JP2022071966A - Image forming apparatus, control program, and control method - Google Patents

Abstract

To prevent transfer unevenness caused by process condition adjustment processing even when an image carrier and a transfer body cannot be in contact with each other or separated from each other.SOLUTION: An image forming apparatus (10) comprises: a photoreceptor drum (36) on a surface of which an electrostatic latent image is formed; and a transfer roller (422) that forms a transfer nip part between the photoreceptor drum (36) and the transfer roller. In the image forming apparatus (10), when the degree of wear of the transfer roller (422) is less than a predetermined threshold, a first toner patch 100A having a width dimension W1 in an axial direction of the transfer roller (422) is formed on the photoreceptor drum (36), and process condition adjustment processing is executed for detecting the concentration of toner in the first toner patch 100A, and according to the concentration of toner in the first toner patch 100A, adjusting an image forming condition. When the degree of wear of the transfer roller is equal to or more than the predetermined threshold, a second toner patch 100B having a width dimension W2 (smaller than W1) in the axial direction of the transfer roller is formed, and the process condition adjustment processing is executed.SELECTED DRAWING: Figure 9

Description

The present invention relates to an image forming apparatus, a control program and a control method, and more particularly to an image forming apparatus, a control program and a control method for forming an image on a recording medium by, for example, an electrophotographic method.

Patent Document 1 discloses an example of an image forming apparatus of a background technique adopting an electrophotographic method. In the image forming apparatus of the background technology, a plurality of density correction toner images (toner patches) are formed on an image carrier such as a photoconductor drum or an intermediate transfer body, and the density of the toner patch is detected by an optical sensor to detect the toner. A so-called process condition adjustment process, in which the image density is corrected according to the density of the patch, is executed.

Japanese Unexamined Patent Publication No. 2020-101629

Conventionally, there is an image forming apparatus that does not have a separation mechanism for separating and contacting an image carrier and a transfer body arranged so as to face the image carrier. When a process condition adjustment process using a toner patch as in the background technique is executed in an image forming apparatus not provided with such a detaching mechanism, toner may adhere to a part of the transfer body. That is, the transfer material may be partially contaminated with toner.

When the transfer body is partially soiled with toner, the electrical resistance between the image carrier and the transfer body changes between the part where the toner is not attached and the part where the toner is attached, and there is a risk that transfer unevenness will occur. There is.

Therefore, a main object of the present invention is to provide a novel image forming apparatus, control program and control method.

Another object of the present invention is an image forming apparatus, a control program, and a control method capable of preventing transfer unevenness due to a process condition adjustment process even when the image carrier and the transfer body cannot be separated from each other. Is to provide.

In the first invention, the image carrier, the transfer body that abuts on the image carrier and forms a transfer nip portion between the image carrier and the transfer body, and the first toner having a first width dimension in the axial direction of the transfer body. Data of a toner patch for adjusting image forming conditions, including a patch and a second toner patch having a second width dimension in which the width dimension in the axial direction of the transfer body is smaller than the first width dimension. It is an image forming apparatus provided with a storage means for storing. The image forming apparatus includes a wear degree detecting means, a toner patch setting means, a toner patch forming means, a toner density detecting means, and an adjusting means. The depletion detection means detects the depletion of the transcript. The toner patch setting means sets the first toner patch as an adjustment patch when the degree of wear of the transfer body is less than a predetermined threshold, and the second toner patch when the degree of wear of the transfer body is equal to or more than a predetermined threshold. Is set as an adjustment patch. The toner patch forming means forms an adjusting patch on the image carrier. The toner concentration detecting means detects the amount of toner adhered to the adjusting patch formed on the image carrier. The adjusting means adjusts the image forming conditions according to the amount of toner adhered to the adjusting patch.

The second invention is subordinate to the first invention, further comprising a length setting means for setting the length of the first toner patch in the transport direction, and the length setting means is the length of the first toner patch in the transport direction. The length is set to be equal to or longer than the circumference of the transfer body.

The third invention is subordinate to the second invention, further comprising environmental information detecting means for detecting environmental information regarding at least one of the temperature and humidity of the apparatus main body and the apparatus main body, and the length setting means is a first toner. Set the length of the patch in the transport direction according to the environmental information.

The fourth invention is dependent on the third invention, and the length setting means sets the length of the first toner patch in the transport direction as the temperature and humidity of the apparatus main body increase.

The fifth invention is subordinate to any one of the first to fourth inventions, and the first toner patch includes a toner patch for halftone adjustment.

The sixth invention is dependent on any one of the first to fifth inventions, and the toner patch setting means is used when a predetermined number of images having a low print rate are continuously printed after the second toner patch is set. In addition, the first toner patch is set as an adjustment patch.

The seventh invention is dependent on any one of the first to sixth inventions, the first width dimension being larger than the size of the largest recording medium and the second width dimension being larger than the size of the largest recording medium. Is also small.

In the eighth invention, the image carrier, the transfer body that abuts on the image carrier and forms a transfer nip portion between the image carrier and the transfer body, and the first toner having the first width dimension in the axial direction of the transfer body. A storage means for storing data of the toner patch for adjusting image forming conditions, including the patch and a second toner patch having a second width dimension smaller than the first width dimension in the axial direction of the transfer body. A control program for an image forming apparatus, in which the processor of the image forming apparatus detects the degree of wear of the transfer body, and when the degree of wear of the transfer body is less than a predetermined threshold, the first toner patch is used as an adjustment patch. A process of setting the second toner patch as an adjustment patch, a process of forming an adjustment patch on the image carrier, and an adjustment formed on the image carrier when the degree of wear of the transfer body is set and is equal to or higher than a predetermined threshold. The process of detecting the amount of toner adhering to the patch and the process of adjusting the image formation conditions according to the amount of toner adhering to the adjustment patch are executed.

In the ninth invention, the image carrier, the transfer body that abuts on the image carrier and forms a transfer nip portion between the image carrier and the transfer body, and the first toner having a first width dimension in the axial direction of the transfer body. The storage means for storing the data of the toner patch for adjusting the image forming conditions, including the patch and the second toner patch having a second width dimension smaller than the first width dimension in the axial direction of the transfer body. In the control method of the image forming apparatus, (a) a step of detecting the degree of wear of the transfer body, and (b) when the degree of wear of the transfer body is less than a predetermined threshold value, the first toner patch is set as an adjustment patch. Then, when the degree of wear of the transfer body is equal to or higher than a predetermined threshold, the step of setting the second toner patch as the adjustment patch, (c) the step of forming the adjustment patch on the image carrier, and (d) the image support. It includes a step of detecting the amount of toner adhered to the adjusting patch formed on the body, and (e) a step of adjusting image forming conditions according to the amount of toner adhered to the adjusting patch.

