JP7769897B2 - Sheet stacking device and image forming apparatus - Google Patents

Description

The present invention relates to a sheet stacking device and an image forming apparatus.

Conventionally, sheet stacking devices equipped with a sheet stacking section for stacking sheets are known.

Patent Document 1 describes a sheet stacking device that includes a detection mechanism that detects the position of a side fence, which acts as a regulating member that regulates the position of sheets stacked on the sheet stacking section, and that detects the size of the sheets stacked on the sheet stacking section based on the position of the side fence detected by the detection mechanism.

However, there were cases where the sheet size could not be detected accurately.

In order to solve the above-mentioned problems, the present invention comprises a sheet stacking section for stacking sheets, an end fence that abuts against the rear end of the sheet stacked on the sheet stacking section to regulate the position of the sheet in the feeding direction, and an imaging means for imaging the entire sheet stacked on the sheet stacking section and the end fence, and is characterized in that it detects whether the sheet stacked on the sheet stacking section is the last one based on whether the difference value between the gap between the end fence and the rear end of the sheet measured based on image data captured by the imaging means when the sheet is set and the gap between the end fence and the rear end of the sheet measured based on image data captured by the imaging means after the feeding means starts feeding the sheet exceeds a threshold value .

According to the present invention, sheet size can be detected with high accuracy.

1 is a cross-sectional view showing the outline of a full-color printer as an example of an image forming apparatus equipped with a double-sided device according to an embodiment of the present invention; FIG. 2 is an explanatory diagram of a conveying path of a full-color printer. FIG. 2 is a schematic perspective view showing a sheet feed cassette serving as a sheet stacking device. FIG. 2 is a schematic configuration diagram illustrating an imaging device that captures an image of the inside of a paper feed cassette. FIG. 10 is a schematic configuration diagram illustrating an example in which an imaging device for imaging a manual feed tray as a sheet stacking device is provided. FIG. 2 is a control block diagram for executing predetermined processing based on paper information, paper set information, etc. acquired based on image data captured by an imaging device. FIG. 4 is a control flow diagram of paper size detection control. FIG. 10 is a diagram showing the state when the paper load is large. FIG. 10 is a diagram showing a state when the paper stack amount is small. FIG. 10 is a control flow diagram of paper load amount detection control. FIG. 2 is a diagram illustrating a state in which paper is set in a paper feed cassette with the side on which an image is formed facing up. FIG. 10 is a control flow diagram of image presence/absence detection control on the front surface. 6A and 6B are diagrams for explaining detection of the presence or absence of a gap between a sheet and a side fence, and a gap between a sheet and an end fence by a processing section. FIG. 10 is a control flow diagram of gap detection control between the paper and the fence. FIG. 4 is a diagram illustrating detection of the final sheet. FIG. 10 is a control flow diagram of final sheet detection control.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing the outline of a full-color printer, which is an example of an image forming apparatus equipped with a double-sided device according to this embodiment.
The printer 100 shown in FIG. 1 has an intermediate transfer belt 11 wound around multiple rollers disposed in the approximate center of the device body 50, and four image forming units 10 (M, C, Y, Bk) disposed along the lower running edge of the intermediate transfer belt 11.

Each imaging unit 10 is equipped with a photosensitive drum 1 as an image carrier. Charging means, a developing device, cleaning means, etc. are arranged around this photosensitive drum 1, and a primary transfer roller 12 as primary transfer means is provided inside the intermediate transfer belt 11 at a position opposite each photosensitive drum 1.

In this printer 100, the four imaging units 10 are configured with the same structure, but the developer colors used in the developing devices of each imaging unit are different: magenta, cyan, yellow, and black. The four imaging units 10 are arranged in the order of magenta, cyan, yellow, and black from left to right in the figure. Each imaging unit 10 is detachably mounted on the device main body as a process cartridge.

An optical writing device 14 is provided below the imaging units 10. The optical writing device 14 includes a polygon mirror, a group of mirrors, etc., and irradiates the surface of the photosensitive drum 1 of each color imaging unit with optically modulated laser light. While the optical writing device 14 may be provided individually for each imaging unit 10, it is more cost-effective to use a common optical writing device. In addition, in this printer 100, the intermediate transfer belt 11 and optical writing device 14 are also unitized, and are configured to be detachable from the device main body.

At the bottom of the device, paper feed cassettes 15 are installed as sheet stacking devices, and paper feed means 16 are provided corresponding to each paper feed cassette. The paper feed means 16 consists of a pick-up roller, a supply roller, and a separation roller. A pair of transport rollers 17 is provided to transport sheets such as transfer paper (hereinafter referred to as paper P) fed by the paper feed means 16. A pair of registration rollers 18 is provided above the pair of transport rollers 17 (downstream in the paper transport direction). A transfer roller 19 serving as secondary transfer means is provided above the pair of registration rollers 18, facing the transfer counter roller 13, which is one of the rollers around which the intermediate transfer belt 11 is stretched, forming a secondary transfer section.

A fixing device 20 is provided above the secondary transfer unit, and above this fixing device 20, first to third switching claws 21, 22, and 23 are arranged to switch the paper transport direction. Each switching claw 21 to 23 is driven by an actuator such as a solenoid to switch the paper transport direction. Reference numerals 24 to 27 denote pairs of transport rollers appropriately positioned along the paper transport path. Reference numerals 35 to 41 denote paper sensors appropriately positioned along the paper transport path.

The top surface of the device main body 50 is configured as a paper output tray 30, and a pair of paper output rollers 29 for ejecting paper onto the output tray 30 is located above and to the left of the fixing device 20.

A switchback conveying path 61 and a re-feeding path 62 are formed within the duplexing unit 60, which is a duplexing device that reverses the front and back of paper P. A first reversing roller pair 31 is provided at the entrance (top of the device) of the switchback conveying path 61, and a second reversing roller pair 32 is provided midway through the switchback conveying path 61. The first and second reversing roller pairs 31, 32 are configured to be rotatable forward and backward. Furthermore, conveying roller pairs 26, 27 are positioned at a position that divides the re-feeding path 62 into approximately three equal parts. The aforementioned third switching claw 23 is located immediately adjacent to the first reversing roller pair 31, at the entrance from the switchback conveying path 61 to the re-feeding path 62.

A manual feed tray 33 serving as a sheet stacking device is provided on the side of the duplexer 60 so that it can be pulled out and stored. Figure 1 shows the manual feed tray 33 pulled out. To feed paper P from this manual feed tray 33, a paper feed means 34 consisting of a pick-up roller, a supply roller, and a separation roller is provided. A re-feed roller 28 is disposed on the side of the paper feed means 34, inside the device. Driven rollers are pressed against the top and bottom of the re-feed roller 28. This re-feed roller 28 is configured to be rotatable in both directions; when refeding paper P from the re-feed path 62, it is rotated counterclockwise in the figure, and when feeding paper P from the manual feed tray 33, it is rotated clockwise in the figure.

