JP2010122377A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To select the output frequency and density stability of a test sheet based on user's demand. <P>SOLUTION: The image forming apparatus includes: an image-forming means 170 which forms and outputs an image; a storage part 105 in which data on the test sheet including a plurality of patches having predetermined density and data on a sample sheet including patches for setting an allowable density variation range are stored; a sensor 190s which detects density of the patch on the test sheet or the sample sheet; a setting means 103 which sets an allowable density variation range in image formation based on the sample sheet; and a control means 101 which decides the number of image forming sheets (specified number of image forming sheets) by which the test sheet is output in accordance with the set value of the allowable density variation range which has been set, and allows the image-forming means to form an image of the test sheet in timing to achieve the specified number of image forming sheets and controls an image forming condition based on a result of detection obtained by detecting the density of the patch on the test sheet by the sensor. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more particularly to an image forming apparatus that controls the image forming conditions by detecting the density of a patch formed on a recording sheet with a sensor.

  An electrostatic latent image is formed on the image carrier based on the image data, and the electrostatic latent image is developed with a developer (toner) to generate a visible image (toner image). The image is transferred from the image carrier to recording paper (recording paper) by the transfer current from the transfer means, the recording paper and the image carrier are separated by the separation current from the separating means, and the recording paper on which the toner image is placed is heated. There is an image forming apparatus that forms an image by fixing with pressure.

  In such an image forming apparatus, an image having an appropriate density is formed by controlling various parameters of image forming conditions. Here, transfer conditions exist as one of the image forming conditions.

  That is, by applying a transfer current from the transfer means to the image carrier and the recording paper, the toner image is transferred to the recording paper, and the ratio of the toner transferred to the recording paper varies depending on the current value of the transfer current. To do. Also, the transfer efficiency depends on the size, thickness, material, temperature, humidity, amount of toner charge on the photoconductor, amount of toner adhesion, dirt on the transfer means, moisture content of the recording paper, It is known to change depending on the contact state with the photoconductor, the rotation speed of the photoconductor, the conveyance speed of the recording paper, etc., and it is necessary to make adjustments in consideration of these various conditions. It is difficult to adjust to the value.

For this reason, a reference density and a plurality of densities to be compared with the reference density are printed on a chart called a sample sheet, the user views the sample sheet, and the user selects a density close to the reference density from the sample sheet. It is described in the following patent document 1 etc. to perform appropriate γ curve correction.
JP2001-130056

In the printer, the density slightly changes even if an image based on the same image data is printed due to a change with time and a change in environmental conditions caused by overlapping the number of formed images.
Therefore, every time hundreds of prints are printed, or every time the temperature and humidity change greatly, the reference density patch is printed on the test sheet, the density is measured, and the laser power and γ ( Gamma) characteristics and the like were corrected to ensure density stability.

  If the density adjustment cycle by reading the test sheet is shortened, the density becomes more stable, but the consumption of the test sheet (recording paper) increases, and the productivity is lowered because the normal image formation is temporarily stopped.

  On the other hand, if the density adjustment cycle by reading the test sheet is lengthened, the consumption of the test sheet (recording paper) is reduced, and the frequency of temporarily suspending normal image formation is reduced, but the density stability may not be ensured.

  Conventionally, there has been a printer in which the user can set the density adjustment cycle. Although this method can grasp the consumption of the test sheet in advance, there is no way to know in advance how much the density is stabilized.

  Some printers automatically determine the next density adjustment execution time based on the amount of deviation between the reference patch density and the reference value, but this is only ensuring the density stability that the manufacturer assumed, and it is somewhat Even if the stability is lowered, it has not been able to meet the needs of users who want to reduce test sheet consumption or improve productivity.

  Further, in Patent Document 1 described above, the reference density and a plurality of densities to be compared with the reference density are printed on the sample sheet, and the user selects a density close to the reference density to perform appropriate γ curve correction. This is an invention for obtaining a more accurate concentration more strictly, and does not solve the above-mentioned problem.

  The present invention has been made to solve the above-described problems, and realizes an image forming apparatus capable of selecting the output frequency and density stability of a test sheet based on a request of a user of the image forming apparatus. For the purpose.

