JP3950592B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to image forming apparatuses such as electrophotographic and electrostatic storage type copying machines and printers, and in particular, images formed by a plurality of juxtaposed image forming units are sequentially transferred and superimposed on an intermediate transfer member. The present invention relates to a color image forming apparatus for obtaining an image.
[0002]
[Prior art]
Conventionally, in an image forming apparatus adopting an electrophotographic method, a plurality of image carriers as image forming means are conventionally arranged in parallel, and a toner image that is a visible image of each color is generated and superimposed on an intermediate transfer member. In some cases, secondary transfer is performed collectively on a transfer material after primary transfer.
[0003]
In such an apparatus, since a plurality of image carriers are arranged side by side, the distance from the image formation start position to transfer onto the transfer material may be long. In this case, since it is necessary to perform image formation before feeding the transfer material, when performing continuous image formation, intermediate transfer is performed while feeding one transfer material from the feeding means. A plurality of images are formed on the body.
[0004]
Therefore, in the image forming apparatus having the transfer material detecting unit configured to detect the presence or absence of the next transfer material while the transfer material is being fed from the feeding unit, when it is determined that there is no transfer material, it is already in the middle. A toner image without a transfer material to be transferred is formed on the transfer body. In this case, the transfer roller for secondary transfer of the image from the intermediate transfer member to the transfer material is once separated, and the toner image on the intermediate transfer member is removed by the cleaning means.
[0005]
[Problems to be solved by the invention]
However, the processing of a toner image without a transfer material to be transferred as described above has a problem that the life of the toner cartridge, the life of the image carrier, and the life of the cleaning means are shortened.
[0006]
Therefore, the present invention confirms the presence of the transfer material when the remaining amount of the transfer material in the feeding unit is reduced in the image forming apparatus configured to form an image before feeding the transfer material. An object of the present invention is to provide an image forming apparatus that does not form a toner image when there is no transfer material by starting image formation from the beginning.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, an image forming apparatus according to the present invention includes a feeding unit that loads a transfer material, an image carrier that carries a latent image, and a developing that develops the latent image into a visible image. means, anda intermediate transfer member for carrying a visualized image on said image bearing member by said developing means, the image I by the be transferred to a transfer material the images on the intermediate transfer body In the image forming apparatus to be formed, presence / absence detecting means for detecting the presence / absence of the transfer material loaded in the feeding means, and the remaining amount of the transfer material loaded in the feeding means are detected at several levels. The minimum remaining number of transfer materials remaining on the feeding means when the remaining amount of the transfer material changes to the first level where the remaining amount of transfer material is lower than the second level. Calculating means, and the remaining amount of the transfer material is determined by the remaining amount detecting means. Until the level of 1 is detected, the interval between the images formed on the intermediate transfer member is set to the first interval, and image formation is started before the transfer material is fed from the feeding means. If the remaining amount of the transfer material by said remaining amount detecting means detects that it is now the first level, until the number of the transfer material in which image formation reaches the minimum number of stacked sheets, the spacing of the image Image formation is started before feeding the transfer material from the feeding means at the first interval, and after the number of image-formed transfer materials reaches the minimum number of stacked sheets, the interval between the images is set. The image forming is started after confirming that there is a transfer material in the feeding means by expanding to a second interval wider than the first interval .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
[ Reference example ]
First, a reference example of the image forming apparatus will be described with reference to the drawings. 1 is an overall configuration diagram of an image forming apparatus, FIG. 2 is a configuration diagram of a feeding unit, FIG. 3 is a diagram illustrating a state in which image formation is performed with a desired throughput, and FIG. 4 is a state in which an image forming interval is changed. FIG. 5 is a flowchart for forming the first image, FIG. 6 is a flowchart for forming the second and subsequent images, and FIG. 7 is the second and subsequent images according to the reference example . It is a flowchart in the case of performing formation.