According to the present invention, even when the image carrier and the transfer body cannot be separated from each other, it is possible to prevent the transfer unevenness caused by the process condition adjustment process.

The above-mentioned object, other object, feature and advantage of the present invention will be further clarified from the detailed description of the following embodiments with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing the internal structure of the image forming apparatus according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing the structure of the developing unit and the photoconductor drum. FIG. 3 is a block diagram showing an electrical configuration of the image forming apparatus of FIG. FIG. 4 is an enlarged cross-sectional view showing an outline of the toner concentration sensor. FIG. 5 is a schematic view showing an example of a transfer roller at the time of image transfer. FIG. 6 is an illustrated diagram showing an example of the shape of the first toner patch. FIG. 7 is an illustrated diagram showing an example of the shape of the second toner patch. FIG. 8 is an illustrated diagram showing an example of the memory map of the RAM shown in FIG. FIG. 9 is a flow chart showing an example of the process condition adjustment process of the image forming apparatus. FIG. 10 is a flow chart showing an example of the process condition adjustment process of the second embodiment.

[First Example]
FIG. 1 is a schematic diagram showing an internal structure of an image forming apparatus 10 which is an embodiment of the present invention. The image forming apparatus 10 shown in FIG. 1 is a multifunction device having a copying function, a printing function (printing function), a scanner function, a facsimile function, and the like, and is a monochromatic image (monochrome image) with respect to a recording medium by an electrophotographic method. To form. However, the image forming apparatus 10 may have at least a printing function, and may be, for example, a printing apparatus (printer). As the recording medium, paper, a sheet for an overhead projector, or the like can be used, but the case where paper is used will be described below.

First, the configuration of the image forming apparatus 10 will be schematically described. As shown in FIG. 1, the image forming apparatus 10 includes an apparatus main body 12 including an image forming unit 30 and an image reading device 14 arranged above the apparatus main body 12.

The image reading device 14 includes a document mounting table 16 formed of a transparent material. A document holding cover 18 can be opened and closed above the document mounting table 16 via a hinge or the like. A document supply tray 20 is provided on the upper surface of the document holding cover 18, and an automatic document feeder (ADF: Auto Document Feeder) is provided inside the document supply tray 20. The ADF automatically supplies the documents placed on the document supply tray 20 one by one to the image reading position 22, and ejects the documents to the document ejection tray 24.

Further, the image reading unit 26 built in the image reading device 14 includes a light source, a plurality of mirrors, an imaging lens, a line sensor, and the like. The image reading unit 26 exposes the surface of the document with a light source, and guides the reflected light reflected from the surface of the document to the imaging lens by a plurality of mirrors. Then, the reflected light is imaged on the light receiving element of the line sensor by the imaging lens. The line sensor detects the luminance and chromaticity of the reflected light imaged on the light receiving element, and generates image data based on the image on the surface of the document. As the line sensor, a CCD, CIS or the like is used.

An operation panel (not shown) that accepts input operations such as printing instructions by the user is provided on the front side of the image reading device 14. The operation panel has a display with a touch panel, a plurality of operation buttons, and the like.

The image forming unit 30 includes an exposure unit (optical scanning unit) 32, a developing unit 34, a photoconductor drum 36, a cleaner unit (cleaning unit) 38, a charging unit 40, a transfer unit 42, a fixing unit 44, a toner replenishing device 46, and the like. An image is formed on the paper conveyed from the paper feed tray 48 or the like, and the image-formed paper is discharged to the paper ejection tray 50. As the image data for forming an image on the paper, the image data read by the image reading unit 26, the image data transmitted from an external computer, or the like is used.

The photoconductor drum 36 is an electrostatic latent image carrier in which a photosensitive layer is formed on the surface of a cylindrical substrate having conductivity, and is around its axis (not shown in FIG. 1) by a rotation drive source (not shown) such as a motor. It is rotated counterclockwise). The photosensitive layer is formed of a material that exhibits conductivity when irradiated with light (for example, amorphous silicon (a—Si), selenium (Se), organic optical semiconductor (OPC), or the like). However, instead of the photoconductor drum 36, a photoconductor belt can also be used as an electrostatic latent image carrier.

The charging unit 40 charges the surface of the photoconductor drum 36 to a predetermined potential. As the charging unit 40, a corona discharge device, a brush type charging device, a roller type charging device, an ion generator, or the like can be used.

The exposure unit 32 is configured as a laser scanning unit (LSU) provided with a laser emitting unit, a reflection mirror, and the like, and by exposing the surface of the charged photoconductor drum 36, an electrostatic latent image corresponding to image data is obtained. It is formed on the surface of the photoconductor drum 36.

The developing unit 34 supplies a developer containing toner to the surface of the photoconductor drum 36, and the electrostatic latent image formed on the surface of the photoconductor drum 36 is visualized by the toner. That is, the developing unit 34 forms a toner image on the surface of the photoconductor drum 36.

As shown in FIG. 2, the developing unit 34 includes a first transport member 72, a second transport member 74, a developing roller 70, a doctor blade 78, and the like, which are integrally held by the developing housing 62 in a predetermined arrangement mode. Will be done.

Inside the developing housing 62, a developing tank 64 in which the developing agent is stored (accommodated) is formed. Each of the first transport member 72 and the second transport member 74 is arranged inside the developing tank 64 so that the rotation axes of the first transport member 72 and the second transport member 74 are parallel to each other. The first transport member 72 and the second transport member 74 are auger screws having spiral blades formed on the outer peripheral surface of a columnar rotating shaft (screw shaft). The first transport member 72 and the second transport member 74 transport the developer while stirring to circulate the developer in a predetermined direction inside the developing tank 64.

The developing roller 70 is a magnet roller that functions as a developer carrier, and is arranged above the second transport member 74. The developing rollers 70 are arranged so that their rotation axes are parallel to each other with respect to the photoconductor drum 36, and are rotated around the axis (clockwise in FIGS. 1 and 2) by a rotation drive source (not shown) such as a motor. Is rotated to.

