JP5216675B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus capable of forming an image by mixing a color image and a monochrome image.

  In recent image forming apparatuses, yellow, magenta, cyan, and black photoconductors are provided, toner images of the respective colors are formed on the photoconductors of the respective colors, and the formed toner images are transferred onto a transfer belt. Some employ a tandem method for forming an image.

  In an image forming apparatus employing such a tandem method, when an image is formed, a yellow, magenta, or cyan photoconductor, that is, a color photoconductor, and a transfer belt are brought into contact with each other as necessary. Or in a separated state. The black photosensitive member and the transfer belt are always in contact with each other.

  FIG. 8 is a view showing a part of the color photoconductor 101 and the transfer belt 102. Referring to FIG. 8, the image forming apparatus moves the color photoconductor 101 in the direction of arrow VIII in FIG. 8 or the opposite direction, thereby moving the color photoconductor 101 and the surface 103 of the transfer belt 102. Abut or separate.

  Specifically, the image forming apparatus moves the color photoconductor 101 in the direction of the arrow VIII to contact the surface 103 of the transfer belt 102. In this case, the image forming apparatus forms a color image by forming a toner image on each color photoconductor 101 or forms a toner image only on a black photoconductor (not shown). To form a monochrome image. On the other hand, the image forming apparatus moves the photosensitive member 101 away from the surface 103 of the transfer belt 102 by moving it in the direction opposite to the direction of the arrow VIII in FIG. In this case, the image forming apparatus forms a monochrome image by forming a toner image on a black photoconductor.

  That is, when forming a monochrome image, the color photoconductor 101 and the transfer belt 102 are in contact with each other, or the color photoconductor 101 and the transfer belt 102 are separated from each other. And exist.

  In addition, in order to bring the color photoconductor 101 and the surface 103 of the transfer belt 102 into contact with or separate from each other, it is necessary to interrupt the operation for image formation, and thus a predetermined time is required.

  An image forming apparatus capable of bringing a color photoconductor and a transfer belt into contact with each other or separating them from each other is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-167238 (Patent Document 1). Is disclosed.

  According to Patent Document 1, in the first embodiment, when more than a certain number of monochrome images are formed, the color photoconductor and the surface of the transfer belt are separated from each other. When the number of copies is less than a certain number, the contact state is maintained without being separated from the surface of the transfer belt. That is, the number of copies that have already been imaged is adopted as the threshold value for determining whether to separate or abut.

  In the second embodiment, the time required for forming a monochrome image is measured, and when the measured time exceeds a predetermined time, the color photoconductor and the surface of the transfer belt Separate them. When the time is shorter than a predetermined time, the contact state is maintained without being separated from the surface of the transfer belt. That is, the time during which an image has already been formed is used as a threshold value for determining whether to separate or abut.

  In the third embodiment, for a document set to form an image, it is determined in advance whether the document is a color document or a monochrome document before image formation, and the copy order and copy of each document are determined. Know the number of sheets. When continuously forming monochrome images, the color photoconductor and the surface of the transfer belt are separated from each other. When monochrome images are not formed continuously, they are brought into contact with each other without being separated from the surface of the transfer belt.

JP-A-11-167238

  However, in the first and second embodiments of the image forming apparatus disclosed in Patent Document 1, since the number of copies and the time in which image formation has already been performed are adopted as the threshold value for determining whether to separate or contact, the image will be used from now on. Even if the number of copies and the time to be formed are small, if they are separated, it takes time to separate them, and the time required for one job to finish image formation after starting image formation becomes longer. There is a fear.

  Also in the third embodiment, only when monochrome images are continuously formed, the color photoconductor and the surface of the transfer belt are separated from each other. There is a risk that the time required for this will become longer.

  An object of the present invention is to provide an image forming apparatus capable of efficiently forming an image.

