JP5682287B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  Image forming apparatuses such as printers, copiers, and facsimiles that form images composed of a developer generally have a plate-like elastic cleaning material (such as an elastic blade) in contact with the surface after the transfer of a rotating photoreceptor. In this state, the developer remaining on the surface of the photoconductor after transfer of the developer image is scraped off and cleaned by the elastic cleaning material.

  In the image forming apparatus in which the elastic cleaning material is arranged, the tip of the elastic cleaning material is in contact with the surface of the rotating photoconductor, so that the frictional force between the surface of the photoconductor and the elastic cleaning material is Due to the increase in the noise, an abnormal sound (squeal) may be generated from the elastic cleaning material, or the tip of the elastic cleaning material may be turned up or easily worn out.

  On the other hand, in an image forming apparatus, a specific developer image (toner having a predetermined pattern on the surface of the photosensitive member is suppressed in order to suppress the occurrence of abnormal noise, turning, abrasion, and the like of the elastic cleaning material. Band, etc.), and the developer image is supplied to the contact surface of the elastic cleaning material with the surface of the photosensitive member without being transferred to the recording medium or intermediate transfer member, and the developer is supplied as a lubricant. There are many. However, even when such a specific developer image is formed to reach the contact portion of the elastic cleaning material with the surface of the photosensitive member, phenomena such as abnormal sound, turning over, and abrasion of the elastic cleaning material are still present. May occur.

  Conventionally, for example, the following is known as an image forming apparatus in which measures against such phenomena such as abnormal noise, turning, and abrasion of the elastic cleaning material are introduced.

  One has an image carrier, a plurality of developing devices, an intermediate transfer member, and a cleaning blade that contacts the image carrier and cleans residual toner remaining on the image carrier. In an image forming apparatus for transferring a color toner image onto a recording sheet to form an image, a toner consumption amount detecting means for detecting a toner consumption amount for each developing device and a developing device having a large toner consumption amount are placed on the image carrier. An image forming apparatus including a control unit that forms a toner image and performs a control mode for supplying the toner image to the cleaning blade without transferring the toner image to an intermediate transfer member (Patent Document 1). The toner consumption amount detecting means is exemplified to detect the toner consumption amount according to the printing rate for each developing device. Patent Document 1 shows that according to this image forming apparatus, it is possible to reliably prevent abnormal noise generated from the cleaning blade even in a state where the low printing rate is continuous.

  Also, a plurality of image forming portions that form developer images, a transport body that transports the medium to each image forming portion, a transfer portion that transfers each developer image to the medium, and a transport body are disposed in contact with each other. An image forming apparatus having a cleaning member, a status determining unit that determines the usage status of the developer in each image forming unit, an instruction unit that instructs supply of the developer to the conveyance body at a predetermined timing, and an instruction A designated unit that designates a specific image forming unit as a designated image forming unit from among the image forming units and a predetermined development on the designated designated image forming unit based on the judgment of the situation judging unit A transfer unit is an image forming apparatus configured to directly transfer a predetermined developer image formed to a conveyance body (Patent Document 2). In Patent Document 2, according to this image forming apparatus, the toner applied to the leading edge of the cleaning member decreases with the execution of the printing process, and the frictional force between the carrier and the blade member increases. It has also been shown that the blade member can be prevented from turning over or breaking.

JP 2006-126664 A JP 2009-205109 A

  The present invention appropriately forms a specific developer image corresponding to the amount of charge on the surface of the photoconductor without actually examining the surface state of the photoconductor (the presence or absence of electrostatic deposits, surface potential, etc.). The present invention also provides an image forming apparatus capable of reducing the occurrence of abnormal noise, turning, abrasion, and the like of a plate-like elastic cleaning material that comes into contact with the surface of the photosensitive member after transfer.

The image forming apparatus of the present invention (A1)
A rotating photoreceptor,
Charging means for charging the surface of the photoreceptor;
Image forming means for forming an image to be developed with a developer on the charged surface of the photoreceptor;
Transfer means for transferring the developer image formed on the surface of the photoreceptor to a recording material or an intermediate transfer body;
A plate-like elastic cleaning material that contacts the surface of the photoreceptor after the transfer and cleans the surface;
A power supply for supplying a charging voltage to the charging means;
A measuring unit for measuring a current value flowing from the power source to the charging unit or a voltage value generated between the power source and the charging unit when a charging voltage or current is supplied from the power source to the charging unit;
Correction means for correcting a specific developer image forming condition that is formed on the surface of the photosensitive member by the image forming means and is not transferred to the recording material or the intermediate transfer body according to the measurement result obtained from the measuring means. It has.

  In the image forming apparatus of the invention (A2), in the image forming apparatus of the invention A1, the charging unit supplies a DC voltage from the power source to charge the surface of the photoconductor, and the measuring unit includes the measuring unit. A voltage value generated between a power source and the charging unit is measured.

  In the image forming apparatus of the invention (A3), in the image forming apparatus of the invention A1, the charging unit supplies a voltage obtained by superimposing direct current and alternating current from the power source to charge the surface of the photoconductor, and The measuring means is configured to measure a current value flowing from the power source to the charging means.

  The image forming apparatus according to the present invention (A4) has a detecting means for detecting temperature and humidity in the internal space of the main body of the image forming apparatus in the image forming apparatus according to any one of the above inventions A1 to A3, and the correcting means The use environment is determined according to the detection result obtained from the detection means, and the specific developer image forming condition is set according to the determined use environment and the measurement result of the measurement means. .

  The image forming apparatus according to the present invention (A5) is the image forming apparatus according to any one of the aforementioned inventions A1 to A4, wherein the specific developer image formation condition is that the developer image of the photoconductor in the elastic cleaning material is The content includes an element that increases or decreases the amount of the developer that reaches and comes into contact with the surface.