Further, the developing roller 70 supports the developer housed in the developing housing 62 (development tank 64) on the surface, and supplies the supported developer to the surface of the photoconductor drum 36. As a result, the electrostatic latent image formed on the surface of the photoconductor drum 36 is visualized by the toner contained in the developer. That is, a toner image is formed on the surface of the photoconductor drum 36.

The doctor blade 78 is arranged inside the developing tank 64 so as to have a predetermined gap with respect to the surface of the developing roller 70. The doctor blade 78 is a plate-shaped member extending in the axial direction of the developing roller 70. The doctor blade 78 regulates the amount of the developer supported on the developing roller 70 (the thickness of the developer supported on the developing roller 70) to a predetermined amount.

In this embodiment, a developer (two-component developer) in which toner and a carrier are mixed is used. However, the carrier is a magnetic material such as iron powder or ferrite. Therefore, a two-component developer composed of a toner and a carrier is housed inside the developing tank 64 of the developing unit 34, and the toner contained in the developing agent is supplied from the developing roller 70 to the photoconductor drum 36.

The cleaner unit 38 includes a cleaning blade or the like that comes into contact with the surface of the photoconductor drum 36, and removes toner (developer) remaining on the surface of the photoconductor drum 36 after development and image transfer.

Returning to FIG. 1, the toner replenishing device 46 is connected to the developing unit 34. The toner replenishing device 46 is a container for storing unused toner, and supplies (replenishes) toner to the developing unit 34 (development tank 64).

The transfer unit 42 is a unit for transferring a toner image formed on the surface of the photoconductor drum 36 to paper. The transfer unit 42 includes a transfer roller 422 as a transfer body. The transfer roller 422 is arranged so as to face the photoconductor drum 36 and is provided so as to press the photoconductor drum 36.

When a normal image forming process is executed (when an image is formed on paper), a predetermined voltage (transfer voltage) is applied to the transfer roller 422 between the photoconductor drum 36 and the transfer roller 422. A transfer electric field is formed in. Then, due to the action of this transfer electric field, the toner image formed on the outer peripheral surface of the photoconductor drum 36 is formed while the paper passes through the nip area (transfer nip portion) between the photoconductor drum 36 and the transfer roller 422. Transferred to paper.

The fixing unit 44 includes a heat roller and a pressure roller, and is arranged on the downstream side of the transfer unit 42 in the paper transport direction. The heat roller is set to a predetermined temperature (fixing temperature), and is transferred to the paper by passing the paper through the nip area (fixing nip portion) between the heat roller and the pressure roller. The toner image is melted, mixed and pressure-welded to heat-fix the toner image to the paper.

Further, in the apparatus main body 12, a first paper transport path P1 for sending the paper placed on the paper feed tray 48 to the paper output tray 50 via the transfer nip portion and the fixing nip portion is formed. Further, in the apparatus main body 12, when double-sided printing is performed on paper, the paper after single-sided printing is completed and has passed through the fixing nip portion is first placed on the upstream side of the transfer nip portion in the paper transport direction. A second paper transport path P2 for returning to the paper transport path P1 is formed. The first paper transport path P1 is provided with a resist roller 56 and a discharge roller 60, and the first paper transport path P1 and the second paper transport path P2 are provided with a plurality of transport rollers for giving propulsive force to the paper. 58 is appropriately provided.

When single-sided printing is performed on the apparatus main body 12, the paper placed on the paper feed tray 48 is guided one by one to the first paper transport path P1 by the pickup roller 52 and the separation roller 54, and is conveyed to the resist roller 56. To. Then, the resist roller 56 conveys the paper to the transfer nip portion at the timing when the tip of the paper and the tip of the image information (toner image) on the photoconductor drum 36 match, and the toner image is transferred onto the paper. After that, the unfixed toner on the paper is heat-fixed by passing the paper through the fixing nip portion. The heat-fixed paper is conveyed through the first paper transport path P1 by the transport roller 58, and is discharged to the paper discharge tray 50 by the discharge roller 60 provided at the downstream end of the first paper transport path P1.

On the other hand, when double-sided printing is performed, when the rear end of the paper that has passed through the fixing nip portion reaches the discharge roller 60 after single-sided printing is completed, the paper is reversed by rotating the discharge roller 60 in the reverse direction. It runs and is guided to the second paper transport path P2. The paper guided to the second paper transport path P2 is conveyed by the transport roller 58 through the second paper transport path P2, and is guided to the first paper transport path P1 on the upstream side of the resist roller 56 in the paper transport direction. At this point, the front and back sides of the paper are reversed, and then the paper passes through the transfer nip portion and the fixing nip portion, so that printing is performed on the back surface of the paper.

The image forming apparatus 10 may be provided with a manual paper feed tray or may be equipped with an external paper feed unit. In such a case, instead of the paper feed tray 48, paper may be fed from the manual paper feed tray or the external paper feed unit to the first paper transport path P1.

FIG. 3 is a block diagram showing an example of the electrical configuration of the image forming apparatus 10 shown in FIG. As shown in FIG. 3, the image forming apparatus 10 includes a CPU 80, and the CPU 80 includes a RAM 84, an auxiliary storage unit 86, an image reading unit 26, an image forming unit 30, an environment detecting unit 88, and a toner concentration via a bus 82. The sensor 90, the toner replenishment control unit 92, and the like are connected. Although not shown, each component such as an operation panel is also connected to the CPU 80 via the bus 82.

The CPU 80 controls the overall control of the image forming apparatus 10, and comprehensively controls the operation of each component of the image forming apparatus 10 described above. The RAM 84 is the main storage device of the image forming apparatus 10, and is used as a work area and a buffer area of the CPU 80.

The auxiliary storage unit 86 is, for example, an HDD, and is an auxiliary storage device of the image forming apparatus 10 that stores a control program for controlling the operation of each component of the image forming apparatus 10 and various data. However, as the auxiliary storage unit 86, another non-volatile memory such as SSD, flash memory, or EEPROM may be used instead of the HDD or together with the HDD.

The environment detection unit 88 is provided to detect information (environmental information) regarding the environment inside the image forming apparatus 10 (around the image forming apparatus 10) or inside the apparatus main body 12 (inside the machine). However, the environment refers to the space temperature (air temperature) and the space humidity, and the environmental information includes information on the space temperature and information on the space humidity. The environment detection unit 88 includes a temperature sensor and a humidity sensor for detecting environmental information inside the installation location of the image forming apparatus 10 or the apparatus main body 12.

