JP2001154558A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more accelerate a printing speed in an image forming device provided with the image forming pars of an electrophotographic system and an ink-jet system. SOLUTION: This device is provided with the image forming part A for forming images by the electrophotographic system, the image forming part B for forming the images by the ink-jet system and a paper feed part C for housing and feeding paper sheets. A guide plate 20 for guiding the paper sheet carried by the carrying roller pair 13 of the image forming part B to the resist roller pair 8 of the image forming part A is turnably constituted. After a paper sheet tip reaches a nip part in a stop state, a guide plate 20 is opened and the slack part of the paper sheet is sent out to the outside of the guide plate 20. After the slack of a length capable of absorbing a linear velocity difference is formed, a timing is presumed and the resist roller pair 8 carries the paper sheet to a transfer roller 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which is applied to a copying machine, a facsimile machine, a printer and the like and has a function of forming an image by an electrophotographic system and an ink jet system.

[0002]

2. Description of the Related Art In a recording method, black and white recording is performed at a speed,
Generally, an electrophotographic method is used depending on image quality and the like. However, in color recording, cost, image quality,
The majority of the market uses the inkjet method depending on the size and the like. Therefore, it is conceivable to incorporate both recording methods into one unit and simultaneously perform black-and-white and color recording so as to take advantage of both.

As a conventional technique of this kind, there is a technique described in Japanese Patent Application Laid-Open No. 7-295344. This publication describes an image forming apparatus in which a black-and-white toner image is formed by an electrophotographic image forming unit on the upstream side and a color ink image is formed by an image forming unit of an ink jet system on the downstream side.

[0004]

However, in the apparatus described in Japanese Patent Application Laid-Open No. 7-295344, an image forming means of an ink jet system is arranged downstream of a fixing unit. There is a possibility that the ink of the means is fixed or the nozzle is clogged, thereby deteriorating the image quality. In addition, by providing an inkjet type image forming unit and an electrophotographic type image forming unit in one paper transport path, it is possible to reduce the size of the apparatus main body. In this case, the linear velocity of the recording paper is reduced. It is necessary to match the slower linear speed, that is, the linear speed of the image forming means of the ink jet system, and the printing speed which is an advantage of the electrophotographic system is reduced.

In other words, when the linear velocity of the paper in the image forming means of the ink jet system is V1 and the linear velocity of the image forming means in the electrophotographic system is V2, the printing apparatus per minute in the ink jet system in the current equipment is used. Number is about 6 pages, the number of printed pages per minute in the electrophotographic system is about 15 pages, and V1
<V2. For this reason, when recording is performed in a mixture of black and white and color, and especially when color printing is performed by the ink jet method and black and white printing is performed by the electrophotographic method, the linear velocity is adjusted to V1.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus having a function of forming an image by an electrophotographic system and an ink jet system, wherein the printing speed is further improved.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a paper feeding section for feeding paper, a developing means for forming a toner image, a transfer means for transferring a toner image to paper, and a paper feeding section. An electrophotographic recording unit having a registration roller for transporting the recording medium to the transfer unit in a timely manner; and an ink ejection type recording unit having an ink ejection unit for ejecting ink onto a sheet. In the image forming apparatus in which the ink discharge type recording unit is arranged between the registration rollers, an opening of a sheet conveyance path is formed between a conveyance roller that conveys a sheet to the registration rollers and the registration rollers. And With this configuration, the sheet can be formed to have a slack in the open portion, so that the difference in the linear speed can be absorbed by the slack, and the linear speed in the ink discharge type recording unit can be reduced by the electrophotographic recording. The linear velocity in the section is not affected.

Further, the present invention is characterized in that a slack is formed on the sheet at the opening. With this configuration, the transport path from the transport roller to the registration roller can be lengthened.

Further, according to the present invention, after the linear velocity of the registration roller is made higher than the linear velocity of the transport roller and a slack is formed on the sheet until the linear velocity difference between the two rollers can be absorbed,
The registration roller is rotated. With this configuration, the paper does not remain on the transport roller when the registration roller is rotated and the paper no longer sags.

Further, the present invention is characterized in that a guide plate for guiding a sheet from the transport roller to the registration roller is rotatable, and the guide plate is rotated to form the opening. With this configuration,
By rotating the guide plate, an open portion can be formed, and the slack can be easily formed on the sheet.

Further, the present invention is characterized in that the guide plate is kept closed until the paper is guided from the transport roller to the registration roller, and the guide plate is rotated after the leading edge of the paper reaches the registration roller to open the opening portion. Is formed. With this configuration, by rotating the guide plate after sandwiching the sheet in the nip portion of the registration roller, it is possible to prevent the sheet from moving and the leading end of the sheet from separating from the nip portion of the registration roller.