The basic image forming operation in the printer 100 configured as above will now be briefly described.
The photosensitive drum 1 of the imaging unit 10 is rotated clockwise in the drawing by a driving means, and the surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity by a charging means. The charged photosensitive surface is irradiated with laser light from an optical writing device 14, thereby forming an electrostatic latent image on the surface of the photosensitive drum 1. At this time, the image information exposed to each photosensitive drum 1 is monochromatic image information obtained by decomposing a desired full-color image into color information of magenta, cyan, yellow, and black. Toner of each color is applied from a developing device to the electrostatic latent image thus formed, and it is visualized as a toner image.

The intermediate transfer belt 11 is driven to run counterclockwise as shown by the arrow in the figure, and in each image forming unit 10, the primary transfer rollers 12 transfer the toner images of each color from the photosensitive drum 1 onto the intermediate transfer belt 11 in succession, superimposed on one another. In this way, the intermediate transfer belt 11 carries a full-color toner image on its surface.
It is also possible to form a single-color image, or a two- or three-color image, using any one of the image-forming units 10. In the case of monochrome printing, the image is formed using the Bk unit on the far right of the figure out of the four image-forming units.

After the toner image is transferred, any residual toner remaining on the photosensitive drum surface is removed by a cleaning device, and the surface is then subjected to the action of a static eliminator to reset the surface potential and prepare for the next image formation.

Meanwhile, paper is selectively fed from the paper feed cassette 15 or manual feed tray 33 and sent by the pair of registration rollers 18 toward the secondary transfer position in time with the toner image carried on the intermediate transfer belt 11. A transfer voltage of opposite polarity to the toner charge polarity of the toner image on the surface of the intermediate transfer belt is applied to the transfer roller 19, thereby transferring the toner image on the surface of the intermediate transfer belt all at once onto the paper. When the paper P with the transferred toner image passes through the fixing device 20, the toner image is melted and fixed to the paper P by heat and pressure. The fixed transfer material is discharged by the pair of paper discharge rollers 29 onto the paper discharge tray 30 located on the top surface of the device main body 50.

FIG. 2 is an explanatory diagram of a conveying path of a full-color printer.
The solid line [1] in FIG. 2 indicates the paper transport path during single-sided printing (when paper is fed from the paper feed cassette 15).
The dashed line [2] in Fig. 2 indicates the paper transport path (after passing through the fixing device) when paper P is discharged to an optional tray. This printer 100 can be equipped with an optional paper output tray (for example, a four-bin tray with a sorting function) on the top surface of the device above the second switching claw 22. The dashed line [2] in Fig. 2 indicates the paper transport path for discharging paper P to the optional tray after fixing.

The two-dot chain line [3] in Figure 2 indicates the transport path when paper enters the switchback transport path 61. When printing on both sides of the paper, the paper P with a toner image fixed on one side of the paper is entered into the switchback transport path 61 by appropriately switching the first to third switching claws 21 to 23. In this case, the first and second switching claws 21, 22 are switched to the positions indicated by the imaginary lines in Figure 2. The third switching claw 23 is also switched to the position indicated by the solid line in Figure 2. The first and second reversing roller pairs 31, 32 are also rotated in the forward direction (clockwise in Figure 1).
When the sensor 40 detects the rear end of the paper that has entered the switchback conveying path 61, the first and second reversing roller pairs 31 and 32 are rotated in the opposite direction (counterclockwise in FIG. 1) to reverse the paper P. At this time, the third switching claw 23 is switched to the position shown by the imaginary line in FIG. 2, so that the reversed paper P is sent to the re-feeding path 62.

The dashed line [4] in FIG. 2 indicates the paper transport path through the paper re-feed path 62 (however, from the third switching claw 23 to the part where it joins with the solid line [1]).
The paper re-feed path 62 merges with the paper transport path from the manual feed tray 33 at its lower end, and further merges with the paper transport path from the paper feed cassette 15 at the rear side of the paper re-feed roller 28. The paper is transported through the paper re-feed path 62 by the transport roller pairs 26 and 27, and is further sent to the registration roller pair 18 by the paper re-feed roller 28.

The paper P is inverted on the switchback transport path 61 and passed through the re-feed path 62, where it is turned over. A toner image is transferred from the intermediate transfer belt 11 to the back side of the paper, and the back side image is fixed by the fixing device 20. The paper P, which carries images on both sides, is transported to the paper transport path (dashed line [2]) when ejecting to the paper output tray 30 or optional tray, and then ejected to the optional tray, completing the double-sided print.

The dotted line [5] in Figure 2 indicates the paper transport path when feeding paper P from the manual feed tray 33 (up to the position after passing through the refeed roller 8).

FIG. 3 is a schematic perspective view showing the sheet feed cassette 15 serving as a sheet stacking device.
The paper feed cassette 15 has a tray housing 101 that is a storage housing for storing paper P. The tray housing 101 is provided with two side fences 102 as regulating members, an end fence 103 as a regulating member, and a bottom plate 104 as a sheet stacking portion.

The two side fences 102 are movable widthwise to match the size of the paper P set in the paper feed cassette 15. After setting the paper P, the user can move them to match the width of the paper P, allowing them to abut against both widthwise ends of the stack of paper P. This regulates the position of the paper P widthwise within the tray housing 101.

The end fence 103 is movable in the feed direction, and after setting the paper P, the user moves the end fence 103 downstream in the feed direction until it abuts against the rear end of the stack of paper P. By abutting the end fence 103 against the rear end of the paper P, the front end of the paper P abuts against the front wall 101a of the tray housing 101, thereby restricting the position of the paper P in the feed direction within the tray housing 101.

The bottom plate 104 is held rotatably around the bottom plate pivot shaft 104a relative to the tray housing 101, supporting the underside of the downstream side (leading edge side) of the paper P in the feed direction, with the downstream end moving up and down in the feed direction. When a large number of sheets of paper P are set, the downstream end of the bottom plate 104 in the feed direction is lowered, but when the number of sheets of paper P set decreases, it rises, maintaining the leading edge of the top surface of the paper P in contact with the pick-up roller of the paper feed means 16. This allows the paper P to be sent to the next process regardless of the number of sheets of paper P set.

In addition, the inner surface of the tray housing 101 of this paper feed cassette 15, the side fences 102, the end fences 103, and the bottom plate 104 have optical differences that make them distinguishable from the white paper P, such as a different color, reflectivity, or texture.

FIG. 4 is a schematic diagram illustrating the configuration of an imaging device 110 that captures an image of the inside of the paper feed cassette 15. As shown in FIG.
The imaging device 110 has an imaging unit 111 formed of a CCD or CMOS sensor or the like, and an optical unit 112 formed of lenses, mirrors, and the like. As shown by the dashed-dotted line in the figure, the imaging device 110 is configured so that the entire interior of the paper feed cassette 15 is within an imaging range S. The imaging device 110 uses an ultra-wide-angle lens, such as a fisheye lens, as the optical unit 112, thereby enabling imaging of the entire interior of the paper feed cassette 15. Alternatively, a rotatable mirror may be used as the optical unit 112, and the entire interior of the paper feed cassette may be imaged by scanning with the mirror. The imaging device 110 also has an illumination unit that illuminates the interior of the paper feed cassette, and the illumination unit is turned on when imaging the interior of the paper feed cassette.