The present invention for solving the problems is configured as follows.
(1) According to the first aspect of the present invention, there is provided an image forming means for forming and outputting an image according to data on a recording sheet, test sheet data including a plurality of patches having a predetermined density, and setting an allowable density fluctuation range. Storage means for storing data of a sample sheet including a patch, a sensor for detecting the density of the patch on the test sheet or the sample sheet, and an allowable density variation range at the time of image formation based on the sample sheet Determining the number of images formed (specified image forming number) for outputting the test sheet according to the set value of the allowable density variation range set by the setting means, and determining the specified image forming number The test sheet is caused to form an image on the image forming means based on the data stored in the storage means at the timing of An image forming apparatus characterized by and a control unit for controlling the image forming conditions based on the obtained detection results obtained by detecting the density of the patches on over preparative by the sensor.

  (2) According to the second aspect of the present invention, the image forming means for forming and outputting an image according to the data on the recording paper, the data of the test sheet including a plurality of patches having a predetermined density, and the allowable density fluctuation range setting Storage means for storing data of a sample sheet including a patch, a sensor for detecting the density of the patch on the test sheet or the sample sheet, and an allowable density variation range at the time of image formation based on the sample sheet A setting unit configured to determine a specified temperature change for outputting the test sheet according to a set value of the allowable density fluctuation range set by the setting unit, and the storage at a timing when the specified temperature change occurs Based on the data stored in the means, the test sheet is caused to form an image by the image forming means, and the package on the test sheet is formed. And control means for controlling said image forming condition based on the obtained detection results obtained the concentration is detected by the sensor is an image forming apparatus comprising the.

  (3) In the invention according to claim 3, the control means accepts resetting of the allowable density fluctuation range from the setting means, and based on the resetting, determines the prescribed image forming number or the prescribed temperature change. The image forming apparatus according to claim 1, wherein the image forming apparatus is re-determined.

  (4) In the invention according to claim 4, the control means refers to a detection result obtained by detecting the density of the patch on the test sheet by the sensor, and the detection result is the allowable density fluctuation range. 4. The image forming apparatus according to claim 1, wherein the image forming operation is stopped when the value exceeds the threshold value. 5.

  (5) In the invention according to claim 5, the control means controls to form an image of data input from the outside in the same condition as the patch in an area other than the patch on the sample sheet. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

  (6) In the invention described in claim 6, the image forming unit is configured to form a color image by using a plurality of colors of recording materials, and the sensor is configured such that the density of each patch of each of the plurality of colors of the recording material. The image forming apparatus according to claim 1, wherein the image forming apparatus detects an image of the image forming apparatus.

  (7) In the invention according to claim 7, a paper type of the recording paper for forming the sample sheet or a tray in which the recording paper for forming the sample sheet is stored is determined, and the information on the paper type or the tray is defined. Is stored in the storage means, and the control means selects and feeds the recording paper for forming the sample sheet and the test sheet according to the paper type or the tray information stored in the storage means. The image forming apparatus according to claim 1, wherein the image forming unit causes the sample sheet and the test sheet to be formed and output.

According to the present invention, the following effects can be obtained.
(1) In the first aspect of the invention, first, the control means determines the output timing of the test sheet (the number of prescribed image formations) according to the set value of the allowable density fluctuation range set by the user in the setting means. To do. The control unit causes the image forming unit to form an image based on the data stored in the storage unit at the determined output timing. Furthermore, the control means controls the image forming conditions based on the detection result obtained by detecting the density of the patch on the test sheet with the sensor.

  In this way, the allowable density fluctuation range desired by the user is set, and the test sheet is output at the timing based on this allowable density fluctuation range (the number of prescribed image formations), so the test sheet (recording paper) consumption is wasted. In addition, it is possible to eliminate the problem that productivity is reduced by frequently temporarily stopping normal image formation in order to output a test sheet.

  In addition, in this way, the allowable density fluctuation range desired by the user is set, and the test sheet is output at a timing (specified number of images formed) based on this allowable density fluctuation range, so that the density stability is within the range desired by the user. Is kept stable.

As a result, it is possible to realize an image forming apparatus that can select the output frequency and density stability of the test sheet based on the user's request (allowable density fluctuation range).
(2) In the invention described in claim 2, first, the control means determines the specified temperature change value for outputting the test sheet in accordance with the set value of the allowable density fluctuation range set by the user in the setting means. . The control means causes the image forming means to form an image on the test sheet based on the data stored in the storage means when the determined specified temperature change occurs. Furthermore, the control means controls the image forming conditions based on the detection result obtained by detecting the density of the patch on the test sheet with the sensor.

