JP7434753B2 - image forming device - Google Patents

Description

The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus capable of preventing deterioration in image quality due to erroneous detection of the paper type of a recording sheet.

In recent years, electrophotographic image forming apparatuses have become capable of forming high-quality images on a wide variety of paper types by changing image forming conditions such as paper transport speed and toner image fixing temperature. There is. For this reason, for example, there is a method in which the user selects the paper type and sets image forming conditions, such as changing the paper conveyance speed and toner image fixing temperature, depending on the selected paper type.

However, since the user does not necessarily know exactly the type of paper set in the paper feed tray, it is not always easy to select the appropriate paper type.

Therefore, Patent Document 1 proposes an image forming apparatus that irradiates light onto paper, detects the paper type based on the amount of transmitted light, and sets image forming conditions. In this way, erroneous settings by the user can be avoided, and high-quality image formation can be achieved.

Japanese Patent Application Publication No. 2003-112840

Instead of the method using the amount of transmitted light in Patent Document 1, there is a configuration that detects the paper type based on the amount of reflected light from the paper, and a method that detects the paper type based on both the amount of transmitted light and the amount of reflected light in order to further improve detection accuracy. It is also possible to adopt a configuration in which the detection is performed.

However, the amount of transmitted light and the amount of reflected light tend to change not only depending on the type of paper but also depending on the color of the paper. As a result, even if the paper type is the same, the detection results may differ depending on whether the paper is colored or not. For example, if the paper has a tint (low whiteness), it will be detected as coated paper or recycled paper, and if the paper has no tint (high whiteness), it will be detected as plain paper. There is a possibility that it will be stored away.

In addition, when paper is used for postcards, especially official postcards, which contain recycled paper, they have a certain color tone, but since the proportion of recycled paper in distributed postcards is not constant, the color tone of postcards is also not constant. Such paper with uneven color may include types other than postcards, such as business card-sized paper.

As mentioned above, the amount of transmitted light and reflected light changes depending on the color of the paper, and the color of paper such as postcards in circulation is not constant, making it difficult to detect the paper type properly. Sometimes. As a result, there is a problem in that it may not be possible to set image forming conditions suitable for the paper, and therefore it may not be possible to form a high-quality image.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus that can achieve high-quality image formation on paper whose paper type cannot be detected well. .

In order to achieve the above object, an image forming apparatus according to an embodiment of the present disclosure includes a detection unit that detects the paper type of a sheet fed from a paper storage unit during job execution, and a detection unit that detects the paper type by the detection unit. a switching section that switches between enabling and disabling; an image forming section that forms an image on a sheet fed from the storage section; and when the switching section is switched to enable detection of the paper type, a When the size of the fed sheet is other than the predetermined size, the size of the sheet fed from the storage unit is the predetermined size under image forming conditions according to the paper type detected during the execution of the job. In some cases, the detection unit further comprises: a control unit that performs size priority control that causes the image forming unit to form an image under image forming conditions based on the predetermined size regardless of a paper type detection result during the job execution; The part includes an optical sensor that detects the amount of light reflected by the sheet and the amount of transmitted light transmitted through the sheet among the light emitted towards the sheet, and the paper type of the different sheet. A first table in which the amount of transmitted light is associated with each paper type of the different sheets, and the amount of transmitted light associated with each paper type is associated with the amount of transmitted light in the first table. and a third table indicating which of the first table and the second table is used for paper type detection depending on the amount of reflected light; With reference to a table, one of the first table and the second table is determined that corresponds to the amount of reflected light detected by the sensor, and with reference to the determined table, the amount of reflected light detected by the sensor is determined. An image forming apparatus characterized in that the paper type of the sheet corresponding to the amount of transmitted light is determined to be the paper type of the fed sheet .

Further, the predetermined size may be a postcard size.

The invention further includes an image forming condition storage unit that stores image forming conditions suitable for postcards, and in the size priority control, the control unit determines that the paper type detection is effective and that the sheet fed from the storage unit is When the size is a postcard size, the image forming section may form the image under image forming conditions suitable for the postcard stored in the image forming condition storage section.

The image forming apparatus may further include a panel that accepts operations from a user, and image forming conditions suitable for the postcard size may be specified by the user via the panel.

Further, the apparatus may further include a panel that receives an operation from a user, and the switching section may switch between enabling and disabling the detection of the paper type in accordance with the user's operation input via the panel.

Further, the image forming apparatus may further include a sheet size detection section that detects the size of the sheet accommodated in the storage section.

Further, an image forming apparatus according to another aspect of the present disclosure includes a detection unit that detects the paper type of a sheet fed from a paper storage unit during job execution, and a switch between enabling and disabling detection of the paper type by the detection unit. a switching unit, an image forming unit that forms an image on a sheet fed from the storage unit, and, when the switching unit is switched to enable detection of the paper type, an image forming unit that forms an image on a sheet fed from the storage unit; When the size of the sheet is other than the predetermined size, the image forming conditions according to the paper type detected during the execution of the job, and when the size of the sheet fed from the storage unit is the predetermined size, the job is executed. a control unit that performs size priority control that causes the image forming unit to form an image under image forming conditions based on the predetermined size regardless of a paper type detection result during execution; and a size of the sheet stored in the storage unit. a sheet size detection unit configured to detect the size of the sheet, the control unit configured to detect the size of the sheet stored in the storage unit when the size of the sheet stored in the storage unit is smaller than the detectable size of the sheet size detection unit; The present invention is characterized in that it is determined that the size of the accommodated sheet is a predetermined specific sheet size.