[0009]
(overall structure)
First, the overall configuration of the image forming apparatus will be described with reference to FIG. This image forming apparatus is a color laser printer, which forms an electrostatic latent image with image light formed based on an image signal obtained by scanning an original in an image forming unit, and develops the electrostatic latent image to form a visible image. Then, the color visible image is formed by primary transfer in a superimposed manner, the color visible image is secondarily transferred to the transfer material S at once, and the color visible image on the transfer material S is fixed. It is something to be made.
[0010]
The image forming apparatus 1 includes a plurality of image forming units 2Y, 2M, 2C, and 2K. These image carriers 2 are configured by applying an organic photoconductive layer to the outer periphery of an aluminum cylinder, and are rotated in response to an image forming operation by transmitting a driving force of a driving motor (not shown).
[0011]
Each image carrier 2 is uniformly charged by injection chargers 3Y, 3M, 3C, and 3K sleeves 3YS, 3MS, 3CS, and 3KS, which are primary charging means, and selectively selected by scanner units 4Y, 4M, 4C, and 4K. By exposure, an electrostatic latent image is formed on the surface. The formed electrostatic latent image is developed with yellow, magenta, cyan, and black toner images by developing means 5Y, 5M, 5C, and 5K. Each developing means 5 has sleeves 5YS, 5MS, 5CS, and 5KS, and is configured to be detachable from the apparatus main body. Each developing means 5 is provided with toner cartridges 6Y, 6M, 6C, 6K filled with toner of each color, and supplies the toner to the developing means 5.
[0012]
The intermediate transfer member 7 is stretched around the driving rollers 8a to 8c, contacts each image carrier 2, and rotates with the rotation of the image carrier 2 when forming an image. Further, primary transfer rollers 9Y, 9M, 9C, and 9K are arranged inside the intermediate transfer body 7 and are urged to the image carrier 2, and the toner image is primarily transferred in a superimposed manner.
[0013]
Further, a secondary transfer roller 10 is provided below the intermediate transfer member 7, and the transferred transfer material S is nipped and conveyed with the intermediate transfer member 7, thereby superimposing the superimposed toner images in a secondary manner. Transcript. The secondary transfer roller 10 is brought into contact with the intermediate transfer member while the toner image is superimposed and transferred to the intermediate transfer member 7, but is separated to a position 10a indicated by a broken line at the end of the image forming process.
[0014]
The transfer material S is loaded on a feeding cassette 11 and a manual feed tray 12 which are feeding means described later, and is separated and fed one by one by a feeding roller 13. The fed transfer material passes through the pre-registration sensor 15 by the conveying roller pair 14, and after the skew is corrected by the registration roller pair 16, reaches the secondary transfer roller 10, and after the toner image is transferred, the fixing unit 17 Sent to.
[0015]
The fixing unit 17 fixes the transferred toner image while conveying the transfer material S, and includes a fixing roller 18 that heats the transfer material S and a pressure roller that presses the transfer material S against the fixing roller 18. 19 and. The fixing roller 18 and the pressure roller 19 are formed in a hollow shape, and have heaters 20 and 21 built therein, respectively. That is, the transfer material S holding the toner image is conveyed by the fixing roller 18 and the pressure roller 19 and is fixed by applying heat and pressure. Thereafter, the transfer material S on which the toner image is fixed is discharged to a discharge portion (not shown) by a discharge roller (not shown), and the image forming operation is finished.
[0016]
The intermediate transfer member 7 is provided with a cleaning means 22 for removing the toner remaining on the image carrier 2 and the intermediate transfer member 7 after the secondary transfer. The removed waste toner is stored in the cleaner container 22a.
[0017]
(Feeding means)
The feeding cassette 11 which is a feeding means is provided with a lever 23 which is a remaining amount detecting means and a presence detecting means. The lever 23 is rotatable about a shaft 24, has a paper surface detection portion 23a that contacts the paper surface of the transfer material S at the tip, and a detection flag portion 23b at the other end. The detection flag portion 23b is provided with a plurality of flags 25a, 25b, and 25c, and a plurality of photo interrupters 26a, 26b, and 26c are provided correspondingly.
