Information
-
Patent Grant
-
6349193
-
Patent Number
6,349,193
-
Date Filed
Thursday, March 9, 200024 years ago
-
Date Issued
Tuesday, February 19, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 399 388
- 399 381
- 399 204
- 399 195
- 399 393
- 399 392
- 271 901
- 271 905
- 271 907
-
International Classifications
-
Abstract
An image forming apparatus of the present invention has a photosensitive drum for carrying an electrostatic latent image, an image forming section for forming the electrostatic latent image on the photosensitive drum, a developing unit for supplying a developing agent to the electrostatic latent image formed by the image forming section, a transfer charger for transferring a developing agent image which is developed by the developing unit to a sheet, supplying mechanism for supplying the sheet to the photosensitive drum, and a control section for allowing a plurality of electrostatic latent images to be formed at a time in a parallel sheet array on the photosensitive drum as required through an image forming mechanism, in which the supplying mechanism has a supplying section for holding sheets in a parallel array as required and first and second supply sections for allowing the sheets which are held in a parallel array to be picked up in units of one sheet in a parallel array at a time and supplying these parallel sheets to the photosensitive drum.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus applied, for example, as an electrophoto-graphic copier. The electrophotographic copier forms an electrostatic latent image on a photosensitive drum, supplies a developing agent to the electrostatic latent image to develop the image and transfers the developing agent image to a sheet as a transfer medium.
In the prior art, sheets are supplied to a photosensitive drum only on a one-by-one basis and, in the case where, for example, a large quantity of copies are taken for a shorter time, there has been left no other way but to increase a copying speed. For this reason, the copier becomes larger in size and the noise becomes louder.
Further, in the case where sheets of smaller size are continuously supplied to the copier and a larger quantity of copies is taken, the photosensitive drum is deteriorated at a surface area corresponding to the sheet size. In the case where a larger quantity of copies is taken with a continuous supply of smaller-size sheets and then a copy is taken with the use of a maximum-size sheet, a defective image results.
BRIEF SUMMARY OF THE INVENTION
The present invention is achieved with the above-mentioned situation in view and it is accordingly the object of the present invention to provide an image forming apparatus which can take a large quantity of copies for a shorter time and obtain a better quantity of image even in the case where, after a larger quantity of copies has been taken, a copy is taken with the supply of a sheet of larger size.
An image forming apparatus of the present invention comprises an image carrier for carrying an electrostatic latent image, image forming means for forming the electrostatic latent image on the image carrier, developing means for supplying a developing agent to the electrostatic latent image formed by the image forming means and developing the latent image, transfer means for transferring the developing agent image developed by the developing means to be transferred to a transfer medium, supplying means for supplying the transfer medium to the image carrier, and control means for allowing a plurality of electrostatic latent images to be formed at a time in a parallel array on the image carrier as required through the image forming means, wherein the supplying means has a holding section for holding the transfer medium in a parallel sheet array as required and first and second supply sections for allowing the transfer medium which is held in a parallel sheet array in the holding section to be picked up in units of one sheet in a parallel way at a time and supplying these parallel sheets to the image carrier.
An image forming apparatus of the present invention comprises an image carrier for carrying an electrostatic latent image, image forming means for forming the electrostatic latent image on the image carrier, developing means for supplying a developing agent to the electrostatic latent image formed by the image forming means and developing the latent image, transfer means for allowing a developing agent image which is developed by the developing means to be transferred to a transfer medium, supplying means for supplying the transfer medium to the image carrier, and control means for allowing a plurality of electrostatic latent images to be formed in a parallel array at a time as required on the image carrier through the image forming means wherein the supplying means has a holding section for, when a plurality of electrostatic latent images are formed in a parallel array at a time, holding the transfer medium in a parallel sheet array and, when the electrostatic latent image is formed as a single image, holding the transfer medium in a single individual form, first and second supply sections for allowing the transfer medium which is held in a parallel sheet array in the holding section to be picked up in units of one sheet at a time and supplying these parallel sheets to the image carrier and a third supply section for allowing the transfer medium which is held in a single individual form in the holding section to be picked up in a one-by-one way and supplying the single individual sheet to the image carrier.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.
