Information
-
Patent Grant
-
6442360
-
Patent Number
6,442,360
-
Date Filed
Friday, November 17, 200024 years ago
-
Date Issued
Tuesday, August 27, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Antonelli, Terry, Stout & Kraus, LLP
-
CPC
-
US Classifications
Field of Search
US
- 399 122
- 399 320
- 399 328
- 399 330
- 219 216
- 219 469
- 219 470
- 432 60
-
International Classifications
-
Abstract
The work involved in replacing the fixing lamps in a printer is made easy, and the non-operational period of the printer associated with such maintenance work is shortened. A portion of a fixing lamp is formed in a lamp cartridge which includes a first lamp holder for holding one end of the fixing lamp; a second lamp holder for holding the other end of the fixing lamp; and a protective member holding portion for holding a lamp protective member which is attached depending on necessity. The protective member holding portion is arranged around a region where the lamp holding member is placed, and, thereby, all of the plurality of fixing lamps are capable of being attached to and removed from the heating roller as a unit from one end of the heating roller.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a fixing unit for fixing a toner image onto a print material, and to a lamp holder, a lamp cartridge using the lamp holder and a fixing unit using the lamp holder.
As fixing units of a printer, typical of a laser printer, a copier machine and the like, there is known a fixing unit in which print material holding a toner image is heated and pressed while it is being transferred between a heating roller and a pressing roller to fix the toner image onto the print material. Lamps operating as a heat source are located inside of the heating roller, and in general, the number of the lamps placed inside the heating roller is increased as the printing speed of the printer is increased.
In the use of such a heating roller having a plurality of lamps, when the heating roller is exchanged due to, for example, the expiration of the lifetime of the heating roller, the roller is replaced by a new heating roller by removing the lamps one by one and then removing the heating roller from the fixing unit. Therefore, the amount of work required to detach and attach the lamps from and to the heating roller is in proportion to the number of lamps, and, accordingly, the work efficiency of this maintenance task has been low.
A structure to solve such a problem is proposed, for example, in published Japanese PCT international publication for patent application No.5-504633(1997). According to Japanese PCT international publication for patent application No.5-504633, the disclosed structure is designed such that the lamps can be pulled off from the back side of the fixing unit in a state in which the heating roller remains attached to the fixing unit.
lamp used in a fixing unit of this kind has a long and slender shape with a diameter about 10 mm and a length above 600 mm. In the case of the structure disclosed in Japanese PCT international publication for patent application No.5-504633, because the attaching and removing of the lamps to and from the heating roller is performed in a state in which the lamps are exposed, there has been a problem in that the lamp surface is scratched or the lamps are broken due to contact between the lamps and the edge of the heating roller or between the lamps and other parts, when the lamps are being attached to or removed from the heating roller.
SUMMARY OF THE INVENTION
An object of the present invention is to make the work of replacing the fixing lamps easy and to shorten the non-operational time period of the printer associated with the maintenance work.
Further, another object of the present invention is to hold the fixing lamps attached inside the heating roller in a correct position without displacement in the heating roller.
The above object can be attained by a fixing unit comprising a heating roller having a plurality of fixing lamps inside; and a pressing roller arranged so as to be capable of pressing against the heating roller, a print material having a toner image being transferred between said heating roller and the pressing roller to fix the toner image onto the print material, wherein the fixing lamps are formed as a lamp cartridge which comprises a first lamp holder for holding one end of the fixing lamps; a second lamp holder for holding the other end of the fixing lamps; and a protective member holding portion for holding a lamp protective member which is attached to the heating roller depending on necessity. The protective member holding portion is arranged around a region where the lamp holding member is placed, whereby all of the plurality of fixing lamps are capable of being attached to and removed from the heating roller together from one end of the heating roller.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1
is a perspective view showing the overall structure of an embodiment of a lamp cartridge in accordance with the present invention.
FIG. 2
is an exploded perspective view showing a first embodiment of a lamp cartridge in accordance with the present invention.
FIG. 3
is an exploded perspective view showing a second embodiment of a lamp cartridge in accordance with the present invention.