  In this way, the allowable density fluctuation range desired by the user is set, and the test sheet is output at the timing (specified temperature change) based on the allowable density fluctuation range, so the test sheet (recording paper) consumption is wasted. In addition to not increasing, it is possible to solve the problem that normal image formation is frequently temporarily stopped to output a test sheet, thereby reducing productivity.

  In addition, since the allowable density fluctuation range desired by the user is set and the test sheet is output at a timing (specified temperature change) based on this allowable density fluctuation range, the density stability is within the range desired by the user. It is kept stable.

As a result, it is possible to realize an image forming apparatus capable of selecting a specified temperature change value and density stability for outputting a test sheet based on a request (allowable density fluctuation range) of the user of the image forming apparatus.
(3) In the invention according to claim 3, the control means accepts resetting of the allowable density fluctuation range from the setting means, and based on the resetting, resets the output timing (specified image forming number) or specified temperature change. decide.

  As a result, based on the request of the user of the image forming apparatus (resetting of the allowable density fluctuation range), an image for which the test sheet output timing (specified image forming number and specified temperature change value) and density stability can be selected. A forming apparatus can be realized.

  (4) In the invention described in claim 4, the control means refers to the detection result obtained by detecting the density of the patch on the test sheet with the sensor, and the detection result exceeds the allowable density fluctuation range. In this case, by stopping the image forming operation, it is possible to prevent the output of an image with poor image quality and to maintain the density stability when the density fluctuation exceeds a predetermined level. That is, when the density fluctuation range allowable by the user is exceeded, it is possible to minimize the number of printing rework steps and waste paper.

  (5) In the invention according to claim 5, the control means controls to form an image of data input from the outside in an area other than the patch on the sample sheet under the same image forming conditions as the patch, It is possible to confirm the allowable density fluctuation range using an image suitable for the use situation of the user, and it is possible to maintain good density stability.

  (6) In the invention described in claim 6, the image forming means is configured to form a color image with a recording material of a plurality of colors, and the sensor detects the density of each patch of the plurality of colors of the recording material. Thus, it is possible to effectively eliminate density fluctuation (that is, color shift) of each color when forming a color image.

  (7) In the invention according to claim 7, the control means selects and feeds the recording paper for forming the sample sheet and the test sheet in accordance with the paper type or tray information stored in the storage means, and supplies the image forming means. Since the chart is imaged and output every time a test sheet is output, density fluctuation prevention control can be executed using an appropriate recording paper under the same conditions as the sample sheet, so that density stability can be maintained over a long period of time. It becomes possible to keep good. In addition, the image density can be strictly stabilized within a density fluctuation range that is acceptable to the user.

The best mode (embodiment) for carrying out the present invention will be described below in detail with reference to the drawings.
[Configuration of Embodiment]
Here, the configuration of the image forming apparatus 100 of the first embodiment will be described in detail based on FIG. 1 (block diagram) to FIG. 2 (cross-sectional configuration diagram).

In FIG. 1 and FIG. 2, descriptions of general portions that are known and are not directly related to the characteristic operation and control of the present embodiment are omitted.
In the image forming apparatus 100, the control unit 101 is a control unit configured by a CPU or the like for controlling each unit of the image forming apparatus 100, and a set value of an allowable density fluctuation range set by a setting unit such as an operation unit. The output timing of a predetermined test sheet is determined in accordance with the test sheet, and the test sheet is formed on the image forming means based on the data stored in the storage unit at the output timing, and the density of the patch on the test sheet is detected by the sensor. The function of controlling the image forming conditions based on the detection result obtained by the detection in step S1.

  The operation unit 103 is used by an operator of the image forming apparatus to perform various operation inputs, and is provided with various switches and keys. The operation unit 103 constitutes setting means for setting an allowable density fluctuation range in the claims.

  The storage unit 105 is a storage unit that stores various types of data. In this embodiment, sample sheet data used for setting an allowable density variation range under image forming conditions, and patch density used when controlling the image forming conditions. And patterns, set values for the allowable density fluctuation range, test sheet output timing, various data during control, and the like.