[0018]
These photo-interrupters 26 are configured to detect the flag 25 when the lever 23 rotates, but the degree of rotation of the lever 23 by arranging a plurality of flags 25 so as to be detected by changing the phase. It can be detected. Here, since the paper surface detection unit 23a at the tip of the lever 23 is in contact with the paper surface, the remaining amount of the transfer material loaded on the feeding cassette 11 can be detected from this configuration.
[0019]
For example, in FIG. 2, the remaining amount level 1 indicates that the remaining amount of the transfer material is the smallest. As the remaining amount level in the feeding cassette 11 increases to 2, 3, and 4, the paper surface detection unit 23a is 28a. , 28b, 28c, 28d. At this time, the detection flag portion rotates in the direction of arrow A, and the extent of the flag 25a, 25b, 25c can be known by crossing the photo interrupters 26a, 26b, 26c. Although the remaining amount detecting means configured as described above cannot detect the remaining amount in detail, the remaining amount of the transfer material in the feeding cassette 11 can be detected at several levels depending on the state of the photo interrupters 26a, 26b, and 26c. Is possible.
[0020]
Further, a hole 11b is provided in the bottom surface 11a of the feeding cassette 11, and the paper surface detecting portion 23a is arranged so as to enter the hole 11b without the transfer material so that the presence or absence of the transfer material can be detected. Yes. However, the presence / absence of the transfer material can be detected only after the last transfer material in the feeding cassette 11 has been fed and the trailing end has passed the paper surface detection unit 23a.
[0021]
(Operation)
In the case where image formation is continuously performed using the image forming apparatus having the above configuration, first image formation will be described with reference to FIGS. 3 and 5. Prior to image formation, it is determined whether or not there is a transfer material S1 in the feeding cassette 11 designated by the lever 23 as presence / absence detecting means (S1). If it is determined that there is no transfer material S1, the image forming operation is not started (S9).
[0022]
On the other hand, when it is determined that there is the transfer material S1, exposure is started, a toner image 28 is formed on the image carrier 2, and primary transfer is performed on the intermediate transfer member 7 (S2). After a predetermined time from the start of image formation (S3), feeding of the first transfer material S1 is started (S4). When the leading edge of the fed transfer material S1 reaches the registration roller pair 16 (S5), the feeding operation is temporarily interrupted (S6), and synchronized with the intermediate transfer member 7 carrying the toner image (S7). (S8), and the toner image is secondarily transferred to the transfer material S1.
[0023]
Next, the conventional second and subsequent image formation will be described with reference to FIG. Exposure is started after a predetermined image interval 29 after the first toner image is formed, and a toner image 28 is formed on the image carrier 2 and is primarily transferred onto the intermediate transfer member 7 (S10). At this time, since the rear end of the first transfer material S1 fed from the feeding cassette 11 is on the paper surface detection unit 23a, is the second transfer material S2 in the feeding means? It cannot be judged.
[0024]
Accordingly, the presence or absence of the second transfer material S2 is detected at the timing when the trailing edge of the first transfer material S1 passes through the paper surface detection unit 23a (S11), and if it is determined that there is the transfer material S2, image formation is performed. After a predetermined time from the start (S12), the feeding is started (S13), and then the toner image is transferred in the same manner as the first sheet (S14-17). If it is determined that there is no second transfer material S2, image formation for the second and subsequent sheets is stopped (S18), and after the transfer of the first sheet is completed, the secondary transfer roller 10 is not soiled. The intermediate transfer body 7 is rotated until the toner image 28 formed on the intermediate transfer body 7 and on the image carrier 2 is removed by the cleaning means 22 (S20).
[0025]
The second and subsequent image forming operations have an advantage that image formation can always be performed with a desired throughput. However, every time there is no transfer material S2 to be transferred in the feeding cassette 11, an extra toner image is formed on the intermediate transfer member 7, so that the life of the toner cartridge 6, the life of the image carrier 2, the cleaner container 22a There are problems that the service life is shortened and unnecessary contamination of the intermediate transfer member 7 is caused.