In this way, by configuring the optical unit 112 so that it can capture the entire surface of the paper in the paper feed cassette 15, a movement mechanism for moving the imaging unit 111 is not required, and the imaging device 110 can be installed without increasing the size of the device itself.

As described above, this paper feed cassette 15 has optically differentiated surfaces of the inner surface of the tray housing 101, the side fences 102, the end fence 103, and the bottom plate 104 relative to the paper P. This allows the paper P to be easily recognized from the image captured by the imaging device 110.

FIG. 5 is a schematic diagram illustrating an example in which a manual feed imaging device 120 for imaging the manual feed tray 33 as a sheet stacking device is provided.
5, the manual-feed imaging device 120 is disposed on the right side of the device body 50 in the drawing, above the manual feed tray 33. The manual feed imaging device 120 also has an imaging section 111 formed of a CCD or CMOS sensor, etc., and an optical section 112 formed of lenses, mirrors, etc. An ultra-wide-angle lens such as a fisheye lens is used as the optical section 112 so that the entire manual feed tray 33 becomes the imaging range S.

As for the manual feed tray 33, the sheet loading surface of the manual feed tray 33, the side fence 33a, which serves as the sheet loading section, has optical differences from the white paper P, such as a different color, reflectivity, or texture.

Based on the image data captured by the imaging devices 110 and 120, information about the paper set in the paper feed cassette 15 (paper size, presence or absence of an image, etc.) and paper set information (number of sheets loaded, restriction status by side fences and end fences) are obtained. Then, predetermined processing is performed based on the paper information and paper set information based on the image data.

FIG. 6 is a control block diagram for detecting paper information, paper set information, and the like based on image data captured by the imaging device 110, and for executing predetermined processing based on the detection results.
6 processes image data captured by the imaging devices 110 and 120. This processing unit 80 performs image processing such as contrast processing and trapezoidal correction on the image data captured by the imaging devices 110 and 120, and acquires paper information and paper set information.

The storage unit 90 is composed of a HDD, flash memory, etc., and stores information such as determination information for whether or not to execute a specified process based on paper information and paper set information obtained from image data. For example, it stores standard paper size data for specifying the size of the loaded paper, and threshold values for determining whether the paper set status is normal.

The operation panel 70, which serves as a notification means, functions as an input reception unit that receives various instruction inputs in response to user operations, and also has a notification function that displays and notifies various information (such as received operation information, information indicating the printer's operating status, and information indicating the setting status).

The operation panel 70 is, for example, configured as a liquid crystal display (LCD) equipped with a touch panel function, but is not limited to this. For example, it may be configured as an organic electroluminescence (EL) display equipped with a touch panel function. Furthermore, in addition to or instead of this, operation units such as hardware keys and display units such as lamps may be provided. Furthermore, an audio unit such as a speaker may be provided as a notification means to notify the user by voice.

The processing unit 80 performs the determination process described in Examples 1 to 5 below based on the paper information and paper set information acquired through image processing and the determination information stored in the memory unit 90. Based on the determination results, the processing unit 80 displays the result information on the operation panel 70 and notifies the user.

Next, we will explain in detail how paper information and paper set information are detected based on image data captured by the imaging device 110.

[Example 1]
In the first embodiment, the paper size is detected as paper information based on image data captured by the imaging device 110 .

Automatic paper size detection, which automatically detects the size of paper set in the paper feed cassette 15, manual feed tray 33, etc., has been around for some time. Conventional automatic paper size detection systems identify the positions of the side fence 102 and end fence 103 by providing information to sensors or switches using levers that move in conjunction with the side fence 102 and end fence 103. Most systems then detect the standard size based on the identified positions of the side fence 102 and end fence 103.

The method of detecting paper size based on the position of the side fence 102 and the end fence 103 allows the user to load paper into the paper feed cassette 15 or manual feed tray 33, and then have the user press the side fence 102 or end fence 103 against the paper to properly position it, thereby detecting the correct paper size. Therefore, if the user forgets to operate the side fence 102 or end fence 103 and the side fence 102 or end fence 103 does not press against the paper (there is a large gap between the paper and the fence), the paper size will be detected incorrectly.

In addition, if the user operates the side fence 102 or end fence 103 to bring the side fence 102 or end fence 103 into contact with the paper, but then returns the paper feed cassette 15 to the device main body 50 forcefully or roughly, there is a risk that the end fence 103 or side fence 102 may move due to play. As a result, the side fence or end fence may not come into contact with the paper, and the paper size may be detected incorrectly. If the paper size is detected incorrectly, various problems may occur, such as image position errors, paper misfeeds, paper jams, skews, and wrinkles.

In contrast, in Example 1, the paper size is detected based on image data captured by the imaging device 110. This allows the paper size to be accurately detected even when the side fence 102 or end fence 103 is not in contact with the paper due to the user forgetting to operate the side fence 102 or end fence 103, for example.

FIG. 7 is a control flow diagram of the paper size detection control.
7, detection of the size of the paper set in the paper feed cassette 15 will be described.
The paper feed cassette 15 is pulled out from the device body and paper is set in the paper feed cassette 15 (S1). The imaging device 110 starts imaging at a predetermined timing and acquires image data of the entire paper feed cassette (S2-S4). After acquiring the image data, the processing unit 80 identifies the size of the paper set in the paper feed cassette (S5).

An example of the specified timing for starting imaging is when the set detection sensor, which detects the setting of the paper feed cassette 15 in the device body, switches from a state where it does not detect the setting to a state where it does. At this time, it is possible that the paper in the paper feed cassette 15 has been replaced. Therefore, it is preferable to take an image of the inside of the paper feed cassette and identify the size of the paper that has been set when the sensor switches from a state where it does not detect the setting to a state where it detects the setting. Also, because it is possible that the paper in the paper feed cassette 15 has been replaced while the device is turned off, it is preferable to take an image of the inside of the paper feed cassette and identify the size of the paper that has been set even when the device is turned on.

In this way, if an image of the inside of the paper feed cassette is taken before printing and the set paper size is identified, the paper size information set in this paper feed cassette is displayed on the operation panel, etc. (S6). Then, when printing, it is preferable to prevent the selection of paper sizes other than the set paper size.

Furthermore, examples of the predetermined timing for starting imaging include when printing begins, such as when the user operates the operation panel 70 to select the paper size to be printed on, when a paper feed command is received, or when the user presses the start button on the operation panel.

When starting printing in this manner, if an image of the inside of the paper cassette is taken to identify the paper size set, after the paper size is identified, a determination is made as to whether it differs from the paper size set by the user using the operation panel 70. If the identified paper size differs from the paper size set by the user, the identified paper size information is displayed on the operation panel 70 (S6). The operation panel 70 also displays a message such as "Please set the correct size paper in the paper cassette" (S7-1).