FIG. 4
is a rear view showing the first embodiment of the lamp cartridge.
FIG. 5
is a cross-sectional view showing an embodiment of a heating roller.
FIG. 6
is a cross-sectional view showing the heating roller in a state in which a lamp protective member is inserted into the heating roller.
FIG. 7
is a perspective view showing the overall structure of the lamp cartridge over which the lamp protective member is attached.
FIG. 8
is a diagrammatic view showing the overall construction of a printer.
FIG. 9
is a cross-sectional view showing another embodiment of a heating roller.
FIG. 10
is a cross-sectional view showing the heating roller in a state in which a lamp protective member is inserted into the heating roller.
FIG. 11
is a cross-sectional view showing the main portion of the heating roller in the state that a lamp protective member is inserted into the heating roller.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments in accordance with the present invention will be described below with reference to the accompanying drawings.
Initially, as an example of a printer to which the present invention is applied, a laser beam printer using electrophotography will be described with reference to FIG.
8
.
In
FIG. 8
, the reference character
1
is the laser beam printer, in which a photosensitive drum
21
is rotated in the direction shown by an arrow based on a print operation start signal from a controller
22
. The photosensitive drum
21
is rotated at a speed corresponding to a printing speed of the laser beam printer
1
and continues to be rotated until the print operation is completed. As rotation of the photosensitive drum
21
is started, a high voltage is applied to a corona charger
2
to uniformly charge the surface of the photosensitive drum
21
, for example, with positive charges.
A rotating polygon mirror
3
starts to rotate immediately after the switching on of the power to the laser beam printer
1
, and it is rotated at a constant speed with a high accuracy while the power is supplied. A light beam emitted from a light source
4
, such as a semiconductor laser, is reflected by the rotating polygon mirror
3
, which operates to irradiate and scan the beam on the surface of the photosensitive drum
21
, after the beam has passed through an fθ lens
5
.
As character data and pattern data converted into dot images are transmitted to the laser beam printer from the controller
22
as ON/OFF signals of the laser beam, portions irradiated by the laser beam and portions not irradiated by the laser beam are formed on the surface of the photosensitive drum
21
to form a so-called electrostatic latent image. When the area of the photosensitive drum holding the electrostatic latent image arrives at a position opposite to a developing unit
6
, toner is supplied onto the electrostatic latent image, and a toner image is formed on the surface of the photosensitive drum
21
by attracting the toner charged with, for example, positive charges to the positions on the surface of the photosensitive drum
21
where charges are eliminated by the irradiation of the laser beam.
A continuous paper sheet
7
contained in a paper hopper
11
is transported by a paper transport tractor
8
toward a gap between the photosensitive drum
21
and a transfer unit
10
in synchronism with a timing at which the toner image of the print data formed on the surface of the photosensitive drum
21
arrives at the transfer position.
The toner image formed on the surface of the photosensitive drum
21
is attracted to the paper sheet
7
by the operation of the transfer unit
10
applying charges having a polarity inverse to the polarity of charges of the toner image on the rear surface side of the paper sheet
7
.
As described above, the paper sheet
7
set in the paper hopper
11
is transported to a fixing unit
12
through the paper transport tractor
8
, the transfer unit
10
, a paper transport tractor
9
and a buffer plate
24
. The paper sheet
7
arriving at the fixing unit
12
is pre-heated by a per-heater
13
, and then driven between and transported by a nip portion constructed of a pair of fixing rollers composed of a heating roller
14
having a fixing lamp (hereinafter, referred to as “heater lamp”) and a pressing roller
15
, so that it is heated and pressed by the nip portion to melt-fix the toner image onto the paper sheet
7
.
The paper sheet
7
delivered by the heating roller
14
and the pressing roller
15
is dispensed to a stacker table
19
by a paper conveying roller
16
, and, alternatively, it is folded along the tear-off edge by a swinging operation of a swing fin
17
, and further the folding state of the paper sheet is prepared by rotating paddle
18
and stacked on the stacker table
19
. The area of the surface of the photosensitive drum
21
which has passed through the transfer position is cleaned by a cleaning unit
20
so as to be prepared for the next print operation.
