JP3181755B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can be applied to an image recording apparatus for recording an image on a sheet using a heat-fusible toner, such as a printer, a copying machine, a facsimile, and a printing machine, using a laser. More specifically, the present invention relates to a fixing device for fixing an unfixed image on a recording surface by heating a printed sheet with a heating element in such an image recording apparatus.

[0002]

2. Description of the Related Art Conventionally, for example, in a fixing device of a laser printer, as shown in FIG.
A pressure roller 3 having an elastic layer is pressed against a roller (heating element) 2, and the heating roller 2 is driven with the sheet S sandwiched between the heating roller 2 and the pressure roller 3. The sheet S was heated by the heating roller 2 while fixing the unfixed image on the recording surface.

However, in such a fixing device, the heat capacity of the heating roller 2 must be increased in order to prevent a so-called offset phenomenon in which the toner is transferred to the heating roller 2. As a result, there has been a problem that the temperature rise is slow and the standby time is long when the apparatus is used.

Therefore, some of the conventional fixing devices include those shown in FIG.
As shown in FIG. 5, a heat-resistant sheet 4 that comes into contact with the recording surface of the sheet S is wound around a feed shaft 5 and wound around a take-up shaft 6, and the take-up shaft 6 is rotatably provided in a direction indicated by an arrow. There is a configuration in which a heating element 7 for heating the sheet S via the heat-resistant sheet 4 is provided.

The sheet S after recording on the heat-resistant sheet 4
When the sheet S is sandwiched and conveyed between the heating element 7 and the pressure roller 9 via the heat-resistant sheet 4, the sheet S is energized in a pulsed manner to instantaneously raise the heating surface 8 of the heating element 7 to about 260 ° C. The temperature was raised, and the sheet S was heated by the heating element 7 via the heat-resistant sheet 4 to fix an unfixed image on the recording surface (see JP-A-63-313182).

[0006]

However, in such a conventional fixing device, since the heat-resistant sheet 4 is provided so as to be able to run, there is a problem that the number of parts is increased and the size is increased.

An object of the present invention is to provide a fixing device which is small in size, has a small number of parts, and has a fast rise in temperature.

[0008]

Accordingly, the present invention provides
For example, as in the illustrated embodiment below, a vibrating body such as an ultrasonic vibrating body 41 that contacts the recording surface of the sheet S, a heating element 40 that heats the sheet S through the vibrating body, and a current flowing through the vibrating body Electrical control means for conveying the sheet S by vibrating the sheet S.

According to a second aspect of the present invention, in the fixing device 25 according to the first aspect, the peak position of the temperature distribution of the heating element 40 is set to the front side in the sheet conveying direction. It is characterized by being biased toward.

According to a third aspect of the present invention, in the fixing device 25 of the first aspect, the vibrating body and the heating element 40 are connected via an insulating member 44 as in the following illustrated embodiment. It is characterized by becoming.

According to a fourth aspect of the present invention, in the fixing device 25 of the first aspect, the sheet S is conveyed with the sheet S sandwiched between the vibrating member, as in the following illustrated embodiment. A guide plate 42 for guiding is provided.

According to a fifth aspect of the present invention, in the fixing device 25 of the first aspect, a sheet S is interposed between the vibrating body and the driven body by the vibrating body, as in the following illustrated embodiment. A roller 47 for rotating and transporting the sheet S is provided.

According to a sixth aspect of the present invention, in the fixing device 25 of the first aspect, the sheet S is conveyed with the sheet S sandwiched between the vibrating body, as in the following illustrated embodiment. A belt 48 is provided.

[0014]

According to the present invention, an unfixed image on the recording surface of the sheet S is heated by the heating element 40 through the vibrating body while the sheet S is conveyed by vibrating the vibrating body by energizing the electric control means. To establish.

According to the second aspect of the present invention, the peak of the temperature distribution of the heating element 40 is on the front side in the sheet conveying direction.

According to the third aspect, the vibrating body and the heating element 40 are electrically separated.

According to the fourth aspect, when the sheet S is conveyed by vibrating the vibrating body, the sheet S
Is guided by the guide plate 42.

According to the fifth aspect, when the sheet S is conveyed by vibrating the vibrator, the roller 47 is driven to rotate by the vibration of the vibrator to convey the sheet S.

