JP2008201531A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of reducing water vapor generated from a fixing unit. <P>SOLUTION: A sheet material P taken out by a pickup roll 132 and fed out to a conveying route 108 by a paper feeding roll 122 and a separation roll 124 by every one sheet is pressed to a horn of an excitation member 22 by a pressurization roll 24, and supersonic vibration generated on a distal end of the horn is instantly transmitted to the sheet material P. Because the supersonic vibration is transmitted to the sheet material P, air bubbles are generated inside a moisture content contained in the sheet material P by vibration, and the moisture content is released from the sheet material P as water vapor. The water vapor is discharged to the outside the image forming device 100 from a discharge port 36. Thus, by releasing the moisture content contained in the sheet material P to the outside the image forming device 100, the fixing unit 116 heats the sheet material P and can reduce the generated amount of water vapor. Thereby, moisture condensation generated near the fixing unit 116 can be prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image on a sheet material.

  In the image forming apparatus, the toner image on the photosensitive drum provided in the image forming unit is transferred to a sheet material (recording medium), and then heat-pressed to the sheet material by a fixing device, and is discharged to a discharge tray by a discharge roll. The

  Here, when the sheet material contains a large amount of moisture, the sheet material is heated and pressure-bonded by the fixing device, whereby the moisture contained in the sheet material is released upward as water vapor. In some cases, the water vapor condenses in the apparatus to form water droplets and adheres to the sheet material, resulting in a paper jam, sheet material contamination, and sheet material deformation.

Therefore, an image forming apparatus has been proposed in which a heat insulating material is provided on the lower surface of the metal member provided on the upper portion of the fixing device to prevent water vapor from coming into direct contact with the metal member, thereby preventing water vapor condensation. . (Patent Document 1)
Japanese Patent Laid-Open No. 1-251072

  However, according to this image forming apparatus, it is not sufficient to provide a heat insulating material, and it is conceivable that water vapor is condensed on the surface of the heat insulating material.

  Here, as a means for preventing condensation, it is conceivable to provide an opening for discharging water vapor above the fixing device. However, if the opening is provided, there is a problem that noise of the fixing device leaks out of the apparatus. .

  An object of the present invention is to provide an image forming apparatus capable of reducing water vapor generated from a fixing device in consideration of the above facts.

  An image forming apparatus according to a first aspect of the present invention is provided in a sheet material conveyance path, and abuts on the sheet material conveyed along the conveyance path to vibrate the sheet material at a frequency higher than an audible frequency. It is provided with a vibration member and a discharge port for discharging water vapor generated from the sheet material vibrated by the vibration member.

  According to the above configuration, the vibration member provided in the conveyance path of the sheet material comes into contact with the sheet material conveyed along the conveyance path and vibrates the sheet material at a frequency higher than the audible frequency.

  By vibrating the sheet material at a frequency higher than the audible frequency, bubbles due to vibration are generated inside the moisture contained in the sheet material P, moisture is released as water vapor, and the released water vapor is discharged from the outlet to the outside of the apparatus. Discharged.

  Thus, by releasing the moisture contained in the sheet material to the outside of the apparatus, the water vapor of the sheet material generated by the fixing device can be reduced, thereby preventing dew condensation.

  Further, by reducing the water vapor of the sheet material generated by the fixing device, there is no need to provide an opening for discharging water vapor in the vicinity of the fixing device, so that the noise of the fixing device can be prevented from leaking out of the apparatus.

  An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, further comprising a pressing member that presses the sheet material against the vibration member.

  According to the above configuration, since the pressing member presses the sheet material against the vibration member, the vibration of the vibration member is efficiently transmitted to the sheet material, and the moisture of the sheet material can be efficiently discharged.

  An image forming apparatus according to a third aspect of the present invention is the image forming apparatus according to the first or second aspect, further comprising a paper feed roll that separates and feeds the sheet material one by one from a sheet storage portion that stores the sheet material. The vibrating member is disposed downstream of the paper feed roll in the transport direction.