  The image processing unit 110 executes image processing for bringing the image data to be imaged into a state suitable for image formation. Further, based on the data stored in the storage unit 105, image processing for generating (image development) of the sample sheet or test sheet is also performed when forming an image of the sample sheet or test sheet.

The paper feed unit 150 is a paper feed unit that feeds the recording paper placed on a plurality of paper feed trays 150T to the image forming position by a paper feed roller.
The transport unit 160 is a transport unit that transports the recording paper fed from the paper feed unit 150 at a predetermined transport speed, and includes a registration roller, various other transport rollers, a transport belt, and the like. In addition, a conveyance sensor 160s such as a leading edge detection sensor that detects the leading edge of the recording paper is disposed at a predetermined position of each part of the conveyance unit 160.

  The process unit 170 is a means for executing various operations for forming an image on recording paper. The process unit 170 is a charging unit 171 that charges the photosensitive member unit with a predetermined charge, an exposure unit 172 that exposes the photosensitive member unit according to image data, and an exposure unit. The electrostatic latent image is formed on the photosensitive member 173, the developing unit 174 that develops the electrostatic latent image on the photosensitive member 173 and converts it into a toner image, and the toner image on the photosensitive member 173 is transferred to the toner image. Are provided with an intermediate transfer member 175 as an image carrier for supporting the transfer member 175, and a transfer unit 176 having a transfer roller 176a and a transfer roller 176b.

  When the image forming apparatus is a color image forming apparatus that combines toner images of a plurality of colors, as shown in FIG. 2, in the process unit 170, a charging unit 171, an exposure unit 172, a photoconductor unit 173, and a development unit. The units 174 are provided corresponding to the respective colors, and are configured such that the toner images of the respective colors are superimposed on the intermediate transfer member 175 and finally transferred onto the recording paper.

The fixing unit 180 pinches and conveys the recording paper onto which the toner image has been transferred, and executes fixing by heating and pressurization to make the toner image stable on the recording paper.
As shown in FIGS. 3 and 4, the sensor 190 s reads the density of the patch of the sample sheet or the test sheet as a toner image fixed on the recording paper on the downstream side of the fixing unit 180.

  In the above configuration, the image forming apparatus has a printer function and a copying function using a scanner unit (not shown). Further, a facsimile transmission / reception function may be provided using a transmission / reception function (not shown).

Upon operation of the printer function, the control unit 101 that has received a print instruction from a host computer (not shown) issues an image development instruction to the image processing unit 110 and issues a print operation start instruction to each unit.
On the other hand, during the copying function operation, the control unit 101 is notified that the copy button of the operation unit 103 has been pressed. Give each instruction.

  FIG. 4 is a perspective view showing how the respective color sensors 190 sY, 190 sM, 190 sC, and 190 sK read the YMCK color patches in the case of color image formation. In FIG. 4, a holding mechanism that holds each sensor and a moving mechanism that moves the sensor are omitted.

  Details of the configuration of the sensor 190s are shown in FIG. Here, the sensor 190 s includes a light source 1901 such as an LED, a lens 1902 that collects reflected light, and a light receiving unit 1903 that detects light collected by the lens 1902. Here, the distance between the lens 1902 and the light receiving unit 1903 is set equal to the focal length (f) of the lens 1902.

  In the case of a color image forming apparatus, as the sensor 190s, the density of each color patch of YMCK is read. However, the color sensor corresponding to each color may read each color, or each color patch. May be read as a density by a monochrome sensor.

  Since the wavelength of the reflected light differs depending on the color of the toner, the detection capability is increased by changing the wavelength of the light source and increasing the amount of reflection. That is, when using a color sensor, as shown in FIG. 3B, the yellow patch is illuminated with a complementary blue LED and read with a yellow sensor, and the magenta patch is illuminated with a complementary green LED and read with a magenta sensor. The cyan patch is illuminated with a complementary red LED and read with a cyan sensor, and the black patch is illuminated with a red LED and read with a monochrome density sensor.

  Further, a position-movable backup roller 190br is arranged so that the patch of the chart can be read at a predetermined position (reference distance (d) in FIG. 3A) where position accuracy is maintained as a position read by the sensor 190s. Yes. Here, in a state where the backup roller 190br is raised, the recording paper P or the chart can be read at a predetermined position where the positional accuracy is maintained.