FIG. 1
is a diagrammatic view showing an electrophotographic copier according to a first embodiment of the present invention;
FIG. 2
is a plan view showing a sheet supply mechanism;
FIG. 3
is a plan view showing sheet supply cassettes;
FIG. 4
is a plan view showing a register roller;
FIG. 5
is a plan view showing a post card supply mechanism;
FIG. 6
is a side cross-sectional view showing the post card supply mechanism;
FIG. 7
is a block diagram showing a drive control system of the sheet supply mechanism; and
FIG. 8
is a plan view showing a sheet supply mechanism in a second embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The embodiments of the present invention will be explained below with reference to the accompanying drawing.
FIG. 1
is a diagrammatic view showing an electrophotographic copier as an image forming apparatus according to a first embodiment of the present invention.
Reference numeral
1
in
FIG. 1
shows a body of a copier and a photosensitive drum
2
is rotatably provided at a substantially center area within the body of the copier
1
and serves as an image carrier for carrying an image thereon. A charger
3
, light exposure section
4
, developing unit
5
, transfer and separation chargers
6
and
7
, cleaning unit
8
and discharger
9
are arranged around the photosensitive drum
2
along a rotation direction of the photosensitive drum
2
, thus constituting an image forming mechanism
10
.
The charger
3
charges the surface of the photosensitive drum
2
to a predetermined potential and the light exposure section
4
forms a toner image corresponding to a document image. The developing unit
5
supplies a toner as a developing agent to an electrostatic latent image on the photosensitive drum
2
and develops it.
The transfer charger
6
transfers the toner image on the photosensitive drum
2
to a sheet as a transfer medium and the separation charger
7
separates a toner image-transferred sheet from the photosensitive drum
2
.
The cleaning unit
8
removes a remaining toner on the photosensitive drum
2
and the discharger
9
removes a surface potential of the photosensitive drum
2
.
At a lower side within the copier body
1
, a sheet supply mechanism
16
is provided as will be set out in more detail below. A sheet picked up from the supply mechanism
16
is fed via a sheet supply path
15
to a conveying path
17
. At the conveying path
17
, a register roller
18
, transfer and separation chargers
6
,
7
, fixing roller
19
and sheet discharge roller
20
are sequentially arranged, the register roller serving as an aligning means for arraying a sheet along a conveying direction.
At a time of forming an image, the surface of the photosensitive drum
2
is charged by the charger
3
and an electrostatic latent image corresponding to a document image is formed by the light exposure section
4
on the charged surface of the photosensitive drum
2
. This electrostatic latent image is sent to the developing agent
5
by the rotation of the photosensitive drum
2
and developed by supplying a toner from the developing unit
5
to provide a toner image.
At this time, on the other hand, a sheet is taken out by the sheet supply mechanism
16
. This sheet is sent via the sheet supply path
15
onto the conveying path
17
and, after being aligned by the register roller
18
, sent between the photosensitive drum
2
and the transfer charger
6
. Under the action of the transfer charger
6
, the toner image on the photosensitive drum
2
is transferred to the sheet P. Under the action of the separating charger
9
the toner image-transferred sheet P is separated from the photosensitive drum
2
and conveyed. This sheet P is sent to the fixing roller
19
where its transferred toner image is fixed to the sheet P. After this fixing step, the sheet is discharged onto a sheet discharge tray
20
a.
FIG. 2
is a plan view showing the sheet supply mechanism
16
for supplying the above-mentioned sheet.
This sheet supply mechanism
16
has first, second and third supply section A, B, and C, respectively. The first, second and third supply sections A, B and C are mounted at predetermined intervals on a shaft
24
.
The first supply section A has an electromagnetic clutch
25
and sheet supply roller
27
mounted on the shaft
24
and a pulley
26
is incorporated in the electromagnetic clutch
25
. A claw section (not shown) is projected at a side surface of the pulley
26
and, through this claw section, the pulley
26
and sheet supply roller
27
are formed as an integral unit. Further, the first supply section A has one pair of swinging arms
27
,
29
mounted on the shaft
24
and, between the swinging end portions, a pick-up roller
31
and pulley
32
are mounted through a support shaft
30
. A claw, not shown, is projected at a side surface area of the pulley
32
and, through the claw, the pulley
32
and pick-up roller
31
are formed as an integral unit. A power transmission belt is trained between the pulley
26
and the pulley
32
.
Incidentally, the second and third supply sections B and C are constructed in the same way as the first supply section A and any further explanation of these is omitted with the same reference numerals applied to corresponding parts.