Further, the detection section may include an optical sensor.

Further, the optical sensor may irradiate the sheet being conveyed with light from a light source and detect the transmitted light with a light receiving section.

Further, the light source may be an LED that emits blue or red light.

The light receiving section of the sensor of the optical system may also be used to irradiate the sheet being conveyed with light from a light source different from the light source and to receive the reflected light.

Further, the light from the separate light source may be applied to a surface of the sheet being conveyed on which an image is to be formed.

Furthermore, the separate light source may be an LED that emits green light.

Further, an image forming apparatus according to still another aspect of the present disclosure includes a detection unit that detects the paper type of a sheet fed from a paper storage unit during job execution, and an enable/disable function for detecting the paper type by the detection unit. a switching section for switching, an image forming section for forming an image on a sheet fed from the storage section, and when the switching section is switched to enable the detection of the paper type, the sheet feeding from the storage section is activated. When the size of the sheet fed from the storage section is other than the predetermined size, the image forming conditions according to the paper type detected during the execution of the job are the same. a control unit that performs size priority control that causes the image forming unit to form an image under image forming conditions based on the predetermined size regardless of a paper type detection result during job execution; further comprising a second storage section different from the first storage section, wherein the control section performs the size priority control when the sheet feeding source is the first storage section; Detection result priority control is performed when the paper feed source of the sheet is the second storage unit, and the detection result priority control is performed when the switching unit is switched to enable the paper type detection. The present invention is characterized in that the image forming section forms an image under image forming conditions according to the detected paper type, regardless of the size.

Further, when the surface on which an image is formed on the sheet being conveyed is the first surface, and the back surface of the first surface is the second surface, it is possible to form an image on the sheet stored in the first storage section. The sheet further includes a guide member that transports the sheet in a curved position such that the first surface is on the inside and the second surface is on the outside, and the detection section is configured to transmit light to the first surface. It may also include a light source that irradiates.

Further, when the surface on which an image is formed on the sheet being conveyed is the first surface, and the back surface of the first surface is the second surface, the image formation on the sheet stored in the second storage section is performed. The sheet further includes a guide member that transports the sheet in a curved position such that the first surface is on the outside and the second surface is on the inside, and the detection unit is configured to transmit light to the first surface. It may also include a light source that irradiates.
An image forming apparatus according to another aspect of the present disclosure includes: a detection unit that detects the paper type of a sheet fed from a storage unit; a switching unit that switches between enabling and disabling detection of the paper type by the detection unit; If the image forming unit forms an image on the sheet fed from the storage unit and the switching unit is switched to enable detection of the paper type, the size of the sheet fed from the storage unit is set to a predetermined size. If the size is other than the paper type, the image forming conditions are based on the detected paper type, and if the size of the sheet fed from the storage unit is a predetermined size, the image forming condition is based on the predetermined size regardless of the paper type detection result. The control unit includes a control unit that performs size priority control to cause the image forming unit to form an image under image forming conditions, and a sheet size detection unit that detects the size of the sheet accommodated in the storage unit, and the control unit includes: When it is detected that the size of the sheet stored in the storage section is smaller than the detectable size of the sheet size detection section, the size of the sheet stored in the storage section is set to a predetermined specific sheet size. It is characterized by determining that
An image forming apparatus according to still another aspect of the present disclosure includes: a detection unit that detects the paper type of a sheet fed from a storage unit; a switching unit that switches between enabling and disabling detection of the paper type by the detection unit; When the image forming unit forms an image on the sheet fed from the storage unit and the switching unit is switched to enable detection of the paper type, the size of the sheet fed from the storage unit is When the size is other than the predetermined size, the image forming conditions are set according to the detected paper type, and when the size of the sheet fed from the storage section is the predetermined size, the image is formed to the predetermined size regardless of the paper type detection result. a control unit that performs size priority control to cause the image forming unit to form an image under image forming conditions based on the image forming conditions, the storage unit being a first storage unit, and a second storage unit different from the first storage unit; The control unit further includes a storage unit, and the control unit performs the size priority control when the sheet feeding source is the first storage unit, and controls the detection result when the sheet feeding source is the second storage unit. Priority control is performed, and the detection result priority control is such that when the switching unit is switched to enable detection of the paper type, image forming conditions are performed according to the detected paper type, regardless of the sheet size. The present invention is characterized in that the image forming section forms an image.

In this way, image forming conditions suitable for a paper such as a postcard whose paper type can be specified from the paper size can be set, and a high-quality image can be formed.

1 is a diagram showing the main configuration of an image forming apparatus 100. FIG. 2 is a block diagram showing the main configuration of a control unit 110. FIG. 3 is a diagram showing the main configuration of a media sensor 160. FIG. 3 is a diagram showing the main configuration of a paper size sensor 170. FIG. 5 is a diagram illustrating an example of a paper setting screen for tray 1 displayed on operation panel 150. FIG. 5 is a diagram showing an example of a minimum paper size setting screen for tray 1 displayed on operation panel 150. FIG. 5 is a diagram illustrating an example of a determination table for determining the paper type stored in the HDD 204. FIG. 5 is a diagram illustrating an example of information stored in an HDD 204 indicating image forming conditions according to paper types. FIG. 5 is a diagram illustrating an example of paper setting information for each tray stored in the HDD 204. FIG. 3 is a flowchart illustrating the operation of image forming apparatus 100. FIG. 3 is a flowchart illustrating the operation of image forming apparatus 100. FIG. FIG. 2 is a diagram illustrating a conveyance path of a recording sheet in the image forming apparatus 100. 7 is a diagram illustrating an example of the relationship between the amount of reflected light and the distance between the reflected light light source and the recording sheet S being conveyed. FIG.

Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.
[1] First Embodiment An image forming apparatus according to a first embodiment will be described.
(1-1) Configuration of Image Forming Apparatus Next, the configuration of the image forming apparatus 100 will be described.

As shown in FIG. 1, an image forming apparatus 1 according to the present embodiment is a so-called tandem color printer, and includes a paper feeding section 120, an image forming section 130, an operation panel 150, and a control section 110. .
(1-1-1) Paper feed section 120
In the paper feed section 120, paper feed trays 121a and 121b that accommodate recording sheets S are installed. Paper feed rollers 122a and 122b feed recording sheets S from paper feed trays 121a and 121b, respectively. During this sheet feeding, the separating rollers 123a and 123b prevent double feeding of the recording sheets S. The recording sheets S fed out from the paper feed trays 121a and 121b are conveyed to a sheet conveyance path 125 via sheet conveyance paths 124a and 124b, respectively. The recording sheet S fed from the manual feed tray 126 is conveyed from the sheet conveyance path 128 to the sheet conveyance path 125 by the manual feed roller 127.

A media sensor 160 is located downstream of the confluence of the sheet conveyance paths 124a, 124b, and 127 and upstream of the registration roller pair (sometimes referred to as a timing roller pair) 129 in the sheet conveyance path 125. It is arranged. The media sensor 160 optically detects the characteristics of the recording sheet S passing through the sheet conveyance path 125.

When the recording sheet S reaches the pair of registration rollers 129, it collides with the pair of registration rollers 129 that is stopped, forming a loop, thereby correcting the skew.

Thereafter, the registration roller pair 129 starts rotating in synchronization with the color toner image being conveyed to the secondary transfer nip 136 by the rotation of the intermediate transfer belt 131 of the image forming section 130, and the recording sheet S is It is transported to the next transfer nip 136.
(1-1-2) Image forming section 130
The image forming section 130 forms toner images of each color of Y (yellow), M (magenta), C (cyan), and K (black) using image forming sections 140Y, 140M, 140C, and 140K.

The intermediate transfer belt 131 is an endless belt, and is stretched around a driving roller 132 and a driven roller 133. The intermediate transfer belt 131 rotates in the direction of arrow A as the motor 134 rotationally drives the drive roller 132 . While the intermediate transfer belt 131 is rotating, the toner images of each color formed by the image forming units 140Y, 140M, 140C, and 140K are transferred onto the intermediate transfer belt 131 so as to be superimposed (primary transfer). As a result, a color toner image is formed on the intermediate transfer belt 131.

A secondary transfer roller 135 is in pressure contact with the drive roller 132 with the intermediate transfer belt 131 in between, thereby forming a secondary transfer nip 136.

The recording sheet S conveyed to the secondary transfer nip 136 has a color toner image electrostatically transferred from the intermediate transfer belt 131 to the recording sheet S by the secondary transfer roller 135 (secondary transfer).

After the secondary transfer, the cleaning device 145 scrapes off the toner remaining on the intermediate transfer belt 131 and discards it. After the secondary transfer, the recording sheet S is conveyed to the fixing device 137. The fixing device 137 includes a heating roller 146, a fixing belt 147, a fixing roller 148, and a pressure roller 149. The heating roller 146 is heated by a heater (not shown) and heats the fixing belt 147 to a fixing temperature.

The fixing belt 147 is an endless belt and rotates following the fixing roller 148. The fixing roller 148 is rotationally driven by a motor (not shown). The pressure roller 149 forms a fixing nip by coming into pressure contact with the fixing roller 148 with the fixing belt 147 in between. The color toner image is thermally fixed on the recording sheet S when it passes through the fixing nip.

After fixing, the recording sheet S is discharged onto a paper discharge tray 139 above the image forming apparatus 1 by a discharge roller 138.
(1-1-3) Operation panel 150
The operation panel 150 is provided with a display section composed of a liquid crystal display panel or the like, and displays various display screens. For example, the display section of the operation panel 150 displays a settings screen for setting whether to enable automatic detection of paper type and paper size for each tray. The operation panel 150 is also provided with an input unit including a start button for starting various jobs, a touch sensor provided on the surface of the display unit, etc., and allows the user to input instructions and settings for print jobs, etc. accept.
(1-1-4) Control unit 110
As shown in FIG. 2, the control unit 110 includes a CPU (Central Processing Unit) 201, a RAM 202, a ROM 203, and an HDD 204, and includes a paper feed unit 120, an image forming unit 130, an operation panel 150, a media sensor 160, and a paper size detection sensor. is connected to.

The control unit 110 receives a print job from a user via the operation panel 150, and controls the paper feed unit 120 and the image forming unit 130 in accordance with the received print job to perform image forming processing. At this time, image forming conditions such as sheet conveyance speed and fixing temperature are determined based on the detection results of the media sensor 160 and paper size sensor 170, and the image forming unit 130 is caused to execute image forming processing under the image forming conditions.

The CPU 201 includes a fetch section, a decoding section, an execution section, a register file, an instruction counter, and the like. The fetch unit reads out each instruction code included in the control program one by one from the control program stored in the ROM 203 . The decoder decodes the read instruction code. The execution unit operates according to the decoding result. In this way, the CPU 201 operates according to the control program stored in the ROM 203.