According to the sixth aspect, when the sheet S is conveyed by vibrating the vibrator, the belt 48 is rotated to convey the sheet S.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a schematic view of a laser printer provided with a fixing device according to an embodiment of the present invention, showing the entire internal mechanism thereof.

The reference numeral 10 in the drawing denotes the apparatus main body. In the apparatus main body 10, a drum-shaped photoconductor 11 is provided substantially at the center. A charging device 12, a developing device 13, a transfer device 14, and a cleaning device 15 are arranged around the photoconductor 11 in the driving direction indicated by the arrow in FIG. An optical writing device 16 is arranged below the developing device 13. Further, on the right front side of the apparatus main body 10 in the figure, paper feed cassettes 17 and 18 containing the sheets S are removably mounted vertically.

The first paper supply means A to which the paper supply cassette 17 is attached is provided with a paper supply roller 19, a pair of separation rollers 20, and the like. On the other hand, the second
The paper supply means B includes a paper supply roller 21 and a pair of separation rollers 22.

When recording is to be performed, the paper feed roller 1 is controlled by an electric control means provided in the electrical component storage unit 23.
9 and 21 are appropriately selected and driven, and the sheet S is sent out from the sheet feeding cassette 17 or 18 to the registration roller pair 2.
4, and is conveyed to the upper side of the photoconductor 11 in a timely manner.

On the other hand, the photoconductor 11 is driven in a counterclockwise direction as indicated by an arrow. At this time, the surface of the photoconductor 11 is uniformly charged by the charging device 12, and the photoconductor 11 is irradiated with laser light from the optical writing device 16. An electrostatic latent image is formed thereon. This latent image is stored in the developing device 1
When passing through three positions, a visible image is formed by the toner. Then, the visible image is transferred to the sheet S by the transfer device 14. Then, the transferred sheet S is conveyed to the fixing device 25 of the present invention to fix the transferred image. And then
The sheet S that has exited the fixing device 25 is guided by the switching guide claws 33 and discharged to the discharge tray 27 by the discharge rollers 26.

On the other hand, the photoreceptor 11 after the image transfer is cleaned by a cleaning device 15 to remove the residual toner, and thereafter the charge is removed.

The laser printer of the illustrated embodiment has a duplex unit 30 above the apparatus main body 10. The duplex unit 30 includes a sheet reversing unit 30a and a switchback unit 30b. The sheet reversing section 30a is provided with a reversing conveyance path 31, and a plurality of pairs of conveyance rollers 32 are provided on the reversing conveyance path 31. On the other hand, the switchback unit 30b
A horizontal switchback path 34 is provided, and a refeed path 35 branched from the switchback path 34 and inclined downward is provided. Then, a switchback roller 36 is provided in the switchback path 34. Further, a switchback tray 37 is provided in the switchback section 30b so as to protrude outward from the front of the apparatus body 10.

When two-sided recording is performed by the laser printer shown in FIG.
3, the sheet is conveyed through the reversing conveyance path 31 by the conveyance roller 32, and is reversed and guided to the switchback path 34. The front end side of the sheet is switched on the switchback tray 37 by the switchback roller 36. To send out. When the rear end of the sheet is held by the switchback roller 36, the switchback roller 3
6 after the rotation of the switchback roller 36 is stopped.
To switch back the sheet. And
The sheet is fed again into the apparatus main body 10 through the sheet feeding path 35. Thus, after performing recording on the reverse side of the sheet is discharged onto the discharge tray 2 7 in the sheet discharge roller 2 6.

The fixing device 25 according to the present invention is configured as shown in FIGS. 1 and 2 in detail. Reference numeral 40 in the figure
Is a heating element for heating the sheet. The heating element 40
Is a bar having a rectangular cross section that is long in the direction perpendicular to the sheet conveying direction indicated by the arrow in FIG. 2 and provided with both ends supported by side plates (not shown), has a heat source (not shown), and is electrically connected to the electric control means. Connect. The heat generating body 40 is provided with a heat generating surface 40a on a lower surface, and an ultrasonic vibrating body 41 is connected thereto in contact therewith. The ultrasonic vibrator 41 is formed of a member having a high thermal conductivity, and is electrically connected to an electric control unit. At a position facing the lower surface of the ultrasonic vibrator 41,
A guide plate 42 is provided. The guide plate 42 is formed in a slightly narrow plate shape from a plastic member having a small thermal conductivity, and is provided with both sides in the sheet conveyance direction slightly curved downward.