  According to the above configuration, the vibration member is disposed downstream in the transport direction from the paper feed roll that separates and feeds the sheet material one by one from the sheet storage unit.

  Here, when the sheet feeding roll separates the sheet materials one by one, the sheet materials may rub against each other and noise may be generated. However, since the sheet material passes through the paper feed roll before water vapor is released by the vibration member, the sheet material when passing through the paper feed roll contains moisture. In other words, since the sheet material passes through the sheet feeding roll in a state of containing moisture, noise generated by rubbing between the sheet materials can be reduced as compared with a sheet material having less moisture.

  The image forming apparatus according to a fourth aspect of the present invention is the image forming apparatus according to any one of the first to third aspects, wherein the excitation member includes a piezoelectric element that vibrates when a drive waveform is applied.

  According to the above configuration, the excitation member includes the piezoelectric element that vibrates when the drive waveform is applied.

  Compared with the vibrator, the power consumption of the piezoelectric element is low, so the running cost can be suppressed.

  An image forming apparatus according to a fifth aspect of the present invention is the image forming apparatus according to any one of the second to fourth aspects, wherein the pressure member is a pressure roller that is rotationally driven. A moisture-absorbing member that absorbs moisture is provided.

  According to the above configuration, since the pressure member is a pressure roll that is rotationally driven, it can be conveyed in a stable state while pressing the sheet material against the vibration member.

  Furthermore, since the moisture-absorbing member that absorbs moisture is provided on the surface of the pressure roll, the moisture released from the sheet material can be absorbed, and the diffusion of the moisture can be prevented.

  An image forming apparatus according to a sixth aspect of the present invention is the image forming apparatus according to the fifth aspect, wherein the moisture-absorbing member provided on the surface of the pressure roller is vibrated by the vibrating member. .

  According to the above configuration, since the moisture absorbing member provided on the surface of the pressure roll is vibrated by the vibrating member, the moisture absorbed by the moisture absorbing member can be discharged from the outlet as water vapor. it can.

  The image forming apparatus according to a seventh aspect of the present invention is the image forming apparatus according to any one of the first to sixth aspects, wherein the moisture content of the uppermost sheet material stacked in the sheet accommodating portion in which the sheet material is accommodated is detected. And a control unit that changes a vibration amplitude of the vibration member based on a moisture content detected by the detection means.

  According to the above configuration, the detection unit detects the moisture content of the uppermost sheet material stacked in the sheet storage unit.

  Further, the control unit changes the vibration amplitude of the vibration member based on the moisture content detected by the detection means.

  In this way, by changing the vibration amplitude of the vibration member, the amount of water vapor released from the sheet material can be controlled, and the amount of water contained in the sheet material after passing through the vibration member can be adjusted. can do.

  That is, a high-quality image can be formed on the sheet material by adjusting the amount of water contained in the sheet material when the image is formed on the sheet material.

  An image forming apparatus according to an eighth aspect of the present invention is the image forming apparatus according to any one of the first to seventh aspects, wherein a cylindrical discharge path is provided between the excitation member and the discharge port. To do.

  According to the above configuration, since the cylindrical discharge path is provided between the vibration member and the discharge port, the water vapor released from the sheet material diffuses in the apparatus, and the water vapor adheres to the frame and the frame is Rust can be prevented.

  According to the present invention, water vapor generated from the fixing device can be reduced.

  An image forming apparatus 100 according to a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a paper feed cassette 18 is disposed in the lower part of the housing 102 of the image forming apparatus 100, and is supplied to the image forming unit 111 of the image forming apparatus 100. Sheet materials P to be processed are stacked.

  Further, the sheet cassette 18 is provided with a bottom plate 16 on which the sheet material P is placed. When the sheet material P is fed to the image forming unit 111, the bottom plate 16 is lifted and lowered (not shown). Therefore, it moves upward. The uppermost sheet material P placed on the bottom plate 16 is pressed against the pickup roll 132.

  Further, when the paper feed cassette 18 is pulled out from the housing 102, the bottom plate 16 is moved downward by the lifting means so that the sheet material P can be accommodated in the paper feed cassette 18.