To identify the paper size based on the image data captured by the imaging device 110, the processing unit 80 first performs a specified image processing on the image data to identify the paper set in the paper feed cassette. Next, the processing unit 80 acquires standard size paper size data from the memory unit 90. Based on the standard size paper size data obtained from the memory unit 90, the processing unit 80 identifies the standard size paper size data that matches the paper data obtained from the image data. Based on the identified paper size data, the processing unit 80 identifies the paper size (standard size) set in the paper feed cassette 15.

The standard size paper size data stored in the memory unit 90 can be, for example, image data captured by placing standard size paper in a paper feed cassette in advance.

The imaging device 110 captures an image of the entire paper feed cassette, so it can capture an image of all the paper set in the paper feed cassette. This makes it possible to accurately detect the width of the paper and the length of the paper in the sheet transport direction, making it possible to accurately detect the paper size.

Furthermore, as described above, the inner surface of the tray housing 101, the side fence 102, the end fence 103, and the bottom plate 104 of this paper feed cassette 15 are optically differentiated from the paper P. This allows the boundary between the paper and the components of the paper feed cassette 15 to be accurately determined from the image data captured by the imaging device 110, and the paper can be accurately detected from the image data.

Furthermore, for example, by providing a reference mark that serves as a measurement reference at a predetermined position on the tray housing 101, it is possible to accurately identify the set paper size and compare it with standard paper size data pre-stored in the memory unit. This is preferable as it allows for highly accurate identification of the paper size. The reference mark may be a sticker, or may be printed directly on the tray housing 101. It may also be engraved into the tray housing 101.

For the manual feed tray 33, the specified timing for starting imaging is when the paper set detection sensor, which detects that paper has been set in the manual feed tray, detects that paper has been set. As with the paper feed cassette, imaging may also start when printing begins, such as when the user operates the operation panel 70 to select the paper size to be printed, when a paper feed command is received, or when the user presses the start button on the operation panel.

[Example 2]
In the second embodiment, the amount of paper stacked is detected as paper set information based on image data captured by the imaging device 110 .

There is a mark (105 in Figure 8) on the side fence 102 etc. that indicates the upper stacking limit, but some users may load paper above this limit, resulting in an overload. If the paper cassette is loaded with too much paper, the bottom plate lift function will not function properly, which may result in a false detection of a tray abnormality and a temporary inoperability of the device, such as requiring a service call.

In contrast, in this second embodiment, the amount of paper loaded is detected based on image data captured by the imaging device 110. Therefore, if there is an overload or if the loaded paper runs out, the user can be notified and asked to reload the paper, etc. Furthermore, if the bottom plate lift function does not function properly, the imaging device 110 can detect whether there is an overload from the image data captured, and if there is an overload, it can be determined that there is no tray abnormality, making it possible to reduce device downtime due to false detection of a tray abnormality.

FIG. 8 shows the state when the paper stack amount is large, and FIG. 9 shows the state when the paper stack amount is small.
8 and 9, in the second embodiment, a detection mark 106 for detecting the amount of paper stacked is formed on the leading edge in the sheet conveyance direction of one of the two side fences 102. This detection mark 106 is a mark that allows easy distinction from paper and paper feed cassette parts such as the side fences from captured image data.

As shown in Figure 8, when the number of loaded sheets of paper is large, a larger portion of the detection mark 106 is hidden by the loaded sheets, and the exposed area of the detection mark 106 is small. On the other hand, as shown in Figure 9, when the number of loaded sheets of paper is small, the portion hidden by the loaded sheets becomes smaller, and the exposed area of the detection mark 106 becomes larger.

In Example 2, the exposed area of the detection mark 106 is calculated based on the captured image data, and the paper load amount is detected based on the calculated exposed area. For example, if this exposed area is less than a threshold, it is determined that there is an overload of paper, and the user is prompted to reload the paper. In addition, the relationship between the paper load amount and the exposed area of the detection mark 106 is examined in advance, and the paper load amount is determined based on the calculated exposed area.

In Figures 8 and 9, the detection mark 106 is provided on the leading edge of the side fence 102 in the sheet transport direction, but it may also be provided on the trailing edge of the side fence 102 in the sheet transport direction. The detection mark may also be provided on the end fence. Alternatively, for example, a reference mark may be provided as a height reference, and the paper load amount may be detected from the distance between this reference mark and the top surface of the paper stack. Note that the height of the leading edge of the top surface of the paper stack is kept constant by the bottom plate 104, so the paper load amount is detected from the distance between the trailing edge of the top surface of the paper stack and the reference mark.

FIG. 10 is a control flow diagram of the paper stack amount detection control.
The paper load amount detection control also starts imaging at the same timing as the paper size detection, and acquires image data of the entire paper feed cassette 15 (S11 to S14). After acquiring the image data, the processing unit 80 detects the amount of paper loaded in the paper feed cassette 15 (S15).

When the set detection sensor, which detects the setting of the paper feed cassette 15 in the device body, switches from a state where it does not detect the setting to a state where it does, it is possible that paper has been added or replaced in the paper feed cassette 15. As a result, the amount of paper loaded may have changed. Therefore, when the sensor switches from a state where it does not detect the setting to a state where it detects the setting, it is preferable to take an image of the inside of the paper feed cassette and detect the amount of paper loaded. Also, because it is possible that paper has been replaced in the paper feed cassette 15 while the device is turned off, it is preferable to take an image of the inside of the paper feed cassette and detect the amount of paper loaded even when the device is turned on.

By detecting the amount of paper loaded when the paper feed cassette 15 is inserted into the device body or when the power is turned on, if there is an overload of paper, a message indicating that there is an overload of paper is displayed on the operation panel, prompting the user to reload paper (S17-1). Also, if there is no paper loaded in the paper feed cassette because paper was forgotten to be loaded, a message indicating that there is no paper is displayed on the operation panel 70, prompting the user to load paper (S17-1).

To detect the paper load amount based on the image data captured by the imaging device 110, the processing unit 80 first performs a specified image processing on the image data to identify the detection mark 106 and calculate the area of the identified detection mark 106. Next, the processing unit 80 reads a threshold value from the memory unit 90 to determine whether or not there is an overload, and if the calculated area of the detection mark 106 is less than the threshold value, it determines that there is an overload. If it determines that there is an overload, as shown in S17-1, the operation panel 70 displays a message indicating that there is an overload, and prompts the user to reduce the number of sheets in the stack of paper and reset it.

Furthermore, if the processing unit 80 cannot detect paper from the image data, it determines that there is no paper and displays a message on the operation panel 70 to that effect, prompting the user to load paper (S17-1).

If the image data detects paper and the calculated area of the detection mark 106 is equal to or greater than the threshold, data indicating the relationship between the number of loaded sheets and the area of the detection mark is read from the memory unit 90. The number of loaded sheets is then determined from the calculated area of the detection mark 106 and the data indicating the relationship between the number of loaded sheets and the area of the detection mark, and the determined number of loaded sheets is displayed on the operation panel as the remaining paper amount (S16). Note that the detection of the number of loaded sheets based on this image data is performed when the paper feed cassette 15 is inserted into the device body or when the power is turned on, and thereafter the number of loaded sheets is reduced according to the number of printed sheets. Alternatively, the operation panel 70 may display a rough remaining amount, such as "XX%" of paper remaining.

