JP2022105422A - Image forming apparatus - Google Patents

Abstract

To solve a problem in which: a separable sheet may be partially cut off during image formation depending on a storage state of the sheet or how the sheet is handled by a user, and a piece of paper may remain in an image forming apparatus; in addition, a normal paper jam detection mechanism may not be able to detect the piece of paper depending on how the sheet is cut off and the position of the remaining piece of paper; when the image forming apparatus cannot detect paper jam, it cannot warn the user of the cut-off either; as a result, image formation is continued while the piece of paper is not removed and remains inside the image forming apparatus, which may cause trouble in image formation and damage the image forming apparatus.SOLUTION: According to the present invention, based on a result of detection performed by means for detecting the remaining of a recording material, a user is notified, through a user interface, that a piece of paper cut off from the recording material remains inside an image forming apparatus. This makes it possible to urge the user to remove the cut-off piece of paper.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image forming apparatus.

Conventionally, there are image forming devices such as multifunction printers, laser beam printers, facsimiles, and printing devices that use an electrophotographic method or an electrostatic recording method. In recent years, image forming apparatus such as an electrophotographic method has come to be used in the field of light printing, and it is required to meet various needs related to recording materials. Some recording materials are premised on being separated and used after printing. To give a specific example, when making price tags, business cards, admission tickets, delivery notes, etc., perforations are applied vertically and horizontally in advance, and perforations and label papers that can be separated at the perforations are possible. Paper such as is used.
Patent Document 1 and Patent Document 2 disclose that the position of a perforation is input by using an operation unit or reading information, and image data is arranged based on the input information.

Japanese Unexamined Patent Publication No. 2008-05495 Japanese Unexamined Patent Publication No. 2008-124615

However, a part of the paper that can be separated is missing during image formation depending on the storage state of the paper and the handling method of the user, and a piece of paper that is a part of the paper remains in the image forming apparatus. It may end up. Further, depending on how the paper is missing and the position where the piece of paper remains, it may not be detected by a normal paper jam detection mechanism.
If the image forming apparatus cannot detect the paper jam, it cannot warn the user of the omission. As a result, the user may not be aware of the missing piece of paper and the missing piece of paper may not be removed. If the image formation is continued while the unremoved piece of paper remains in the image forming apparatus, the image forming may be defective or the image forming apparatus may be damaged.

For example, the next piece of paper may collide with a piece of paper remaining in the image forming apparatus, causing a paper jam. Further, if the high voltage is adjusted while the missing piece of paper is sandwiched between the high voltage application portions, the high voltage necessary and sufficient for image formation cannot be output, which may cause an image defect. Further, when the operation is performed with a piece of paper remaining in the cleaner part or the fixing part, the cleaner part, the fixing part or the facing member thereof is damaged, and even if the missing piece of paper is removed, the abnormality continues. and so on.

In view of the above problems, the present invention provides an image forming apparatus capable of detecting the remaining pieces of paper so that the user can be prompted to remove the pieces of paper remaining in the image forming apparatus when the paper is missing. The purpose.

In the image forming apparatus of the present invention, a bias voltage is applied to the transport means for transporting the recording material along the transport path, the transfer means for transferring the image to the recording material transported by the transport means, and the transfer means. In this case, it was measured by the first measuring means for measuring the current flowing through the transfer means or the voltage applied to the transfer means when a bias current was passed through the transfer means, and the first measuring means. It has a residue detecting means for detecting the presence or absence of a piece of paper missing from the recording material remaining in the transport path based on a voltage or a current, and a notification means for notifying the user of the detection result by the residue detecting means. It is characterized by.
Further, in the image forming apparatus of the present invention, the image is transferred by the transport means for transporting the recording material along the transport path, the transfer means for transferring the image to the recording material transported by the transport means, and the transfer means. The recording material remaining in the transport path based on the fourth measuring means for measuring at least one of the surface characteristics or the thickness of the recording material and the surface characteristics or the thickness measured by the fourth measuring means. It is characterized by having a residue detecting means for detecting the presence or absence of a piece of paper missing from the sheet and a notification means for notifying the user of the detection result by the residue detecting means.

According to the present invention, it is possible to provide an image forming apparatus capable of detecting the residue of a piece of paper when the paper is missing.

Flowchart showing the flow of print jobs Schematic cross-sectional view of the image forming apparatus Hardware block diagram of image forming equipment Equivalent circuit of secondary transfer Diagram illustrating missing paper The figure which shows the change of the measured current The figure which shows the change of the measured current UI display example The figure which shows the change of the measured current UI display example Flowchart showing the flow of print jobs A table that explains the presence or absence of omissions and how to identify the position. Diagram illustrating the lack of a medical band The figure which shows the layer structure of a medical band Flowchart showing the flow of print jobs A table that explains the presence or absence of omissions and how to identify the position. Layout of each sensor Media sensor output example Media sensor output example Diagram illustrating missing label paper Line sensor output example Line sensor output example Flowchart showing the flow of print jobs A table that explains the presence or absence of omissions and how to identify the position. UI display example UI display example The figure which shows the detection operation of the surface roughness of a paper The figure which shows the detection operation of the thickness of a paper Configuration diagram of media sensor

Hereinafter, each embodiment for carrying out the present invention will be described with reference to the drawings.
However, the examples described below are merely examples, and are not intended to limit the scope of the present invention to them. In addition, not all combinations of features described in the following examples are essential for the means of solving the present invention.