  According to the image forming apparatus of the invention A1, the specific developer corresponding to the charge amount on the surface of the photoreceptor without actually examining the state of the surface of the photoreceptor, compared with the case where the configuration of the invention is not provided. Appropriate image formation can reduce the occurrence of abnormal noise, turning, wear, and other phenomena of the plate-like elastic cleaning material that contacts the surface after the transfer of the photoconductor.

  In the image forming apparatus of invention A2, the plate-like elastic cleaning material is more appropriately formed with a specific developer image corresponding to the charge amount on the surface of the photoconductor than in the case of not having the configuration of the invention. The occurrence of phenomena such as abnormal noise, turning over, and wear can be accurately reduced.

  In the image forming apparatus of the invention A3, a plate-like elastic cleaning material is more appropriately formed with a specific developer image corresponding to the charge amount on the surface of the photoconductor than in the case of not having the configuration of the invention. The occurrence of phenomena such as abnormal noise, turning over, and wear can be accurately reduced.

  In the image forming apparatus according to the invention A4, the specific developer image corresponding to the charge amount on the surface of the photoreceptor is more appropriately formed and the plate-like elastic cleaning is performed as compared with the case where the configuration of the invention is not provided. It is possible to more accurately reduce the occurrence of phenomena such as abnormal noise, turning, and wear of the material.

  In the image forming apparatus according to the invention A5, as compared with the case where the configuration of the invention is not provided, a specific developer image corresponding to the charge amount on the surface of the photoconductor is appropriately formed, and the abnormal sound of the elastic cleaning material, It is possible to appropriately reduce the occurrence of turning and wear.

1 is an explanatory diagram showing an overview of an image forming apparatus according to an embodiment. FIG. 2 is an explanatory diagram showing an enlarged image forming unit in the image forming apparatus of FIG. 1. FIG. 4A illustrates a toner band forming operation, FIG. 4A illustrates a state when one image forming apparatus is viewed from the front side, and FIG. 4B is an explanatory diagram conceptually illustrating a relationship among a photosensitive drum, an elastic blade, and a toner band. It is. FIG. 6 is an explanatory diagram showing a configuration relating to correction of toner band formation conditions. 7 is a flowchart showing a flow of a toner band forming condition correction operation. It is a chart of an example of the 1st look-up table which shows the combination of temperature and humidity, and use environment. (A) is a chart of an example of the 2nd look-up table which shows the combination of use environment and a voltage value, (b) is a chart of an example of the 2nd look-up table which shows the combination of a use environment and an electric current value. is there. It is a graph which shows the test result with the adhesion amount of the discharge product to the surface of a photoreceptor with respect to the increase rate of the voltage for charging.

  Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as “embodiments”) will be described with reference to the accompanying drawings.

[Embodiment 1]
FIG. 1 shows an outline of an image forming apparatus according to Embodiment 1, and FIG. 2 shows an image forming unit of the image forming apparatus.

  The image forming apparatus 1 according to the first embodiment is configured as a color printer, for example. The image forming apparatus 1 is developed based on input image information in an internal space of a housing 10 composed of a support member, an exterior cover, and the like by using an image recording method such as a known electrophotographic method or electrostatic recording method. A plurality of image forming apparatuses 2 that form toner images developed with toner (colored powder or the like) as an agent, and the toner images formed by the image forming apparatus 2 are finally recorded As an example, the intermediate transfer device 3 for transferring to the recording paper 9, the paper feeding device 4 for accommodating and transporting the required recording paper 9 to be supplied to the intermediate transfer device 3, and the intermediate transfer device 3 transfer the toner image. A fixing device 5 and the like for fixing the toner image through the recording sheet 9 is provided. 1 and 2 indicate the main conveyance path of the recording paper 9.

  The image forming device 2 includes four image forming devices (2Y, 2M) that can form four color toner images exclusively for yellow (Y), magenta (M), cyan (C), and black (black: K). , 2C, 2K). The four image forming devices 2 (Y, M, C, K) are arranged in a state of being arranged in series in the upper space of the housing 10. In addition, the image forming apparatuses 2 (Y, M, C, K) have a substantially common configuration as shown below.

  Each image forming device 2 (Y, M, C, K) includes a rotating photosensitive drum 21 as shown in FIG. 2 and the like, and the following devices are mainly disposed around the photosensitive drum 21. Is arranged. The main devices are a charging device 22 for charging the image holding surface (surface portion holding the toner image) of the photosensitive drum 21 to a required potential, and image information (signal) on the charged image holding surface of the photosensitive drum 21. The exposure device 23 that forms an electrostatic latent image having a potential difference (for each color) by irradiating light based on the image, and developing the electrostatic latent image with the corresponding color (Y, M, C, K) toner. A developing device 24 (Y, M, C, K) that forms a visible toner image, a primary transfer device 25 that transfers the toner image to the intermediate transfer device 3 (the intermediate transfer belt 31 thereof), and the transfer end A drum cleaning device 26 that scrapes off and removes adhering matter such as toner remaining on the image holding surface of the subsequent photosensitive drum 12.

  The photosensitive drum 21 is formed by forming an image holding surface having a photoconductive layer (photosensitive layer) made of an organic photosensitive material on the peripheral surface of a cylindrical or columnar conductive substrate to be grounded, not shown. It receives power from the rotary drive device and rotates in the direction indicated by the arrow. The charging device 22 is a contact type charging device that is disposed in contact with the image holding surface of the photosensitive drum 21 and includes a contact member such as a charging roll to which a charging voltage is supplied. The charging roll has a structure in which an elastic body layer having a required volume resistivity is formed on a conductive rotating shaft, and is supported so as to rotate following the rotation of the photosensitive drum 21. When the developing device 24 performs reversal development, a voltage having the same polarity as the charging polarity of the toner supplied from the developing device is supplied as the charging voltage. In the first embodiment, a DC voltage is applied as the charging voltage.