  Here, the control unit 101 instructs image formation of a test sheet having a predetermined patch once for a predetermined number of prints (for example, about several hundreds of prints) to be described later, and detects the timing at which the chart passes the sensor 190s. Using the sensor 160s, etc., the toner density of each color patch is measured and the density correction is performed using the sensor 160s. The density correction method will be described later.

  For example, in the case of yellow, a plurality of patches whose density is changed stepwise from yellow patch 1 in the lightest density area to yellow patch N where the density is the darkest are printed on a chart, and the density of each patch is measured by the color sensor 190sY. The γ curve is corrected based on the amount of deviation between each density reference value and the current density. If the overall density is low or high, the overall density characteristics are corrected by changing the laser power or changing the development conditions.

[Operation of Embodiment]
Hereinafter, the operation of the characteristic part of the image forming apparatus of the present embodiment will be described with reference to the flowchart of FIG.

Therefore, a general image forming process (latent image formation by charging / exposure, development, transfer, fixing, etc.) is omitted.
In this embodiment, a patch having a predetermined density is formed when a predetermined number of image formations (a predetermined number of image formations to be described later) or a predetermined temperature change (a predetermined temperature change to be described later) is reached. The test sheet is imaged and output, and the image forming condition is controlled based on the detection result obtained by reading the test sheet with the sensor 190s. A sheet (chart) having a predetermined patch used at this time is called a test sheet. An example of this test sheet is shown in FIG.

  On the other hand, a predetermined patch or color sample is similarly formed, and a sheet (chart) on which an image is formed in order to set an allowable range of density fluctuation and color misregistration after being visually recognized by a user is referred to as a sample sheet. Call.

  First, in the operation unit 103, an instruction to output a sample sheet is given to the user (step S1 in FIG. 5). For example, assuming that the normal operation screen is as shown in FIG. 6, the user presses the switch or icon of the sample sheet output (FIG. 6 (1)).

  In response to the operation of the operation unit 103, the control unit 101 reads sample sheet data from the storage unit 105, develops the image in the image processing unit 110, and the process unit 170 converts the sample sheet toner image to the intermediate transfer body 175. The toner image is transferred from the intermediate transfer member 175 via the transfer unit 176 onto the recording paper P formed from the paper supply unit 150.

  Further, the control unit 101 fixes the toner image on the recording paper P by the fixing unit 180, and causes the sensor 190s to detect the sample sheet on the recording paper P. Then, the detection result by the sensor 190s of the reference density and density variation patch density of each color of the sample sheet is stored in the storage unit 105 (step S2 in FIG. 5).

  An example of patches and images formed on the sample sheet is shown in FIG. The image formed on this sample sheet sets the allowable density fluctuation range of the user, and is as follows, for example.

  It should be noted that here, it is possible to distinguish between a user who has a general demand for density fluctuation, a user who has a loose demand for density fluctuation, and a user who has a severe demand for density fluctuation. It is desirable to form patches and color samples with slightly shifted densities as follows.

  For Y, a Y-sample (PY) with multiple densities before and after a predetermined reference density slightly shifted from the predetermined reference density. (CLY) In the same manner as the Y color sample, the Y density is changed in the same manner as the Y patch, and the other colors MCK are Y sample images (PicY) with reference densities.

  As for M, M patches (PM) having a plurality of densities before and after a predetermined reference density slightly shifted from the predetermined reference density, and the M density is changed in the same manner as the M patch, and the other color YCK is an M color sample near gray which is set to the reference density. (CLM) is an M sample image (PicM) in which the M density is changed in the same manner as the M patch and the other color YCK is set to the reference density in the same manner as the M color sample.

  For C, a C density sample (PC) having a plurality of densities before and after the predetermined reference density is slightly shifted from the predetermined reference density, the C density is changed in the same manner as the C patch, and the other colors YMK are C color samples near gray which are set to the reference density. (CLC) Similar to the C color sample, the C density is changed in the same way as the C patch, and the other colors YMK are C sample images (PicC) with reference densities.

  For K, a K density sample near the gray, where the density is slightly different from the predetermined reference density and the density is changed by a plurality of density K patches (PK). (CLK) Similar to the K color sample, the K density is changed in the same manner as the K patch, and the other colors YMC are K sample images (PicK) with the reference density.