At the time of fixing, the sheet S after transfer is conveyed to the fixing device 25 and the ultrasonic vibrator 41 and the guide plate 42
Put between. On the other hand, in the fixing device 25, the heating unit 40 is heated by the electric control unit to generate heat, and the ultrasonic vibration unit 41 is heated by the heating unit 40, and the ultrasonic vibration unit 41 is supplied by the electric control unit to energize the ultrasonic vibration unit 41. Drive and ultrasonically vibrate the surface. Then, while conveying the sheet S by the ultrasonic vibration, the sheet S is heated by the heating element 40 via the ultrasonic vibrator 41 to fix the unfixed image on the recording surface of the sheet S. At this time, the sheet S to be conveyed is guided by the guide plate 42.

If a jam occurs during use of the illustrated laser printer, as shown in FIG.
The energization to 0 is turned off. Then, it is checked whether or not there is jam paper between the ultrasonic vibrator 41 and the guide plate 42, and if it is confirmed that there is jam paper, it is further checked whether or not the upper cover portion of the apparatus main body 10 is closed. Then, when the cover is closed, the flow of the current is changed to make the ultrasonic vibration reverse to the sheet conveying direction, and the jam paper is moved to the ultrasonic vibrator 4.
1 and the guide plate 42 to remove the jammed paper easily. By the way, when the upper cover portion of the apparatus main body 10 is open, an instruction to close the cover is issued, and the above operation is repeated again. On the other hand, when there is no jammed paper in the fixing device 25, the process ends.

The heating element 40 of the fixing device 25 is
As shown in FIG. 5, a vertical section may be formed in a semi-cylindrical shape. Then, the heat radiation of the heating element 40 is reduced, and the thermal efficiency is improved.

The ultrasonic vibrator 4 of the fixing device 25
As shown in FIG. 6, the lower end 1 may have a curved surface 41a at the lower end on the rear side in the sheet conveying direction. Then, when the post-transfer sheet S is conveyed to the fixing device 25, the front end of the sheet S is curved
The jam is prevented by guiding at 1a.

Further, as shown in FIG.
Arranges the guide plate 42 on the sheet S (not shown),
The heat generating surface 40a provided on the upper surface of the heating element 40, may be contact therewith connecting the ultrasonic vibrator 41, a configuration of providing the guide plate 42 opposite to the upper surface of the ultrasonic vibrator 41. Then, the heat of the heating element 40 is easily transmitted to the ultrasonic vibration body 41, and the heat transmitted to the ultrasonic vibration body 41 is easily transmitted to the sheet S.

In the fixing device 25 of the illustrated embodiment, the peak position of the temperature distribution of the heating element 40 may be biased forward in the sheet conveying direction. That is, as shown in FIG. 8, the temperature of the heating element 40 is gradually increased by gradually increasing the upper end of the heating element 40 on the front side in the sheet conveying direction. Further, as shown in FIG. 9, the heat source 43 is disposed so as to be biased to the front side of the heating element 40 in the sheet conveying direction. At the time of fixing, the heat efficiency is improved to improve the fixing property.

Further, the fixing device 25 of the illustrated embodiment described above
In this configuration, the heating element 40 and the ultrasonic vibrating element 41 are connected in contact with each other. However, as shown in FIG. 10, a configuration may be adopted in which the heating element 40 and the ultrasonic vibration element 41 are connected via the insulating member 44.

Further, the fixing device 2 of the illustrated embodiment described above
5, the guide plate 42 is provided to guide the conveyance of the sheet S with the sheet S sandwiched between the ultrasonic vibrator 41 and the ultrasonic vibration body 41. However, instead of the guide plate 42, as shown in FIG. 11, the sheet S is sandwiched between the ultrasonic vibrator 41 and the roller 47 which is driven by the ultrasonic vibrator 41 to rotate and convey the sheet S. May be provided. Then, the roller 47 is driven to rotate by receiving the driving force by the ultrasonic vibration, and conveys the sheet S. At this time, friction between the roller 47 and the sheet S is eliminated.