The RAM 202 is composed of a semiconductor memory, and temporarily stores various control variables and the like, and also provides a work area when the CPU 201 executes a program.

The ROM 203 is composed of a semiconductor memory, and stores in advance control programs for executing print jobs and the like.

For example, the control unit 110 receives a print job from a user via the operation panel 150 by operating according to a control program, and causes the image forming unit 130 to perform image forming processing based on the print job.

The HDD 204 is a hard disk drive that stores a determination table for determining the paper type of the recording sheet S based on the detection result of the media sensor 160, image forming conditions according to the paper type, paper setting information for each tray, and the like.
(1-2) Media Sensor Next, the media sensor 160 will be explained.

As shown in FIGS. 3A and 3B, the media sensor 160 includes a transmitted light light source 601, a light amount detection sensor 302, and a reflected light light source 303.

The light source 301 for transmitted light and the light source 303 for reflected light are so-called light emitting diodes (LEDs), and emit a beam of light to the recording sheet S. In this embodiment, the light source 301 for transmitted light emits red and blue beams, and the light source 303 for reflected light emits green beam light.

The light amount detection sensor 302 is a so-called photodiode, and measures the amount of beam light emitted from the transmitted light light source 301 and transmitted through the recording sheet S (transmitted light amount), and the amount of beam light emitted from the reflected light source 303 and reflected by the recording sheet S. Detects the amount of light beam (reflected light amount).

Note that the recording sheet S is conveyed along conveyance guides 304 and 305. The conveyance guides 304 and 305 are provided with through holes 304a and 305a in the irradiation range of the beam light of the transmitted light light source 301 and the reflected light light source 303. The beam light, transmitted light, and reflected light enter the light amount detection sensor 302 without being blocked by the conveyance guides 304 and 305.
(1-3) Paper Size Sensor The paper size sensor 170 will be explained.

FIG. 4 is a top view of the paper feed tray 121a. The paper feed tray 121a is provided with two regulation guides 401A and 401B that regulate the positions of both ends of the recording sheet S in the width direction perpendicular to the conveyance direction of the recording sheet S (direction B in the figure). . The regulation guides 401A and 401B are configured to be slidable in conjunction with each other along a slide groove 402 extending in the width direction of the recording sheet S. After placing the recording sheet S on the paper feed tray 121a, the recording sheet S can be positioned in the width direction by moving the two regulation guides 401A and 401B so as to contact both ends of the recording sheet S in the width direction. can.

The paper feed tray 121a is provided with a plurality of capacitance type proximity sensors 403 as part of the paper size sensor 170, and is equipped with a plurality of capacitance type proximity sensors 403 as part of the paper size sensor 170. Detect changes in capacitance. By detecting which one of the plurality of capacitive proximity sensors 403 provided corresponding to the detectable paper size is nearby, the widthwise length of the set paper can be determined. Detectable.

The paper feed tray 121a is provided with a regulation guide 405 that regulates the position of the recording sheet S in the transport direction. The regulation guide 405 is configured to be slidable along a slide groove 406 extending in the conveyance direction of the recording sheet S. After placing the recording sheet S so that the downstream end of the recording sheet S in the transportation direction is aligned with the downstream end of the paper feed tray 121a in the transportation direction, the regulation guide 405 is moved so as to contact the upstream end of the recording sheet S in the transportation direction. With this, the recording sheet S can be positioned in the conveyance direction.

Further, the paper feed tray 121a is provided with a plurality of capacitance type proximity sensors 407 as part of the paper size sensor 170, and a detection object 408 provided inside the regulation guide 405 is disposed close to the paper feed tray 121a. Detects changes in capacitance. The length of the set paper in the transport direction can be detected by detecting which of the capacitive proximity sensors 407 provided corresponding to the detectable paper size is in close proximity. It is.

The size of the paper set in the paper feed tray 121a (for example, A3, B4, A4, postcard, etc.) can be detected from the detected length of the paper in the width direction and the length in the transport direction.

Note that if the detection object 404 (408) is located inside the capacitance type proximity sensor 403 (407) for detecting the smallest size due to the movement of the guides 401A and 405, multiple capacitance type proximity sensors From the output value of the proximity sensor 403 (407), it can be known that paper smaller than the detectable size has been set.
(1-4) Tray paper settings/minimum paper size settings The image forming apparatus 100 of this embodiment allows the user to enable or disable automatic paper type detection and automatic paper size detection for each tray. be. Further, in the image forming apparatus 100 of the present embodiment, even if automatic paper type detection is enabled, if the paper size is set as "postcard", the paper type is set as "postcard" regardless of the detection result by the media sensor 160. It is set as "Thick Paper 3". With this, it is possible to perform image formation under appropriate image forming conditions for postcards, which are prone to erroneous paper detection because the used paper content ratio is not constant and the colors are different.

FIG. 5 is an example of a paper setting screen 501 for tray 1 displayed on the display section of the operation panel 150. Here, tray 1 refers to the upper paper feed tray (paper feed tray 121a in FIG. 1). As shown in FIG. 5, a check box 502 for automatic paper type detection is checked, indicating that automatic paper type detection is enabled. Similarly, a check box 503 for automatic paper size detection is checked, indicating that automatic paper size detection is enabled. The user can enable/disable automatic paper type detection and enable/disable automatic paper size detection by operating the operation panel 150.