The image forming apparatus according to the present invention includes a first photosensitive member capable of forming a color image, a second photosensitive member capable of forming a monochrome image, and an image formed on the first and second photosensitive members. And a transfer body to be transferred. The image forming apparatus includes a separating unit that separates and contacts the first photosensitive member and the surface of the transfer member, a receiving unit that receives a request for image formation so as to form an image based on a plurality of documents, and a receiving unit. The monochrome image formation time calculation means for calculating the monochrome image formation time required for forming the monochrome image based on the image formation request received by the apparatus, and the first photosensitive member and the transfer body are separated by the separation / contact means. A separation time calculation unit that calculates a separation time required for the image forming process, and a monochrome image formation time calculated by the monochrome image formation time calculation unit when forming a monochrome image based on an image formation request received by the reception unit. In accordance with the separation time calculated by the separation time calculation means, the first photosensitive member and the transfer member are separated from each other or brought into contact with each other by the separation means. E Bei and control means for controlling whether the state, the control means, or the ratio of the separation time for the monochrome image formation time, depending on whether larger or not than a predetermined threshold value, so as to be brought into spaced, those Control whether to make contact .

  As another embodiment, the image forming apparatus includes a first speed at which an image is formed in a state where the first photosensitive member and the transfer member are separated from each other by the separation / contact unit, and a transfer from the first photosensitive member to the first photosensitive member by the separation / contact unit. A switching time for calculating a switching time required to switch between the first speed and the second speed, the second speed being different from the first speed for image formation in a state where the body is in contact with the body And a control unit that determines whether the switching time calculated by the switching time calculation unit is longer than the separation time, and according to the determination result, the first contact member and the transfer member are separated by the separation unit. Are set in a separated state or in a contact state.

As yet another embodiment, the monochrome image formation time calculating means is configured to form a first monochrome image formation time required to form a monochrome image at the first speed and to form a monochrome image at the second speed. A second monochrome image formation time required for the first monochrome image formation time, and a control means includes a difference time calculation means for calculating a difference time between the first monochrome image formation time and the second monochrome image formation time, and the difference time Depending on the difference time calculated by the calculation means and the longer switching time and separation time , the first photoconductor and the transfer body are separated or contacted by the separation means. To control.

  As described above, the image forming apparatus calculates the monochrome image formation time required for forming a monochrome image and the separation time required for separation. Then, when the monochrome image is formed, it is controlled whether the separated state or the abutted state is set according to the calculated result. As a result, it is possible to form an image by determining whether to separate or contact in consideration of the processing time required for image formation such as the separation time. As a result, an image can be formed efficiently.

1 is a block diagram illustrating a configuration of a digital multifunction peripheral when an image forming apparatus according to an embodiment of the present invention is applied to the digital multifunction peripheral. It is a figure which shows an example of an image formation part. FIG. 3 is a diagram illustrating a part of a first photoconductor and a transfer belt. 10 is a flowchart illustrating a case where a color image and a monochrome image are mixed to form an image. FIG. 5 is a diagram showing a time and a flow required for each operation in the image forming operation shown in the flowchart of FIG. 4. FIG. 5 is another embodiment of the flowchart shown in FIG. 4 and is a flowchart showing a case where a color image and a monochrome image are mixed to form an image. FIG. 7 is a diagram showing a time and a flow required for each operation in the image forming operation shown in the flowchart of FIG. 6. FIG. 3 is a diagram illustrating a part of a color photoconductor and a transfer belt.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a digital multifunction peripheral 10 when an image forming apparatus according to an embodiment of the present invention is applied to the digital multifunction peripheral 10. Referring to FIG. 1, the digital multifunction peripheral 10 displays a control unit 11 that controls the entire digital multifunction peripheral 10, a DRAM 12 for writing and reading image data and the like, and information that the digital multifunction peripheral 10 has. An operation unit 13 that includes a display screen and serves as an interface with the user in the digital multifunction peripheral 10, a document feeder 14 that automatically transports a document to a predetermined document reading position, and a document that has been transported by the document feeder 14 An image reading unit 15 that reads the image at a predetermined reading position with a scanner, an image forming unit 16 that forms the image from a document read by the image reading unit 15, a hard disk 17 that stores image data and the like, and a public A FAX communication unit 18 connected to the line 20 and a network IF ( And a centers face) unit 19.

  The control unit 11 compresses and writes the original data supplied from the image reading unit 15 in the DRAM 12, reads the data written in the DRAM 12, decompresses and decodes the data, and outputs it by the image forming unit 16.