  The exposure device 23 charges the light (LBy, LBm, LBc, LBk) output based on the image signal of each color component obtained by processing the image information input to the image forming device 1 with the image processing device 15. Then, the image holding surface of each photosensitive drum 21 is irradiated and exposed to form an electrostatic latent image of each color component. As the exposure device 22, a scanning type device using optical components such as a semiconductor laser and a polygon mirror is used. In addition, for example, a light emitting diode and an optical component are used. A non-scanning exposure apparatus may be used. The image processing apparatus 15 performs necessary image processing on image information input from an image reading apparatus connected to the image forming apparatus 1, an external connection device (information terminal), a storage medium reading apparatus, and the like, and an exposure apparatus 23. To generate an image signal to be transmitted.

  The developing device 24 includes a developer container that stores a developer (for example, a two-component developer including a non-magnetic toner and a magnetic carrier), and rotates the developer stored in the developer container. A developing roll 26 that is held and transported to the developing region that is close to and faces the photosensitive drum 21, a stirring and transporting member 27 that transports the developer contained therein to the developing roll 26 while rotating and stirring, and a developing roll 26 has a layer thickness regulating member that regulates the amount (layer thickness) of the developer held by H.26. Further, the developing device 24 is supplied with a developing voltage composed of a direct current in which an alternating current is superimposed on the developing roll 26, and the developing roll 26 and the agitation transport member 27 are rotated in a required direction. The toner of the developer is agitated by the agitating / conveying member 27 in the developer container and rubs against the carrier to be frictionally charged to a required polarity (negative polarity in the first embodiment).

  The primary transfer device 25 is a contact-type transfer device including a primary transfer roll that rotates in contact with the image holding surface of the photosensitive drum 21 and is supplied with a primary transfer voltage. In the primary transfer device 25, a DC voltage (DC voltage having a polarity opposite to the toner charging polarity) is supplied to the primary transfer roll 25 as a voltage for primary transfer. The drum cleaning device 26 includes an elastic blade 26a that contacts at least an image holding surface area in the axial direction of the photosensitive drum 21, a recovery device 26b that recovers deposits such as toner scraped off by the elastic blade 26a, and the like. . The elastic blade 26a is formed by molding an elastic material such as rubber into a plate shape, and makes contact at a required pressure in a state where a tip portion thereof is inclined to an image holding surface (surface) region in the axial direction of the photosensitive drum 21. It is attached as follows.

  As shown in FIGS. 1 and 2, the intermediate transfer device 3 is positioned below the image forming devices 2 (Y, M, C, K) arranged in series in the upper space of the housing 10. It is arranged to exist. The intermediate transfer device 3 includes an intermediate transfer belt 31 that rotates in a direction indicated by an arrow while passing a primary transfer position between a photosensitive drum 21 and a primary transfer device 25 (primary transfer roll), and an intermediate transfer belt 31. A plurality of support rolls 32 to 34 that are held in a desired state from the inner surface and are rotatably supported, and a secondary transfer roll that rotates in contact with the intermediate transfer belt 31 supported by the support roll 34 with a predetermined pressure. 35 and a belt cleaning device 36 that removes toner and the like remaining on the intermediate transfer belt 31 after passing through the secondary transfer roll 35.

  The intermediate transfer belt 31 is formed, for example, into an endless belt having a predetermined thickness and volume resistivity using a material in which a resistance adjusting agent such as carbon is dispersed in a synthetic resin such as polyimide resin or polyamide resin. Is used. The support roll 32 is configured as a drive roll, and the support roll 33 is configured as a tension applying roll. The support roll 34 is supplied with a secondary transfer voltage composed of a direct current having the same polarity as the charging polarity of the toner through a power supply member (not shown) at a required time. The secondary transfer voltage may be supplied to the secondary transfer roll 35 with a DC component having a polarity opposite to the charging polarity of the toner.

  The paper feeding device 4 is disposed so as to exist at a position below the intermediate transfer device 3 in the lower space area of the housing 10. The paper feeding device 4 is attached so that it can be pulled out to the front side (side surface that a user faces for operation) of the housing 10 and loaded with recording paper 9 of a desired size and type. The paper container 41 is mainly configured by a state, and a feeding device 42 that feeds the recording paper 9 from the paper container 41 one by one. In this embodiment, three box-like ones whose upper surfaces are opened are used as the sheet containers 41, and recording sheets 9 of different sizes and types are distributed and accommodated in each sheet container 41. A required recording sheet 9 can be selected and sent out from the stored sheet container 41. The paper feeding device 4 may use a different housing from the housing 10 in which the image forming device 2, the intermediate transfer device 3, and the like are arranged.

  The fixing device 5 is disposed in a space between one side of the secondary transfer device 3 and the paper feeding device 4 (uppermost paper container 41). The fixing device 5 rotates inside the casing 51 in a direction indicated by an arrow and is heated by a heating unit 52 such as a roll type or a belt type that is heated by heating means so that the surface temperature is maintained at a predetermined temperature. In addition, a pressurizing rotator 53 such as a roll type or a belt type that is driven and rotated in contact with a predetermined pressure in a state substantially along the axial direction of the heating rotator 52 is provided. Between the secondary transfer position 3 and the fixing device 5, a belt-type paper transport device 55 that transports the recording paper 9 to the fixing device 5 after the secondary transfer is disposed.

  The housing 10 is installed between the feeding device 42 in each paper container 41 of the paper feeding device 4 and the secondary transfer position of the image forming device 2 in a state of approaching one side surface of the housing 10. Are provided with a plurality of transport roll pairs 45a, 45b, 45c, 45d, 45e,... The transport roll pair 45e is configured as a feed roll pair having functions such as adjusting the transport timing and transport state of the recording paper 9. The recording paper 9 sent out from each paper container 41 of the paper feeding device 4 passes between the intermediate transfer belt 31 of the intermediate transfer device 3 and the secondary transfer roll 35 via a paper feeding path 45 for paper feeding. To the secondary transfer position.