<Example 1>
<Image forming device>
First, the overall configuration of the image forming apparatus 1 according to this embodiment will be described.
FIG. 2 is a schematic view showing a cross-sectional configuration example of the image forming apparatus 1. The image forming apparatus 1 forms an image in an image forming unit using an electrophotographic process, transfers the formed image to a paper P as a recording material in the transfer unit, and heats the paper P to which the image is transferred in a fixing unit. This is a device for fixing an image on the paper P. The image forming apparatus 1 according to the present embodiment is a four-color full-color multifunction printer (color image forming apparatus) using an electrophotographic process. Hereinafter, it will be described in detail.

The image forming apparatus 1 includes a controller 100 that controls each configuration in the apparatus. The controller 100 functions as a control unit that performs various controls, and based on the input print information signal (for example, image data, paper information, etc.), comprehensively controls various configurations in the apparatus to execute an image forming operation. Take a role. Here, the paper P is a recording material on which an image is formed on the surface thereof. Examples of the paper P include plain paper, thick paper, OHP paper P, coated paper, label paper, perforated paper, and the like.

The image forming apparatus 1 forms a multicolor image by superimposing a four-color developer (hereinafter referred to as toner) of yellow (Y), magenta (M), cyan (C), and black (K). Therefore, an image forming station 10 for forming a toner image of each color is provided. In the image forming station 10, since the basic configuration of each color is the same, YMCK is added as a suffix to the reference code in the figure. In the following, the contents applicable to the image forming stations of all colors will be described by omitting this suffix.
The image forming station 10 has a rotating drum type electrophotographic photosensitive member 11 (hereinafter referred to as a photosensitive drum 11) as an image carrier on which an image is formed. Further, it has a cleaning member (not shown) as a process means acting on the photosensitive drum 11, a charging roller 12 which is a charging device, and a developing unit 14 which is a developing device. In the toner accommodating chamber of the developing unit 14, basically, toner of each color charged on the negative is accommodated.

A laser scanner unit 13 as an exposure means for the photosensitive drum 11 is arranged near the image forming station 10, and a cassette 2 for storing the paper P is arranged at the lower part. Further, a transfer belt unit 20 (hereinafter referred to as a transfer unit) is provided on the upper side of the image forming station 10.
The transfer unit 20 has an intermediate transfer belt 21 and a drive roller 22 for driving the intermediate transfer belt 21. Further, inside the intermediate transfer belt 21, four primary transfer rollers 15, which are primary transfer devices, are arranged in parallel. Each primary transfer roller 15 is arranged to face the tourist drum 11 of each image forming station.

The upper surface of the photosensitive drum 11 of each color of the image forming station 10 is in contact with the lower surface of the intermediate transfer belt 21 at the position of each primary transfer roller 15. This contact portion is called a primary transfer portion.
The drive roller 22 is a roller that rotationally drives the intermediate transfer belt 21, and a secondary transfer roller 25, which is a secondary transfer device, is arranged outside the portion of the intermediate transfer belt 21 backed up by the drive roller 22. There is. The intermediate transfer belt 21 is in contact with the secondary transfer roller 25 which is a transfer means, and this contact portion is referred to as a secondary transfer nip portion T2. An intermediate transfer belt cleaner 23 is arranged on the outside of the portion of the intermediate transfer belt 21 backed up by the tension roller.

The toner remaining on the intermediate transfer belt 21 without being transferred to the paper P by the secondary transfer nip portion T2 is a power supply unit (non-transferred) by the intermediate transfer belt cleaner 23 configured by pressing a brush-like elastic body against the intermediate transfer belt 21. A positive cleaning voltage is applied from (shown). As a result, the residual toner has a positive polarity opposite to that of normal. As a result, in the primary transfer unit to which the positive voltage is applied, the normal negatively charged toner is transferred to the intermediate transfer belt 21 side, while the remaining positively charged toner is collected on the photosensitive drum 11 side. The toner collected on the photosensitive drum 11 side is collected by the drum cleaning member.

Further, the image forming apparatus 1 includes a paper transporting apparatus. Above the cassette 2, a paper transport path Q (broken line portion in the figure) for transporting the paper P picked up from the cassette 2 upward is arranged. In the paper transport path Q, a feed roller 3, a separation roller pair 4, a resist roller pair 5, a secondary transfer roller 25, a fixing unit 30, and a discharge roller pair (not shown) are arranged in this order from the upstream. P is conveyed to the paper ejection tray 9. Further, the paper transport device includes a pre-registration sensor R, a loop sensor L, a media sensor ME, which will be described later, as well as paper width sensors KF and KR (not shown), a paper ejection sensor H, a line sensor LN, and the like. Further, the paper transport path Q is provided with a paper jam detecting means J.
Further, the paper P can also be supplied from the multi-tray 6 via the feeding roller 7 and the separation roller pair 8.