The paper size postcard button 504 is highlighted, indicating that "postcard" has been set as the paper size by automatic paper size detection when automatic paper size detection is enabled. Note that if automatic paper size detection is disabled, this indicates that "postcard" has been set as the paper size by the user's operation.

The Paper Type Thick Paper 3 button 505 is highlighted, and if automatic paper type detection is enabled, the paper size is set as "Postcard" and "Thick Paper 3" is set as the paper type. It shows. Note that when automatic paper type detection is enabled and a paper size other than "postcard" is set, the detection result of the media sensor 160 indicates that "thick paper 3" is set as the paper type. Furthermore, if automatic paper type detection is disabled, this indicates that "thick paper 3" has been set as the paper type by the user's operation.

FIG. 6 is an example of a setting screen 601 for setting the minimum paper size of tray 1 displayed on the display section of the operation panel 150. In the illustrated example, the postcard button 602 is highlighted, indicating that the postcard size is set as the minimum paper size for tray 1. This indicates that when it is detected that a paper smaller than the minimum size detectable by the paper size sensor 170 is set in the tray 1, it is assumed that a paper of the size set here is set.
(1-5) Data Data stored in the HDD 204 will be explained.

A determination table for determining the paper type of the recording sheet S will be described. In this embodiment, based on the amount of reflected light and the amount of transmitted light, which are the output values of the media sensor 160, the recording sheet S Determine the paper type. This is because the amount of reflected light and transmitted light differs even for the same type of paper depending on the color of the paper, so first find out how much color the paper has depending on the amount of reflected light, and then Next, a table suitable for determining the paper type based on the amount of transmitted light is selected. This makes it possible to improve the accuracy of paper type detection.

First, using the reflected light amount of the recording sheet S notified from the media sensor 160, the determination table 701 shown in FIG. 7A is referred to to determine the determination table to be used for the second stage determination. In FIG. 7(a), if the amount of reflected light is R ₀ or more and less than R ₁ , determination table A is used in the second stage of determination, and if the amount of reflected light is R ₁ or more and less than R ₂ , the second stage of determination is used. Table B is used, and if the amount of reflected light is greater than or equal to R _n-1 and less than R _n , then determination table N is used in the second stage of determination.

Next, using the amount of transmitted light of the recording sheet S notified from the media sensor 160, refer to the determination table determined in the first stage of determination among the determination tables AN shown in FIG. 3(b), The paper type of the recording sheet S is determined. For example, if it is determined to use determination table A in the first stage of determination, the determination table 702A is referred to, and if the amount of transmitted light is TA ₀ or more and less than TA ₁ , it is determined to be thin paper, and if the amount of transmitted light is TA ₁ or more and less than TA If the amount of transmitted light is less than TA ₂ , it is determined to be plain paper; if the amount of transmitted light is TA ₂ or more and less than TA ₃ , it is determined to be thick paper 1; if the amount of transmitted light is TA ₃ or more and less than TA ₄ , it is determined to be cardboard 2; If TA is ₄ or more and less than TA ₅ , it is determined to be cardboard 3. Note that if it is determined in the first stage of determination to use the determination tables B, ..., determination table N, the paper type is determined by referring to the determination tables 702B, ..., 702N in the second stage of determination. conduct.

FIG. 8A is an image forming condition table 801 that is stored in the HDD 204 and shows image forming conditions for each paper type. When the recording sheet S is determined to be thin paper, the control unit 110 sets the fixing temperature to X1 and the sheet conveyance speed to Y1, and causes the image forming unit 130 to execute image forming processing. Similarly, the control unit 110 sets the fixing temperature to X2 and the sheet conveyance speed to Y2 when the recording sheet S is determined to be plain paper, and sets the fixing temperature to X3 when the recording sheet S is determined to be thick paper 1. , the sheet conveyance speed is set to Y3, and when the recording sheet S is determined to be thick paper 2, the fixing temperature is set to X4, and the sheet conveyance speed is set to Y4, and when the recording sheet S is determined to be thick paper 3, the fixing temperature is set to is set to X5, the sheet conveyance speed is set to Y5, and the image forming section 130 is caused to execute image forming processing.

FIG. 8B is an example of postcard image forming condition information 802 indicating the image forming conditions set when the paper size of the recording sheet S is determined to be the postcard size. The figure shows that when the paper size of the recording sheet S is determined to be postcard size, the image forming process is executed under the same image forming conditions as when the paper type is determined to be thick paper 3. This setting may be stored in advance in the HDD 204 at the time of shipment, or may be stored in the HDD 204 by the user operating the operation panel 150.

FIG. 9 is an example of paper setting information 901 for each tray stored in the HDD 204, and shows setting information for "tray 1" (paper feed tray 121a in FIG. 1).

In the example shown, automatic paper type detection and automatic paper size detection are "ON", and automatic paper type detection using the media sensor 160 and automatic paper size detection using the paper size sensor 170 are enabled. It shows. Then, the paper type and paper size are "Thick Paper 3" and "Postcard", and the paper type of the recording sheet S loaded in "Tray 1" is set as "Thick Paper 3" and the paper size is set as "Postcard". It shows that there is. Also, if the minimum paper size is "Postcard" and it is detected that paper smaller than the minimum detectable size is set in Tray 1, it is assumed that "Postcard" is set. ing.

Note that when automatic paper type detection is disabled, the paper type set by the user via the operation panel 150 is stored in the paper type column. Similarly, when automatic paper size detection is disabled, the paper size set by the user via the operation panel 150 is stored in the paper size column.