[0026]
Therefore, in the image formation for the second and subsequent sheets, when the remaining amount of the transfer material S2 in the feeding cassette 11 decreases, the image interval 30 (see FIG. 4) is widened and there is a transfer material S2 to be transferred. The image is formed after confirming the above.
[0027]
That is, as shown in FIGS. 4 and 7, first, the remaining amount of the transfer material S2 in the feeding cassette 11 is detected (S21). When the remaining amount level in the feeding cassette 11 is other than 1 (about the smallest remaining amount), it is determined that the transfer material S2 is sufficiently loaded in the feeding unit, and a desired throughput is realized. Exposure is started at an image interval 29, and a toner image is formed on the image carrier 2 and the intermediate transfer member 7 (S23). Then, after a predetermined time (S24) from the start of image formation, feeding of the second sheet is started (S25), and the feeding operation is temporarily stopped (S26, S27) by the registration roller pair 16, and then the intermediate transfer member. 7 (S28), re-feeding is started (S29).
[0028]
On the other hand, if it is determined that the remaining amount level of the transfer material S2 in the feeding cassette 11 is 1, it is determined that there is a possibility that there is no transfer material S2 to be transferred during the continuous operation, and the first transfer material Image formation is not performed until the trailing edge of S1 passes through the paper surface detection unit 23a and the presence or absence of the second transfer material S2 can be determined. Then, after it is determined that there is the transfer material S2 (S22), image formation is started (S23).
[0029]
With the above configuration, when there is a sufficient remaining amount of the transfer material S in the feeding cassette 11, an image interval 29 for realizing a desired throughput (that is, a certain toner image transferred to the intermediate transfer body 7). (The distance between the trailing edge of the toner and the leading edge of the next toner image). If the remaining amount is low, the image interval 30 is increased to reduce the throughput, and after confirming the presence or absence of the transfer material S, the image is formed. It can be carried out. Accordingly, it is possible to avoid the formation of an excessive toner image, and it is possible to extend the life of the toner cartridge 6, the image carrier 2, the cleaner container 22a, and the like.
[0030]
[ First embodiment]
Next, a first embodiment of image formation according to the present invention will be described with reference to the drawings. FIG. 8 is a flowchart in the case of forming the second and subsequent images according to the present embodiment, and the same reference numerals are given to the same parts as those in the reference example, and the description is omitted.
[0031]
In the above reference example , when it is determined that the remaining amount level of the transfer material S in the feeding cassette 11 is 1 during the image forming operation, the image interval 30 is widened and the presence or absence of the transfer material S is confirmed before image formation. Was to do.
[0032]
On the other hand, in this embodiment, when the transfer material in the feeding cassette 11 reaches the remaining amount level 1 based on the thickness information of the transfer material S in the feeding cassette 11, it is loaded in the feeding means at least. This is to calculate the minimum number of sheets that may have been used. When the remaining amount level changes from 2 to 1 during continuous image formation, image formation is performed with a desired throughput for the minimum number of sheets, and the image interval is increased for image forming operations exceeding the minimum number of sheets, After confirming that there is a transfer material, image formation is performed.
[0033]
This will be specifically described with reference to the flowchart shown in FIG. First, when starting image formation, the thickness Z of the transfer material S loaded on the feeding cassette 11 is acquired (S30). The information on the thickness Z may be instructed by a user from an operation panel or a computer (not shown), or a detection unit for detecting the thickness may be provided in the main body of the image forming apparatus.
[0034]
Next, the minimum number X of transfer materials when the remaining amount level changes from 2 to 1 is calculated (S31). For example, with the remaining amount detecting means shown in FIG. 2, it is possible to know the height of the sheet surface of the transfer material S loaded when the remaining amount level changes from 2 to 1. At this time, when the height of the paper surface from the cassette bottom surface 11a is Y,
Minimum loading number X = Y / Z
It becomes. Here, in consideration of the mechanical accuracy of the paper surface detection unit 23a, the number of transfer materials reliably stacked is calculated as the minimum stacking number X. Each time feeding is performed, the number of fed sheets is updated, and image formation can be executed with a desired throughput until the minimum number of stacked sheets X is reached.