Furthermore, an image may be taken with the imaging device 110 each time printing is completed or after a predetermined number of sheets have been printed, and the area of the detection mark 106 may be calculated to determine the number of sheets loaded. Furthermore, if the amount of remaining paper falls below a predetermined value, imaging may be started after the paper has been fed (after the rear end of the paper has left the paper feed cassette 15), and the presence or absence of paper may be detected based on the image data.

In this way, by displaying the remaining paper amount on the operation panel 70, the user can refill the paper feed cassette with paper when the paper level is low, based on the remaining paper level displayed on the operation panel. As a result, it is possible to prevent the occurrence of paper shortages. In addition, when the paper level is low, more paper can be prepared, which makes it possible to prevent situations in which the device runs out of paper and there is no paper to refill, resulting in downtime.

[Example 3]
The third embodiment is an embodiment in which, based on image data captured by the imaging device 110, it is detected whether or not an image exists on the surface (front surface) of the paper on which the image is to be printed, as paper information.

The use of reversed paper (reusing paper that has already been printed on one side) is becoming more common these days from the perspective of recycling and energy conservation. However, when using reversed paper, as shown in Figure 11, there are cases where the paper is loaded upside down and the side with the image on it is loaded as the front side. In this case, the image being printed this time will overlap the previously printed image ("R" in the figure), and the desired image will not be obtained.

Conventionally, there are devices that check whether or not there is an image on the front side of the paper before the registration roller pair 18, but with these conventional devices, by the time it is determined that there is an image on the front side, image creation has already begun. As a result, the created toner image is discarded (forced cleaning) and toner is wasted.

In contrast, in Example 3, the presence or absence of an image on the front side can be determined at the time paper is set in the paper feed cassette 15 or manual feed tray 33. This makes it possible to determine the presence or absence of an image on the front side before the image creation operation, thereby reducing unnecessary toner consumption.

FIG. 12 is a control flow diagram of the image presence/absence detection control on the front surface.
The control for detecting the presence or absence of an image on the front side also starts imaging at the same timing as the paper size detection, and acquires image data of the entire contents of the paper feed cassette (S21 to S24). After acquiring the image data, the processing unit 80 detects whether or not there is an image on the front side of the paper set in the paper feed cassette.

When the set detection sensor, which detects the setting of paper cassette 15 in the device body, switches from a state where it does not detect the setting to a state where it does, there is a risk that the paper in paper cassette 15 has been replaced with paper on the back side (paper with an image printed on one side). Therefore, when the sensor switches from a state where it does not detect the setting to a state where it detects the setting, an image of the inside of the paper cassette is taken to detect whether or not there is an image on the front side of the set paper. In addition, there is a risk that the paper in paper cassette 15 has been replaced with paper on the back side when the device is turned off. Therefore, even when the device is turned on, an image of the inside of the paper cassette is taken to detect whether or not there is an image on the front side of the set paper.

Note that imaging by the imaging device 110 to detect the presence or absence of an image on the front surface may be performed at any timing before the start of image creation, and may be performed at a timing other than that described in S22 in Figure 12.

To detect the presence or absence of an image on the front side based on the image data captured by the imaging device 110, the processing unit 80 checks whether there is an image other than the color of the paper (white) within the detection range of the paper in the captured image data. If there is an image other than the color of the paper (white), it is determined that there is an image on the front side of the paper.

Also, for example, if there is no paper color (white) within the paper detection range, it is determined that there is no paper. On the other hand, if there is paper color (white) within the paper detection range and there is an image of a color other than paper color (white) within the paper detection range, it may be determined that there is an image on the front side.

When the processing unit 80 determines that an image exists on the front side of the paper (S25-1), it displays a message on the operation panel 70 indicating that an image exists on the front side of the paper. It also displays a warning message (S26-1) urging the user to check the paper loaded in the paper feed cassette 15. Along with this warning message, an "OK" button is also displayed.

When the user presses the OK button, the printer enters a state in which paper can be fed (S27-1). Meanwhile, if the user pulls out the paper feed cassette and the load detection turns OFF in order to load paper into the paper feed cassette again (S28-1), the warning display is cleared. Then, when the load detection switches from OFF to ON, the printer captures an image of the inside of the paper feed cassette again to detect whether or not there is an image of the front side of the paper.
This makes it possible to prevent the image to be printed this time from unintentionally overlapping the image that was printed previously, and to prevent the wasteful consumption of toner.

Furthermore, if the loaded paper is wavy, curled, or folded, a shadow will appear on the paper portion of the image data. This shadow may lead the processing unit 80 to determine that an image other than the paper's color (white) is present in the paper detection area. For this reason, it is preferable to be able to determine whether an image other than the paper's color (white) is an image corresponding to wavy, curled, or folded, or an image formed on the front surface. For example, by learning images corresponding to wavy, curled, or folded using deep learning, it is possible to determine whether an image other than the paper's color (white) is an image corresponding to wavy, curled, or folded.

When waving, curling, or creases are detected in the loaded paper, this means that the loaded paper has waving, curling, or creases, and there is a possibility that a paper jam may occur. Therefore, when the processing unit 80 detects waving, curling, or creases, it is preferable to display the state of the loaded paper, such as waving, curling, or creases, on the operation panel 70 and prompt the user to replace the paper. This makes it possible to prevent paper jams from occurring.

[Example 4]
The fourth embodiment is an embodiment in which the presence or absence of a gap between a sheet and the side fence 102 and a gap between a sheet and the end fence 103 is detected as sheet set information based on image data captured by the imaging device 110 .

If the user fails to regulate the position of the loaded paper, for example by forgetting to set the side fence 102 or end fence 103 or by not pushing it in enough, there is a risk of non-feeding, paper jams, paper skew, or paper wrinkles. There is also a risk of image position errors, where the image is not formed in the intended position on the paper.

In contrast, in Example 4, the presence or absence of a gap between the paper and the side fence 102 and the gap between the paper and the end fence 103 can be detected based on image data captured by the imaging device 110, and it can be determined whether the paper is correctly positioned. As a result, if the loaded paper is not correctly positioned due to forgetting to set the side fence 102 or end fence 103 or not being pushed in enough, the user can be prompted to operate the side fence 102 or end fence 103. This can prevent non-feeding, paper jams, paper skew, and paper wrinkles. It can also prevent image position errors, where the image is not formed in the intended position on the paper.

FIG. 13 is a diagram for explaining detection by the processing unit 80 of the presence or absence of a gap between the paper and the side fence 102 and a gap between the paper and the end fence 103. In FIG.
The processing unit 80 determines the paper length PL and paper width PW from the image data captured by the imaging device 110. Specifically, the paper size is identified by the method described in the first embodiment, and the paper length PL and paper width PW can be determined from the identified paper size.

The processing unit 80 also measures the distance between the pair of side fences 102 from the captured image data. To enable the processing unit 80 to easily determine the position of the side fences 102 from the image data, it is preferable to provide the side fences 102 with position detection marks that distinguish them from components inside the paper feed cassette. The processing unit 80 then detects the gap between the side fences 102 and the paper based on the measured distance between the pair of side fences 102 and the paper width.