  Further, above the uppermost sheet material P, a microwave moisture detection sensor 20 is provided along with the pickup roll 132 as detection means for detecting the moisture content of the uppermost sheet material P. Details of the microwave moisture detection sensor 20 will be described later.

  Further, when the sheet material P is sent out to the image forming unit 111, the sheet material P is sequentially taken out by the pickup roll 132, and further conveyed one by one by the sheet feeding roll 122 and the separation roll 124 that are driven to rotate. It has become.

  More specifically, the separation roll 124 has a built-in torque limiter (not shown) and rotates without moving relative to the sheet material P when receiving the rotational force of the sheet feeding roll 122 through one sheet material P. However, when two or three sheets P are fed, the frictional resistance between the two or three sheets P is small, so that only the uppermost sheet P is imaged by the sheet feeding roll 122. The lower sheet material P is fed to the forming unit 111 and is prevented from being fed by the rotational resistance force of the separation roll 124. That is, when two to three sheet materials P are double-fed, only the sheet material P that is abutted against the sheet feeding roll 122 by rubbing between the sheet materials P is conveyed.

  Further, a registration roll 120 is provided downstream in the conveyance direction of the paper feed roll 122, and the sheet material P sent out by the paper feed roll 122 is stopped at one end by the registration roll 120, and at a predetermined timing, the image forming unit 111. It is to be sent out.

  Further, on the downstream side of the registration roll 120 in the transport direction, there is provided a vibration member 22 that abuts the transported sheet material P and vibrates the sheet material P at an audible frequency or higher (15000 Hz or higher). In addition, a pressure roll 24 that is rotationally driven is provided on the opposite side of the vibration member 22 across the sheet material P to be conveyed, and the sheet material P to which the pressure roll 24 is conveyed is the vibration member. 22 to be pressed. The details of the vibration member 22 and the pressure roll 24 will be described later.

  Further, a transport roll 106 is disposed at a predetermined position in the housing 102 and constitutes a transport path 108 for transporting the sheet material P. Further, guide members 128 arranged on both sides of the conveyance path 108 guide the sheet material P along the conveyance path 108.

  Further, in the middle of the conveyance path 108, the photosensitive drum 110 is disposed so as to contact the sheet material P, and rotates while contacting the sheet material P. The surface of the photosensitive drum 110 is charged by a charging device (not shown), and then a laser beam corresponding to image information is irradiated by the exposure device 112 to form an electrostatic latent image. Then, toner is supplied from the developing device 114 to the electrostatic latent image, and the electrostatic latent image is visualized as a toner image.

  The image forming unit 111 includes a photoconductive drum 110 and a transfer roll 130, and the photoconductive drum 110 holds the sheet material P between the transfer roll 130 and is in close contact with the sheet material P. Thus, the toner image on the photosensitive drum 110 is transferred to the sheet material P, and an image is formed on the sheet material P.

  Further, a fixing device 116 is disposed on the downstream side of the photosensitive drum 110. The fixing device 116 includes a heating roll 116H provided with a heater therein, and a press-contacting roll 116N pressed against the heating roll 116H. The sheet material P is nipped and conveyed by these two rolls to heat the sheet material P and fix the toner image of the sheet material P to the sheet material P.

  Further, a discharge roll 118 is disposed on the downstream side of the fixing device 116, and the sheet material P on which the toner image is fixed is discharged to a discharge tray 126 provided above the housing 102 by the discharge roll 118. It is the composition which becomes.

  In the image forming apparatus 100 configured as described above, an image is formed as follows.

  First, a charger (not shown) to which a voltage is applied uniformly charges the surface of the photosensitive drum 110 with a predetermined potential.

  Subsequently, the exposure device 112 forms an electrostatic latent image on the charged photosensitive drum 110. That is, an electrostatic latent image corresponding to the image information is formed on the photosensitive drum 110 by turning on and off the laser beam emitted from the exposure device 112 based on image information supplied from a control device (not shown). Further, the electrostatic latent image is visualized as a toner image by the toner supplied from the developing device 114.