  The digital multifunction machine 10 operates as a copying machine by forming an image in the image forming unit 16 via the DRAM 12 using the document read by the image reading unit 15. Further, the digital multifunction peripheral 10 forms an image in the image forming unit 16 via the DRAM 12 using the image data transmitted from the personal computer 22 connected to the network 21 through the network IF unit 19, thereby serving as a printer. Operate. Further, the digital multifunction peripheral 10 forms an image in the image forming unit 16 through the DRAM 12 using the image data transmitted from the public line 20 through the FAX communication unit 18, and also by the image reading unit 15. The image data of the read original is transmitted to the public line 20 through the FAX communication unit 18 to operate as a facsimile machine. That is, the digital multi-function peripheral 10 has a plurality of functions such as a copying (copying) function, a printer function, and a FAX function regarding image processing. Further, each function has functions that can be set in more detail.

  In FIG. 1, thick arrows indicate the flow of image data, and thin arrows indicate the flow of control signals or control data.

  FIG. 2 is a diagram illustrating an example of the image forming unit 16. Referring to FIG. 2, the image forming unit 16 includes yellow, magenta, and cyan photoconductors 30 a to 30 c as a first photoconductor 28, a black photoconductor 30 d as a second photoconductor 29, and each color. And a transfer belt 34 as a transfer body to which toner images of respective colors formed on the photoconductors 30a to 30d are transferred. Note that the rotation direction of the transfer belt 34 is indicated by a dotted arrow in FIG.

  When forming an image, the image forming unit 16 brings the first photosensitive member 28 and the transfer belt 34 into contact with each other or separates them as necessary. The second photoconductor 29 and the transfer belt 34 are always in contact with each other.

  FIG. 3 is a view showing a part of the first photoconductor 28 and the transfer belt 34. Referring to FIG. 3, the image forming unit 16 moves the first photosensitive member 28 and the transfer belt 34 by moving the first photosensitive member 28 in the direction of arrow III in FIG. The surface 34a is brought into contact with or separated from the surface 34a.

  Specifically, the image forming unit 16 moves the first photoconductor 28 in the direction of the arrow III to contact the surface 34 a of the transfer belt 34. In this case, the image forming unit 16 forms a color image by forming a toner image on the first photoconductor 28, or forms a toner image only on the second photoconductor 29. A monochrome image is formed. On the other hand, the image forming unit 16 moves the first photosensitive member 28 in the direction opposite to the direction of the arrow III in FIG. 3 so as to be separated from the surface 34 a of the transfer belt 34. In this case, the image forming unit 16 forms a monochrome image by forming a toner image on the second photoconductor 29. Here, the image forming unit 16 operates as a contact / separation unit.

  That is, when forming a monochrome image, the first photoconductor 28 and the transfer belt 34 are in contact with each other, and the first photoconductor 28 and the transfer belt 34 are separated from each other. There is a case to do. Note that the color image is formed only when the first photoconductor 28 and the transfer belt 34 are in contact with each other.

  In addition, in order to bring the first photoconductor 28 and the surface 34a of the transfer belt 34 into contact with or away from each other, it is necessary to interrupt the operation for image formation, and therefore, a predetermined time, for example, 1 second is required.

  Further, the image forming unit 16 brings the first photosensitive member 28 and the transfer belt 34 into contact with each other at the first speed at which the first photosensitive member 28 and the transfer belt 34 are separated from each other. And a second speed of image formation as a state.

  Here, a case will be described in which the digital multifunction peripheral 10 is used to form an image by mixing a color image and a monochrome image. In this embodiment, the first speed and the second speed are the same speed. Specifically, the time required to form one image in the state where the first photosensitive member 28 and the transfer belt 34, which are the first speed, are separated from each other is 3 seconds, and the first speed, which is the second speed. The time required for forming one image with the photosensitive member 28 and the transfer belt 34 in contact with each other is 3 seconds. FIG. 4 is a flowchart illustrating a case where an image is formed by mixing a color image and a monochrome image. FIG. 5 is a diagram showing the time and flow required for each operation in the image forming operation shown in the flowchart of FIG. This will be described with reference to FIGS.