In
FIG. 8
, the reference character
23
denotes a display screen for displaying information based on the state of the laser beam printer
1
during the print operation. The buffer plate
24
described above is used for absorbing the slack or the tension caused in the paper sheet
7
when a difference in the paper transporting speed occurs between the paper transport tractor
9
and the fixing rollers
14
,
15
. The reference character
26
indicates a web member for cleaning the surface of the heating roller
14
and for applying an erasing agent onto the surface of the heating roller
14
, and the web member
26
is arranged so that it may contact the surface of the heating roller
14
and may be wound.
Referring to
FIG. 1
, the structure of the lamp cartridge which comprises the present invention will be described in detail below.
The lamp cartridge
27
is composed of a plurality of heater lamps
25
(four heater lamps in the present embodiment) of the type described with reference to
FIG. 8
, a first lamp holder
28
for holding one end of each of the heater lamps
25
, a second lamp holder
29
for holding the other end of each of the heater lamps
25
, and a protective member holding portion
30
arranged around the heater lamps
25
held by the first lamp holder
28
. The protective member holding portion
30
is provided for holding a lamp protective member, to be described later, when the protective member is attached, and the protective member holding portion
30
in the present embodiment is formed of a tapered surface, though the invention is not limited particularly to this structure.
As shown in
FIG. 2
, the first lamp holder
28
comprises holes
31
, into each of which one end of a heater lamp
25
is inserted; and a hole
32
for inserting a spacer
33
thereinto. All the holes
31
and the hole
32
are through-holes. Accordingly, when a heater lamp
25
is inserted into the hole
31
, a power supply wire provided for each of the heater lamps can be led to the outside through the hole
31
(refer to FIG.
5
). The spacer
33
is fit into the hole
32
.
The heater lamps
25
are inserted into the holes
31
, and then the parts are fixed with a screw
37
by fastening the lamp holder
28
between a plate
34
and a plate
36
. In
FIG. 2
, the reference character
35
indicates springs. The springs
35
are placed in a groove formed in the rear side of the lamp holder
28
so that backlash and play of the heater lamps in the holes
31
are prevented by applying a pushing force between the two heater lamps in opposite directions to each other.
FIG. 4
shows the rear portion of the lamp holder
28
(a front view showing the lamp holder from the direction of the screw
37
in FIG.
2
). In
FIG. 4
, the reference character
38
indicates the grooves for accommodating the springs
35
. The reference character
39
denotes a depressed portion formed in the front surface portion of the lamp holder
28
. The depressed portion
39
is provided in order to prevent the lamp cartridge attached to the heating roller from being turned. The position of the lamp cartridge
27
is restricted by fitting a stopping member
65
(refer to FIG.
9
and
FIG. 10
) arranged in the main body of the fixing unit into the depressed portion
39
, and the restriction of the circumferential position of the lamp cartridge
27
is released by drawing back the stopping member
65
from the depressed portion
39
.
On the other hand, as shown in
FIG. 3
, the second lamp holder
29
comprises holes
40
, into each of which the other end of a heater lamp
25
is inserted; and a hole
41
for inserting a spacer
42
thereinto. All the holes
31
and the hole
32
are through-holes similar to the first lamp holder
28
. Accordingly, when a heater lamp
25
is inserted into the hole
40
, a power supply wire
63
(refer to FIG.
5
and
FIG. 9
) provided for each of the heater lamps can be led to the outside through the hole
40
. The spacer
42
is fit into the hole
41
.
The heater lamps
25
are inserted into the holes
40
, and then the parts are fixed with a screw
45
by fastening the second lamp holder
29
between a plate
43
and a plate
44
. The second lamp holder
29
may be provided with springs similar to the first lamp holder
28
, if necessary.
Referring to
FIG. 5
, the construction around the heating roller in the state of mounting of the lamp cartridge will be described below.