  Therefore, the sheet material P accommodated in the paper feed cassette 18 is sequentially taken out by the pickup roll 132 and sent out one by one to the transport path 108 by the paper feed roll 122 and the separation roll 124 that are rotationally driven. Further, the sheet material P is stopped at one end by the registration roll 120 and sent to the image forming unit 111 at a predetermined timing.

  The sheet material P sent out by the registration roll 120 passes between the vibration member 22 and the pressure roll 24, and is further nipped and conveyed by the conveyance roll 106 to be an image forming unit between the photosensitive drum 110 and the transfer roll 130. The toner image is transferred to the sheet material P through 111.

  The transferred toner image is fixed on the sheet material P by passing between a heating roll 116H and a pressure contact roll 116N provided in the fixing device 116, and is discharged to a discharge tray 126 by a discharge roll 118.

  Next, the vibration member 22, the pressure roll 24, the microwave moisture detection sensor, etc. are demonstrated.

  As shown in FIG. 2, the vibration member 22 is provided so as to extend in a direction orthogonal to the conveying direction of the sheet material P (the arrow direction shown in FIG. 2), and from the sheet material width of the sheet material P Widely provided.

  Further, the vibration member 22 includes a horn 26 having a round cross-section at the tip that contacts the sheet material P. Furthermore, the horn 26 is vibrated at a frequency higher than the audible frequency on the back surface of the horn 26. Three piezoelectric elements 28 are arranged in the sheet material width direction, and these are fixed to a rectangular base block 30 made of a metal material.

  With this configuration, when a predetermined drive waveform is applied from a piezoelectric element drive circuit (not shown), the piezoelectric element 28 vibrates, and this vibration is resonantly amplified by the horn 26 and has a frequency higher than the audible frequency at the tip of the horn 26. In this configuration, vibration with an amplitude of 20 to 40 μm is generated.

  That is, by vibrating the sheet material P at a frequency higher than the audible frequency, bubbles are generated inside the moisture contained in the sheet material P, and the moisture is released as water vapor.

  Further, as shown in FIG. 4, a pressure roll 24 that is disposed opposite to the vibration member 22 (see FIG. 1) and pressurizes the conveyed sheet material P to the vibration member 22 includes a sponge material on the metal shaft 24A. Is provided so that the water vapor released from the sheet material P can be absorbed.

  Further, as shown in FIG. 1, a sheet conveying guide 34 having a cross-sectional shape with a wide receiving port is provided upstream of the vibrating member 22 in the conveying direction, and the leading end of the sheet material P is reliably vibrated. It is conveyed to the clamping part of the member 22 and the pressure roll 24.

  Further, the pressure roll 24 and the wall surface 102 </ b> A of the housing 102 adjacent to the vibration member 22 are provided with a lattice-shaped discharge port 36 for discharging water vapor generated from the sheet material P vibrated by the vibration member 22. ing.

  As shown in FIG. 3, a microwave moisture detection sensor 20 that detects the moisture content of the uppermost sheet material P is provided above the uppermost sheet material P stacked on the paper feed cassette 18. Yes.

  Specifically, the microwave moisture detection sensor 20 is arranged along the sheet material width direction, and includes a sensor 20A, a sensor 20B, and a sensor 20C that detect moisture content, and the moisture content of the uppermost sheet material P. Can be detected.

  Furthermore, the vibration control part 32 which receives the moisture content detected by the microwave moisture detection sensor 20 is provided, This vibration control part 32 is based on the received moisture content, and the vibration member 22 (FIG. 1) is controlled.

  Next, operations of the vibration member 22, the pressure roll 24, the microwave moisture detection sensor, and the like will be described.

  As shown in FIG. 1, the microwave moisture detection sensor 20 detects the moisture content of the uppermost sheet material P accommodated in the paper feed cassette 18, and transmits this moisture content information to the vibration control unit 32. To do.

  The vibration control unit 32 determines the vibration amplitude necessary for dehumidification of the sheet material P based on the moisture content information, and shows a drive waveform corresponding to the determined vibration amplitude through the piezoelectric element drive circuit as shown in FIG. Applied to the element 28.