An electromagnetic clutch
23
is connected to one end portion of the above-mentioned shaft
24
and a driven gear
21
is incorporated in the electromagnetic clutch
23
and a power is transmitted from a drive system
22
on the copier body side to the driven gear
23
. With the electromagnetic clutch
23
ON, the driven gear
21
is attracted to the electromagnetic clutch
23
to allow a drive force to be transmitted to the shaft
24
.
FIG. 3
shows a sheet supply cassette
37
serving as a sheet holding section of the sheet supply mechanism
16
.
Reference numeral
38
in
FIG. 3
shows a cassette body. First and second sheet holding sections
39
and
40
are provided within the cassette body
38
. The first and second sheet holding sections
39
and
40
, each, comprise a Back plate
41
for supporting a Back end section of sheets and side walls for guiding both side surface sections of the sheets. Copying sheets P
1
, P
2
are arranged in a parallel array in a manner to be held, in a stacked state, between the side walls
42
and
42
. The size of the copying sheets is set to be below one-fourth (ΒΌ) the maximum sheet size used.
The side walls
42
,
42
are removably mounted and removed at a time of supplying a sheet in a normal one-sheet supply mode.
The above-mentioned first sheet supply section A is set opposite to the first sheet holding section
39
of the sheet supply cassette
11
with the pick-up roller
31
set in contact with the sheet P
1
and the second sheet supply section B is set opposite to the second sheet holding section
40
of the sheet supply cassette
11
with the pick-up roller
31
set in contact with the sheet P
2
.
FIG. 4
is a plan view showing the above-mentioned register roller
18
.
To one end portion of a shaft
18
a
of the register roller
18
an electromagnetic roller
45
is mounted and a pulley
46
is incorporated in the electromagnetic clutch
45
. Further, first to third sensors
47
a
to
47
c
are arranged at predetermined intervals over an axial direction of the register roller
18
and operated by being pushed by the leading edge of a copying sheet sent into the sheet introducing side of the register roller
18
from an arrow direction.
A guide plate
49
is provided at the sheet introducing side of the register roller
18
to guide the copying sheet to the register roller
18
.
FIG. 5
is a plan view showing a post card unit
51
set at a manual sheet supply section
11
of the copier body
1
and
FIG. 6
shows a side cross-sectional view.
Reference numeral
52
in
FIG. 5
shows a drive motor and, to a drive shaft of the drive motor, first and second gears
53
and
54
are connected through a gear
52
a. The first and second gears
53
and
54
are connected to one-end side portions of the first and second shafts
55
and
56
.
A pair of electromagnetic clutches
58
,
58
are mounted on the first shaft
55
at a predetermined interval and sheet supply rollers
60
are incorporated in the electromagnetic clutches
58
,
58
. Although the sheet supply roller
60
is normally rotated in an idle state, if the electromagnetic clutch
58
is turned ON, a drive force is transmitted to the sheet supply roller
60
.
A pair of electromagnetic clutches
59
,
59
are mounted on the second shaft
56
and pick-up rollers
61
are incorporated in the electromagnetic clutches
59
,
59
. Although the pick-up roller
61
is normally rotated in an idle state, if the electromagnetic clutch
59
is turned ON, a post card P
4
is picked up and supplied. The post cards P
4
and P
4
are held in the card trays
62
and springs
63
,
63
are normally urged toward the pick-up roller
61
.
FIG. 7
is a block diagram showing a drive control system of the above-mentioned sheet supply mechanism
16
.
Reference numeral
67
in
FIG. 7
shows an operation section by which an image formation is set in a normal image formation mode or in a two-sheets-at-a-time mode. To this operation section
67
a control means
68
is connected via a signal path. An image forming mechanism
10
and first to third sheet supply sections A to B are connected to the control means
68
through a control circuit. With the normal image formation mode set, the control means
68
allows one image to be formed on the photosensitive drum
2
through the image forming mechanism
10
and a sheet P to be supplied through a third sheet supply section C.
Further, with the image formation set to a two-sheets-at-a-time mode, the control means
68
allows two images to be formed in a parallel array on the photo-sensitive drum
1
, through the image forming mechanism
10
, over the axial direction of the drum
1
and the first and second sheet supply sections A and B to be operated to supply the sheets P
1
, P
2
at the same time.
