JP2011227175A - Cooling device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device for cooling efficiently the recording media on which toner is fixed by heat, and to provide an image forming apparatus.SOLUTION: The cooling device comprises: a cooling roller 1 for cooling the recording media P on which the toner is fixed, in contact with a principal surface of the recording media P; a conveyance roller 3 which supports the recording media P which is inserted between the conveyance roller 3 and the cooling roller 1; and an excitation mechanism part 5 for vibrating the cooling roller 1 to a thickness direction of the recording media P to pass through.

Description

  The present invention relates to a cooling device (cooling structure) used for cooling a transfer paper on which a toner image on the transfer paper is fixed by a heat fixing device in an electrophotographic image forming process, and a copying machine including the cooling device. The present invention relates to an image forming apparatus such as a printer.

  Image forming apparatuses such as copying machines and laser printers form a toner image on an electrostatic latent image carrier by electrophotography, and transfer the toner image onto a transfer paper (also called a recording medium or paper) to form an image. Is to do. As these image forming apparatuses, the speed of copying has been increasing year by year, and there is one that performs high-speed copying of 50 sheets or more per minute. In such a high-speed copying machine, copying is repeated one after another in a short time. If the output transfer paper overlaps or the copy is repeated on the back side again, such as when copying on both sides, the toner on the transfer paper is not cooled sufficiently, A phenomenon (blocking) in which transfer papers stick to each other is a problem.

  This is due to the fact that the temperature of the transfer paper does not drop after fixing, where the toner is melted by heat and fused to the transfer paper. That is, if copying is repeated one after another in such a state, there is a problem that the transfer papers stick to each other when they overlap. Also, in the double-sided copy mode, the transfer paper is transported one more time, so there is a problem that the temperature rises due to heat in the machine, or the transfer paper curls due to heat and may cause a jam or the like. Was.

In view of this, measures are taken to rapidly lower the temperature by providing means for cooling the transfer paper after fixing.
For example, Patent Document 1 discloses a method of cooling transfer paper using a heat pipe having excellent thermal conductivity. In this method, the heat of the transfer paper is transported by a heat pipe, and the heat radiation fin provided at the end of the heat pipe is air-cooled by a fan. In this example, it is important to efficiently cool the heat dissipating fins, and therefore forced air cooling is performed by a fan. Moreover, in patent document 2, the ingenuity which raises heat dissipation efficiency is made | formed by making only the thickness of the hollow material which comprises the heat pipe thermal radiation part thin, and it has devised the air intake and discharge of a cooling fan. Yes. However, these techniques cannot obtain sufficient performance in the transfer paper cooling application of the image forming apparatus which is the premise of the present invention.

Further, Patent Document 3 discloses a liquid cooling roller that circulates liquid in the roller and cools the liquid cooling method. However, the transfer paper is only passed through the liquid cooling roller once. The temperature could not be lowered sufficiently.
Further, Patent Document 4 discloses a technique in which liquid cooling rollers and heat pipes are arranged one above the other and the transfer paper is passed between them to cool, but as a result of a small contact area, a sufficient cooling effect is obtained. In some cases, there is a need for higher efficiency.

  SUMMARY An advantage of some aspects of the invention is that it provides a cooling device that efficiently cools transfer paper (recording medium) on which toner has been thermally fixed, and an image forming apparatus including the cooling device. The purpose is to do.

  The inventor has investigated the cause of the above problem, and the heated recording medium comes into contact with the cooling member and is cooled by heat conduction. At this time, a large contact thermal resistance exists between the recording medium and the cooling member. Therefore, it has been understood that the heat of the recording medium is not efficiently transferred to the cooling member and the temperature of the recording medium does not decrease. And based on that knowledge, intensive studies were conducted to solve this problem, and it was found that good heat conduction can be obtained by applying vibration to the cooling member at the time of contact between the recording medium and the cooling member. It came to be accomplished.