Note that the YMCK sample image may be a reduced image of an image set by the user, or may be a sample photographic image held in advance in the image forming apparatus.
In addition, here, the reference density is “0” and the density before and after the reference density is “3”, “2”, “1”, “0”, “1”, “2”, “3”, etc. It is desirable that the mark is attached.

  Then, the user views the patch, color sample, and sample image of the sample sheet, and accepts an allowable density fluctuation (allowable density fluctuation range) via a setting screen (see FIG. 7) displayed by the control of the control unit 101. Thus, numerical values (0, 1, 2, 3) can be input from the operation unit 103.

  It should be noted that the use of a color sample rather than a single color patch can show the state of color shift due to density fluctuation. Further, in the case of a sample image, there is an advantage that it is easy to specify an appropriate density fluctuation range in a situation close to that used by the user.

  Note that this sample sheet may not only form an image on a single sheet, but may also be divided and output on a plurality of sheets. In the case of outputting a plurality of sheets, it is possible to print a large sample image, and there is an advantage that it is easier to specify the density fluctuation range.

  When the user sets the allowable density fluctuation range by operating the operation unit 103, the user presses the sample sheet setting in FIG. In response to this, the control unit 101 displays the allowable density fluctuation range setting screen of FIG. 7 on the operation unit 103.

  When the user sets the allowable density fluctuation range numerically with reference to the sample sheet using the operation screen of FIG. 7 (steps S3 and S4 in FIG. 5), the control unit 101 stores the set allowable density fluctuation range. The data is stored in the unit 105 (step S5 in FIG. 5).

  In the sample sheet setting screen shown in FIG. 7, the user can designate a paper feed tray in which recording paper is stored when the sample sheet is output. Here, the recording paper designated as the sample sheet is also used for image formation output of a test sheet output at a predetermined timing described later. Here, if the user designates a tray used for normal printing as a sample sheet, the test sheet is preferably the same as normal recording paper.

  Note that when printing is temporarily stopped at a certain time during printing and a test sheet is output, the test sheet is normally fed from the tray specified in item 1 in FIG. If the paper type or the amount of paper in the tray has been changed from when the sample sheet was output, the control unit 101 feeds the test sheet from the tray in which the same paper type and amount of paper as the sample sheet are stored. Similarly, when the tray designated in item 1 is out of paper, the control unit 101 feeds a test sheet from a tray containing the same paper type and amount as the sample sheet.

  When the allowable density fluctuation range is set as described above, the control unit 101 changes the specified number of sheets to be formed corresponding to the timing of outputting the test sheet or the specified temperature change according to the allowable density fluctuation range. It is determined and stored in the storage unit 105 (step S6 in FIG. 5).

  Here, “the number of prescribed image formations” is the number of image formations that means how many prints a test sheet is output once. The relationship between the allowable density fluctuation range and the prescribed image forming number is, for example, 500 prints at level 1 (strict tolerance), 2000 prints at level 2 (normal tolerance), and 5000 prints at level 3 (loose tolerance).

  Here, the “specified temperature change” is a temperature change that means how many times the temperature change from the output of the sample sheet reaches the test sheet. As an example, the relationship between the allowable density fluctuation range and the prescribed number of image formation sheets is, for example, level 1 (strict tolerance) ± 3 ° C., level 2 (normal tolerance) ± 5 ° C., level 3 (loose tolerance). ± 10 ° C.

  Here, the three stages are loose and usually severe, but may be defined as two stages, four stages or more. In addition, as the prescribed image formation number and the prescribed temperature change, it is possible to preliminarily store in the storage unit 105 for a loose case and a severe case with reference to the normal prescribed prescribed image formation number and the prescribed temperature change. Good.

  Further, instead of the prescribed image formation number and the prescribed temperature change, a prescribed humidity change, a prescribed power supply voltage change, and the like may be provided. Also, instead of using the specified number of images to be formed, the specified temperature change, the specified humidity change, the specified power supply voltage change, etc. alone, a control is used to output a test sheet when any of the conditions is reached. It may be. In the flowchart of FIG. 5, the description will be continued with the specific image forming number as a specific example.

  When the above setting of the allowable density fluctuation range is completed and normal image formation is started (step S7 in FIG. 5), the control unit 101 counts the number of formed images (steps S8 and S9 in FIG. 5). ).