Then an explanation will be given below of the case where two images are formed at a time in a parallel array on the photosensitive drum
2
through the image formation mechanism
10
. Further, the electromagnetic clutches
25
,
25
of the first and second sheet supply sections A, B in the sheet supply mechanism
16
are turned ON to cause the pulleys
26
,
26
to be rotated. Through the rotation of the pulleys
26
,
26
, the sheet supply rollers
27
,
27
are rotated and, through the power transmission belts
35
,
35
and pulleys
32
,
32
, the pick-up rollers
31
,
31
are rotated.
Through the rotation of the pick-up rollers
31
,
31
, the sheets P
1
, P
2
are simultaneously picked up and these sheets are supplied in a parallel way through the rotation of the sheet supply rollers
27
,
27
.
The sheets P
1
and P
2
are conveyed toward the register roller
18
and, when arriving before the register roller
18
, detected by the first and second sensors
47
a,
47
b.
After a lapse of a predetermined time following the detection of the sheets P
1
, P
2
by the first and second sensors, the electromagnetic clutch
45
is turned ON and a drive force from a body's drive system is transmitted through the pulley
46
. By doing so, the register roller
18
is rotated to send the sheets P
1
, P
2
to the photosensitive drum
2
where corresponding developing agent images are simultaneously transferred to the sheets.
At the time of forming two images at a time, an odd number sheet is input as a copying sheet, only the electromagnetic clutch
25
of any one of the sheet supply sections A, B is turned ON and a final sheet is supplied as one sheet alone.
An explanation will be given below of the case where an image is formed in a normal one-by-one sheet supply mode.
In this case, a normal one-sheet supply cassette is mounted in place of a sheet supply cassette
37
and the electromagnetic clutch
25
only of the third sheet supply section C is turned ON and a sheet P
3
is supplied as only one sheet.
The sheet P
3
thus supplied is detected before the register roller
18
by the third sensor
47
c
and arrayed there and sent to the photosensitive drum
2
.
Although, in the first embodiment, the electromagnetic clutch is employed, the present invention is not restricted thereto and an electromagnetic spring clutch may be used.
FIG. 8
shows a sheet supply mechanism in a second embodiment of the present invention.
The same reference numerals are employed to designate parts or elements corresponding to those shown in the first embodiment and any further explanation is omitted.
Although, in the above-mentioned first embodiment, a drive force has been explained as being supplied from a drive system on the copier body side, the second embodiment is such that a drive motor
73
is connected through gears
71
,
72
to a one-end portion of a shaft
24
with first and second sheet supply sections A and B mounted thereon in which case the first and second sheet supply section A and B are driven by a drive force of the drive motor
73
.
As set out above, the present invention includes the control means for allowing a developing agent image to be formed as a plurality of such images in a parallel array, as required, on the image carrier through the image forming means, a holding section for holding the transfer medium in a parallel sheet array, and supply means for allowing the transfer medium which is held in a parallel sheet array in the holding section to be picked up through the first and second supplying sections and to be supplied in a parallel sheet array to the image carrier. It is, therefore, possible to enhance an image formation speed and obtain an increased number of copies. As a result, it is possible to obviate the need for increasing the size of the image forming apparatus and to prevent noise, etc., from being produced.
Even if copies of greater size are taken after many copies of smaller size are taken, it is possible to obtain an excellent quality image.
Further, in the case where the copy number is set as an odd number, only one of the first and second supplying sections is operated to allow a final sheet to be supplied as a single sheet only.
Further, at the time of forming an image in a normal one-by-one sheet supply mode, a transfer medium is picked up through the third supply section and supplied, so that the present invention can handle any situation in which an image is formed in normal one-by-one sheet supply mode and in a two-sheets-at-a-time supply mode.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
Claims
- 1. An image forming apparatus comprising:an image carrier for carrying an electrostatic latent image; image forming means for forming the electrostatic latent image on the image carrier; developing means for supplying a developing agent onto the electrostatic latent image formed by the image forming means and developing the latent image; transfer means for transferring a developing agent image developed by the developing means to a transfer medium; control means for allowing a plurality of electrostatic latent images to be formed at a time in a parallel manner on the image carrier through the image forming means as required; supplying means including a holding section for holding transfer mediums side by side as required, and a first supplying section and a second supplying section for allowing the transfer mediums, which are held in the holding section side by side, to be picked up in a parallel way at a time and supplying these transfer mediums to the image carrier; and an operating section for setting a number of transfer mediums to be supplied by the supplying means, wherein when an odd number is set, only one of the first and second supply sections of the supplying means is operated to allow a final transfer medium to be taken out.