  The excitation amplitude is determined in consideration of the moisture content of the sheet material P necessary for realizing good image transfer when the image forming unit 111 transfers the image to the sheet material P. .

  When the driving waveform is applied to the piezoelectric element 28, the piezoelectric element 28 vibrates, and this vibration is resonantly amplified by the horn 26, and has a frequency higher than the audible frequency at the tip of the horn 26 and having an amplitude of 20 to 40 μm. Ultrasonic vibration occurs.

  On the other hand, as shown in FIG. 1, the uppermost sheet material P accommodated in the paper feed cassette 18 is sequentially taken out by the pickup roll 132, and is conveyed one by one by the paper feed roll 122 and the separation roll 124. Sent out. Further, it is sent out toward the vibration member 22 at a predetermined timing by the registration roll 120.

  The sheet material P that has reached the vibration member 22 is pressed against the horn 26 by the pressure roll 24, and ultrasonic vibration generated at the tip of the horn 26 is instantaneously transmitted to the sheet material P. By transmitting the ultrasonic vibration to the sheet material P, bubbles are generated inside the moisture contained in the sheet material P, and the moisture is discharged from the sheet material P as water vapor.

  Further, the water vapor released from the sheet material P is discharged out of the image forming apparatus 100 through the discharge port 36.

  Moreover, the roll part 24B formed of the sponge material of the pressure roll 24 absorbs excess water vapor that remains in the apparatus without being discharged from the discharge port 36, and prevents the water vapor from diffusing.

  The vibration control unit 32 acquires the timing at which the leading end portion of the sheet material P reaches the clamping portion between the vibration member 22 and the pressure roll 24 based on information from a sheet material passage sensor (not shown). The vibration member 22 is vibrated according to the arrival timing.

  Further, the vibration control unit 32 periodically vibrates the pressure roll 24 directly by the vibration member 22, evaporates moisture absorbed by the pressure roll 24, and discharges it from the discharge port 36. ing.

  In this way, by releasing the moisture contained in the sheet material P to the outside of the image forming apparatus 100, the amount of water vapor generated by the fixing device 116 heating the sheet material P can be reduced. Condensation that occurs in the vicinity can be prevented.

  Further, by reducing the amount of water vapor of the sheet material P generated by the fixing device 116, it is not necessary to provide an opening for discharging water vapor in the vicinity of the fixing device 116, so that noise of the fixing device 116 leaks out of the image forming apparatus 100. Can be prevented.

  Further, since the pressure roll 24 presses the sheet material P against the horn 26, the vibration of the vibration member 22 is efficiently transmitted to the sheet material P, and the moisture of the sheet material P can be efficiently released as water vapor. .

  Further, the vibration member 22 is disposed downstream in the transport direction from the paper feed roll 122. When the sheet feeding roll 122 separates the sheet materials P one by one, the sheet materials may rub against each other and noise may be generated. However, since the sheet material P passes through the paper feed roll 122 before the water vapor is released by the vibration member 22, the sheet material P when passing through the paper feed roll 122 contains moisture. That is, since the sheet material P passes through the sheet feeding roll 122 in a state of containing moisture, noise generated by rubbing between the sheet materials can be reduced as compared with the sheet material P having little moisture.

  Further, the vibration member 22 is configured to vibrate the sheet material P by vibrating the sheet material P by the piezoelectric element 28. For this reason, since the power consumption of the piezoelectric element 28 is low compared with a vibrator etc., a running cost can be suppressed.

  In addition, the vibration control unit 32 takes into account the moisture content of the sheet material P detected by the microwave moisture detection sensor 20 and the moisture content of the sheet material P necessary for realizing good image transfer. Since the vibration amplitude is determined and the vibration member 22 is vibrated, a good quality image can be formed on the sheet material P.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the above embodiment, the microwave moisture detection sensor 20 is used to detect the moisture content of the sheet material P. However, the ambient humidity around the sheet feeding cassette 18 is detected, and the sheet is based on this information. The moisture content of the material P may be estimated.