The temperature sensor is a general-purpose temperature sensor, and any sensor such as a thermistor, thermocouple, bimetal, and resistance temperature detector can be used. The temperature sensor outputs a signal to the CPU 80 according to the space temperature of the installation location of the image forming apparatus 10.

The humidity sensor is a general-purpose humidity sensor, and any sensor such as a capacitance change type humidity sensor and a resistance change type humidity sensor can be used. The humidity sensor outputs a signal to the CPU 80 according to the spatial humidity of the installation location of the image forming apparatus 10.

The temperature sensor and the humidity sensor may be provided inside the device main body 12 or may be provided outside the device main body 12. Further, a temperature / humidity sensor in which a temperature sensor and a humidity sensor are integrated may be used.

The toner concentration sensor 90 is arranged close to the image carrier (photoreceptor drum 36) and is a sensor for detecting the amount of toner adhered to the toner image on the photoconductor drum 36.

FIG. 4 is an enlarged cross-sectional view showing an outline of the toner concentration sensor 90. In FIG. 4, the surface of the photoconductor drum 36 is represented as a flat surface for convenience of explanation. As shown in FIG. 4, the toner concentration sensor 90 includes a housing 90a, a semiconductor laser 90b, a condensing lens 90c, and a photo sensor (light receiving element) 90d. The semiconductor laser 90b irradiates the surface of the photoconductor drum 36 with the laser beam. The condensing lens 90c narrows the light emitted from the semiconductor laser 90b onto the photoconductor drum 36. The photo sensor 90d receives the reflected light reflected by the toner image on the photoconductor drum 36 and outputs an electric signal according to the amount of the light.

The light receiving amount of the photo sensor 90d correlates with the toner adhesion amount of the toner image on the photoconductor drum 36. Therefore, by acquiring in advance the correlation between the current value or voltage value of the electric signal output according to the received light amount and the toner adhesion amount as a correlation formula or table data, the toner image on the photoconductor drum 36 The amount of toner adhered (image density) can be measured (detected).

Returning to FIG. 3, the toner replenishment control unit 92 drives and controls a motor for supplying (replenishing) toner from the toner replenishing device 46 to the developing unit 34 (development tank 64). It is a driver.

The electrical configuration of the image forming apparatus 10 shown in FIG. 3 is merely an example, and is not limited to this.

In the image forming apparatus configured as described above, process control (process condition adjustment processing) may be executed according to the output of the toner density sensor. The process condition adjustment process is to set various process conditions (image formation conditions) such as charging potential, exposure amount, and developing potential so as to correspond to the environment in which the image forming apparatus is installed and the material change of the developer over time. It means a process (image quality adjustment process) for adjusting and always obtaining a constant image quality.

In the process condition adjustment process, a reference toner image (toner patch) for density correction is formed on the image carrier, and the amount of toner adhered to the toner patch (image density of the toner patch) is detected according to the output of the toner density sensor. Toner. Then, the process conditions are adjusted according to the image density of the toner patch.

Some conventional image forming devices include a separation mechanism for separating and connecting the photoconductor drum and the transfer roller, and separate the photoconductor drum and the transfer roller when the process condition adjustment process is executed.

On the other hand, there is also an image forming apparatus that does not have a detaching mechanism for separating and contacting a photoconductor drum and a transfer roller, and executes a process condition adjustment process in a state where the photoconductor drum and the transfer roller are in contact with each other. The image forming apparatus 10 of the present embodiment does not have a separation / contact mechanism for separating the photoconductor drum 36 and the transfer roller 422, and the photoconductor drum 36 and the transfer roller 422 cannot be separated from each other. In this case, when the process condition adjustment process is executed, the photoconductor drum 36 is charged so as to have the opposite polarity to the toner, and a predetermined voltage is applied so that the transfer roller 422 has the same polarity as the toner. The toner of the toner patch on the body drum 36 is prevented from adhering to the transfer roller 422 as much as possible. However, since the photoconductor drum 36 and the transfer roller 422 are in physical contact with each other, the toner of the toner patch may partially adhere to the transfer roller 422, and the transfer roller may be partially contaminated with the toner.

As shown in FIG. 5, when the transfer roller 422 is partially contaminated with toner, the surface of the transfer roller 422 has a portion where the toner does not adhere (a portion where the toner does not adhere) A1 and a portion where the toner adheres (a portion where the toner does not adhere). Toner adhesion portion) A2 and are generated.

As described above, during normal image formation, a transfer voltage is applied to the transfer roller 422, and a transfer electric field is formed between the photoconductor drum 36 and the transfer roller 422, whereby the toner on the photoconductor drum 36 is released. It is attracted to the paper and the toner image is transferred to the paper. Here, in the toner non-adhering portion A1, the photoconductor drum 36, the paper, and the transfer roller 422 serve as resistance. On the other hand, in the toner adhering portion A2, in addition to the photoconductor drum 36, the paper and the transfer roller 422, the toner stain becomes a resistance. Therefore, the electrical resistance between the photoconductor drum 36 and the transfer roller 422 (the surface resistance of the transfer roller 422) changes between the toner non-adhering portion A1 and the toner adhering portion A2, and in particular, the toner adhering portion A2 is exposed to light. The value of the current flowing between the body drum 36 and the transfer roller 422 decreases. Then, when the current value flowing between the photoconductor drum 36 and the transfer roller 422 is lower than the value required for transferring the toner image, image omission (transfer unevenness) occurs.

However, the resistance difference between the toner non-adhered portion A1 and the toner adhered portion A2 becomes larger when the degree of wear of the transfer roller 422 is low (the transfer roller 422 is close to the unused state), and the transfer roller 422 is used to some extent. As the degree of wear of the transfer roller 422 increases, it tends to decrease. This means that as the transfer roller 422 is used, the entire surface of the transfer roller 422 becomes contaminated with the toner used during normal image formation, so that the toner stain due to the toner patch used in the process condition adjustment process becomes inconspicuous (). This is thought to be because the effect of toner stains caused by the toner patch is reduced).

Therefore, in this embodiment, a plurality of types of toner patches 100 according to the degree of wear of the transfer roller 422 are prepared, and an appropriate type of toner patch 100 is set as an adjustment patch according to the degree of wear of the transfer roller 422. I tried to use it. Specifically, the toner patch 100 of this embodiment includes at least a first toner patch 100A (see FIG. 6) and a second toner patch 100B (see FIG. 7).