[0035]
Specifically, when the remaining amount level in the feeding cassette 11 is detected at the start of image formation (S32), and it is determined that the remaining amount level is 2 or more (S35), the transfer material in the feeding cassette 11 is reliable. Therefore, image formation is executed with a desired throughput (S36). When image formation is continuously performed, the remaining amount level is detected at any time, and a desired throughput is continued while the remaining amount level is 2 or more (S37).
[0036]
When the remaining amount level in the feeding cassette 11 changes from 2 to 1 during continuous image formation, the minimum number of stacked sheets X is decremented by 1 (S38), and the number of stacked sheets in the feeding cassette 11 is updated. Thereafter, the minimum number of stacked sheets X is decremented by -1 for each image formation (S38). If the minimum number of stacked sheets X is 0 or more (S39), it is determined that the next transfer material remains in the feeding cassette 11, and the desired number Image formation is executed at throughput (S40) and continued (S41). If the number of stacked sheets is less than 0 (S39), it is determined that there is no possibility of the next transfer material in the feeding cassette 11, the image interval is widened to reduce the throughput, and the transfer material S is checked. Then, image formation is executed (S33) and continued (S34).
[0037]
If it is determined that the transfer material S in the feeding cassette 11 is at the remaining level 1 at the start of image formation (S32), the number of transfer materials loaded in the feeding means is less than the minimum number of loaded sheets. Therefore, the image formation is executed (S33) and continued (S34) while confirming the transfer material S by widening the image interval.
[0038]
By configuring as described above, even if the remaining amount level in the feeding unit is changed from 2 to 1 during continuous image formation, it is possible to achieve a desired throughput while avoiding the formation of an excessive toner image. Is possible.
[0039]
[ Second Embodiment]
Next, a second embodiment of the image forming apparatus according to the present invention will be described. FIG. 9 is a flowchart when image formation is performed for the second and subsequent sheets according to the present embodiment. The same reference numerals are given to the same parts as those in the reference example and the first embodiment, and the description is omitted. To do.
[0040]
In the first embodiment, the configuration has been described in which a desired throughput is achieved even when the remaining amount level in the feeding cassette 11 is changed from 2 to 1 during continuous image formation. In contrast, the image forming apparatus according to the present embodiment realizes a desired throughput as much as possible even when the remaining amount level is 1 at the start of image formation.
[0041]
This will be specifically described with reference to the flowchart shown in FIG. First, the remaining amount level of the feeding cassette 11 is detected at the start of image formation (S35), and if it is determined that the remaining amount level is 2 or more, the processing described in the first embodiment is performed (S36). If the power level has not been turned off after the remaining level has changed from 2 to 1 (S37), and the feeding cassette 11 has not been removed (S38), it is determined that the number of sheets loaded in the feeding means is valid. can do. Therefore, when the number of stacked sheets is 0 or more (S40), the minimum number of stacked sheets is set to -1 (S41), and then image formation is executed with a desired throughput (S42) and continued (S43).
[0042]
On the other hand, when the power is turned off after the remaining amount level becomes 1, or when the feeding means is removed after the remaining amount level becomes 1, it is determined that the transfer material S may have increased or decreased, The throughput is reduced by invalidating the number of stacked sheets up to that time, and image formation is executed (S44) and continued (S45) while checking the presence or absence of the transfer material.
[0043]
By configuring as described above, a desired throughput can be realized even when the remaining amount level in the feeding cassette 11 is 1 from the start of image formation.