The present invention further comprises means for detecting the black / white / color ratio of the recorded information. Based on the detection result of the means, image recording only by the electrophotographic recording unit, and image recording only by the ink discharge type recording unit. Determine the best image recording method in image recording or image recording using both recording parts together,
It is characterized by switching to at least one of the electrophotographic recording unit and the ink discharge recording unit. With this configuration, when the recording information is black and white only, the image recording is performed only by the electrophotographic recording unit, and when the color ratio is high, the image recording is performed only by the ink discharge type recording unit. If this is the case, by setting image recording using both recording units in combination, an optimal recording method can be set according to the recording information, and the printing speed can be improved.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an explanatory view showing the internal configuration of the apparatus according to the first embodiment of the present invention, wherein A is an image forming unit using an electrophotographic system, B is an image forming unit using an ink jet system, and C is a paper feeding unit. 1, the image forming apparatus according to the present embodiment can be roughly classified into three parts: an image forming part A, an image forming part B, and a paper feeding part C.

First, the configuration of the image forming section A will be described. In FIG. 1, 1 is a photoconductor, 2 is a charging roller, 3 is a writing unit, 4 is a developing roller, 5 is a transfer roller,
Reference numeral 6 denotes a cleaning blade, and 7 denotes a fixing device. The fixing device 7 includes a heat roller 7a and a pressure roller 7b that comes into contact with the heat roller 7a. Reference numeral 8 denotes a pair of registration rollers, and 9 denotes a pair of discharge rollers. On the surface of the photoreceptor 1, a charging roller 2, a developing roller 4,
The transfer roller 5 and the cleaning blade 6 are disposed so as to abut sequentially.

The photosensitive member 1 is charged by the charging roller 2,
The writing unit 3 irradiates the area corresponding to the image area with light, and the potential of the illuminated portion drops to near 0 V, whereby an electrostatic latent image is formed on the surface of the photoconductor 1. next,
When the photoconductor 1 rotates and the electrostatic latent image passes through the developing roller 4, toner adheres to the electrostatic latent image to form a visible image (toner image), and this toner image is transferred to the next transfer roller 5. Is transferred to the sheet sent from the pair of registration rollers 8. Here, the transfer residual toner remaining on the photoconductor 1 is scraped off by the cleaning blade 6. Further, the paper on which the toner image has been transferred is pressed /
By being heated, the toner image is fixed on the paper,
The sheet is ejected outside by the sheet ejection roller pair 9. The above is the image forming process by the image forming unit A. In the following, image recording by the image forming unit A is referred to as electrophotographic recording.

Next, the black and white or color inkjet type image forming section B will be described. In FIG.
Reference numeral 10 denotes a first ink jet recording unit (hereinafter referred to as a 1st I
J unit), 11 is a second ink jet recording unit (hereinafter, referred to as a second IJ unit) arranged at a position facing the first IJ unit 10, and 12 is a sheet conveying paper to the IJ units 10 and 11 at regular intervals. The pair of transport rollers 13 is a pair of transport rollers for transporting the sheet passing through the IJ units 10 and 11 to the pair of registration rollers 8. Hereinafter, the image recording by the image forming unit B is referred to as IJ recording.

The pair of conveying rollers 12 to the pair of registration rollers 8
In between, a guide plate 20 that contacts the lower surface of the sheet and guides the sheet to the pair of registration rollers 8 is provided. A rotation shaft (not shown) is provided at an end of the guide plate 20 on the side of the registration roller pair 8, and is installed in the apparatus main body so as to be rotatable about the rotation shaft. A transmission mechanism driven by a solenoid (not shown) is attached to the end on the side of the conveying roller pair 13 via a spring. When the power to the solenoid is turned on, the guide plate 20 rotates to open the opening 20a. The guide plate 20 is closed by turning it off, and functions as a paper guide. In addition, even when the guide plate 20 is pressed by the action of the spring even in the closed state, the opening 20a can be formed.

Then, the first IJ unit 10 can perform image recording on the upper surface of the sheet conveyed by the conveying roller pair 12, and the second IJ unit 11 can perform image recording on the lower surface. The paper IJ-recorded by at least one of the first IJ unit 10 and the second IJ unit 11 passes through the transport roller pair 13, the guide plate 20, and the registration roller pair 8, and further passes through the transfer roller 5 and the fixing device 7. As a result, the electrophotographic recording is performed, and the image is discharged to the outside by the discharge roller pair 9.