Similar setting information is stored in the HDD 204 for other trays (tray 2 (tray 121b in FIG. 1) and manual tray (manual tray 125 in FIG. 1)).
(1-5) Operation The operation of the image forming apparatus 100 of this embodiment will be explained.

FIG. 10 is a flowchart for executing a print job received by the image forming apparatus 100.

Based on the received print job, the control unit 110 starts transporting the recording sheet S set in the tray specified in the print job (here, tray 1 is specified) (step S1). .

Thereafter, with reference to the paper setting information for tray 1 stored in the HDD 204, it is determined whether or not media detection, that is, automatic paper type detection is enabled (step S2).

If automatic paper type detection is enabled (step S2: Yes), the paper size of the recording sheet S being conveyed is determined to be "postcard" by referring to the paper setting information for tray 1 stored in the HDD 204. It is determined whether the size is the same (step S3).

In step S3, if the paper size of the recording sheet S is the "postcard" size (step S3: Yes), the detection result of the media sensor 160 is Regardless, the paper type in the paper setting information for tray 1 of the HDD 204 is set to "thick paper 3". Furthermore, by referring to the image forming conditions for each paper type in the HDD 204, image forming conditions suitable for "thick paper 3" are read out, and read out as image forming conditions when forming an image on the recording sheet S being conveyed. Image forming conditions are set (step S4).

In step S3, if the paper size of the recording sheet S is not the "postcard" size (step S3: No), the paper type of the recording sheet S being conveyed is determined based on the detection result of the media sensor 160, and the paper type of the recording sheet S being conveyed is determined. The paper type in the paper setting information for tray 1 is set to the one based on the determination result. Here, for example, if it is determined to be "plain paper", image forming conditions suitable for "plain paper" are read out by referring to the image forming conditions for each paper type in the HDD 204, and an image is formed on the recording sheet S being conveyed. The read image forming conditions are set as the image forming conditions when performing (step S5).

In step S2, if automatic paper type detection is disabled (step S2: No), the paper type in the paper setting information of tray 1 of the HDD 204 is read. Note that when automatic paper type detection is disabled, the paper type set in advance by the user via the operation panel 150 is stored in the paper type in the paper setting information for tray 1 of the HDD 204. For example, if "thin paper" is read out, image forming conditions suitable for "thin paper" are read out by referring to the image forming conditions for each paper type in the HDD 204, and an image is formed on the recording sheet S being conveyed. The read image forming conditions are set as the image forming conditions for performing the image forming process (step S6).

Then, the image forming unit 130 is caused to form an image under the image forming conditions set in step S4, S5, or S6 (step S7).

After image formation, it is determined whether or not the print job has been completed. If the print job has not been completed, the process returns to step S2, and if it has been completed, this routine is ended (step S8).

By performing the process in this manner, it is possible to perform image forming processing under appropriate image forming conditions for "postcards" whose paper type is often erroneously detected.
[2] Second Embodiment The image forming apparatus 100 according to the second embodiment has generally the same configuration as the image forming apparatus 100 according to the first embodiment, but has a different configuration in the print job to be executed. The difference is that the control method changes depending on the paper feed tray used. The following description focuses on the differences.

FIG. 11 is a flowchart of the operation of the image forming apparatus 100 according to the second embodiment. The difference from the operation of the image forming apparatus 100 of the first embodiment is that between step S2 and step S3, it is determined whether or not the paper feed source of the recording sheet S is the manual feed tray (step S11). is included. If the paper feed source of the recording sheet S is the manual feed tray, the process advances to step S5, and if the paper feed source of the recording sheet S is tray 1 or tray 2, the process advances to step S3. The subsequent processing is similar to that of the first embodiment.

As described in the first embodiment, the recording sheet S fed from tray 1 (paper feed tray 121a in FIG. 1) and the recording sheet S fed from the manual feed tray (manual feed tray 126 in FIG. 1) is conveyed to a pair of registration rollers 129. A media sensor 160 is arranged on the conveyance path 125 between them, and detects the amount of transmitted light and the amount of reflected light of the recording sheet S being conveyed.

As shown in FIGS. 12(a) and 12(b), in the media sensor 160, the transmitted light light source 301 is located on the side opposite to the surface (first surface) on which an image is formed during image formation on the recording sheet S being conveyed. It is arranged at a position opposite to the surface (second surface). The reflected light light source 303 is arranged to face the first surface. When the recording sheet S is a postcard, it has a large thickness (basis weight) and a short length in the conveying direction, so the paper is characterized by being stiff. As shown in FIG. 12(a), the conveyance guides 304, 305, and 1201 that guide the sheet fed from the paper feed tray 121a are arranged so that when the sheet being conveyed is viewed from the width direction, the first side of the sheet is The guide surface is curved so that the second surface is curved on the inside and the second surface is curved on the outside. Further, as shown in FIG. 12(b), the conveyance guides 304, 305, and 1202 that guide the sheet fed from the manual feed tray are conveyed with the first side of the sheet curved outward and the second side curved inward. The guide surface is curved so that the Therefore, when the recording sheet S is fed from the tray 1, as shown in FIG. 1203 is biased. On the other hand, when the recording sheet S is fed from the manual feed tray, as shown in FIG. 1204 is biased.