The present invention provided to solve the above problems is as follows. In addition, the site | part and code | symbol etc. which respond | correspond in the form for implementing this invention in a parenthesis are shown.
[1] A cooling device that cools the recording medium (recording medium P) on which the toner is fixed by the heat fixing device (thermal fixing unit 103), and cools the recording medium in contact with the main surface of the recording medium. A cooling member (cooling roller 1, heat pipe roller 1 </ b> A, liquid cooling roller 1 </ b> B), an opposing member (transport roller 3) that supports the recording medium directly or indirectly between the cooling member, and the cooling A cooling mechanism (cooling device 10, FIGS. 2 to 5), comprising: a vibration mechanism portion (vibration mechanism portion 5) that vibrates the member or the opposing member in the thickness direction of the recording medium passing therethrough. .
[2] The excitation mechanism unit is an ultrasonic oscillator that is in contact with the cooling member or the counter member, or the support member (support member 1s) of the cooling member or the counter member so as to be able to transmit vibration via a resonator (horn 5b). (1) The cooling device according to [1], including an ultrasonic oscillator 5a.
[3] The cooling device according to [1] or [2] (FIGS. 3 and 5), wherein the cooling member is a heat pipe roller (heat pipe roller 1A).
[4] The cooling device according to [1] or [2] (FIG. 4), wherein the cooling member is a liquid cooling roller (liquid cooling roller 1B).
[5] An image forming apparatus (image forming apparatus 100, FIG. 1) comprising the cooling device (cooling device 10) according to any one of [1] to [4].

According to the cooling device of the present invention, the vibration mechanism unit vibrates the cooling member or the opposing member, so that the contact state between the cooling member and the main surface of the recording medium is improved, and the cooling member further increases the heat of the recording medium. Since the recording medium is taken away, the recording medium can be efficiently cooled.
According to the image forming apparatus of the present invention, the cooling apparatus of the present invention is provided and the recording medium after heat fixing is efficiently cooled, so that toner blocking of the recording medium on the paper discharge side is prevented and the photoconductor in the image forming section is provided. Temperature rise can be prevented.

1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus according to the present invention. It is a section schematic diagram showing composition of a cooling device concerning the present invention. It is a perspective view which shows the structural example (1) of the cooling device which concerns on this invention. It is a perspective view which shows the structural example (2) of the cooling device which concerns on this invention. It is a perspective view which shows the structural example (3) of the cooling device which concerns on this invention.

The configurations of the cooling device and the image forming apparatus according to the present invention will be described below.
FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus provided with a cooling device of the present invention.
As illustrated in FIG. 1, the image forming apparatus 100 includes a paper feeding unit 101, an image forming unit 102, a thermal fixing unit (thermal fixing device) 103, a double-sided unit 104, and a cooling device 10. . Note that some types of image forming apparatuses do not have double-sided portions, and the image forming apparatus to which the cooling device of the present invention is applied is not limited to the configuration shown in FIG.

  Here, the image forming unit 102 includes an optical writing unit (not shown), a photosensitive member 102a, predetermined members (a charging unit, a developing unit, a cleaning unit, and a static eliminating unit) arranged around the photosensitive member 102a, and a transfer mechanism unit. The image is formed on the photosensitive member 102 a based on the image data, and the toner image is transferred to the recording medium conveyed from the paper feeding unit 101.

  The heat fixing unit 103 is disposed downstream of the image forming unit 102 in the recording medium conveyance direction, and is pressed against the heating roller 103a by a rotatable heating roller 103a having a built-in heating source such as a halogen heater and an urging unit (not shown). Pressure roller 103b. In the heat fixing unit 103, the recording medium to which the toner image conveyed from the image forming unit 102 is transferred is passed through the fixing nip portion where the heating roller 103a and the pressure roller 103b are in pressure contact, and heat and pressure are applied. Then, the toner image is fixed on the recording medium.