The heating roller
14
is composed of a metallic base pipe
14
a
made of, for example, aluminum, and a surface layer
14
b
made of Teflon, silicon rubber or the like provided on the base pipe
14
a
, and absorbers
14
c
for preventing heat dissipation are arranged in the inner end portions of the base pipe
14
a
. Both ends of the base pipe
14
a
are supported on a frame
50
of the fixing unit through holding members
48
,
49
having centering members
46
,
47
, respectively.
A bearing
51
is arranged in the holding member
48
, and the bearing
51
is coupled with the heating roller
14
along with the centering member
46
. Further, the bearing
51
is disposed so that the thermal expansion of the heating roller
14
and deviations in dimensions of the surrounding supporting members can be absorbed using a plurality of springs
52
and a guide plate
53
. The holding member
48
is fixed to the frame
50
using wing screws
54
. On the other hand, a gear
55
for receiving a drive force from a drive motor (not shown) for driving the heating roller
14
is arranged in the holding member
49
, and the gear
55
is supported by two housings
58
,
59
containing bearings
56
,
57
.
A projection
60
is provided in each of the centering members
46
,
47
in order to secure coupling with the heating roller
14
, and each projection
60
is engaged with one of the grooves
61
provided at both ends of the heating roller
14
.
Further, in order to prevent heat from flowing out from the heating roller
14
to the centering members
46
,
47
and to prevent damage in the engaging portion of the projection
60
and the groove
61
, collars
62
made of a heat resistant plastic are inserted between both end portions of the heating roller
14
and the centering members
46
,
47
. In
FIG. 5
, the lines led out from both end portions of the lamp cartridge
27
, indicated by the reference characters
63
, are the power supply wires of the heater lamps
25
.
In the construction described above, the lamp cartridge
27
is inserted through a hole
48
a
formed in the holding member
48
and is attached inside the heating roller
14
, as shown in FIG.
5
. The reason why the shape of the first lamp holder
28
is different from the shape of the second lamp holder
29
is to prevent erroneous insertion of the lamp cartridge
27
.
When the lamp cartridge
27
is to be pulled out of the heating roller
14
, an operator comes to the rear side (the side where the second lamp holder
29
exists) of the printer and inserts a cylindrical member
64
of a lamp protective member through a through hole
59
a
formed in the housing
59
, as shown in FIG.
6
. Then the operator pushes in the cylindrical member
64
until the inner front end peripheral surface of the cylindrical member
64
is held by the tapered surface
30
provided in the first lamp holder
28
.
After the setting of the cylindrical member
64
is completed, the operator moves to the front side of the printer and draws back the stopping member described above from the depressed portion
39
of the first lamp holder
28
to release the positional restriction of the lamp cartridge
27
.
As the lamp cartridge
27
in this state is drawn out, the lamp cartridge
27
and the cylindrical member
64
are drawn out together and removed to the outside in the state as shown in FIG.
7
.
Further, when the lamp cartridge
27
is inserted into the heating roller
14
, the lamp cartridge
27
in the state as shown in
FIG. 7
is loaded from the front side of the printer, and the stopping member
65
is moved on the depressed portion
39
of the first lamp holder
28
to restrict the position of the lamp cartridge
27
. After that, the operator comes to the rear side of the printer and draws off the cylindrical member
64
, so that only the lamp cartridge
27
remains inside the heater roller to complete the work of attaching the lamp cartridge
27
.
FIG.
9
and
FIG. 10
show a more practically preferable embodiment having a construction obtained by modifying the above-mentioned construction. Here, the key difference is that the second lamp holder
29
as part of the lamp cartridge
27
engages in a depressed portion
59
b
provided in the inner peripheral portion of a through hole
59
a
of the housing
59
. The depressed portion
59
b
forms the lamp holder means in the present invention, and the lamp cartridge
27
is restricted in its movement in the axial direction as the second lamp holder
29
becomes engaged in the depressed portion
59
b.
In the case of the construction shown in FIG.