  Further, the housing 10 is provided with a paper discharge port 12 on the side surface near the fixing device 5, and the recording paper 9 after the image is formed is discharged and stored through the paper discharge port 12. The discharge container 13 is attached in a state of protruding outward. Further, between the fixing device 5 of the housing 10 and the discharge container 13 (paper discharge port 12), a discharge paper transport path 57 constituted by a pair of paper transport rollers 56a and 56b, a transport guide material, and the like is provided. Has been

  Reference numeral 16 in FIG. 2 is a control device that controls the operation of the operating device of the image forming apparatus 1. The control device 16 includes an arithmetic processing device, a storage element, an input / output device, an external storage device, and the like, and through the input / output device, various detection means for detecting a situation necessary for an operation such as image formation. It is connected to input detection information and the like, and connected to a device to be controlled (its control unit) to transmit necessary control information. That is, when the information that triggers the start of the control operation is input, the control device 16 transmits necessary control information and the like based on various control programs and data stored in the storage element and The operation is controlled.

Incidentally, the image forming apparatus 1 is configured to execute a control operation (so-called process control) for adjusting the image forming conditions by the control device 16 at a required time. In this process control, necessary operating conditions and the like in the image forming apparatus 2 are adjusted in order to correct fluctuations in image density, image displacement, and the like.

  Basic image formation by the image forming apparatus 1 is performed as follows. Here, a case where a full color image formed by combining toner images of four colors (Y, M, C, K) is first described as an example.

  When there is an instruction to request image formation (printing), in each of the four image forming devices 2 (Y, M, C, K), each photosensitive drum 21 rotates in the direction of the arrow, and each charging device 22 corresponds to each photosensitive drum. The image holding surface 21 is charged to a required polarity (for example, negative polarity in the first embodiment) and a potential. The exposure device 23 performs exposure (light LBy) based on the image signal that is separated into color components (Y, M, C, K) by the image processing device 15 and transmitted to the charged image holding surface of the photosensitive drum 21. , LBm, LBc, and LBk) to form an electrostatic latent image of each color component composed of a predetermined potential difference.

  Subsequently, each developing device 24 (Y, M, C, K) is charged to a predetermined polarity (minus polarity) with respect to the electrostatic latent image of each color component formed on the image holding surface of the photosensitive drum 21. The toner of each color (Y, M, C, K) is supplied by the developing roll 26 and developed by electrostatically adhering the toner by a developing electric field formed between the developing roll 26 and the photosensitive drum 21. . Thereby, the electrostatic latent image of each color component on the photosensitive drum 21 is visualized as a toner image of a color corresponding to the color component.

  Subsequently, at each primary transfer position of each image forming device 2 (Y, M, C, K), each color toner image formed on the photosensitive drum 21 is intermediately transferred by a transfer electric field formed by the primary transfer device 25. The primary transfer is performed on the intermediate transfer belt 31 of the apparatus 3 in order and superimposed. In the intermediate transfer device 3, the toner image primarily transferred to the intermediate transfer belt 31 is transferred from the paper supply device 4 to the paper feed conveyance path 45 by a transfer electric field formed by the secondary transfer roll 35 at the secondary transfer position. Secondary transfer is performed collectively on the recording paper 9 conveyed via the transfer.

  After the secondary transfer is completed, the recording paper 9 is peeled off from the intermediate transfer belt 31 and then transported by the transport device 55 and introduced into the fixing device 5. The fixing device 5 melts the toner forming the toner image by passing the contact portion between the heating roll 52 and the pressurizing rotator 53 through the contact portion between the heating roll 52 and the pressurizing rotating body 53 to melt the toner forming the toner image. To settle. The recording paper 9 after the fixing is completed is discharged to the outside of the housing 10 through the paper transport path 57 for discharge and is discharged to the discharge container 13 when only image formation on one side is performed. Be contained.

  As described above, a full color image formed by combining four color toner images is formed on one side of one recording sheet 9.

  When a single color image (for example, a black image) composed of a single color toner image is formed, the black image forming device 2K among the four image forming devices 2 (Y, M, C, K) is used. A black toner image is formed on the photosensitive drum 21. Subsequently, similarly to the full-color image forming operation, the toner image on the photosensitive drum 21 is secondarily transferred to the recording paper 9 via the intermediate transfer device 3 and then fixed by the fixing device 5, and finally the recording paper after fixing. 9 is discharged and stored in the discharge container 13. As a result, a black image (so-called black and white image) composed of a black toner image is formed on one side of one sheet of recording paper 9.

  Further, as shown in FIG. 3, the image forming apparatus 1 performs an intermediate transfer onto the surface of the photosensitive drum 21 in each image forming apparatus 2 (Y, M, C, K) as one of the control operations by the control apparatus 16. An operation for forming a toner band (specific toner image) TB that is not transferred to the belt 31 is executed.

  As illustrated in FIG. 3B, the toner band TB is a band having a constant width w over the entire area (image formable area E) of the image holding surface in the rotation axis direction (direction indicated by the arrow B) of the photosensitive drum 21. It is a toner image having a shape (elongated rectangle). The width w of the toner band TB corresponds to the length along the rotation (circumferential) direction of the photosensitive drum 21. Further, the toner band TB is formed with a constant density (image area ratio, etc.). Further, the toner band TB is, as a general rule, between the area (image formation allocation area) where an image for one side of the recording paper is formed during image formation in the rotation direction of the photosensitive drum 21 and the next image formation allocation area. It is formed in a part (so-called inter-image part). The image pattern information of the toner band TB is stored in the storage unit of the image processing device 15. The time when the operation of forming the toner band TB is executed is, for example, the time when the number of images to be formed (number of prints) reaches a preset specified number.

  The toner band TB is formed by executing substantially the same operation as a general image forming operation except that no transfer voltage is supplied to the primary transfer device 25.