  The cooling device 10 is installed downstream of the thermal fixing unit 103 in the recording medium conveyance direction, and cools the recording medium that has passed through the thermal fixing unit 103. Detailed configuration will be described later. Thereby, it is possible to prevent toner blocking at the paper discharge unit and the double-sided stack unit 142 downstream of the heat fixing unit 103 and to prevent the temperature of the photosensitive member 102a from increasing at the image forming unit 102.

  When the image forming apparatus 100 is set to the double-sided image forming mode, the double-sided unit 104 reverses the recording medium on which an image has been formed on one side by rotating the paper supply roller 141 in the clockwise direction and After the set number of recording sheets are stacked, the sheet feeding roller 141 is rotated counterclockwise to refeed the image forming unit 102. Some image forming apparatuses do not have a double-sided portion (that is, do not have a double-sided image forming mode).

With the above configuration, first, an image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on the photoconductor 102a in the image forming unit 102, and a toner image is formed on the photoconductor 102a. Then, the toner image is transferred to the recording medium sent from the paper supply unit 101.
Next, the recording medium onto which the toner image has been transferred is conveyed to the thermal fixing unit 103, and the toner image is thermally fixed when it passes between the heating roller 103a and the pressure roller 103b.
Thereafter, the recording medium is conveyed to the cooling device 10, cooled, and then discharged to the paper discharge unit. Alternatively, the cooled recording medium is sent to the double-sided portion 104, and after being reversed, the toner image is fixed on the back side again through the image forming unit 102 and the thermal fixing unit 103, and then cooled by the cooling device 10. The paper is discharged to the paper discharge unit.

Next, the cooling device according to the present invention will be described.
The cooling device according to the present invention is a cooling device that cools a recording medium on which toner is fixed by a thermal fixing device (thermal fixing unit 103), and cools the recording medium in contact with the main surface of the recording medium. A cooling member, an opposing member that supports the recording medium directly or indirectly between the cooling member, and an excitation mechanism that vibrates the cooling member or the opposing member in the thickness direction of the recording medium passing therethrough. And a section. Hereinafter, the cooling device of the present invention will be described with reference to the drawings.

FIG. 2 is a sectional view showing a conceptual configuration of the cooling device according to the present invention.
As shown in FIG. 2, the cooling device 10 conveys the recording medium P between the cooling roller 1, which is a cooling member that contacts the main surface of the recording medium P and cools the recording medium P, and the cooling roller 1. A conveying roller 3 that is an opposing member supported by being sandwiched via a belt 2 and a vibration mechanism unit 5 that vibrates the cooling roller 1 in the thickness direction (vertical direction in the drawing) of the recording medium P that passes therethrough are provided.

  Further, the cooling device 10 includes an elastic conveyance belt 2 made of heat-resistant rubber or the like wound around a plurality of rollers including the tension roller 4, and the conveyance belt is driven by driving any one of the plurality of rollers. 2 is designed to rotate. The cooling roller 1 and the conveyance roller 3 are arranged with the conveyance belt 2 interposed therebetween, and rotate with the rotation of the conveyance belt 2.

  When the recording medium P is conveyed from the thermal fixing unit 103 to the cooling device 10, the recording medium P is carried on the conveying belt 2 so that the toner image fixing surface of the recording medium P contacts the cooling roller 1. And passes between the cooling roller 1 and the conveying belt 2 (cooling nip portion). At this time, the conveyance roller 3 supports the recording medium P from the back side of the conveyance belt 2, and the cooling roller 1 and the recording medium P are in contact with each other with a predetermined surface pressure.

  Here, the vibration mechanism unit 5 includes an ultrasonic oscillator 5a and a horn 5b that is a resonator, and the ultrasonic oscillator 5a is connected to the rotating shaft (shaft) of the cooling roller 1 via the horn 5b. The vibration generated by the ultrasonic oscillator 5a is in contact with the transmission. The ultrasonic oscillator 5a may be in contact with the opposing member (conveying roller 3), the cooling roller 1 or the supporting member of the conveying roller 3 via the horn 5b so as to be able to transmit vibration.