The processing unit 80 also measures the length from the front wall 101a of the tray housing 101 to the end fence 103 from the captured image data. In this case, too, it is preferable to provide position detection marks on the end fence 103 and front wall 101a that distinguish them from components inside the paper feed cassette, so that the processing unit can easily determine the positions of the end fence 103 and front wall 101a from the image data. The processing unit 80 then detects the gap between the end fence 103 and the paper from the measured length from the front wall 101a to the end fence 103 and the length of the paper.

FIG. 14 is a control flow diagram of the gap detection control between the paper and the fence.
Imaging is started at the same timing as the paper size detection, and image data of the entire paper feed cassette is acquired (S31 to S34). After acquiring the image data, the processing unit 80 identifies the paper size and measures the distance between the pair of side fences 102 and the length from the front wall 101a to the end fence 103 (S35).

Next, the processing unit 80 calculates the difference between the paper width determined from the identified paper size and the spacing between the side fences 102, and detects the gap between the paper and the side fences. It also calculates the difference between the paper length determined from the identified paper size and the length from the front wall 101a to the end fence 103, and detects the gap between the paper and the end fence 103 (S36).

Next, the processing unit 80 reads the threshold value for the gap between the fence and the paper from the memory unit 90 and determines whether the calculated gap between the paper and the side fence 102 is equal to or greater than the threshold value. It also determines whether the calculated gap between the paper and the end fence 103 is equal to or greater than the threshold value (S37).

If the calculated gap between the paper and the side fence 102, or the gap between the paper and the end fence 103, is equal to or greater than the threshold (S38-1), a message is displayed on the operation panel 70 indicating that the paper is not correctly positioned. A message is also displayed urging the user to check the end fence 103 and side fence 102, along with an OK button (S39-1).

When the user presses the OK button, the machine is ready to feed paper. Meanwhile, to check the positions of the end fence 103 and the side fence 102, the user pulls out the paper feed cassette 15, and when the set detection is turned OFF, the warning display is cleared. Then, when the set detection is switched from OFF to ON, an image of the inside of the paper feed cassette is captured again to check whether the end fence 103 and the side fence 102 are correctly regulating the paper position.
This makes it possible to prevent the paper from being unintentionally fed without being positioned by the end fence 103 and the side fence 102 .

[Example 5]
The fifth embodiment is an embodiment in which it is detected whether the last sheet of paper has been set based on image data captured by the imaging device 110.

Previously, a message urging the user to load paper into the paper cassette 15 was displayed only after the paper ran out, which meant that when printing continuously, the image toner had to be discarded (forced cleaning) after the last sheet.

In contrast, in Example 5, the last sheet of loaded paper is detected based on captured image data, so during continuous printing, the image creation operation can be temporarily suspended after the last sheet of paper is created based on this detection result. This prevents situations where image toner used in the last sheet of paper needs to be discarded (forced cleaning) and reduces wasted toner consumption.

FIG. 15 is a diagram for explaining the detection of the last sheet.
The leading edges of the top few sheets of paper in the stack of sheets on the bottom plate do not face the front wall 101a, and the front wall 101a does not restrict the sheets from moving downstream in the paper transport direction. Furthermore, the paper feed unit 16 forms a separation nip by abutting a separation roller against the supply roller downstream in the paper transport direction from the pick-up roller. The separation nip separates multiple sheets of paper transported by the pick-up roller, and transports the topmost sheet toward the pair of registration rollers. Therefore, in most cases, when the topmost sheet of a stack of sheets is fed, the second sheet immediately below the topmost sheet also moves into the separation nip due to frictional forces, etc. Therefore, the next sheet to be transported is located downstream in the paper transport direction from the paper set position.

As for the final sheet, when the sheet before the final sheet is fed by the paper feed means 16, it moves to the vicinity of the separation nip together with the sheet before the final sheet, as shown in Figure 15. Therefore, by detecting the movement of the rear edge position of the sheet detected from the captured image data, it is possible to determine whether or not the sheet in the paper feed cassette is the last sheet.

FIG. 16 is a control flow diagram of the final sheet detection control.
The paper feed means 16 is driven to start feeding paper (S41), and after a predetermined time has elapsed, the imaging device 110 starts capturing an image of the inside of the paper feed cassette, and image data of the image captured inside the paper feed cassette is obtained (S42).

Next, the processing unit 80 detects the position of the rear end of the paper in the paper feed cassette based on the captured image data. The position of the rear end of the paper is detected from the boundary between the paper image portion (white image) of the image data and the colored image showing the bottom plate or the inner surface of the tray housing 101. The position of the end fence 103 is also detected based on the captured image data. By providing a position detection mark on the end fence 103 that distinguishes it from components inside the paper feed cassette and detecting the position of the end fence 103 based on this position detection mark, the position of the end fence 103 can be easily detected, which is preferable. Next, the processing unit 80 measures the gap between the rear end of the paper and the end fence 103 based on the detected positions of the rear end of the paper and the end fence 103 (S44).

Next, the processing unit 80 reads the gap between the trailing edge of the paper and the end fence 103, measured based on the image data captured when the paper was set and stored in the memory unit 90, and the threshold value for detecting the last sheet. It then calculates the difference between the gap between the trailing edge of the paper and the end fence 103 this time and the gap between the trailing edge of the paper and the end fence 103 when the paper was set, and measures the increase in the gap between the trailing edge of the paper and the end fence 103.

If there are three or more sheets of paper in the paper feed cassette when feeding begins, the leading edge of the last sheet of paper in contact with the bottom plate 104 will be abutting the front wall 101a, restricting movement in the paper transport direction. Therefore, the last sheet of paper is not moving, and the increase in the gap between the trailing edge of the paper and the end fence 103 is almost zero. Therefore, in this case, the increase is below the threshold, and the processing unit 80 determines that this is not the last sheet of paper (S45-2).

On the other hand, if there are two sheets of paper in the paper feed cassette when feeding begins, the leading edge of the last sheet does not abut against the front wall 101a. Therefore, when feeding begins, the last sheet is transported to the separation nip together with the second sheet. As a result, the increase in the gap between the trailing edge of the paper and the end fence 103 when the paper is set exceeds the threshold value. This detects that there is only one sheet of paper left in the paper feed cassette.

In the above description, whether or not the paper is the last sheet is determined based on the increase in the gap between the end fence and the paper when the paper is set. However, if the gap between the paper and the end fence 103 exceeds a threshold value, it can be determined that the last sheet has moved and that it is the last sheet.

If the increase in the gap between the trailing edge of the paper and the end fence 103 exceeds a threshold and the processing unit 80 detects that there is only one sheet of paper left in the paper feed cassette (S45-1), a paper out message is displayed on the operation panel 70 after the next paper feed (S46-1). Alternatively, the paper out notification may be made by sound such as a buzzer.

When the processing unit 80 detects that there is only one sheet of paper left in the paper feed cassette, the operation panel 70 may display a message indicating that the next sheet is the last. This allows paper to be prepared before the paper supply runs out, and allows paper to be replenished in the paper feed cassette 15 when or before the paper supply runs out.