  That is, first, the image holding surface of the photosensitive drum 21 is charged by the charging device 22, and the electrostatic latent image is formed on the charged image carrying surface by exposure for the toner band TB from the exposure device 23. The electrostatic latent image is developed by the developing device 24, whereby a toner band TB as a toner image is formed on the photosensitive drum 21. Subsequently, the toner band TB is conveyed along with the rotation of the photosensitive drum 21, and finally conveyed so as to reach the elastic blade 26 a of the drum cleaning device 26. At this time, the toner band TB passes through the position transfer position facing the primary transfer device 25 via the intermediate transfer belt 31. At this time, no transfer voltage is supplied to the primary transfer device 25. Therefore, the toner constituting the toner band TB is not transferred to the intermediate transfer belt 31. The toner band TB that has passed through the position transfer position in this manner reaches the elastic blade 26a of the drum cleaning device 26 (the tip portion that contacts the image holding surface of the photosensitive drum 21).

Toner band TB, when it reaches the elastic blade 26a of the drum cleaning device 26, a part of the toner constituting the band TB is scraped off, while the remainder of the toner Tc is of the elastic blade 26a and the photosensitive drum 21 It stays (see Fig. 3a). This staying toner Tc (toner particles and their external additives, etc.) acts like a lubricant and reduces the frictional force between the elastic blade 26a of the drum cleaning device 26 and the image holding surface of the photosensitive drum 21. As a result, it is difficult to generate a harsh abnormal sound from the elastic blade 26a, or a phenomenon that the tip of the elastic blade 26a is turned over or easily worn.

However, even when the toner band TB forming operation is executed as described above, phenomena such as abnormal noise, turning up, and abrasion of the elastic blade 26a may occur remarkably. The inventors of the present application have made extensive studies on this point. As a result, it has been found that the charge amount (charge application amount) of the photosensitive drum 21 may increase, and the above phenomenon tends to occur correspondingly. The case where the charge amount of the photosensitive drum 21 increases is, for example, a direction in which the value of the charging voltage of the charging device 22 is increased (photosensitive) when a control operation for adjusting the image forming conditions ( the process control described above ) is performed. it may be adjusted in the direction) to raise the charged potential on the image holding surface of the drum 21, as a result, it may charge the photosensitive drum 21 is charged by the charging device 22 increases.

  FIG. 8 shows the results of a test for examining the relationship between the magnitude of charging by the charging device 22 and the amount of discharge products (for example, ammonium) adhering to the image holding surface of the photosensitive drum 21. In the test, two types of photosensitive drums 21 composed of photosensitive layer materials A and B were charged while the charging voltage was forcibly increased from the initial value at a predetermined rate (increase rate with respect to the initial value). In addition, the amount of discharge product adhering to the surface (image holding surface) of each photosensitive drum 21 is measured. The measurement of the amount of discharge product attached was sampled by dissolving ammonium (ion), one of the discharge products attached to the surface of the photosensitive drum, in water soaked in a wiping material (nonwoven fabric, etc.) It was performed by diluting it with pure water and measuring its ion concentration.

  As is apparent from the test results, when the charging voltage is gradually increased from the initial value and the charging of the photosensitive drum 21 by the charging device 22 is strengthened, the adhesion amount of the discharge product tends to increase. Also, in this test, it was confirmed that when the amount of discharge product increased, the frictional force between the elastic blade 26a and the image holding surface of the photosensitive drum 21 increased, and the above phenomenon was likely to occur. . When the charging voltage supplied to the charging device 22 is increased, the charge amount (charge application amount) of the image holding surface of the photosensitive drum 21 is increased.

Therefore, in this image forming apparatus 1, as shown in FIGS. 4 and 5, a charging voltage (implementation) is performed from the power supply device 17 to each charging device 22 in each image forming device 2 (Y, M, C, K). In the first embodiment, as described above, the measuring device 18 (Y, M, C, K) for measuring the voltage value Vdc generated between the power supply device 17 and the charging device 22 when the DC voltage is supplied, respectively. A detection sensor 19 for detecting the temperature t and humidity h inside the housing 10 is arranged, and the measurement result obtained from the measuring device 18 (Y, M, C, K) and the detection information obtained from the detection sensor 19 Accordingly, a means (control device 16 in the first embodiment) for correcting the formation condition of the toner band TB described above is provided.

The measuring device 18 (Y, M, C, K) is composed of a voltmeter that can measure the voltage value Vdc flowing from the power supply device 17 to each charging device 22. Each measuring device 18 (Y, M, C, K) has a charging voltage at the time of charging for forming an image on one side of one recording sheet 9 when an image forming operation (printing operation) is executed. Each time is applied, the voltage value Vdc is measured. Each voltage value Vdc measured by each measuring device 18 (Y, M, C, K) is individually accumulated and stored in a storage element (such as a RAM) of the control device 16. The power supply device 17 at this time supplies a DC voltage as a charging voltage under a constant current control method. Further, such a measuring device 18 does not need to be independent from the power supply device 17 and may be incorporated as a part of the power supply device 17.

  The detection sensor 19 is installed around the position where the photosensitive drum 21 is installed (for example, around the photosensitive drum 21 of the image forming device 2K as shown in FIG. 2) in the housing 10. The temperature t and humidity h detected by the detection sensor 19 are accumulated and stored in the storage element of the control device 16 as one detection result every time an image is formed on one side of one recording sheet 9. . Humidity h is detected as relative humidity.

  As for the formation conditions of the toner band TB, as shown in FIGS. 6 and 7A, a first lookup table (for selecting a use environment corresponding to the temperature t and the humidity h detected by the detection sensor 19). LUT1) and a second look-up table (LUT2) for selecting the toner band formation conditions corresponding to each use environment and voltage value Vdc are prepared, and the controller 16 detects the temperature t and the humidity h. The formation conditions of the toner band TB are set by referring to two look-up tables from the result and the measurement result of the voltage value Vdc. Both the detection result of the temperature t and the humidity h and the measurement result of the voltage value Vdc use an average value calculated by averaging each value between a predetermined number of image forming sheets (number of printed sheets). In particular, it is considered that the charge amount on the image holding surface of the photosensitive drum 21 increases as the measurement result (average value) of the voltage value Vdc increases.