  When the specified number of image formations has been reached (YES in step S9 in FIG. 5), the control unit 101 reads the test sheet image data from the storage unit 105 and executes the test sheet image formation (in FIG. 5). Step S10). Note that it is desirable to perform this test sheet image formation at the timing when the ongoing job is completed.

Then, the control unit 101 causes the sensor 190s to detect each patch on the test sheet (step S11 in FIG. 5).
Here, the result of detection by the sensor 190s of the density of each color patch on the test sheet is compared with the original density value, and if it is within the set allowable density fluctuation range (YES in step S12 in FIG. 5), the density. Image forming conditions such as γ correction are controlled so as to return to the original density at the time when the sample sheet is output after the fluctuation is eliminated (step S13 in FIG. 5). If the density fluctuation is within the set allowable density fluctuation range (YES in step S12 in FIG. 5) and the density fluctuation is extremely small, it is not necessary to control the image forming conditions.

  Also, here, the result of detection by the sensor 190s of the density of each color patch on the test sheet is compared with the original density value, and if it exceeds the set allowable density fluctuation range (NO in step S12 in FIG. 5). ) Since there is a possibility that some trouble has occurred, the control unit 101 stops the image forming operation, displays a warning message such as a message for calling a service person on the operation unit 103, and stops the error of the image forming apparatus. (Step S14 in FIG. 5).

[Effect obtained in the embodiment]
As described above, the allowable density fluctuation range desired by the user is set, and the test sheet is output at the timing (the number of prescribed image formations) based on the allowable density fluctuation range. In addition to the unnecessary increase, it is possible to solve the problem that the normal image formation is frequently paused in order to output the test sheet, thereby reducing the productivity. In addition, in this way, the allowable density fluctuation range desired by the user is set, and the test sheet is output at a timing (specified number of images formed) based on this allowable density fluctuation range, so that the density stability is within the range desired by the user. Is kept stable. As a result, it is possible to realize an image forming apparatus that can select the output frequency and density stability of the test sheet based on the user's request (allowable density fluctuation range).

  In addition, as described above, an allowable density fluctuation range desired by the user is set, and a test sheet is output at a timing (specified temperature change) based on the allowable density fluctuation range. Can be eliminated, and normal image formation is frequently paused to output a test sheet, thereby reducing the productivity. In addition, since the allowable density fluctuation range desired by the user is set and the test sheet is output at a timing (specified temperature change) based on this allowable density fluctuation range, the density stability is within the range desired by the user. It is kept stable. As a result, it is possible to realize an image forming apparatus capable of selecting a specified temperature change value and density stability for outputting a test sheet based on a request (allowable density fluctuation range) of the user of the image forming apparatus.

  In the flowchart of FIG. 5, the allowable density fluctuation range is set first, but the user calls the operation screen of FIG. 6 or 7 at an arbitrary timing to reset the allowable density fluctuation range. Can be done. As a result, based on the request of the user of the image forming apparatus (resetting of the allowable density fluctuation range), the test sheet output timing (specified image forming number and specified temperature change value) and density stability can be selected. A forming apparatus can be realized.

  Further, the control unit 101 refers to the detection result obtained by detecting the density of the patch on the test sheet with the sensor 190s, and when the detection result exceeds the allowable density fluctuation range (step S12 in FIG. 5). NO), the image forming operation is stopped (step S14 in FIG. 5), thereby preventing the output of an image with poor image quality and maintaining the density stability when the density fluctuation exceeds a predetermined level. Is possible. That is, when the density fluctuation range allowable by the user is exceeded, it is possible to minimize the number of printing rework steps and waste paper.

  Further, in the above embodiment, an image of data input from the outside by the user in an area other than the patch on the sample sheet or an image stored in advance and selected by the user is the same image as the patch. By controlling to form under the forming conditions, it is possible to confirm the allowable density fluctuation range using an image suitable for the use situation of the user, and it is possible to maintain good density stability.

  In the above embodiment, a color image forming apparatus has been described as a specific example. However, the present invention can be similarly executed when an image is formed with a color other than YMCK (two colors or five colors or more). Further, even monochrome image formation can be executed in the same manner.