Furthermore, when the last sheet of paper is detected during continuous printing, the image creation operation is paused at the next image creation, and an out-of-paper message is displayed on the operation panel 70. This reduces the waste of toner. Furthermore, the user can be notified that the paper has run out before the last sheet of paper is fed, which allows for more paper to be prepared more quickly than if the user were notified that the paper has run out after the last sheet has been fed, and continuous printing can be resumed more quickly.

Note that this printer may have any one of the above-mentioned Examples 1 to 5, may have multiple examples 1 to 5, or may have all of Examples 1 to 5. Also, while the above-mentioned Examples 1 to 5 were described in relation to the paper feed cassette 15, Examples 1 to 5 can also be adopted for the manual feed tray 33.

The above description is merely an example, and each of the following aspects provides unique effects.
(Aspect 1)
A sheet stacking device such as a paper feed cassette 15 is provided with a sheet stacking section such as a bottom plate 104 for stacking sheets such as paper P, and an imaging means such as an imaging device 110 for imaging the entire sheets stacked in the sheet stacking section, and detects the size of the sheets stacked in the sheet stacking section based on image data captured by the imaging means.
In the sheet stacking device described in Patent Document 1, users sometimes forget to operate the side fences, which can result in the side fences not abutting the widthwise edges of the sheet and not restricting the sheet's position. Furthermore, structural play can create gaps between the side fences and the widthwise edges of the sheet. When the side fences do not abut the widthwise edges of the sheet, the position of the side fences does not correspond to the widthwise position of the sheet. As a result, sheet size information detected based on the position of the side fences can be incorrect.
In contrast, in the first aspect, the imaging unit captures an image of the entire sheet stacked on the sheet stacking section, and the width and length of the sheet in the conveying direction can be determined based on the captured image data, thereby enabling the sheet size to be detected. This allows the sheet size to be detected accurately even if the side fences do not abut against the sheets.

(Aspect 2)
In aspect 1, an imaging means such as the imaging device 110 simultaneously captures an image of the sheets loaded on a sheet loading section such as the bottom plate 104 and a detection mark for detecting the height position of the sheets, and detects the amount of sheets loaded on the sheet loading section based on image data captured simultaneously of the detection mark and the sheets loaded on the sheet loading section.
According to this, as described in the second embodiment, by simultaneously capturing an image of the sheets loaded on the sheet loading section such as the bottom plate 104 and the detection mark 106 for detecting the height position of the sheets, it is possible to grasp the relationship between the detection mark 106 and the sheets loaded on the sheet loading section (in the second embodiment, the area of the detection mark 106 that is not hidden by the sheets, which changes depending on the sheet height) based on the image data captured by the imaging unit. This makes it possible to grasp the amount of sheets loaded on the sheet loading section based on the image data captured by the imaging unit.
By detecting the sheet load amount, it is possible to detect an overloaded state or when there is no paper loaded, and to notify the user and request that the paper be reloaded, etc. Furthermore, when there is an operational abnormality in the sheet stacking section such as the bottom plate, it is possible to determine whether the operational abnormality is due to an overloaded state, and it is possible to prevent downtime of the device due to false detection of an operational abnormality.
Furthermore, the sheet size and the amount of loaded sheets can be detected from the image data captured by the imaging means, which reduces the number of parts and makes the device less expensive compared to when a device for detecting the sheet size and a device for detecting the amount of loaded sheets are provided separately.

(Aspect 3)
In the first or second aspect, it is detected whether the sheet stacked on the sheet stacking section such as the bottom plate 104 is the last sheet based on image data captured by an imaging unit such as the imaging device 110.
According to this, as described in the fifth embodiment, the last sheet of paper moves toward a separation position such as a separation nip together with the previous sheet. Therefore, when it is the last sheet, the position of the sheet stacked in the sheet stacking section is located downstream in the sheet conveyance direction compared to when it is not the last sheet. Therefore, by having the imaging unit capture an image of the entire sheet, it is possible to determine from the captured image data whether the sheet has shifted downstream in the conveyance direction. Then, if it is detected from the captured image data that the sheet has shifted downstream in the conveyance direction, it can be determined that the sheet stacked in the sheet stacking section is the last sheet.
In this way, by being able to determine whether the sheet stacked in the sheet stacking section is the last sheet, when it is detected that the sheet is the last during continuous printing, it is possible to perform image formation on this last sheet and then stop the image formation operation. This prevents situations where image formation toner has to be discarded (forced cleaning) and reduces wasteful toner consumption. The user can be notified that paper is running out before the sheet runs out, which shortens device downtime compared to notifying the user after the paper runs out.
In addition, from the image data captured by the imaging means, it is possible to detect whether the sheet is the last one and to perform other detections (at least one of detecting the sheet size and detecting the sheet stack amount), which allows the number of parts to be reduced and the device to be made cheaper than when a device for detecting the other things mentioned above and a device for detecting whether the sheet is the last one are provided separately.

(Aspect 4)
A sheet stacking device such as a paper feed cassette 15 is provided with a sheet stacking section such as a bottom plate 104 for stacking sheets such as paper P, and an imaging means such as an imaging device 110 for imaging the entire sheets stacked in the sheet stacking section, and detects whether the sheet stacked in the sheet stacking section is the last one or not based on image data captured by the imaging means.
According to this, as described in the fifth embodiment, the last sheet of paper moves toward a separation position such as a separation nip together with the previous sheet. Therefore, when it is the last sheet, the position of the sheet stacked in the sheet stacking section is located downstream in the sheet conveyance direction compared to when it is not the last sheet. Therefore, by having the imaging unit capture an image of the entire sheet, it is possible to determine from the captured image data whether the sheet has shifted downstream in the conveyance direction. Then, if it is detected from the captured image data that the sheet has shifted downstream in the conveyance direction, it can be determined that the sheet stacked in the sheet stacking section is the last sheet.
In this way, by being able to determine whether the sheet stacked in the sheet stacking section is the last sheet, when it is detected that the sheet is the last during continuous printing, it is possible to perform image formation on this last sheet and then stop the image formation operation. This prevents situations where image formation toner has to be discarded (forced cleaning) and reduces wasteful toner consumption. The user can be notified that paper is running out before the sheet runs out, which shortens device downtime compared to notifying the user after the paper runs out.

(Aspect 5)
In any of the aspects 1 to 4, the presence or absence of an image on the surface on which an image is to be formed, such as the front surface of the sheet, is detected based on image data captured by an imaging unit such as the imaging device 110.
This makes it possible to detect when a user accidentally places a sheet on the sheet stacking section with the imaged side as the front side, in what is called reverse printing, in which an image is formed on the side opposite to the imaged side, as described in the third embodiment. This makes it possible to prevent an image from being unintentionally formed on the imaged side, thereby reducing toner waste.
Furthermore, from the image data captured by the imaging means, in addition to detecting whether or not an image exists on the surface on which an image is to be formed, such as the front surface of the sheet, at least one of the following can be detected: sheet size, sheet stack amount, and whether or not this is the last sheet. In this way, multiple detections can be performed based on the image data captured by the imaging means, and the number of parts can be reduced compared to when separate detection devices are used for each detection, making the device less expensive.