FIG. 13 shows an example of the relationship between the amount of reflected light and the distance D between the reflected light light source 303 and the recording sheet S being conveyed. As shown in the figure, there is a relationship in which the shorter the distance D is, the larger the amount of reflected light is, but the longer the distance D is, the smaller the amount of reflected light is. The color of a sheet is determined by how much reflected light is attenuated on the surface of the sheet, and the detection accuracy can be improved by increasing the amount of reflected light. Due to the above relationship, when paper is fed from the manual feed tray, the amount of reflected light is large and the detection accuracy of the media sensor 160 is high, but when the same type of paper is fed from tray 1, the amount of reflected light is small and the media sensor 160 has a high detection accuracy. The detection accuracy of the sensor 160 will deteriorate. If paper is fed from a manual tray with high detection accuracy, it is possible to accurately determine the paper type even if the recording sheet S has a variety of colors, such as a postcard. Based on the above, in the second embodiment, when feeding paper from the manual feed tray, unlike the first embodiment, the image forming conditions are set using the detection results of the media sensor 160 even for the postcard size. is set.
[3] Modifications Although the present invention has been described above based on the embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and the following modifications can be implemented. .
(3-1) In the above embodiment, the transmitted light light source 301 emits red and blue beams, and the reflected light light source 303 emits green beam light. The light source 301 may emit a green beam, and the reflected light light source 303 may emit a red or blue beam.

In addition, in the embodiment, the accuracy of paper type detection was improved by a combination of a reflective sensor and a transmissive sensor, but if it is possible to ensure paper type detection accuracy above a certain level, a reflective sensor may be used. Only one of the transmission type optical sensors may be used.
(3-2) In the embodiment described above, when it is detected that the paper size of the recording sheet S being conveyed is the "postcard" size, image forming conditions suitable for printing postcards, especially official postcards are set. Although this is assumed to be the case, it is not limited to this.

For example, since the paper size is small and the thickness (basis weight) is large like postcards such as business cards and photo paper, image forming conditions for photo printing and image forming conditions for business card printing are stored in the HDD 204, and the image forming conditions for printing business cards are stored in the HDD 204 and When the paper size of the recording sheet S is detected to be the "L" size (89 x 127 [mm]) or the "business card" size (91 x 55 [mm]), the memorized image forming conditions are set. It may be.
(3-3) In the above embodiment, the paper types are "thin paper", "plain paper", "thick paper 1", "thick paper 2", and "thick paper 3", and the paper sizes are "A3" to "A6". ", "B4"-"B6", and "Postcard" can be set, but other paper types and other paper sizes may also be settable.
(3-4) In the above embodiment, the case where the image forming apparatus is a tandem type color printer is explained as an example, but it goes without saying that the present invention is not limited to this. It may be a color printer or a monochrome printer.

Furthermore, the same effect can be obtained even if the present invention is applied to a single-function machine such as a copying machine equipped with a scanner or a facsimile machine equipped with a facsimile communication function, or a multi-function peripheral (MFP) that has both of these functions. can be obtained.

The image forming apparatus according to the present invention is useful as an image forming apparatus equipped with a media sensor.

100...Image forming apparatus 110...Control unit 120...Paper feed unit 130...Image forming unit 150...Operation panel 160...Media sensor 170...Paper size sensor

Claims (18)