As shown in FIG. 6, the first toner patch 100A has a size in the axial direction (main scanning direction) of the transfer roller 422 (photoreceptor drum 36), that is, a size in the width direction of the paper (first width dimension). W1 is set to be larger than the maximum paper size used in the image forming apparatus 10. Further, the width dimension W1 of the first toner patch 100A is larger than the width dimension of the image forming region on the transfer roller 422 (photoreceptor drum 36). The axial direction of the transfer roller 422 can also be said to be a direction orthogonal to the transport direction of the toner patch 100.

Further, the length L1 of the first toner patch 100A in the transport direction (sub-scanning direction) is set to a predetermined length. The length L1 of the first toner patch 100A in the transport direction may be less than the circumference of the transfer roller 422, but is preferably set to a length equal to or greater than the circumference of the transfer roller 422.

As shown in FIG. 7, in the second toner patch 100B, the axial size (second width dimension) W2 of the transfer roller 422 is set to be smaller than the maximum paper size used in the image forming apparatus 10. Toner. That is, the width dimension W2 of the second toner patch 100B is smaller than the width dimension of the image forming region on the transfer roller 422 (photoreceptor drum 36), and is smaller than the width dimension W1 of the first toner patch 100A.

Further, the length L2 of the second toner patch 100B in the transport direction is shorter than the length L1 of the first toner patch 100A in the transport direction. Further, the length L2 of the second toner patch 100B in the transport direction is shorter than the peripheral length of the transfer roller 422.

For example, the width dimension W2 of the second toner patch 100B and the length L2 of the second toner patch 100B in the transport direction are each set to the minimum size that can be detected by the toner concentration sensor 90. Further, the second toner patch 100B is formed at a position corresponding to the toner concentration sensor 90 in the axial direction (main scanning direction) of the transfer roller 422.

In this embodiment, the first toner patch 100A and the second toner patch 100B are solid black (concentration 100%) toner images (so-called solid images).

Further, here, the axial width dimension W1 of the transfer roller 422 of the first toner patch 100A is set to be larger than the size of the maximum recording medium, but the present invention is not necessarily limited to this. That is, the width dimension W1 of the first toner patch may be set to be the same as or smaller than the size of the maximum recording medium. However, the axial width dimension W2 of the transfer roller 422 of the second toner patch 100B used when the degree of wear of the transfer roller 422 is larger (higher) is when the degree of wear of the transfer roller 422 is smaller (lower). It is set smaller than the width dimension W1 of the first toner patch 100A used for.

The first toner patch 100A is set as an adjustment patch when the degree of wear of the transfer roller 422 is less than a predetermined threshold value (for example, the cumulative number of printed sheets is 100), and the second toner patch 100B is the wear of the transfer roller 422. When the degree is above the threshold value, it is set as an adjustment patch. That is, when the degree of wear of the transfer roller 422 is low, the process condition adjustment process using the first toner patch 100A is executed. When the first toner patch 100A is used, the toner of the first toner patch 100A adheres to the entire transfer roller 422. That is, when the process condition adjustment process is executed when the degree of wear of the transfer roller 422 is low, the toner adheres to the entire surface of the transfer roller 422, and the entire surface of the transfer roller 422 becomes the toner adhesion portion A2. Therefore, the surface resistance of the transfer roller 422 becomes substantially uniform (unevenness is eliminated), and transfer unevenness is less likely to occur.

That is, transfer unevenness is suppressed by using toner patches having different width dimensions W depending on the degree of wear of the transfer roller 422. As described above, for example, when the degree of wear of the transfer roller 422 (transfer body) is small, a toner patch having a large width dimension W is used, and when the degree of wear is large, a toner patch having a small width dimension W is used.

It is also known that the electrical resistance of the transfer roller 422 changes as the temperature and humidity change. Specifically, when the temperature is high or the humidity is high, the electric resistance of the transfer roller 422 decreases, and when the temperature is low or the humidity is low, the electric resistance of the transfer roller 422 increases. Therefore, it is considered that the influence of the toner stain on the transfer roller 422 due to the toner patch changes depending on the environment of the image forming apparatus 10. Therefore, the inventors of the present invention conducted an experiment to clarify the relationship between the environment of the image forming apparatus 10 and the length of the toner patch in the transport direction, which is necessary for eliminating the transfer unevenness.

The image forming apparatus used in the following experiments has the same configuration as the image forming apparatus 10 of the present embodiment shown in FIGS. 1 to 3.

Specifically, the present inventors change the temperature and humidity around the image forming apparatus and the space humidity around the image forming apparatus to convey the temperature and humidity and the toner patch necessary for eliminating the transfer unevenness. An experiment was conducted to clarify the relationship with the length of. However, in this experiment, a transfer roller with extremely low consumption (cumulative number of printed sheets is about several tens) is used, and the influence of time-dependent factors (transfer roller consumption) is minimized. This was carried out using a transfer roller having almost the same degree (the difference in the total number of printed sheets is about 10). Further, in this experiment, the first toner patch 100A is used, the length of the toner patch in the transport direction is the same as the circumference of one round of the transfer roller 422, and the image for the experiment is displayed after the process condition adjustment process. It was printed on paper and evaluated for uneven transfer.

The experimental results will be described with reference to Table 1. The presence or absence of transfer unevenness is determined by visually observing the image printed on the paper. The case where it occurred frequently was regarded as "x".

As shown in Table 1, it was found that transfer unevenness is unlikely to occur at low temperature and low humidity, and transfer unevenness is likely to occur at high temperature and high humidity. That is, it was found that if the temperature is low and the humidity is low, the transfer unevenness can be eliminated by setting the length of the toner patch in the transport direction to be equal to or longer than the circumference of one round of the transfer roller 422.

Although not shown, when the length of the toner patch in the transport direction is changed to the same length as the circumference of two rounds of the transfer roller 422, the “△” part in Table 1 becomes “〇”. , The part of "x" in Table 1 became "△". Further, when the length of the toner patch in the transport direction was changed to the same length as the circumference of three rounds of the transfer roller 422, it became "○" in all environments.

Through the above experiment, the inventors have come to be convinced that when the degree of wear of the transfer roller 422 is less than the threshold value, the length of the toner patch in the transport direction should be changed according to the temperature and humidity. rice field.