(Aspect 6)
A sheet stacking device such as a paper feed cassette 15 is provided with a sheet stacking section such as a bottom plate 104 for stacking sheets such as paper P, and an imaging means such as an imaging device 110 for imaging the sheets stacked in the sheet stacking section, and detects whether or not there is an image of the surface on which an image is to be formed, such as the front surface of the sheet, based on image data captured by the imaging means.
This makes it possible to detect when a user accidentally places a sheet on the sheet stacking section with the imaged side as the front side, in what is called reverse printing, in which an image is formed on the side opposite to the imaged side, as described in the third embodiment. This makes it possible to prevent an image from being unintentionally formed on the imaged side, thereby reducing toner waste.

(Aspect 7)
In any of aspects 1 to 6, a regulating member (side fence 102 or end fence 103) is provided to regulate the position of sheets such as paper loaded on a sheet loading section such as a bottom plate 104, and an imaging means such as an imaging device 110 simultaneously images the regulating member and the sheets loaded on the sheet loading section, and detects the distance between the sheets and the regulating member based on image data of the regulating member and the sheets simultaneously captured.
This makes it possible to determine whether or not a sheet such as paper is properly positioned by a regulating member, as described in the fourth embodiment. This allows the user to be prompted to operate the regulating member when the loaded paper is not properly positioned due to forgetting to use a regulating member such as a side fence or end fence, or due to insufficient paper positioning. This can prevent non-feeding, paper jams, paper skew, and paper wrinkles. It can also prevent image position errors, where an image is not formed at the intended position on the paper.
Furthermore, from the image data captured by the imaging means, it is possible to detect at least one of the following, in addition to the distance between the sheet and the regulating member: presence or absence of an image on the surface on which an image is to be formed, such as the front surface of the sheet; detection of the sheet size; detection of the amount of stacked sheets; and detection of whether or not this is the last sheet. In this way, multiple detections can be performed based on the image data captured by the imaging means, and the number of parts can be reduced compared to when separate detection devices are used for each detection, making the device less expensive.

(Aspect 8)
A sheet stacking device such as a paper feed cassette 15 includes a sheet stacking section such as a bottom plate 104 for stacking sheets such as paper P, regulating members (side fences 102 and end fences 103) for regulating the position of the sheets stacked in the sheet stacking section, and an imaging means such as an imaging device 110 for simultaneously capturing images of the regulating members and the sheets stacked in the sheet stacking section, and detects the distance between the sheets and the regulating member based on image data captured by the imaging means.
This makes it possible to determine whether or not a sheet such as paper is properly positioned by a regulating member, as described in the fourth embodiment. This allows the user to be prompted to operate the regulating member when the loaded paper is not properly positioned due to forgetting to use a regulating member such as a side fence or end fence, or due to insufficient paper positioning. This can prevent non-feeding, paper jams, paper skew, and paper wrinkles. It can also prevent image position errors, where an image is not formed at the intended position on the paper.

(Aspect 9)
In any of aspects 1 to 8, image data captured by an imaging means such as the imaging device 110 shows that the components of the sheet stacking device (such as side fences, end fences, bottom plates, and tray housings) have reflection characteristics that allow them to be distinguished from sheets.
According to this, the boundary between the sheets stacked on the sheet stacking section and the components of the sheet stacking device can be easily determined from the captured image data, and the sheets can be detected with high accuracy.

(Aspect 10)
In an image forming apparatus that includes a sheet stacking device such as a paper feed cassette 15 and feeds sheets from the sheet stacking device to form images on the sheets, any one of the sheet stacking devices of aspects 1 to 9 is used as the sheet stacking device.
This makes it possible to prevent abnormal images, sheet jams, wasteful toner consumption, and the like.

(Aspect 11)
In the tenth aspect, a notification unit such as an operation panel 70 is provided that notifies the user of information detected based on image data captured by an imaging unit such as the imaging device 110 .
This allows the user to be notified of information about sheets loaded in a sheet loading device such as the paper feed cassette 15 or manual feed tray 33, as described in the embodiment, and encourages the user to take the appropriate action.

1: Photosensitive drum 10: Imaging unit 15: Paper feed cassette 16: Paper feed means 33: Manual feed tray 33a: Side fence 34: Paper feed means 50: Device main body 70: Operation panel 80: Processing unit 90: Memory unit 100: Printer 101: Tray housing 101a: Front wall 102: Side fence 103: End fence 104: Bottom plate 104a: Bottom plate rotation shaft 106: Detection mark 110: Imaging device 111: Imaging unit 112: Optical unit 120: Manual feed imaging device P: Paper PW: Paper width S: Imaging range

Patent No. 4324562

Claims (8)

a sheet stacking section for stacking sheets;
an end fence that abuts against a rear end of the sheet stacked on the sheet stacking section to regulate a position of the sheet in a feeding direction;
an imaging unit for imaging the entire sheets stacked on the sheet stacking section and the end fence;
A sheet stacking device characterized in that it detects whether the sheet stacked in the sheet stacking section is the last one based on whether the difference value between the gap between the end fence and the rear end of the sheet measured based on image data captured by the imaging means when the sheet is set and the gap between the end fence and the rear end of the sheet measured based on image data captured by the imaging means after the feeding means starts feeding the sheet exceeds a threshold value . 2. The sheet stacking device according to claim 1,
A sheet stacking device, characterized in that the sheet size of the sheets stacked on the sheet stacking section is detected based on image data captured by the imaging means. 3. The sheet stacking device according to claim 1,
the imaging means simultaneously images the sheet stacked on the sheet stacking section and a detection mark for detecting the position of the sheet in the height direction,
a sheet stacking device for detecting the amount of sheets stacked on the sheet stacking section based on image data obtained by simultaneously capturing images of the detection mark and the sheets stacked on the sheet stacking section; 4. The sheet stacking device according to claim 1,
A sheet stacking device, characterized in that the presence or absence of an image on the surface of a sheet on which an image is to be formed is detected based on image data captured by said imaging means. 5. The sheet stacking device according to claim 1,
a side fence that abuts against an edge of the sheet in the width direction when the sheet is loaded on the sheet loading section to regulate the position of the sheet in the width direction;
the imaging means simultaneously images the side fence and the sheets stacked on the sheet stacking section,
A sheet stacking device, characterized in that a distance between the side fence and the sheets stacked on the sheet stacking section is detected based on image data obtained by simultaneously capturing images of the side fence and the sheets. 6. The sheet stacking device according to claim 1,
A sheet stacking device, characterized in that, from the image data captured by the imaging means, components of the sheet stacking device have optical differences with respect to the sheets. A sheet stacking device;
In the image forming apparatus, a sheet is fed from the sheet stacking device and an image is formed on the sheet,
7. An image forming apparatus, comprising: the sheet stacking device according to claim 1; 8. The image forming apparatus according to claim 7,
An image forming apparatus comprising: a notification unit that notifies a user of information detected based on image data captured by the imaging unit.