a detection unit that detects the paper type of the sheet fed from the storage unit during job execution;
a switching unit that switches between enabling and disabling paper type detection by the detection unit;
an image forming unit that forms an image on a sheet fed from the storage unit;
When the switching unit is switched to enable the paper type detection, if the size of the sheet fed from the storage unit is other than the predetermined size, the paper type detection is performed according to the paper type detected during the job execution. When the size of the sheet fed from the storage unit is a predetermined size under the image forming conditions based on the predetermined size, regardless of the paper type detection result during the job execution, the image forming conditions based on the predetermined size A control unit that performs size priority control to cause the image forming unit to form an image ,
The detection unit includes:
an optical sensor that detects the amount of light reflected by the sheet and the amount of transmitted light transmitted through the sheet among the light emitted toward the sheet;
a first table in which the amount of transmitted light is associated with each paper type of different sheets;
a second table in which the amount of transmitted light associated with each paper type of the different sheets is different from the amount of transmitted light in the first table;
a third table indicating which of the first table and the second table is used for paper type detection according to the amount of reflected light;
with reference to the third table, determining a table among the first table and the second table that corresponds to the magnitude of the amount of reflected light detected by the sensor;
Referring to the determined table, determine the paper type of the sheet that is associated with the amount of transmitted light detected by the sensor as the paper type of the fed sheet.
An image forming apparatus characterized by: The image forming apparatus according to claim 1, wherein the predetermined size is a postcard size. further comprising an image forming condition storage section that stores image forming conditions suitable for postcards;
In the size priority control, if the paper type detection is valid and the size of the sheet fed from the storage unit is a postcard size, the control unit controls the size of the postcard stored in the image forming condition storage unit. The image forming apparatus according to claim 2, wherein the image forming section forms an image under suitable image forming conditions. It is further equipped with a panel that accepts operations from the user.
The image forming apparatus according to claim 3, wherein the image forming conditions suitable for the postcard size are specified by the user via the panel. It is further equipped with a panel that accepts operations from the user.
The image forming apparatus according to any one of claims 1 to 3, wherein the switching unit switches between enabling and disabling detection of the paper type in accordance with a user's operation input via the panel. The image forming apparatus according to any one of claims 1 to 5, further comprising a sheet size detection section that detects the size of the sheet accommodated in the storage section. a detection unit that detects the paper type of the sheet fed from the storage unit during job execution;
a switching unit that switches between enabling and disabling paper type detection by the detection unit;
an image forming unit that forms an image on a sheet fed from the storage unit;
When the switching unit is switched to enable the paper type detection, if the size of the sheet fed from the storage unit is other than the predetermined size, the paper type detection is performed according to the paper type detected during the job execution. When the size of the sheet fed from the storage unit is a predetermined size under the image forming conditions based on the predetermined size, regardless of the paper type detection result during the job execution, the image forming conditions based on the predetermined size a control unit that performs size priority control that causes the image forming unit to form an image;
a sheet size detection unit that detects the size of the sheet accommodated in the storage unit;
When the control unit detects that the size of the sheet stored in the storage unit is smaller than the detectable size of the sheet size detection unit, the control unit determines the size of the sheet stored in the storage unit in advance. An image forming apparatus characterized in that the image forming apparatus determines that the sheet size is a specific sheet size. a detection unit that detects the paper type of the sheet fed from the storage unit during job execution;
a switching unit that switches between enabling and disabling paper type detection by the detection unit;
an image forming unit that forms an image on a sheet fed from the storage unit;
When the switching unit is switched to enable the paper type detection, if the size of the sheet fed from the storage unit is other than the predetermined size, the paper type detection is performed according to the paper type detected during the job execution. When the size of the sheet fed from the storage unit is a predetermined size under the image forming conditions based on the predetermined size, regardless of the paper type detection result during the job execution, the image forming conditions based on the predetermined size A control unit that performs size priority control to cause the image forming unit to form an image,
The accommodating part is a first accommodating part,
further comprising a second accommodating part different from the first accommodating part,
The control unit performs the size priority control when the sheet feeding source is the first storage unit, and performs the detection result priority control when the sheet feeding source is the second storage unit,
In the detection result priority control, when the switching unit is switched to enable detection of the paper type, the image forming unit is configured to perform image forming under image forming conditions according to the detected paper type, regardless of the sheet size. An image forming device characterized by forming an image. When the surface on which an image is formed on the sheet being conveyed is the first surface, and the back surface of the first surface is the second surface,
a guide that conveys the sheet in a curved posture such that the first surface is on the inside and the second surface is on the outside until the sheet stored in the first storage section reaches a position where an image is formed; further comprising a member;
The image forming apparatus according to claim 8 , wherein the detection unit includes a light source that irradiates the first surface with light. When the surface on which an image is formed on the sheet being conveyed is the first surface, and the back surface of the first surface is the second surface,
A guide for conveying the sheet in a curved position such that the first surface is on the outside and the second surface is on the inside until the sheet is stored in the second storage section and reaches a position where an image is formed. further comprising a member;
The detection unit includes a light source that irradiates the first surface with light.
The image forming apparatus according to claim 8 . The image forming apparatus according to claim 7 , wherein the detection section includes an optical sensor. 12. The image forming apparatus according to claim 1 , wherein the optical sensor irradiates the sheet being conveyed with light from a light source and detects the transmitted light with a light receiving section. The image forming apparatus according to claim 12 , wherein the light source is an LED that emits blue or red light. 14. The light receiving section of the sensor of the optical system is used for irradiating light from a light source different from the light source onto the sheet being conveyed and for receiving the reflected light. Image forming device. The image forming apparatus according to claim 14 , wherein the light from the separate light source is irradiated onto a surface of the sheet being conveyed on which an image is to be formed. The image forming apparatus according to claim 14 or 15 , wherein the separate light source is an LED that emits green light. a detection unit that detects the paper type of the sheet fed from the storage unit;
a switching unit that switches between enabling and disabling paper type detection by the detection unit;
an image forming unit that forms an image on a sheet fed from the storage unit;
When the switching unit is switched to enable the paper type detection, and the size of the sheet fed from the storage unit is other than the predetermined size, image forming conditions are set according to the detected paper type, When the size of the sheet fed from the storage unit is a predetermined size, size priority control is performed to cause the image forming unit to form an image under image forming conditions based on the predetermined size regardless of the paper type detection result. A control unit that performs
a sheet size detection unit that detects the size of the sheet accommodated in the storage unit,
When the control unit detects that the size of the sheet stored in the storage unit is smaller than the detectable size of the sheet size detection unit, the control unit determines the size of the sheet stored in the storage unit in advance. An image forming apparatus characterized in that the image forming apparatus determines that the sheet size is a specific sheet size. a detection unit that detects the paper type of the sheet fed from the storage unit;
a switching unit that switches between enabling and disabling paper type detection by the detection unit;
an image forming unit that forms an image on a sheet fed from the storage unit;
When the switching unit is switched to enable the paper type detection, and the size of the sheet fed from the storage unit is other than the predetermined size, image forming conditions are set according to the detected paper type, When the size of the sheet fed from the storage unit is a predetermined size, size priority control is performed to cause the image forming unit to form an image under image forming conditions based on the predetermined size regardless of the paper type detection result. a control unit for performing
The accommodating part is a first accommodating part,
further comprising a second accommodating part different from the first accommodating part,
The control unit performs the size priority control when the sheet feeding source is the first storage unit, and performs the detection result priority control when the sheet feeding source is the second storage unit,
In the detection result priority control, when the switching unit is switched to enable detection of the paper type, the image forming unit is configured to perform image forming under image forming conditions according to the detected paper type, regardless of the sheet size. An image forming device characterized by forming an image.

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