Next, the sheet feeding section C will be described. In FIG. 1, reference numeral 14 denotes a paper feed cassette which is detachably provided at a lower portion of the apparatus main body, and stores paper. Reference numeral 15 denotes a paper feed roller for feeding out sheets of the paper feed cassette 14 one by one. A pair of transport rollers for transporting the fed paper to the pair of transport rollers 12, 17 is a manual paper feed tray attached to a side portion of the apparatus main body, and 18 is a manual paper feed tray 1.
7 illustrates a sheet feeding roller that feeds the sheets placed on the sheet 7 one by one to the transport roller pair 12 side.

The paper in the paper feed cassette 14 or the manual paper feed tray 17 first passes through the image forming section B, and further passes through the image forming section A and is sent to the outside.

Next, the image recording operation will be described.

When a start signal is sent from an external device (not shown) to the image forming apparatus, the sheet feeding roller 15 is operated, and the sheet is sent out from the sheet feeding cassette 14 and the conveying roller pair 1
It is sent further in 6. Then, the sheet is once advanced at the nip portion of the pair of conveying rollers 12 and then advanced by the pair of conveying rollers 12, and an image is formed on the sheet surface by at least one of the IJ unit 10 and the IJ unit 11. At this time, the paper feed speed is controlled in conjunction with the movement of the IJ units 10 and 11. Similar control is performed on the transport roller pair 13.

The leading end of the sheet that has passed through the transport roller pair 13 reaches a nip portion of the registration roller pair 8 after being detected just before the registration roller pair 8 by a sensor (not shown). When the leading edge of the sheet reaches the registration roller pair 8 and is nipped by the nip portion, the guide plate 20
Is opened.

Here, the registration roller pair 8 is temporarily stopped until the sheet is sent to the transfer roller 5, while the IJ recording is performed at the linear velocity V1, and the sheet is slackened. The portion moves out of the paper transport path to the open portion 20. Here, since the leading end of the sheet is held by being sandwiched by the pair of registration rollers 8, the leading end of the sheet does not separate from the pair of registration rollers 8 due to the weight of the sheet.

When a certain amount of time has passed since the guide plate 20 was opened and the slack became large, the guide plate 2
Close 0. At this time, since the guide plate 20 is pressed by the slack portion of the sheet, the open state of the guide plate 20 is maintained. After the IJ recording of a certain portion until the slack that can absorb the linear velocity difference on the paper is completed, the timing is adjusted so that the leading edge of the toner image on the photoconductor 1 of the image forming unit A and the leading edge of the paper coincide. The paper is sent out at a linear velocity V2 by rotating the registration roller pair 8 by the guessed amount. At this time, the slack of the sheet is reduced, and the guide plate 20 is gradually rotated in the closing direction by the pressing of the spring.

With this configuration, the image forming unit B of the ink jet system is provided between the paper cassette 14 or the manual paper feed tray 17 and the image forming unit A of the electrophotographic system. Since the sheet having heat in B is not conveyed, conventionally, the IJ unit 1
0 and 11 are prevented from being adversely affected. Further, when performing image recording on the same sheet using both the image forming unit A and the image forming unit B, it is possible to perform IJ recording at a linear velocity V1 and then perform electrophotographic recording at a linear velocity V2. Therefore, the printing speed can be improved as compared with the linear speed of only V1.

FIG. 2 is a flow chart showing the control of sheet transport in the apparatus according to the second embodiment of the present invention.

First, when a start signal is sent from an external device (not shown) to the image forming apparatus (YES in S1), image data is transferred from the external device and the image data is stored in the memory of the image forming apparatus ( S2).

Next, the ratio between black and white and color in the image data stored in the memory is detected (S3). If it is determined that the black and white information is 100% and only black and white information is included (S3). YES), only the electrophotographic recording is performed (S4).

When color information is included (NO in S3)
If the ratio of the color information is a constant value, for example, 80% or more (YES in S5), even if the color information is IJ-recorded and black-and-white electrophotography is recorded, most of the color information is governed by the linear velocity V1. The IJ recording is performed while the paper is being conveyed at the linear velocity V1 for both color and black and white (S6).

If the ratio of the color information is less than the predetermined ratio, for example, if it is less than 80% (NO in S5), first,
The image forming unit B is operated, and the image forming unit A is stopped.
In particular, the registration roller pair 8 is stopped (S7). Then, the sheet is conveyed while the color portion image is IJ-recorded on the sheet. When the leading end of the sheet reaches the nip portion of the registration roller pair 8, the guide plate 20 is opened (S8). Then, after the paper is slackened and the IJ recording of a certain portion until the slack that can absorb the linear velocity difference on the paper is completed, the registration roller pair 8 is rotated to feed the paper at the linear velocity V2 (S9). .