  The vibration mechanism 5 oscillates the ultrasonic oscillator 5a and vibrates in the thickness direction (vertical direction in the drawing) of the recording medium P passing through the cooling roller 1 at least while the recording medium P passes through the cooling nip. The vibration conditions (vibration frequency, amplitude, etc.) of the vibration object (here, the cooling roller 1) at this time are appropriately set based on the conveyance speed of the recording medium P, the contact state between the cooling roller 1 and the recording medium P, and the like. The amplitude of the cooling roller 1 is such that the cooling roller 1 is not separated from the recording medium P.

  Thereby, the contact state between the roller surface of the cooling roller 1 and the main surface of the recording medium P is improved as compared with the case where the recording medium P is passed between the cooling roller 1 and the conveying belt 2 without vibrating the cooling roller 1. Then, since the cooling roller 1 takes more heat from the recording medium P, the recording medium P can be efficiently cooled.

The cooling roller 1 is preferably a heat pipe roller. FIG. 3 shows an example of the configuration.
A cooling device 10 shown in FIG. 3 includes a cooling pipe body (hereinafter referred to as a roller body) 1a made of a heat pipe made of a metal material such as stainless steel or Al, and dozens of disc-shaped metal plates serving as support shafts of the roller body 1a. The heat pipe roller 1 </ b> A includes a heat dissipating fin 1 f that dissipates heat from the roller body 1 a. In addition, a cooling fan (not shown) for air-cooling the radiating fins 1f is provided. Further, the roller body 1a is rotatably supported by support members 1s and 1s on support shafts at both ends thereof, and is supported so as to be slightly movable in the thickness direction (vertical direction) of the recording medium P passing therethrough. . Or it is good also as a structure which can move slightly in the thickness direction (up-down direction) of the recording medium P which the roller main body 1a and supporting member 1s, 1s pass. In the roller body 1a, a portion outside the width of the conveyor belt 2 in the axial direction is referred to as a support shaft.

  The vibration mechanism unit 5 is disposed on the upper side of the roller body 1a opposite to the conveyor belt 2, and vibrates in the roller body 1a via a horn 5b that is in sliding contact with the roller surface of the roller body 1a. Is provided with an ultrasonic oscillator 5a. Or you may provide the ultrasonic oscillator 5a in the upper part of either support member 1s and 1s so that the vibration oscillated to the roller main body 1a can be transmitted via the horn 5b.

  With the above configuration, when the recording medium P transported from the thermal fixing unit 103 is placed on the transport belt 2 and transported to the cooling nip portion, the vibration mechanism unit 5 causes at least the recording medium P to pass through the cooling nip. While passing through the section, the ultrasonic oscillator 5a is oscillated to vibrate in the thickness direction of the recording medium P passing through the roller body 1a, and the contact state between the roller surface of the roller body 1a and the main surface of the recording medium P is changed. It is possible to improve and to make the roller body 1a take more heat from the recording medium P. When the roller main body 1a takes the heat of the recording medium P, the heat is instantaneously uniform in the heat pipe roller 1A, and then cooled from the cooling fan to the heat radiating fin 1f provided in the heat radiating portion of the heat pipe roller 1A. By supplying air, the heat taken from the recording medium P from the radiation fins 1f is radiated into the air.