  Next, a second embodiment of the image forming apparatus 100 of the present invention will be described with reference to FIGS.

  In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 5, in this embodiment, as in the first embodiment, the vibration member 22 is not provided in the vicinity of the wall surface 102 </ b> A but is disposed inside the housing 102.

  Further, the sheet material P with which the vibration member 22 abuts is not conveyed in the vertical direction when abutting, but instead is conveyed in the horizontal direction. Further, the water vapor released from the sheet material P by the vibration member 22 is guided along the cylindrical discharge path 42 by the fan 40 and is discharged from the discharge port 36 provided in the wall surface 102A.

  As described above, even when the vibration member 22 is disposed inside the housing 102, the provision of the fan 40 and the discharge path 42 allows image formation without causing water vapor to stay in the image forming apparatus 100. It can be discharged out of the device 100.

  The fan 40 is disposed at a distance of 40 mm or more from the housing 102. With this arrangement, the noise of the fan 40 is attenuated when propagating through the discharge path 42, and the noise of the fan 40 can be prevented from being discharged out of the image forming apparatus 100.

  Further, as shown in FIG. 6, the pressure roll 24 is formed of a metal shaft 24 </ b> A, a cylindrical rubber portion 24 </ b> D provided around the metal shaft 24 </ b> A, and zeolite that is a water absorbing material provided on the outer surface. A zeolite portion 24E is provided. That is, excess water vapor can be absorbed by the zeolite portion 24E.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view showing a vibration member of the image forming apparatus according to the first embodiment of the present invention. FIG. 2 is a perspective view showing the vicinity of a paper feed cassette of the image forming apparatus according to the first embodiment of the present invention. (A) It is a front view of the pressure roll employ | adopted as the image forming apparatus which concerns on 1st Embodiment of this invention. (B) It is sectional drawing of the pressure roll employ | adopted as the image forming apparatus which concerns on 1st Embodiment of this invention. It is a schematic block diagram of the image forming apparatus which concerns on 2nd Embodiment of this invention. (A) It is a front view of the pressure roll employ | adopted as the image forming apparatus which concerns on 2nd Embodiment of this invention. (B) It is sectional drawing of the pressure roll employ | adopted as the image forming apparatus which concerns on 2nd Embodiment of this invention.

Explanation of symbols

20 Microwave moisture detection sensor (detection means)
22 Excitation member 24 Pressure roll (Pressure member)
24B Roll part (moisture absorbing member)
24E Zeolite part (moisture absorbing member)
28 Piezoelectric element 30 Base block 32 Excitation control unit (control unit)
36 Discharge port 42 Discharge path 108 Conveyance path

Claims (8)

A vibration member that is provided in a conveyance path of the sheet material and abuts on the sheet material conveyed along the conveyance path to vibrate the sheet material at a frequency equal to or higher than an audible frequency;
A discharge port for discharging water vapor generated from the sheet material vibrated by the vibration member;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, further comprising a pressure member that presses the sheet material against the vibration member.   A sheet feeding roll that separates and feeds the sheet materials one by one from a sheet accommodating unit that accommodates the sheet material is provided, and the vibration member is disposed downstream in the transport direction from the sheet feeding roll. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The image forming apparatus according to claim 1, wherein the vibration member includes a piezoelectric element that vibrates when a driving waveform is applied.   5. The pressure member according to claim 2, wherein the pressure member is a pressure roller that is rotationally driven, and a moisture moisture absorbing member that absorbs moisture is provided on a surface of the pressure roller. Image forming apparatus.   The image forming apparatus according to claim 5, wherein the moisture absorbing member provided on the surface of the pressure roller is vibrated by the vibration member. Detection means for detecting the moisture content of the uppermost sheet material stacked in the sheet storage unit in which the sheet material is stored;
A controller that changes the excitation amplitude of the excitation member based on the moisture content detected by the detection means;
The image forming apparatus according to claim 1, further comprising: The image forming apparatus according to claim 1, wherein a cylindrical discharge path is provided between the vibrating member and the discharge port.

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