Environments A to C indicating the use environment in the first look-up table are, for example, environment A is “high temperature and high humidity environment”, environment B is “room temperature and humidity environment”, and environment C is “low temperature and low humidity environment”. Show. Further, “band amounts L, M, H ” and “no band” indicating the formation conditions of the toner band TB in the second lookup table of FIG. 7A correspond to the amount of toner constituting the toner band TB. It is a magnitude relationship of L <M <H . “No band” indicates a case where the band amount is zero (that is, when the toner band TB is not formed). The formation conditions of the toner band TB are set such that the band amount increases as the voltage value increases regardless of the use environment.

The specific means for realizing the band amounts L, M, H and no band is that the toner band TB reaches the contact portion of the elastic blade 26a with the surface of the photosensitive drum 21 and the amount of toner supplied (toner supply amount). What is necessary is just to be comprised with the content in which the element which increases / decreases is included. For example, the toner supply amount per toner band TB may be increased or decreased. In this case, the width w, length (dimension along the rotational axis direction B of the photosensitive drum 21), density, and other factors of the toner band TB Increase or decrease one or more of these. At this time, in order to increase the toner supply amount, the width w of the toner band TB is widened, the length is lengthened, and the density is increased. The conditions at this time are stored, for example, in a storage unit of toner band formation pattern information in the image processing apparatus 15. In addition, the frequency of forming the toner band TB may be increased or decreased. In this case, a determination threshold value for determining the formation time of the toner band TB (a threshold value determined by the cumulative value of the number of image formations, or a cumulative value of pixels in which images have been formed). Increase / decrease threshold values). At this time, in order to increase the toner supply amount, a condition for reducing the determination threshold is set. The conditions at this time are stored as determination threshold information in a storage element (ROM or the like) in the control device 16 , for example.

  Hereinafter, the operation for correcting the formation condition of the toner band TB will be described.

As shown in FIG. 5, when the image forming (printing) instruction is given (step S10), the image forming apparatus 1 starts the image forming operation (printing operation) as described above (S11). At the start of this printing operation, the temperature t and humidity h are detected by the detection sensor 19 and the measurement of the voltage value Vdc by the measuring device 18 is started (S12) .

  The detection of the detection sensor 19 and the measurement of the measuring instrument 18 are performed until the number of prints reaches a predetermined number (N) set in advance (S13), and the detection results and the measurement results obtained for each printing operation are the control device. Accumulated and stored in 16 storage units. The predetermined number of prints (N) is set in the range of 20 to 500, for example.

  Subsequently, when the printing operation reaches the predetermined number of prints (N), the control device 16 calculates the average value of the temperature t and the humidity h and the average value of the voltage value Vdc during the predetermined number of prints (N) (S14). ). The average value of the voltage value Vdc is calculated for each imaging device 2 (Y, M, C, K).

  For the average values of the calculated temperature t and humidity h, “temperatures ta, tb, tc, td, td” and “humidities ha, hb, hc, hd” in the first lookup table (LU table) shown in FIG. , He ”is assigned to any value (numeric range). The temperatures ta, tb, tc, td, and td at this time have a magnitude relationship of “ta <tb <tc <td <te” as shown in FIG. The humidity ha, hb, hc, hd, and he have a magnitude relationship of “ha <hb <hc <hd <he” as shown in FIG. Therefore, for example, when the temperature t is a relatively high temperature te and the humidity h is a relatively high humidity he, the use environment at that time is the environment A (high temperature and high humidity environment). It will be determined to be applicable. Further, the average value of the calculated voltage value Vdc is any one of “voltage values a1, b1, c1, d1, e1” in the second lookup table (LU table) shown in FIG. Numerical range). The voltage values a1, b1, c1, d1, and e1 have a magnitude relationship of “a1 <b1 <c1 <d1 <e1” as shown in FIG.

  Subsequently, after the use environment is determined based on the average value of the temperature t and the humidity h and the first LU table (FIG. 6), the determined environment, the average value of the voltage value Vdc, and the second LU table (FIG. 6). The formation conditions of the toner band TB are selected based on 7a) (S15). This formation condition is selected for each image forming device 2 (Y, M, C, K).

  At this time, for example, when the environment A is selected as described above, if the average value of the voltage value Vdc is “voltage a1”, it is considered that the charge amount of the photosensitive drum 21 is relatively low, and the toner The band amount L with the relatively smallest supply amount is selected. When the environment A is selected and the average value of the voltage value Vdc is “voltage e1”, it is considered that the charge amount of the photosensitive drum 21 is relatively high, and the toner supply amount is relatively high. The largest band amount H is selected. In addition, in the case of the environment B or C, it is considered that the charging amount of the photosensitive drum 21 is not increased by the average value of the voltage value Vdc, and “no band” is selected. In this case, the toner band TB is not formed during the printing operation.

  Then, after the toner band formation conditions are selected, it is determined whether or not to form a toner band (S16). The case where the toner band TB is formed is when any of “band amounts L, M, H” is selected as the toner band forming condition in step S15. On the other hand, the case where the toner band TB is not formed is when “no band” is selected as the toner band forming condition in step S15.

  At this time, if it is determined that the toner band TB is to be formed, the toner band TB forming operation based on the selected forming condition is executed during the printing operation being executed (S17). The toner band TB is formed at this time because the toner band TB is formed in the inter-image portion of the photosensitive drum 21 as described above, and there is no problem in the printing operation.