The cooling roller 1 is preferably a liquid cooling roller. FIG. 4 shows an example of the configuration.
The cooling device 10 shown in FIG. 4 has a roller body 1b, which is a hollow tubular pipe made of stainless steel, and a non-rotating state that fits the roller body 1b in a rotatable state through a rubber ring for sealing. A liquid-cooled roller 1B including a rotary joint 1c, which is a pipe member, and a refrigerant inlet / outlet 1d that is discharged after the refrigerant is introduced into the roller body 1b from the rotary joint 1c and circulated. Moreover, it has a radiator (not shown) that is connected to the refrigerant inlet / outlet 1d so that the refrigerant can be circulated and cools the refrigerant by air cooling using a fan. The roller body 1b is rotatably supported by support members 1s and 1s on the support shafts at both ends thereof, and is supported so as to be slightly movable in the thickness direction (vertical direction) of the recording medium P passing therethrough. . Alternatively, the roller main body 1b and the support members 1s and 1s may be configured to be slightly movable in the thickness direction (vertical direction) of the recording medium P. In the roller body 1b, a portion outside the width of the conveyor belt 2 in the axial direction is referred to as a support shaft.

  The vibration mechanism unit 5 is disposed on the upper side of the roller body 1b opposite to the conveyor belt 2, and vibrates in the roller body 1b via a horn 5b that is in sliding contact with the roller surface of the roller body 1b. Is provided with an ultrasonic oscillator 5a. Or you may provide the ultrasonic oscillator 5a in the upper part of either support member 1s and 1s so that the vibration oscillated to the roller main body 1b can be transmitted via the horn 5b.

  With the above configuration, when the recording medium P transported from the thermal fixing unit 103 is placed on the transport belt 2 and transported to the cooling nip portion, the vibration mechanism unit 5 causes at least the recording medium P to pass through the cooling nip. While passing through the section, the ultrasonic oscillator 5a is oscillated to vibrate in the thickness direction of the recording medium P passing through the roller main body 1b, and the contact state between the roller surface of the roller main body 1b and the main surface of the recording medium P is changed. It is possible to improve and to make the roller body 1b take more heat from the recording medium P. When the roller main body 1b takes the heat of the recording medium P, the heat is instantaneously made uniform in the roller main body 1b, and then the refrigerant inside the roller main body 1b takes the heat and is discharged out of the roller main body 1b. The refrigerant is cooled by heat exchange with an external radiator and sent again into the roller body 1b.

Further, the vibration mechanism unit 5 may be provided on the transport roller 3 side. FIG. 5 shows an example of the configuration.
The cooling device 10 shown in FIG. 5 is the same as that shown in FIG. 3 except that the arrangement of the vibration mechanism unit 5 is changed in the cooling device 10 shown in FIG.
That is, the vibration mechanism unit 5 includes an ultrasonic oscillator 5a and a horn 5b that is a resonator. The ultrasonic oscillator 5a is connected to the rotation shaft (shaft) of the transport roller 3 via the horn 5b. The vibration generated by the ultrasonic oscillator 5a is in contact with the transmission.

  With the above configuration, when the recording medium P transported from the thermal fixing unit 103 is placed on the transport belt 2 and transported to the cooling nip portion, the vibration mechanism unit 5 causes at least the recording medium P to pass through the cooling nip. While passing through the section, the ultrasonic oscillator 5a is oscillated to vibrate the conveying roller 3 in the thickness direction of the recording medium P passing through the cooling nip, and the roller surface of the roller body 1a of the heat pipe roller 1A and the recording medium It is possible to improve the contact state with the main surface of P, and to make the roller body 1a take more heat from the recording medium P.

Examples of the present invention will be described below.
Example 1
The recording medium P heated by the heat fixing unit 103 was passed through the cooling device 10 shown in FIG. 3, and the temperature of the recording medium P before and after passing (before and after cooling) was measured to confirm the cooling effect.
The test conditions at that time were as follows.
(Cooling device 10)
・ Heat pipe roller 1A
..Roller body 1a: The outer diameter is 30 mm and the axial length is 320 mm.
・ Excitation mechanism 5
..Oscillation conditions of ultrasonic oscillator 5a; frequency 19.5 kHz, amplitude 50 μm
(Recording medium P)
・ A4 size plain paper (conveyance direction A4 vertical)
・ Temperature at the time of introduction into the cooling device 10; 120 ° C. target ・ Conveying speed; Speed corresponding to 50 cpm (50 pages per minute copy processing speed)

The measurement results are shown in Table 1. As Comparative Example 1, the temperature measurement result of the recording medium P when the recording medium P is passed through the cooling device 10 without oscillating the ultrasonic oscillator 5a is also shown.
As a result, while the temperature of the recording medium P was cooled from 120 ° C. to 83 ° C. in Comparative Example 1, it was cooled from 121 ° C. to 56 ° C. in Example 1, and the cooling efficiency was remarkably improved. .