  First, the digital multi-function peripheral 10 sets a plurality of documents on the document feeder 14 and accepts an image formation request to form an image based on the plurality of documents (step S11 in FIG. 4; the following steps are omitted). To do). Here, the control unit 11 operates as an accepting unit. Then, the document is fed to a predetermined document reading position by the document feeder 14 and sequentially read by the image reading unit 15 (S12). At this time, as shown in FIG. 5, the digital multi-function peripheral 10 forms images in order of three color images “a”, one monochrome image “b”, and three color images “c”, as shown in FIG. Then recognize.

  Then, after the color image a is formed, the control unit 11 needs to separate the first photosensitive member 28 and the transfer belt 34 as the time required to form the monochrome image b in a separated state. The separation time is calculated (S13). For example, time C is assumed. Specifically, it is 1 second. Here, the control unit 11 operates as a separation time calculation unit.

  Further, the control unit 11 calculates a monochrome image formation time required for forming the monochrome image b (S14). For example, time B is assumed. Specifically, 1 sheet × 3 seconds = 3 seconds. Here, the control unit 11 operates as a monochrome image formation time calculation unit.

  Then, when forming the monochrome image b, the control unit 11 determines whether the first photoconductor 28 and the transfer belt 34 are separated according to the calculated monochrome image formation time and separation time. To control the contact state.

  Specifically, the ratio of the separation time to the monochrome image formation time is calculated, and it is determined whether or not the calculated ratio is larger than a predetermined threshold value (S15). That is, it is determined whether B / C is larger than a predetermined threshold value. The monochrome image formation time is 3 seconds, and the separation time is 1 second. Therefore, the ratio of the separation time to the monochrome image formation time is 3/1 = 3. The predetermined threshold is 5 here. This predetermined threshold is a value that is appropriately determined according to the performance of the digital multifunction peripheral 10 or the convenience of the user. Then, since 3 <5, it is determined that the ratio of the separation time to the monochrome image formation time is smaller than the predetermined threshold (YES in S15).

  Then, the control unit 11 can determine that the monochrome image formation time is not sufficiently longer than the separation time, and the first photoreceptor 28 and the transfer belt 34 are formed when the monochrome image b is formed. Are separated from each other, it is determined that the processing efficiency of one job shown in FIG. That is, the predetermined threshold is a threshold for determining processing efficiency.

  Then, the control unit 11 performs image formation according to the calculated monochrome image formation time and separation time. That is, control is performed so that the monochrome image b is formed with the first photoconductor 28 and the transfer belt 34 in contact with each other (S16). Here, the control unit 11 operates as control means.

  Then, according to the order, the digital multifunction peripheral 10 first forms three color images a in a state where the first photosensitive member 28 and the transfer belt 34 are in contact with each other. Next, the digital multi-function peripheral 10 forms a single monochrome image b in a state where the first photoconductor 28 and the transfer belt 34 are in contact with each other. Finally, the digital multi-function peripheral 10 forms three color images c in a state where the first photoconductor 28 and the transfer belt 34 are in contact with each other.

  As described above, the digital multi-function peripheral 10 calculates the monochrome image formation time required for forming a monochrome image and the separation time required for separation. Then, when the monochrome image is formed, it is controlled whether the separated state or the abutted state is set according to the calculated result. As a result, it is possible to form an image by determining whether to separate or contact in consideration of the processing time required for image formation such as the separation time. As a result, an image can be formed efficiently.

  If it is determined in S15 that the ratio of the separation time to the monochrome image formation time is greater than the predetermined threshold (NO in S15), the control unit 11 determines that the monochrome image formation time is less than the separation time. It can be determined that the image is sufficiently long, and the processing efficiency of one job is relatively good even when the first photosensitive member 28 and the transfer belt 34 are separated from each other when the monochrome image b is formed. Judge. Then, control is performed so that the monochrome image b is formed with the first photosensitive member 28 and the transfer belt 34 separated (S17).

  Next, as another embodiment, a case where the first speed and the second speed are different, specifically, a case where the first speed is higher than the second speed will be described. Specifically, the time required to form one image in the state where the first photosensitive member 28 and the transfer belt 34, which are the first speed, are separated from each other is 2 seconds, and the first speed, which is the second speed. The time required for forming one image with the photosensitive member 28 and the transfer belt 34 in contact with each other is 3 seconds. FIG. 6 is a flowchart showing another embodiment of the flowchart shown in FIG. 4, in which a color image and a monochrome image are mixed to form an image. FIG. 7 is a diagram showing the time and flow required for each operation in the image forming operation shown in the flowchart of FIG. This will be described with reference to FIGS.