9
and
FIG. 10
, when the lamp cartridge
27
is to be pulled out of the heating roller
14
, an operator comes to the rear side (the side where the second lamp holder
29
exists) of the printer and inserts a cylindrical member
64
, which serves as a lamp protective member, through a through hole
59
a
formed in a housing
59
, as shown in FIG.
10
. The operator then pushes in the cylindrical member
64
until the inner front end peripheral surface of the cylindrical member
64
is held by the tapered surface
30
provided in the first lamp holder
28
.
As the cylindrical member
64
is inserted in the state described above, the front end of the cylindrical member
64
picks up the second lamp holder
29
and disengages it from the depressed portion
59
b
, so as to release the positional restriction of the lamp cartridge
27
against movement in the axial direction caused by the depressed portion
59
b.
As described above, according to the present invention, since the fixing lamps are protected by the lamp protective member when the fixing lamps are attached to and removed from the heating roller, the attaching and removing of the fixing lamps can be performed efficiently and safely.
Further, since the fixing lamps attached inside the heating roller are held at the correct position inside the heating roller without displacement, the range of the heating region in the axial direction of the heating roller becomes stable, and, accordingly, any fixing deficiency caused by over heating or insufficient heating can be reduced.
Claims
- 1. A lamp holder for holding a plurality of fixing lamps, comprising:a plurality of lamp holding portions, each of said lamp holding portions holding one end of each fixing lamp; and a protective member holding portion for holding a lamp protective member which is attached depending on necessity, said protective member holding portion being arranged around a region where said lamp holding portion is placed.
- 2. A lamp cartridge comprising:a plurality of fixing lamps; a first lamp holder for holding one ends of said fixing lamps; a second lamp holder for holding the other ends of said fixing lamps; and a protective member holding portion for holding a lamp protective member which is attached depending on necessity, said protective member holding portion being arranged around a region where at least one of said first and second lamp holders is placed.
- 3. A fixing unit comprising a heating roller having a plurality of fixing lamps inside; a and a pressing roller arranged so as to be capable of pressing against said heating roller, a print material having a toner image being transferred by being put between said heating roller and said pressing roller for fixing said toner image onto said print material, whereina portion of said fixing lamps are formed in a lamp cartridge which comprises a first lamp holder for holding one end of said fixing lamps; a second lamp holder for holding the other end of said fixing lamps; and a protective member holding portion for holding a lamp protective member attached depending on necessity, said protective member holding portion being arranged around a region where at least one of said first and second lamp holders is placed, and thereby all of said plurality of fixing lamps are capable of being attached to and detached from said heating roller together from one end side of said heating roller.
- 4. A fixing unit comprising a heating roller having a fixing lamp inside; and a pressing roller arranged so as to be capable of pressing against said heating roller, a print material having a toner image being transferred by putting between said heating roller and said pressing roller for fixing said toner image onto said print material, whereina portion of said fixing lamp is formed in a lamp cartridge which comprises a first lamp holder for holding one end of said fixing lamp; a second lamp holder for holding the other end of said fixing lamp; and a protective member holding portion for holding a lamp protective member attached depending on necessity, said protective member holding portion being arranged around a region where at least one of said first and second lamp holders is placed, and said lamp cartridge is capable of being attached to and detached from said heating roller together from one end side of said heating roller, and a lamp holder restricting means for restricting motion of said lamp cartridge in an axial direction by engaging said lamp cartridge with said second lamp holder in a state that said lamp cartridge is attached to said heating roller.
- 5. A fixing unit according to claim 4, wherein restriction of the second lamp holder by said lamp holder restricting means is released by inserting said lamp protective member from a side of the second lamp holder.
- 6. A fixing unit according to claim 4, wherein a plurality of fixing lamps are held between said first lamp holder and said second lamp holder.
Priority Claims (2)
Number |
Date |
Country |
Kind |
11-328915 |
Nov 1999 |
JP |
|
2000-206657 |
Jul 2000 |
JP |
|
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4493982 |
Romansky |
Jan 1985 |
A |
5301000 |
Heigi |
Apr 1994 |
A |
Foreign Referenced Citations (1)
Number |
Date |
Country |
5-504633 |
Jul 1993 |
JP |