Further, as shown in FIG. 12, a structure may be provided in which a belt 48 for conveying the sheet S with the sheet S sandwiched between the ultrasonic vibrator 41 and the ultrasonic vibration body 41 is provided. Belt 48
Is wound around the drive shaft 49 and the driven shaft 50. Then, the driving force is transmitted from the independent driving source to drive the driving shaft 49,
Belt 4 at the same speed as the sheet conveyance speed by ultrasonic vibration
The sheet S is conveyed by rotating the sheet 8. At this time, friction between the belt 48 and the sheet S is eliminated. Note that, as shown in FIG. 13, a back plate 51 may be provided on the belt 48. Then, the sheet S can be conveyed while sufficiently applying pressure to the sheet S.

[0038]

Therefore, according to the present invention, while the sheet is being conveyed by energizing the electric control means and vibrating the vibrating body, the sheet is conveyed and heated by the heating element via the vibrating body so that the sheet is recorded on the recording surface. Since the image is fixed, the number of components can be reduced and the size can be reduced as compared with the related art, and the heat capacity of the heating element can be reduced and the temperature rise can be accelerated.

According to the second aspect, the temperature of the heating element is increased on the front side in the sheet conveying direction, so that the thermal efficiency can be improved and the fixing property can be improved.

According to the third aspect, since the vibrating body and the heating element are electrically separated from each other, it is possible to prevent malfunction due to leakage of current or the like.

According to the fourth aspect, when a sheet is conveyed by vibrating the vibrating body, the conveyance of the sheet is guided by the guide plate, so that occurrence of a jam can be prevented.

Further, when the sheet is conveyed by vibrating the vibrator, the roller is driven to rotate according to the fifth aspect, and the belt is rotationally driven according to the sixth aspect. So you can eliminate the rubbing of the sheet,
For example, blurring of a recorded image can be prevented during double-sided printing.

[Brief description of the drawings]

FIG. 1 is a fixing device according to an embodiment of the present invention,
FIG. 3 is a side view as viewed from a direction orthogonal to a sheet conveying direction.

FIG. 2 is a plan view thereof.

FIG. 3 is a schematic configuration diagram of an entire internal mechanism in a laser printer including the fixing device.

FIG. 4 is a flowchart when a jam occurs during use of the laser printer.

FIG. 5 is a side view showing another example of the heating element in the fixing device.

FIG. 6 is a side view showing another example of the ultrasonic vibrator in the fixing device.

FIG. 7 is a side view showing another example of the fixing device.

FIG. 8 is a side view of a fixing device showing still another example.

FIG. 9 is a side view of a fixing device showing still another example.

FIG. 10 is a side view of a fixing device showing still another example.

FIG. 11 is a side view of a fixing device showing still another example.

FIG. 12 is a side view of a fixing device showing still another example.

FIG. 13 is a side view showing another example of the fixing device.

FIG. 14 is a schematic configuration diagram of a conventional fixing device.

15 is a schematic diagram of the fixing device the peripheral portion of another conventional example.

[Explanation of symbols]

 S sheet 25 Fixing device 40 Heating element 41 Ultrasonic vibrator (vibrator) 42 Guide plate 44 InsulationElement  47 Roller 48 Belt

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (6)

(57) [Claims] A vibrating body that contacts a recording surface of a sheet, a heating element that heats the sheet via the vibrating body, an electric control unit that conveys the sheet by energizing the vibrating body and vibrating the vibrating body, A fixing device comprising: 2. The fixing device according to claim 1, wherein a peak position of a temperature distribution of the heating element is biased forward in a sheet conveying direction. 3. The fixing device according to claim 1, wherein the vibrating body and the heating element are connected via an insulating member. 4. The fixing device according to claim 1, further comprising a guide plate that guides sheet conveyance with the sheet sandwiched between the vibrating body. 5. The fixing device according to claim 1, further comprising a roller that sandwiches the sheet between the vibrator and the roller that is driven by the vibrator to rotate and convey the sheet. 6. The fixing device according to claim 1, further comprising a belt that conveys the sheet with the sheet interposed between the vibrating body.