  Here, for example, when the band amount L is selected, it is considered that the increase in the charge amount of the photosensitive drum 21 is generally small, and the width w, length, and density of the preset toner band TB are considered. The toner band TB is formed under a condition (setting value) in which at least one of them is relatively smallest. On the other hand, when the band amount H is selected, it is considered that the charging amount of the photosensitive drum 21 is generally increased, and at least one of the preset width w, length, and density of the toner band TB is assumed. The toner band TB is formed under the condition (setting value) that is relatively largest.

  Regarding the correction of the width w and length of the toner band TB, as described above, the toner band formation pattern information stored in the image processing apparatus 15 is transmitted to the exposure apparatus 23, and the exposure apparatus 23 is based on the pattern information. This is performed by forming an electrostatic latent image of the toner band TB having a width and a length.

  As described above, according to the operation for correcting the formation condition of the toner band TB, the printing operation is performed between the power supply device 17 and the charging device 22 of each image forming device 2 in consideration of the use environment at that time. The formation condition of the toner band TB is appropriately corrected according to the situation of the actually generated voltage value Vdc.

  As a result, it can be predicted that the charging amount of the photosensitive drum 21 has increased, especially when the average value of the voltage value Vdc is high in a high-temperature and high-humidity environment, and the abnormality of the elastic blade 26a of the drum cleaning device 26 can be predicted. In this case, a phenomenon such as noise, turning, and wear is likely to occur. In this case, the “band amount H” is selected as the formation condition of the toner band TB, so that the toner supply amount relative to the elastic blade 26a is relative. Increased to As a result, more toner Tc is supplied to the portion of the elastic blade 26a that comes into contact with the photosensitive drum 21, so that the occurrence of the above phenomenon can be accurately reduced.

  On the other hand, when the average value of the voltage value Vdc becomes relatively low, it is predicted that the increase in the charge amount of the photosensitive drum 21 is small. In this case, the “band amount M” is set as the formation condition of the toner band TB. ”Or“ band amount L ”is selected, the toner supply amount is reduced, and the toner consumption amount is suppressed.

  If it is determined in step S16 that the toner band TB is not to be formed, or if the toner band TB forming operation has been completed, it is determined whether or not all the printing operations instructed by the print request have been completed. (S18). At this time, if the printing operation is not finished, the remaining printing operation is continued and executed until it is finished.

[Embodiment 2]
In the image forming apparatus 1 according to the second embodiment, as the charging device 22 in each image forming device 2 (Y, M, C, K), an apparatus that applies a voltage in which direct current and alternating current are superimposed from the power supply device 17 is applied. Further, the image forming apparatus according to the first embodiment is changed except that the measuring device 18 (Y, M, C, K) is changed by applying one that measures the current value Iac flowing from the power supply device 17 to each charging device 22. 1 has the same configuration.

  As the measuring device 18 (Y, M, C, K), a measuring device comprising an ammeter capable of measuring the current value Iac flowing from the power supply device 17 to each charging device 22 was used. At this time, the power supply device 17 supplies the superimposed voltage as a charging voltage under a constant voltage control method.

  The means for correcting the formation condition of the toner band TB at this time is the measuring instrument 18 (see FIG. 5 (particularly, the content of the portion indicated by “Iac” in parentheses) and FIG. 7B). According to the measurement result of the current value Iac obtained from Y, M, C, K) and the detection information obtained from the detection sensor 19, the formation condition of the toner band TB is corrected. As the second lookup table, the UK table shown in FIG. 7B is used.

  Hereinafter, the operation of correcting the formation conditions of the toner band TB by the image forming apparatus 1 according to the second embodiment will be described.

  In this image forming apparatus 1, as shown in FIG. 5, when there is a print instruction (S10), the requested print operation is started (S11), and by the detection sensor 19 at the start of this print operation. The temperature t and the humidity h are detected and the measurement of the current value Iac by the measuring device 18 is started (S12). The detection by the detection sensor 19 and the measurement by the measuring instrument 18 at this time are performed until the number of prints reaches a predetermined number (N) set in advance (S13), as in the case of the first embodiment. Detection results and measurement results obtained in the operation are accumulated and stored in the storage unit of the control device 16.

  Subsequently, when the printing operation reaches a predetermined number of prints (N), the control device 16 calculates an average value of the temperature t and humidity h and an average value of the current value Iac between the predetermined number of prints (N) (S14). ). The average value of the current value Iac is calculated for each imaging device 2 (Y, M, C, K).

  The average value of the current value Iac calculated at this time is any one of “current values a2, b2, c2, d2, e2” in the second lookup table (LU table) shown in FIG. (Numerical range). The current values a2, b2, c2, d2, and e2 have a magnitude relationship of “a2 <b2 <c2 <d2 <e2” as shown in FIG. 7B.

  Subsequently, after the use environment is determined based on the average value of the temperature t and the humidity h and the first LU table (FIG. 6), the determined environment, the average value of the current value Iac, and the second LU table (FIG. The formation conditions of the toner band TB are selected based on 7b) (S15). The selection of the formation conditions is also performed for each image forming device 2 (Y, M, C, K).

  At this time, for example, when the environment A is selected as described above, if the average value of the current value Iac is “voltage a 2”, it is considered that the charge amount of the photosensitive drum 21 is relatively low, and toner supply is performed. The band amount L having the smallest amount is selected. When the environment A is selected and the average value of the current value Iac is “voltage e 2”, it is considered that the charge amount of the photosensitive drum 21 is relatively high, and the toner supply amount is relatively high. The largest band amount H is selected. In addition, in the case of the environment B or C, depending on the average value of the current value Iac, it is considered that the charge amount of the photosensitive drum 21 has not increased, and “no band” is selected. In this case, the toner band TB is not formed during the printing operation.