(Example 2)
In Example 1, it changed into the cooling device 10 shown in FIG. 4, and it tested on the same conditions as Example 1 except it. The roller body 1b in the heat pipe roller 1B has an outer diameter of 30 mm and an axial length of 320 mm.

The measurement results are shown in Table 2. As Comparative Example 2, the temperature measurement result of the recording medium P when the recording medium P is passed through the cooling device 10 of FIG. 4 without oscillating the ultrasonic oscillator 5a is also shown.
As a result, in Comparative Example 2, the temperature of the recording medium P was cooled from 119 ° C. to 63 ° C., whereas in Example 2, it was cooled from 120 ° C. to 45 ° C., and the cooling efficiency was remarkably improved. .

(Example 3)
In Example 1, it changed into the cooling device 10 shown in FIG. 5, and it tested on the same conditions as Example 1 except it.

Table 3 shows the measurement results. As Comparative Example 3, the temperature measurement result of the recording medium P when the recording medium P is passed through the cooling device 10 of FIG. 5 without oscillating the ultrasonic oscillator 5a is also shown.
As a result, in Comparative Example 3, the temperature of the recording medium P was cooled from 120 ° C. to 83 ° C., whereas in Example 2, it was cooled from 121 ° C. to 69 ° C., and the cooling efficiency was improved.

Example 4
The cooling device (cooling device shown in FIG. 3) 10 of Example 1 was applied to the image forming apparatus 100 shown in FIG. 1, and copy printing was continuously performed (copy processing speed: 50 cpm). As a result, there was no sticking of the recording media P on the paper discharge side, the temperature of the surface of the recording media P was lowered, and a sufficient cooling effect by the cooling device 10 was obtained.

  Although the present invention has been described with the embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and other embodiments, additions, modifications, deletions, etc. Can be changed within the range that can be conceived, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited.

DESCRIPTION OF SYMBOLS 1 Cooling roller 1A Heat pipe roller 1a Roller body 1f Radiation fin 1s Support member 1B Liquid cooling roller 1b Roller body 1c Rotary joint 1d Refrigerant inlet / outlet 2 Conveying belt 3 Conveying roller 4 Tension roller 5 Excitation mechanism 5a Ultrasonic oscillator 5b Horn 10 Cooling device 100 Image forming apparatus 101 Paper feeding unit 102 Image forming unit 102a Photoconductor 103 Thermal fixing unit 103a Heating roller 103b Pressure roller 104 Double-sided part 141 Paper feeding roller 142 Stack part P Recording medium

JP-A-10-207155 JP-A-11-007218 2006-3819 2006-225115

Claims (5)

A cooling device for cooling a recording medium on which toner is fixed by a thermal fixing device,
A cooling member that cools the recording medium in contact with the main surface of the recording medium;
An opposing member that supports the recording medium directly or indirectly with the cooling member; and
An excitation mechanism that vibrates the cooling member or the opposing member in the thickness direction of the recording medium passing therethrough;
A cooling device comprising:   The said vibration mechanism part has an ultrasonic oscillator which contact | connects the said cooling member or an opposing member, or the support member of the said cooling member or an opposing member through a resonance body so that a vibration transmission is possible. Cooling system.   The cooling device according to claim 1, wherein the cooling member is a heat pipe roller.   The cooling device according to claim 1, wherein the cooling member is a liquid cooling roller.   An image forming apparatus comprising the cooling device according to claim 1.

Images