  Further, the control unit 101 selects and feeds a recording sheet for forming a sample sheet and a test sheet in accordance with the paper type or tray information stored in the storage unit 105, and causes the image forming unit to form and output a chart. Thus, every time a test sheet is output, the density fluctuation prevention control can be executed using an appropriate recording paper under the same conditions as the sample sheet, so that the density stability can be kept good over a long period of time. Become. In addition, the image density can be strictly stabilized within a density fluctuation range that is acceptable to the user.

[Other Embodiments (1)]
In the above embodiment, the electrophotographic image forming apparatus has been described as a specific example, but the present invention is not limited to this type of image forming apparatus. In other words, even in an ink jet method or a heat-sensitive image forming apparatus, by applying the above embodiment, a test sheet can be output based on the user's request (setting of allowable density fluctuation range). It is possible to realize an image forming apparatus capable of selecting the timing (number of prescribed image formations and prescribed temperature change value) and density stability.

[Other embodiment (2)]
In the specific examples of the above embodiments, different sample sheets and test sheets are employed, but a common sheet may be used so as to include both patches, color samples, sample images, and the like. Is possible.

1 is a configuration diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment of the present invention. 1 is a configuration diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment of the present invention. It is explanatory drawing which shows the sensor used by embodiment of this invention. It is explanatory drawing which shows the test sheet | seat used by embodiment of this invention. 6 is a flowchart illustrating an operation state of the image forming apparatus according to the embodiment of the present invention. It is explanatory drawing which shows the setting screen of the image forming apparatus of embodiment of this invention. It is explanatory drawing which shows the setting screen of the image forming apparatus of embodiment of this invention. It is explanatory drawing which shows the sample sheet | seat used by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 101 Control part 103 Operation part 105 Storage part 110 Image processing part 150 Paper feed part 160 Conveyance part 170 Process unit 180 Fixing part 190s Sensor

Claims (7)

Image forming means for forming and outputting an image according to data on a recording paper; and
Storage means for storing test sheet data including a plurality of patches having a predetermined density and sample sheet data including a patch for setting an allowable density variation range;
A sensor for detecting the density of the patch on the test sheet or the sample sheet;
Setting means for setting an allowable density fluctuation range during image formation based on the sample sheet;
In accordance with the set value of the allowable density variation range set by the setting means, the number of image formations (the number of prescribed image formations) for outputting the test sheet is determined, and at the timing of the prescribed number of image formations, the storage means Based on the stored data, the image forming unit forms an image on the test sheet, and the image forming condition is controlled based on a detection result obtained by detecting the density of the patch on the test sheet by the sensor. Control means to
An image forming apparatus comprising: Image forming means for forming and outputting an image according to data on a recording paper; and
Storage means for storing test sheet data including a plurality of patches having a predetermined density and sample sheet data including a patch for setting an allowable density variation range;
A sensor for detecting the density of the patch on the test sheet or the sample sheet;
Setting means for setting an allowable density fluctuation range during image formation based on the sample sheet;
A prescribed temperature change for outputting the test sheet is determined in accordance with a set value of the allowable density fluctuation range set by the setting means, and the data stored in the storage means at a timing when the prescribed temperature change occurs. Control means for controlling the image forming condition based on a detection result obtained by causing the image forming means to form an image based on the test sheet and detecting a density of the patch on the test sheet by the sensor;
An image forming apparatus comprising: The control unit accepts resetting of the allowable density fluctuation range from the setting unit, and re-determines the prescribed image forming number or the prescribed temperature change based on the resetting;
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The control means refers to a detection result obtained by detecting the density of the patch on the test sheet with the sensor, and when the detection result exceeds the allowable density fluctuation range, an image forming operation is performed. To stop,
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The control means controls to form an image of data input from the outside in the same condition as the patch in an area other than the patch on the sample sheet.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The image forming means is configured to form a color image with a recording material of a plurality of colors,
The sensor detects the density of each patch of each of the plurality of colors of the recording material;
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The paper type of the recording paper that forms the sample sheet or the tray that contains the recording paper that forms the sample sheet is defined, and the information on the paper type or the tray is stored in the storage means,
The control means selects and feeds the recording paper for forming the sample sheet and the test sheet according to the paper type or tray information stored in the storage means, and supplies the sample to the image forming means. Image formation output of the sheet and the test sheet,
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

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