  Then, after the toner band formation conditions are selected, it is determined whether or not to form a toner band (S16). At this time, if it is determined that the toner band TB is to be formed, the toner band TB forming operation based on the selected forming condition is executed during the printing operation being executed (S17). Here, for example, when the band amount H is selected, as in the case of the first embodiment, it is considered that there is a large increase in the charge amount of the photosensitive drum 21 as a whole, and a preset toner is set. The toner band TB is formed under a condition (setting value) in which at least one of the width w, length, and density of the band TB is relatively largest.

  As described above, according to the operation for correcting the formation condition of the toner band TB, the value of current flowing from the power supply device 17 to the charging device 22 of each image forming device 2 in consideration of the use environment at the time of printing operation. The formation condition of the toner band TB is appropriately corrected according to the situation of Iac.

  As a result, it can be predicted that the charging amount of the photosensitive drum 21 has increased, particularly when the average value of the current value Iac is high in a high-temperature and high-humidity environment, and the elastic blade 26a of the drum cleaning device 26 is abnormal. In this case, a phenomenon such as noise, turning, and wear is likely to occur. In this case, the “band amount H” is selected as the formation condition of the toner band TB, so that the toner supply amount relative to the elastic blade 26a is relative. Increased to As a result, more toner Tc is supplied to the portion of the elastic blade 26a that comes into contact with the photosensitive drum 21, so that the occurrence of the above phenomenon can be accurately reduced.

  On the other hand, when the average value of the current value Iac becomes relatively low, it is predicted that the increase in the charge amount of the photosensitive drum 21 is small. In this case, “band amount M is set as the formation condition of the toner band TB. ”Or“ band amount L ”is selected, the toner supply amount is reduced, and the toner consumption amount is suppressed.

[Other embodiments]
In the first and second embodiments, a case where the toner band TB forming condition is set using the detection result of the temperature t and the humidity h inside the housing 10 in the correction operation of the toner band TB forming condition is exemplified. However, it is possible not to use the detection result of the temperature t and the humidity h, but to set the formation condition of the toner band TB using only the measurement result of the voltage value Vdc or the current value Iac. is there. Further, although the case where the control device 16 is used as means for correcting the formation condition of the toner band TB is illustrated, a dedicated control device or the like may be provided as the correction means.

  In the first and second embodiments, the image forming apparatus 1 is exemplified to have four image forming apparatuses 2 (Y, M, C, K). However, the above-described problem phenomenon occurs mainly. If measures are required, other types of image forming apparatuses can be employed. As other image forming apparatuses, for example, an image forming apparatus equipped with a plurality of image forming apparatuses 2 other than four, or each primary transfer position in the plurality of image forming apparatuses 2 instead of the intermediate transfer apparatus 3 is passed. An image forming apparatus that employs a sheet conveying apparatus that holds and conveys the sheet 9, an image forming apparatus in which a plurality of developing devices 24 are arranged on one photosensitive drum 21, and one image forming apparatus 2 (this image forming apparatus 2) In this case, the intermediate transfer device 3 is not necessary, and the sheet 9 supplied from the sheet feeding device 4 is conveyed so as to pass through the primary transfer position).

  Further, in the first and second embodiments, the case where a contact-type charging device is applied as the charging device 22 is exemplified, but a non-contact-type charging device may be applied. In the first and second embodiments, the case where the drum-shaped photosensitive drum 21 is applied as the photosensitive member is illustrated. However, a belt-forming photosensitive belt may be applied as the photosensitive member.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 9 ... Recording paper (recording material)
10. Case (main body of image forming apparatus)
16 ... Control device (correction means)
17 ... Power supply 18 ... Measuring instrument (measuring means)
19: Detection sensor (detection means)
21 ... Photosensitive drum (photoconductor)
22: Charging device (charging means)
23. Exposure apparatus (part of image forming means)
24. Developing device (part of image forming means)
25. Primary transfer device (transfer means)
26a ... Elastic blade (plate-like elastic cleaning material)
TB ... Toner band (specific developer image)
Vdc ... Voltage value Iac ... Current value

Claims (5)

A rotating photoreceptor,
Charging means for charging the surface of the photoreceptor;
Image forming means for forming an image to be developed with a developer on the charged surface of the photoreceptor;
Transfer means for transferring the developer image formed on the surface of the photoreceptor to a recording material or an intermediate transfer body;
A plate-like elastic cleaning material that contacts the surface of the photoreceptor after the transfer and cleans the surface;
A power supply for supplying a charging voltage to the charging means;
A measuring unit for measuring a current value flowing from the power source to the charging unit or a voltage value generated between the power source and the charging unit when a charging voltage or current is supplied from the power source to the charging unit;
Correction means for correcting a specific developer image forming condition that is formed on the surface of the photosensitive member by the image forming means and is not transferred to the recording material or the intermediate transfer body according to the measurement result obtained from the measuring means. It has a door,
The condition for forming the specific developer image in the correcting means is an element that increases or decreases the amount of developer supplied when the developer image reaches the contact portion of the elastic cleaning material with the surface of the photoreceptor. An image forming apparatus comprising the content included . The charging means supplies a DC voltage from the power source to charge the surface of the photoconductor,
The image forming apparatus according to claim 1, wherein the measurement unit is configured to measure a voltage value generated between the power source and the charging unit. The charging means supplies a voltage in which direct current and alternating current are superimposed from the power source to charge the surface of the photoconductor,
The image forming apparatus according to claim 1, wherein the measuring unit is configured to measure a current value flowing from the power source to the charging unit. The correction unit corrects the formation condition of the specific developer image to a condition in which the amount of the supplied developer is relatively increased when the charge amount on the surface of the photoconductor is relatively increased. Item 4. The image forming apparatus according to any one of Items 1 to 3. Having detection means for detecting temperature and humidity in the internal space of the main body of the image forming apparatus;
The correction unit determines the use environment according to the detection result obtained from the detection unit, and sets the specific developer image forming condition according to the determined use environment and the measurement result of the measurement unit. the image forming apparatus according to any one of claims 1 to 4.

Images