control means for controlling the temperature of the heating section based on the temperature detected by the first temperature detection means, and two or more paper discharges selectively switched in accordance with the width size of the object to be heated Means, a heat transfer means having high thermal conductivity for contacting the pressurizing rotator to make the heat of the pressurizing rotator uniform, and a width outside the region through which the object to be heated having the smallest width passes. Second temperature detecting means for detecting the temperature on the pressure rotating body in a region inside the region through which the largest heated body passes,
Switching means for switching the paper feed timing based on the detection signal from the second temperature detection means or the paper feed timing and the temperature control of the heating section; and the heat transfer means in conjunction with the switching operation of the paper discharge means And a contact / separation control unit for bringing the pressure rotary member into and out of contact with the pressure rotating body. And a first temperature for detecting a temperature of the pressing rotator which is directly or indirectly heated by the heating unit and which detects a temperature of the pressing rotator within a minimum width region of a width size of the target to be heated capable of passing paper. Detecting means, temperature control means for controlling the temperature of the heating section based on the temperature detected by the first temperature detecting means, and two or more switching means for selectively switching in accordance with the width size of the object to be heated; A heat transfer means having high thermal conductivity for contacting the pressurizing rotator to equalize the heat of the pressurizing rotator, and a width size outside the region through which the heated object having the smallest width size passes, Second temperature detecting means for detecting the temperature on the heating portion in an area inside the area through which the largest object passes, and sheet feeding timing or sheet feeding based on a detection signal from the second temperature detecting means. Switching means for switching the timing and temperature control of the heating section; A heating device comprising: a contact / separation control unit that moves the heat transfer unit toward and away from the pressurizing rotating body in conjunction with a switching operation of the sheet discharge unit. 5. The paper discharging means comprises a face-up tray for discharging a material to be heated having a minimum width and a face-down tray for discharging a material to be heated having a maximum width.
The heating device according to any one of claims 1, 3, and 4, wherein a heat transfer member is brought into contact with the pressure rotating body in conjunction with an operation of setting the face-up tray to a use state. . 6. The apparatus according to claim 1, wherein the face-up tray has a conveyance guide for guiding the discharged heated material to the face-down tray when the face-up tray is stored in the apparatus and is not used. The heating device according to any one of claims 3 and 4. 7. A temperature detecting method for detecting a temperature on the pressure rotating body in a region outside a region through which a heated object having the smallest width passes and inside a region through which a heated object having the largest width passes. The heating device according to claim 3, wherein the temperature detecting means is covered with a heat-resistant member. 8. The heating device according to claim 1, wherein the heat transfer means is made of aluminum or copper. 9. An image forming apparatus comprising: an image forming unit that forms an unfixed image on a body to be heated; and a heating and fixing unit that heats and fixes the unfixed image to the body to be heated.
9. An image forming apparatus, wherein the heating device according to claim 1 is applied as the heat fixing unit.