However, as can be seen from Table 1 and the like, it is not necessary to include both temperature and humidity as environmental conditions, and at least one of temperature and humidity may be detected as environmental conditions.

In this embodiment, when the degree of wear of the transfer roller 422 is less than the threshold value, that is, when the first toner patch 100A is used, the toner patch transfer direction is used by using the length setting table shown in Table 2. The length of is set.

In the length setting table shown in Table 2, numbers indicating the number of turns of the transfer roller 422 are described according to the temperature and humidity. For example, when "1" is described, the length is set to be the same as the circumference of one round of the transfer roller 422, and when "2" is described, the transfer roller is set. It is set to the same length as the circumference of two laps of 422, and in the environment where "3" is described, it is set to the same length as the circumference of three laps of the transfer roller 422.

By doing so, the length of the toner patch in the transport direction can be set to an appropriate length according to the environment of the image forming apparatus 10, and transfer unevenness can be effectively prevented.

The above-mentioned operation of the image forming apparatus 10 is realized by the CPU 80 executing a control program stored in the RAM 84. The specific processing will be described later using a flow chart.

FIG. 8 is an illustrated diagram showing an example of the memory map 300 of the RAM 84 shown in FIG. As shown in FIG. 8, the RAM 84 includes a program storage area 302 and a data storage area 304. As described above, the control program of the image forming apparatus 10 is stored in the program storage area 302 of the RAM 84. The control program includes an image formation program 302a, a wear degree detection program 302b, an environment detection program 302c, a toner patch setting program 302d, a toner patch formation program 302e, a toner concentration detection program 302f, and a process condition adjustment program 302g.

The image forming program 302a controls each component of the image forming apparatus 10 based on image data or the like input from an external computer to form a multicolored or monochromatic image on paper (executes a normal image forming process). It is a program for).

The wear degree detection program 302b is a program for detecting the wear degree of the transfer roller 422 according to the usage degree (use frequency) of the image forming apparatus 10. Specifically, the wear degree detection program 302b detects the wear degree of the transfer roller 422 according to the cumulative number of prints of the image forming apparatus 10 and the cumulative rotation speed of the transfer roller 422 from the unused state of the transfer roller 422. It is a program for.

The environment detection program 302c is a program for detecting the environment information of the image forming apparatus 10 according to the output of the environment detection unit 88. Specifically, the environment detection program 302c is for detecting the temperature and humidity inside the installation location of the image forming apparatus 10 or the device main body 12 according to the outputs of the temperature sensor and the humidity sensor included in the environment detection unit 88. It is a program.

The toner patch setting program 302d is a program for setting a toner patch (adjustment patch) to be used in the process condition adjustment process from among a plurality of types of toner patches 100 according to the degree of wear of the transfer roller 422. For example, the CPU 80 sets the first toner patch 100A when the degree of wear of the transfer roller 422 is lower than the threshold value according to the toner patch setting program 302d, and sets the first toner patch 100A when the degree of wear of the transfer roller 422 exceeds the threshold value. , Set the second toner patch 100B.

The toner patch forming program 302e is a program for controlling the image forming unit 30 (exposure unit 32 and developing unit 34) to form the toner patch 100 set as the adjustment patch on the photoconductor drum 36.

The toner density detection program 302f is a program for detecting the toner adhesion amount, that is, the toner density of the toner image (toner patch) on the photoconductor drum 36 according to the output of the toner density sensor 90.

The process condition adjustment program 302g adjusts various process conditions such as charge potential, exposure amount, and development potential according to the toner adhesion amount (or toner concentration according to the toner adhesion amount) of the toner patch on the photoconductor drum 36. It is a program for.

Although not shown, the program storage area 302 also stores programs for selecting and executing various functions of the image forming apparatus 10.

The data storage area 304 of the RAM 84 stores wear degree data 304a, environment data 304b, table data 304c, toner patch data 304d, adhesion amount data 304e, and the like.

The wear degree data 304a is data on the wear degree of the transfer roller 422 detected according to the wear degree detection program 302b. The wear degree data 304a is initialized when the transfer roller 422 is replaced. The environmental data 304b is data of environmental information (temperature and humidity) inside the installation location of the image forming apparatus 10 or the apparatus main body 12 detected according to the environmental detection program 302c. The table data 304c includes data such as a length setting table. The toner patch data 304d is image data corresponding to each toner image of the plurality of types of toner patches 100, and includes, for example, image data of the first toner patch 100A and image data of the second toner patch 100B. The adhesion amount data 304e is the toner concentration data of the toner patch on the photoconductor drum 36 detected according to the toner concentration detection program 302f.

Although not shown, the data storage area 304 is provided with a register necessary for executing the control program, or stores other data necessary for executing the control program.

FIG. 9 is a flow chart showing an example of the process condition adjustment process of the CPU 80 of the image forming apparatus 10. This process condition adjustment process is executed (started) at a predetermined timing, avoiding the time when the normal image forming process is executed. As shown in FIG. 9, when the CPU 80 starts the process condition adjustment process, the consumption degree of the transfer roller 422 (transfer body) is acquired (detected) in step S1, and the consumption degree of the transfer roller 422 is reduced in step S3. Determine if it is above the threshold.

If "YES" in step S3, that is, if it is determined that the degree of wear of the transfer roller 422 is equal to or higher than the threshold value, the second toner patch 100B is set as the adjustment patch in step S5, and step S13 is performed. move on.

On the other hand, if it is "NO" in step S3, that is, if it is determined that the degree of wear of the transfer roller 422 is less than the threshold value, the environmental information of the image forming apparatus 10 is acquired in step S7, and the environmental information of the image forming apparatus 10 is acquired in step S9. The first toner patch 100A is set as the adjustment patch, and in step S11, the length of the toner patch in the transport direction is set according to the environmental information of the image forming apparatus 10, and the process proceeds to step S13.

In step S13, the image forming unit 30 is controlled to form the set toner patch on the photoconductor drum 36, in step S15, the toner concentration of the toner patch on the photoconductor drum 36 is detected, and in step S17, the toner patch is detected. The process conditions are adjusted according to the toner concentration of the toner patch on the photoconductor drum 36, and the process condition adjustment process is completed.