  First, as in S11 to S12 of FIG. 4, the digital multi-function peripheral 10 sequentially forms images of three color images a, one monochrome image b, and three color images c as shown in FIG. recognize.

  Then, after the color image a is formed, the control unit 11 switches the separation time, the first speed, and the second speed as the time required to form the monochrome image b in a separated state. The switching time required for is calculated. As shown in FIG. 7, the separation time and the switching time can be performed simultaneously after the color image a is formed. Therefore, the longer time is adopted as the time required for forming the monochrome image b in a state where the color image a is separated after the color image a is formed.

  Specifically, first, a separation time required to separate the first photosensitive member 28 and the transfer belt 34 is calculated (S41). For example, time C is assumed. Specifically, it is 1 second.

  Further, the control unit 11 calculates a switching time required for switching between the first speed and the second speed (S42). Here, the control unit 11 operates as a switching time calculation unit. For example, time D is assumed. Specifically, it is 5 seconds.

  Then, the control unit 11 determines whether or not the switching time is longer than the separation time (S43). The switching time is 5 seconds and the separation time is 1 second. Therefore, it is determined that the switching time is longer than the separation time (YES in S43), and control is performed to adopt the switching time (S44).

  The switching time is a time that is delayed in the processing time of one job by switching between the first speed and the second speed when the monochrome image b is formed.

  In addition, the control unit 11 performs the first monochrome image formation time required for forming the monochrome image b at the first speed at which the first photoreceptor 28 and the transfer belt 34 are separated from each other. Is calculated (S45). For example, time F is assumed. Specifically, 1 sheet × 2 seconds = 2 seconds.

  Further, the control unit 11 forms the second monochrome image required for forming the monochrome image b at the second speed for forming the image with the first photoconductor 28 and the transfer belt 34 in contact with each other. Time is calculated (S46). For example, time E is assumed. Specifically, 1 sheet × 3 seconds = 3 seconds.

  Then, the control unit 11 calculates a difference time between the first monochrome image formation time and the second monochrome image formation time (S47). That is, from FE, the difference time is 2 seconds-3 seconds = -1 second. Here, the control unit 11 operates as a difference time calculation unit.

  This difference time is a time that can be shortened in the processing time of one job by switching between the first speed and the second speed when the monochrome image b is formed.

  And the control part 11 judges whether switching time is larger than difference time (S48). That is, when the monochrome image b is formed, it is determined whether or not the time delayed by switching is larger than the time that can be shortened by switching. Here, the switching time is two times for one job, when the monochrome image b is formed from the color image a and when the color image c is formed from the monochrome image b. Therefore, 2 × D, specifically, 2 times × 5 seconds = 10 seconds. The difference time is -1 second. Thereby, since switching time−difference time, that is, 10 − (− 1)> 0 from 2D− (FE), it is determined that the switching time is larger than the difference time (YES in S48).

  Then, the control unit 11 determines that the time delayed by switching is larger than the time that can be shortened by switching, and the first photoconductor 28 is switched by switching the speed when forming the monochrome image b. If the transfer belt 34 and the transfer belt 34 are separated from each other, it is determined that the processing time of one job becomes long and the efficiency of image formation is deteriorated.

  Then, the control unit 11 performs image formation according to the calculated monochrome image formation time and switching time. That is, control is performed so that the monochrome image b is formed with the first photoconductor 28 and the transfer belt 34 in contact with each other (S49).

  Then, according to the order, the digital multifunction peripheral 10 first forms three color images a in a state where the first photosensitive member 28 and the transfer belt 34 are in contact with each other. Next, the digital multi-function peripheral 10 forms a single monochrome image b in a state where the first photoconductor 28 and the transfer belt 34 are in contact with each other. Finally, the digital multi-function peripheral 10 forms three color images c in a state where the first photoconductor 28 and the transfer belt 34 are in contact with each other.