- 2. An image forming apparatus according to claim 1, wherein the holding section holds the transfer medium in a parallel array, the sheet size of the transfer medium being below one-fourth (¼) the maximum sheet size of the holding section.
- 3. An image forming apparatus according to claim 1, further comprisingan aligning means for arraying the sheet sent toward the image carrier; and a plurality of detecting means arranged at predetermined intervals at a sheet introducing side of the aligning means in a direction perpendicular to a conveying direction of the sheet to detect those sheets conveyed in a parallel array, wherein, after these detecting means detect the sheets conveyed in a parallel array, the aligning means is operated to send the sheets to the image carrier.
- 4. An image forming apparatus according to claim 1, wherein the holding section has a guide member for guiding each side surface and back surface of the transfer medium held in a parallel sheet array.
- 5. An image forming apparatus according to claim 4, wherein the guide member is detachably mounted at the holding section.
- 6. An image forming apparatus comprising:an image carrier for carrying an electrostatic latent image; image forming means for forming the electrostatic latent image on the image carrier; developing means for supplying a developing agent onto the electrostatic latent image formed by the image forming means and developing the latent image; transfer means for transferring a developing agent image developed by the developing means to a transfer medium; control means for allowing a plurality of electrostatic latent images to be formed at a time in a parallel manner on the image carrier through the image forming means as required; supplying means including a holding section for holding transfer mediums side by side as required, and a first supplying section and a second supplying section for allowing the transfer mediums, which are held in the holding section side by side, to be picked up in a parallel way at a time and supplying these transfer mediums to the image carrier; and post card supplying means, having a manual feeding section for manually feeding transfer mediums, for holding post cards in a parallel manner in the manual feeding section, picking up these parallel post cards and supplying the parallel post cards to the image carrier.
- 7. An image forming apparatus comprising:an image carrier for carrying an electrostatic latent image; an image forming means for forming the latent image on the image carrier; developing means for supplying a developing agent to the latent image formed by the image forming means and developing the latent image; transfer means for allowing a developing agent image which is developed by the developing means to be transferred to a transfer medium; supplying means for supplying the transfer medium to the image carrier; and control means for allowing a plurality of electrostatic latent images to be formed in a parallel array on the image carrier as required through the image forming means, wherein the supplying means has a holding section for, when a plurality of electrostatic latent images are formed in a parallel array at a time, holding the transfer medium in a parallel sheet array and, when the electrostatic latent image is formed as a single image, holding the transfer medium in a single individual form, first and second supply sections for allowing the transfer medium which is held in a parallel sheet array in the holding section to be picked up in units of one sheet in a parallel array at a time and supplying these parallel sheets to the image carrier, and a third supply section for allowing the transfer medium which is held in a single individual form in the holding section to be picked up in a one-by-one way and supplying the single individual sheet to the image carrier.
- 8. An image forming apparatus comprising:an image carrier for carrying an electrostatic latent image; an image forming device for forming the electrostatic latent image on the image carrier; a developing device for supplying a developing agent onto the electrostatic latent image formed by the image forming device and developing the latent image; a transfer device for transferring a developing agent image developed by the developing device to a transfer medium; a control device for allowing a plurality of electrostatic latent images to be formed at a time in a parallel manner on the image carrier through the image forming device as required; a supplying device including a holding section for holding transfer mediums side by side as required, and a first supplying section and a second supplying section for allowing the transfer mediums, which are held in the holding section side by side, to be picked up in a parallel way at a time and supplying these transfer mediums to the image carrier; and an operating section for setting a number of transfer mediums to be supplied by the supplying device, wherein when an odd number is set, only one of the first and second supply sections of the supplying device is operated to allow a final transfer medium to be taken out.
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Number |
Name |
Date |
Kind |
5573234 |
Petocchi |
Nov 1996 |
A |
H21 |
Schieck |
Feb 1986 |
H |
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Number |
Date |
Country |
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Apr 1981 |
JP |
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Jan 1990 |
JP |