According to the second embodiment configured as described above, the recording method can be selected in accordance with the ratio between black and white and color in the image data, so that printing can be performed in an optimal recording method and the printing speed can be improved. it can.

In the above embodiment, the guide plate 20 is opened and closed by the solenoid. However, the present invention is not limited to this. The free end of the guide plate 20 is supported by a spring (not shown) having a small spring constant. Alternatively, the opening may be made by the weight of the sheet and the stress received from the slack portion of the sheet. Further, in the above-described embodiment, the sheet is slackened downward by rotating the guide plate 20 downward, but the invention is not limited thereto. For example, in the case where the guide plate between the transport roller pair 13 and the registration roller pair 8 is in an arc shape such that it is convex upward, and the sheet easily sags upward, the transport roller pair 1
The upper surface of the sheet between the pair 3 and the registration roller pair 8 may be opened to absorb the slack of the sheet upward. If it is more convenient to secure a space for absorbing the slack above, a means for lifting the paper is provided on the guide plate on the lower surface side so that the paper is slackened upward. May be configured.

After the leading edge of the sheet reaches the pair of registration rollers 8, the pair of registration rollers 8 is slightly rotated so that the leading edge of the sheet is completely held in the nip portion of the pair of registration rollers 8, and then the pair of registration rollers is moved. 8 may be stopped and the guide plate 20 may be opened. With such a configuration, when the guide plate 20 is opened, the sheet moves by its own weight, and the nip portion of the registration roller pair 8 is formed. The leading end of the sheet is completely prevented from separating from the sheet.

[0036]

According to the present invention configured as described above, when printing is performed by a plurality of printing methods having different linear velocities, when printing is performed from the previous printing method to the next printing method, paper is printed. Because it can cause sag,
The linear velocity difference can be absorbed, and a plurality of recording methods having different linear velocities can be simultaneously and smoothly operated. Further, it is possible to improve the printing speed as compared with the case of recording only with the ink discharge type recording section.

Further, by selecting a recording method according to the content of the image information to be recorded, printing can be performed at an optimum and fastest speed according to the image.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an internal configuration of an apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating sheet conveyance control of an apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 photoconductor 5 transfer roller 7 fixing device 8 registration roller pair 10 first inkjet unit (first IJ unit) 11 second inkjet unit (second IJ unit) 12, 13, 16 transport roller pair 14 paper cassette 15 paper feed roller 20 Guide plate 20a Open part

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuhiro Kawashima 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Akio Kutta 1-3-6 Nakamagome, Ota-ku, Tokyo Share Ricoh Co., Ltd. (72) Inventor Hideki Tanaka 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2C055 KK05 KK06 2H027 ED17 EE17 FA28 ZA07 ZA10 2H072 CB09 3F101 FB02 FE02 LA02 LB03 3F102 A06 BA02 BB02 DA08 EA03 FA04 FA08

Claims (6)

[Claims] 1. An electronic apparatus comprising: a sheet feeding unit for feeding a sheet; a developing unit for forming a toner image; a transfer unit for transferring the toner image to the sheet; and a registration roller for conveying the sheet to the transfer unit in a timely manner. An image forming apparatus comprising: a photographic recording unit; and an ink ejection type recording unit having an ink ejection unit for ejecting ink onto a sheet, wherein the ink ejection type recording unit is arranged between the paper feeding unit and the electrophotographic recording unit. An image forming apparatus, wherein an opening portion of a sheet conveyance path is formed between a conveyance roller for conveying a sheet to the registration roller and the registration roller. 2. The image forming apparatus according to claim 1, wherein a slack is formed on the sheet at the opening. 3. The method according to claim 1, wherein the linear speed of the registration roller is made higher than the linear speed of the transport roller, and the registration roller is rotated after forming a slack on the sheet until the difference in linear speed between the two rollers can be absorbed. The image forming apparatus according to claim 1, wherein: 4. The apparatus according to claim 1, wherein a guide plate for guiding a sheet from the transport roller to the registration roller is rotatable, and the guide plate is rotated to form the opening. Image forming apparatus. 5. A guide plate is closed until a sheet is guided from the transport roller to the registration roller;
5. The image forming apparatus according to claim 4, wherein the opening is formed by rotating the guide plate after the leading edge of the sheet reaches the registration roller. 6. A means for detecting a black-and-white / color ratio of recording information, and based on a detection result of the means, image recording only by the electrophotographic recording unit, image recording only by the ink discharge type recording unit, or 4. An image recording method according to claim 1, further comprising: determining an optimal image recording method among image recording using both recording units, and switching to at least one of the electrophotographic recording unit and the ink discharge recording unit. , 3,
6. The image forming apparatus according to 4 or 5.