In this embodiment, when the degree of wear of the transfer roller 422, which is greatly affected by toner stains due to the toner patch, is low, the first toner patch 100A whose width dimension is larger than the maximum paper size used in the image forming apparatus 10 is used. do. Therefore, the toner adheres to the entire transfer roller 422, and the surface resistance of the transfer roller 422 becomes substantially uniform. Therefore, even if the photoconductor drum 36 and the transfer roller 422 cannot be separated from each other, the process condition adjustment process is performed. It is possible to prevent transfer unevenness caused by.
[Second Example]
In the image forming apparatus 10 of the second embodiment, the type of toner patch and the first type of toner patch set in the adjustment patch according to the degree of wear of the transfer roller 422 until the degree of wear of the transfer roller 422 exceeds the threshold value. Since it is the same as the first embodiment except that the length of the toner patch is changed when the toner patch 100A is set, the contents different from those of the first embodiment will be described, and duplicated explanations will be omitted. do.

As described above, as the transfer roller 422 is used (as the degree of wear of the transfer roller 422 increases), the influence of toner stains due to the toner patch becomes smaller, so that the degree of wear of the transfer roller 422 is less than the threshold value. However, the length of the toner patch required to eliminate the transfer unevenness changes depending on the degree of wear of the transfer roller 422. Specifically, as the degree of wear of the transfer roller 422 increases, the length of the toner patch required to eliminate the transfer unevenness becomes shorter.

Further, even if the degree of wear of the transfer roller 422 is less than the threshold value, the first toner patch 100A may not be used depending on the degree of wear of the transfer roller 422 and the environment of the image forming apparatus 10 (second toner patch 100B, etc.). Even if you use), transfer unevenness may not occur. Specifically, if the degree of wear of the transfer roller 422 exceeds a predetermined ratio (for example, 50%) with respect to the threshold value and the environment is such that transfer unevenness is unlikely to occur (for example, low temperature or low humidity), the first step is made. 1 It is not necessary to use the toner patch 100A.

Therefore, in the second embodiment, even if the degree of wear of the transfer roller 422 is less than the threshold value, the type of toner patch and the first toner patch 100A are determined according to the degree of wear of the transfer roller 422 and the environment of the image forming apparatus 10. The length of the toner patch, if set, is set. The toner patch setting table shown in Table 3 is a table used when the degree of wear of the transfer roller 422 is 90% with respect to the threshold value.

In the toner patch setting table shown in Table 3, a number or "-" indicating the number of turns of the transfer roller 422 is described according to the temperature and humidity. When the environment is such that no numerical value is described (“-” is described) (when the degree of wear of the transfer roller 422 and the environment of the image forming apparatus 10 satisfy predetermined conditions (first condition)), the first toner It is not necessary to use patch 100A, and the second toner patch 100B is set as the adjustment patch. On the other hand, in an environment where numbers are described, the first toner patch 100A is set as the adjustment patch, and the length of the toner patch is the same as the circumference of the transfer roller 422 corresponding to the number. Set to length.

Hereinafter, the process condition adjustment process in the second embodiment will be described with reference to the flow chart. However, the same process as the process condition adjustment process described in the first embodiment is designated by the same reference numeral, and duplicated contents are described. , The explanation will be omitted or briefly explained.

FIG. 10 is a flow chart showing an example of the process condition adjustment process of the second embodiment. As shown in FIG. 10, when the CPU 80 starts the process condition adjustment process, the CPU 80 acquires the environmental information of the image forming apparatus 10 in step S7, and in step S31, the degree of wear of the transfer roller 422 and the image forming apparatus 10 of the image forming apparatus 10. Determine if the environment meets the first condition. Here, it is determined whether the degree of wear of the transfer roller 422 and the environment of the image forming apparatus 10 are the environment in which the first toner patch 100A needs to be used. If "YES" in step S31, the process proceeds to step S5, and if "NO" in step S31, the process proceeds to step S9.

Since the contents of the processes in steps S1 to S17 are the same as those in the first embodiment, the description thereof will be omitted.

According to the second embodiment, even if the degree of wear of the transfer roller 422 is less than the threshold value, the length of the toner patch required for eliminating the transfer unevenness becomes shorter as the degree of wear of the transfer roller 422 increases. It is possible to suppress the amount of toner consumed in the process condition adjustment process.

Further, according to the second embodiment, even if the degree of wear of the transfer roller 422 is less than the threshold value, the first toner patch 100A is satisfied when the degree of wear of the transfer roller 422 and the environment of the image forming apparatus 10 satisfy predetermined conditions. Since the second toner patch 100B is set without setting, the toner consumption in the process condition adjustment process can be suppressed.
[Third Example]
The image forming apparatus 10 of the third embodiment adjusts the process conditions using the first toner patch 100A when the predetermined condition (second condition) is satisfied even when the wear degree of the transfer roller 422 is equal to or higher than the threshold value. Since it is the same as the first embodiment except that the processing is carried out, the contents different from those of the first embodiment will be described, and the duplicated description will be omitted.

When a predetermined number of images having a low printing rate are continuously printed, the toner remaining on the surface of the photoconductor drum 36 may slip through the cleaning blade of the cleaner unit 38. If the toner on the photoconductor drum 36 slips through the cleaning blade, it causes an image defect.

In order to solve such a problem, in the third embodiment, after the transfer roller 422 is consumed to a predetermined number or more and is changed to the second toner patch 100B, a predetermined number of images with a low print rate (for example, 100 sheets) are displayed. ) A process using the first toner patch 100A instead of the second toner patch 100B even if the degree of wear of the transfer roller 422 is equal to or higher than the threshold value in the case of continuous printing (when the second condition is satisfied). Condition adjustment processing is executed. However, the low print rate means that the print rate is 3 to 5% or less.

In the third embodiment, after changing to the second toner patch 100B, when a predetermined number of images having a low print rate are continuously printed, the process condition adjustment process using the first toner patch 100A is executed. Therefore, when the process condition adjustment process using the first toner patch 100A is executed, the toner on the photoconductor drum 36 is less likely to slip through the cleaning blade, and the occurrence of image defects can be suppressed.

In the above embodiment, the case where the toner patch 100 (the first toner patch 100A and the second toner patch 100B) is a solid image has been described as an example, but the present invention is not limited to this. For example, the toner patch 100 may be a toner image for halftone adjustment (less than 100% and an arbitrary density). Even in this case, transfer unevenness due to the process condition adjustment process can be prevented as in the above embodiment.