[0045]
【The invention's effect】
As explained above, in the image forming apparatus according to the present invention, detects that the remaining amount of the transfer material reaches the first level by the remaining amount detecting means for detection known the remaining amount of the transfer material in the feeding means In this case, until the number of image-formed transfer materials reaches the minimum number of stacked sheets, the image interval is set to the first interval, and image formation is started before the transfer material is fed from the feeding unit. After the number of transfer materials reaches the minimum number of stacked sheets, the interval between the images is expanded to a second interval wider than the first interval, and it is confirmed that there is a transfer material in the feeding means. By configuring so as to start the formation, it is possible to avoid the formation of an excess toner image even after the level of the remaining amount of the transfer material in the feeding unit has changed and the remaining amount of the transfer material has decreased. Can be achieved .
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an image forming apparatus.
FIG. 2 is a configuration diagram of a feeding unit.
FIG. 3 is a diagram illustrating a state in which image formation is performed with a desired throughput.
FIG. 4 is a diagram illustrating a state in which an interval for forming an image is changed.
FIG. 5 is a flowchart for forming the first image.
FIG. 6 is a flowchart when performing conventional image formation for the second and subsequent sheets.
FIG. 7 is a flowchart when performing image formation on the second and subsequent sheets according to a reference example .
FIG. 8 is a flowchart in the case of performing image formation for the second and subsequent sheets according to the first embodiment.
FIG. 9 is a flowchart in the case of performing image formation for the second and subsequent sheets according to the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS S ... Transfer material 1 ... Image forming apparatus 2 ... Image carrier 3 ... Injection charger 4 ... Scanner part 5 ... Developing means 6 ... Toner cartridge 7 ... Intermediate transfer body 8 ... Drive roller 9 ... Primary transfer roller
10 ... Secondary transfer roller
11… Feed cassette
11a ... Bottom
11b ... hole
12… Bypass tray
13 ... Feed roller
14… Conveying roller pair
15… Sensor before registration
16… Registration roller pair
17… Fixing part
18… Fixing roller
19… Pressure roller
20… Heater
21… Heater
22… Cleaning means
22a ... cleaner container
23… Lever
23a: Paper surface detection unit
23b Detection flag part
24… axis
25… flag
26… Photo interrupter
28 ... Toner image
29… Image spacing
30… Image interval

Claims (4)

A feeding unit for loading a transfer material ; an image carrier for carrying a latent image; a developing unit for developing the latent image to make a visible image; and an image visualized on the image carrier by the developing unit in the image forming apparatus having an intermediate transfer member, and forms an image I by the be transferred to a transfer material the images on the intermediate transfer member for carrying a
Presence / absence detecting means for detecting the presence / absence of a transfer material loaded in the feeding means;
A remaining amount detecting means for detecting the remaining amount of the transfer material loaded in the feeding means at several levels ;
Means for calculating a minimum number of sheets of transfer material remaining in the feeding means when the remaining amount of transfer material is changed to a first level where the remaining amount of transfer material is lower than a second level; Have
Until the remaining amount of the transfer material is detected to be at the first level by the remaining amount detecting means, the interval between the images formed on the intermediate transfer member is set to the first interval, and the feeding is performed. Start image formation before feeding the transfer material from the means,
If the remaining amount of the transfer material by said remaining amount detecting means detects that it is now the first level, until the number of the transfer material in which image formation reaches the minimum number of stacked sheets, the spacing of the image Image formation is started before the transfer material is fed from the feeding means at the first interval, and after the number of image-formed transfer materials reaches the minimum stacking number, the image interval is set to the first interval. An image forming apparatus, wherein the image forming apparatus starts the image formation after confirming that there is a transfer material in the feeding unit, expanding to a second interval wider than the first interval . The image forming apparatus according to claim 1, wherein a capable of forming a color image having a plurality of said image bearing member and said developing means. 3. The image forming apparatus according to claim 1, wherein the remaining amount detecting unit also serves as the presence / absence detecting unit. The power supply of the image forming apparatus is turned off after the remaining amount detecting means detects that the remaining amount of the transfer material has reached the first level, or the feeding means is removed from the image forming apparatus. 2. The image forming apparatus according to claim 1, wherein after the removal, the image interval is expanded to the second interval, and image formation is started after confirming that there is a transfer material in the feeding unit. The image forming apparatus according to any one of 1 to 3.

Images