  As described above, even when the first speed and the second speed are different, the digital multi-function peripheral 10 can efficiently form an image in consideration of the processing time required for image formation accompanying different speeds. It can be controlled as possible.

  If it is determined in S48 that the switching time is smaller than the difference time (NO in S48), the control unit 11 recovers the time delayed by switching so that it can be shortened by switching. Therefore, even when the first photosensitive member 28 and the transfer belt 34 are separated from each other when forming the monochrome image b, the processing time for one job is not increased, and the efficiency of image formation is improved. Judged to be relatively good. Then, the first photoconductor 28 and the transfer belt 34 are separated from each other, and control is performed so as to form the monochrome image b (S50).

  If it is determined in S43 that the switching time is shorter than the separation time (NO in S43), control is performed to adopt the separation time (S51), and in S48, whether or not the separation time is greater than the difference time. Determine whether.

  In the above embodiment shown in FIG. 4, the example in which the predetermined threshold value is 5 has been described. However, the present invention is not limited to this, and the threshold value may be changed according to the monochrome image formation time or the like. It may be possible to change according to the circumstances. Thereby, an image can be efficiently formed according to the convenience of the user.

  In the above-described embodiment illustrated in FIG. 6, the example in which it is determined whether or not the switching time−the difference time is greater than 0 in the determination of whether or not the switching time is greater than the difference time has been described. For example, it may be determined whether the switching time-difference time is larger than another predetermined value according to the convenience of the user.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  DESCRIPTION OF SYMBOLS 10 Digital multifunction device, 11 Control part, 12 DRAM, 13 Operation part, 14 Document feeder, 15 Image reading part, 16 Image formation part, 17 Hard disk, 18 FAX communication part, 19 Network IF part, 20 Public line, 21 Network , 22 personal computer, 28 first photoconductor, 29 second photoconductor, 30a, 30b, 30c, 30d photoconductor, 34 transfer belt, 34a surface.

Claims (3)

A first photosensitive member capable of forming a color image; a second photosensitive member capable of forming a monochrome image; and a transfer member onto which an image formed on the first and second photosensitive members is transferred. An image forming apparatus,
Separation means for separating and abutting the first photosensitive member and the surface of the transfer member;
Accepting means for accepting an image formation request to form an image based on a plurality of originals;
Monochrome image formation time calculating means for calculating a monochrome image formation time required for forming a monochrome image based on the image formation request received by the reception means;
A separation time calculating means for calculating a separation time required for separating the first photosensitive member and the transfer member by the separation means;
The monochrome image formation time calculated by the monochrome image formation time calculation unit when forming a monochrome image based on the image formation request received by the reception unit;
According to the separation time calculated by the separation time calculation unit, whether the first photosensitive member and the transfer member are separated or contacted by the separation unit. for example Bei and control means for controlling,
The control means controls whether the separated state or the contacted state is set depending on whether the ratio of the separated time to the monochrome image forming time is larger than a predetermined threshold value . Image forming apparatus. The image forming apparatus includes: a first speed at which an image is formed in a state where the first photosensitive member and the transfer member are separated by the separation / contact unit; and the first photosensitive member and the first unit by the separation / contact unit. A second speed different from the first speed for forming an image in a state where the transfer body is in contact with the transfer body;
A switching time calculating means for calculating a switching time required for switching between the first speed and the second speed;
The control means determines whether or not the switching time calculated by the switching time calculation means is longer than the separation time, and according to the determination result, the separation and contact means and the first photoconductor and the first photoreceptor. The image forming apparatus according to claim 1 , wherein the image forming apparatus controls whether the transfer body is in a separated state or a contact state. The monochrome image formation time calculation means is a first monochrome image formation time required for forming a monochrome image at the first speed and a second required for forming a monochrome image at the second speed. The monochrome image formation time of
The control means includes difference time calculation means for calculating a difference time between the first monochrome image formation time and the second monochrome image formation time, and the difference time calculated by the difference time calculation means Whether the first photosensitive member and the transfer member are separated from each other or brought into contact with each other by the separation / contact means according to the switching time and the longer separation time. The image forming apparatus according to claim 2 , wherein the image forming apparatus is controlled.

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