Further, in the above embodiment, the first toner patch 100A is used when the degree of wear of the transfer roller 422 is lower than the threshold value, and the second toner patch 100B is used when the degree of wear of the transfer roller 422 exceeds the threshold value. However, it does not have to be limited to this. For example, the process condition adjustment process may be started using the first toner patch 100A first, and then the width dimension of the toner patch may be continuously changed to the size of the second toner patch 100B. In this case, it is desirable that the length from the tip of the toner patch to the change of the width dimension be set to a length equal to or longer than the peripheral length of the transfer roller 422.

Further, in addition to the first toner patch 100A and the second toner patch 100B, the toner patch 100 has a width smaller than the width dimension W1 of the first toner patch 100A and a width wider than the width dimension W2 of the second toner patch 100B. It may contain one or more types of toner patches having a large size. In this case, the first toner patch 100A may be selected when the transfer roller 422 is in an unused state, and a type of toner patch having a smaller width dimension may be selected as the degree of wear of the transfer roller 422 increases. That is, three or more toner patches in which the width dimension W is set to be gradually reduced according to the degree of wear of the transfer roller 422 may be used.

Furthermore, in the above embodiment, the image forming apparatus 10 is configured as a monochrome multifunction device, but the image forming apparatus of the present invention may be configured as a color printing machine or a color multifunction device. In this case, for example, for each color of Y (yellow), M (magenta), C (cyan), K (black), an image forming station including a photoconductor drum 36, a charging unit 40, a developing unit 34, and the like is configured. An intermediate transfer belt and a transfer roller (secondary transfer roller) are provided. The intermediate transfer belt is provided so as to be in contact with the photoconductor drum 36 of each image forming station, and the toner images of each color formed on each photoconductor drum 36 are sequentially superimposed on the intermediate transfer belt and transferred to the intermediate. A multicolored toner image is formed on the transfer belt. Further, when the paper passes through the nip area (transfer nip portion) between the intermediate transfer belt and the transfer roller, the toner image formed on the intermediate transfer belt is transferred to the paper. In the case of a color printing machine or a color multifunction device, the toner density control process is executed for each image station (for each color).

Further, the specific configuration and the like given in the above-described embodiment are examples, and can be appropriately changed according to the actual product. Furthermore, the order in which each step of the flow chart shown in the above-described embodiment is processed can be appropriately changed as long as the same result can be obtained.

10 ... Image forming device 36 ... Photoreceptor drum 70 ... Developing roller 100 ... Toner patch

Claims (9)

Image carrier,
A transfer body that abuts on the image carrier and forms a transfer nip portion between the image carrier and the image carrier.
A first toner patch having a first width dimension in the axial direction of the transfer body and a second toner patch having a second width dimension smaller than the first width dimension in the axial direction of the transfer body are included. A storage means for storing toner patch data for adjusting image formation conditions,
A wear degree detecting means for detecting the wear degree of the transfer body,
When the degree of wear of the transfer body is less than a predetermined threshold value, the first toner patch is set as an adjustment patch, and when the degree of wear of the transfer body is equal to or higher than a predetermined threshold value, the second toner patch is used. Toner patch setting means to set as an adjustment patch,
A toner patch forming means for forming the adjusting patch on the image carrier,
A toner concentration detecting means for detecting the amount of toner adhered to the adjusting patch formed on the image carrier, and an adjusting means for adjusting the image forming conditions according to the amount of toner adhered to the adjusting patch are provided. , Image forming device. Further provided with a length setting means for setting the length of the first toner patch in the transport direction is provided.
The image forming apparatus according to claim 1, wherein the length setting means sets the length of the first toner patch in the transport direction to a length equal to or larger than the peripheral length of the transfer body. Further provided with environmental information detecting means for detecting environmental information regarding the main body of the device and at least one of the temperature and humidity of the main body of the device.
The image forming apparatus according to claim 2, wherein the length setting means sets the length of the first toner patch in the transport direction according to the environmental information. The image forming apparatus according to claim 3, wherein the length setting means sets the length of the first toner patch in the transport direction as the temperature and humidity of the apparatus main body increase. The image forming apparatus according to any one of claims 1 to 4, wherein the first toner patch includes a toner patch for adjusting halftones. The toner patch setting means sets the first toner patch as the adjustment patch when a predetermined number of images having a low print rate are continuously printed after the second toner patch is set. The image forming apparatus according to any one of 1 to 5. The image forming apparatus according to any one of claims 1 to 6, wherein the first width dimension is larger than the size of the maximum recording medium, and the second width dimension is smaller than the size of the maximum recording medium. .. An image carrier, a transfer body that abuts on the image carrier and forms a transfer nip portion between the image carrier, a first toner patch having a first width dimension in the axial direction of the transfer body, and the transfer. An image forming apparatus comprising a storage means for storing data of a toner patch for adjusting image forming conditions, including a second toner patch having a second width dimension smaller than the first width dimension in the axial direction of the body. It is a control program of
To the processor of the image forming apparatus
A process for detecting the degree of wear of the transcript,
When the degree of wear of the transfer body is less than a predetermined threshold value, the first toner patch is set as an adjustment patch, and when the degree of wear of the transfer body is equal to or higher than a predetermined threshold value, the second toner patch is used. Processing to set as a patch for adjustment,
The process of forming the adjustment patch on the image carrier,
A control program for executing a process of detecting the amount of toner adhered to the adjusting patch formed on the image carrier and a process of adjusting the image forming conditions according to the amount of toner adhered to the adjusting patch. .. An image carrier, a transfer body that abuts on the image carrier and forms a transfer nip portion with the image carrier, a first toner patch having a first width dimension in the axial direction of the transfer body, and the above. Image forming with a storage means for storing toner patch data for adjusting image forming conditions, including a second toner patch having a second width dimension smaller than the first width dimension in the axial direction of the transfer body. It ’s a device control method.
(A) Step of detecting the degree of wear of the transcript,
(B) The first toner patch is set as an adjustment patch when the degree of wear of the transfer body is less than a predetermined threshold value, and the second toner is used when the degree of wear of the transfer body is equal to or higher than a predetermined threshold value. Steps to set the patch as the adjustment patch,
(C) The step of forming the adjustment patch on the image carrier,
(D) A step of detecting the amount of toner adhered to the adjusting patch formed on the image carrier, and (e) a step of adjusting the image forming conditions according to the amount of toner adhered to the adjusting patch. Control methods, including.

Images