The fixing unit 30, which is a fixing device, includes a pair of rollers (fixing roller pair) for pressing the paper P and a heater for heating the paper P, and by heating while pressing the paper P, unfixed on the paper P. The toner image of No. 1 is melted and fixed on the paper P. In the fixing unit 30, by applying a voltage to the surface, it is possible to prevent the toner from electrically adhering to the fixing roller pair.

Further, the image forming apparatus 1 is equipped with an image reader 40. The image reader 40 has a function of reading an image of a document by an optical sensor and converting it into an image signal. The image reader 40 is equipped with a document feeding unit 41. The document feeding unit 41 has a function of feeding the documents set upward on the document tray 42 one by one in order from the first page and reading the document image with the reader scanner 43. The scanned document is ejected to the document ejection unit 44. The reader scanner 43 includes a light irradiation unit (not shown) and an image sensor (not shown), and converts a document into an image signal by forming an image on the image pickup surface of the image sensor. The reader scanner 43 extends in the main scanning direction (direction orthogonal to the document transport direction), and can read an image of the entire page by transporting the document.

When reading a document without using the document feeding section 41, the document feeding section 41 is lifted, the document is placed on the platen glass 45, and the reader scanner 43 is scanned from left to right to scan the document. Read.
Further, the image forming apparatus 1 includes a UI (user interface) unit 50 for displaying the state of the image forming apparatus 1 and performing input from the user.

<Image formation control unit>
FIG. 3 is a hardware block diagram of the image forming apparatus 1. In the figure, the parts necessary for explaining the characteristic operation of this embodiment are mainly described, and other parts known as image control are omitted.
First, the controller 100 that controls the control will be described. The controller 100 is an electric circuit board including a calculation unit such as a CPU 101 and a memory (storage unit) 102 such as a ROM / RAM. The controller 100 functions as a control unit that performs various controls by reading the program stored in the memory 102 by the CPU 101. Further, the controller 100 is electrically connected to an external information terminal such as a personal computer (not shown), an input device such as an image reader 40, and various blocks such as a UI unit 50, and can exchange signal information. The controller 100 comprehensively controls various configurations in the device based on the print information signal (for example, image data, paper information, etc.) input from the input device, and executes the image forming operation.

Next, each block controlled by the CPU 101 will be described.
The UI unit 50 exchanges information with the CPU 101. The UI unit 50 outputs a key signal corresponding to the operation of each key of the input unit 502 to the CPU 101, and displays the corresponding information on the display unit 501 based on the signal from the CPU 101.

The image forming unit includes a plurality of high voltage power supplies 151, 231, 251 and 301.
The high-voltage power supply 151 is controlled by the CPU 101 and applies a voltage to the primary transfer roller 15. The voltage applied at that time is measured by the measuring device 152 and is grasped by the CPU 101.
Similarly, the voltage applied to the intermediate transfer belt cleaner 23 by the high voltage power supply 231 is measured by the measuring device 232. The voltage applied to the secondary transfer roller 25 by the high voltage power supply 251 is measured by the measuring device 252. The voltage applied to the fixing unit 30 by the high voltage power supply 301 is measured by the measuring device 302.

The CPU 101 also controls the paper transport device.
The paper transport device includes a pre-registration sensor R, a paper width sensor KF and KR, a loop sensor L, a paper ejection sensor H, a line sensor LN, a media sensor ME, and the like. The CPU 101 detects jams and determines whether a piece of paper remains based on the output of each sensor.
Further, as shown in FIG. 16, the pre-registration sensor R and the loop sensor L, the paper width sensor (front) KF and the sub thermistor (front) SF, and the paper width sensor (back) KR and the sub thermistor (back) SR have main scanning directions. It is installed in the same position.

<Image formation sequence>
When the image forming apparatus 1 performs an image forming operation, the controller 100 executes the following control for each component involved in the image forming operation, and forms a full-color image on the paper P.
First, the controller 100 starts rotating and driving the photosensitive drum 11 in the image forming station 10 and the driving roller 22 in the transfer unit 20 at a predetermined speed in accordance with the image forming timing. Specifically, the photosensitive drum 11 is rotated in the clockwise direction in the figure, and the drive roller 22 is rotated in the direction in which the intermediate transfer belt 21 is rotated forward with respect to the rotation direction of the photosensitive drum 11 (counterclockwise in the figure). Let me.

Subsequently, the image forming station 10 executes operation control for developing an image on the photosensitive drum 11 of each color. First, the charging roller 12 uniformly charges the surface of the photosensitive drum 11 to a predetermined potential with negative polarity. Next, the laser scanner unit 13 scans and exposes the surface of the photosensitive drum 11 using a laser beam modulated according to the image information signals of each color of Y, M, C, and K, whereby the electrostatic latency of each color is latent. Form an image. Next, the toner is electrostatically adhered to the formed electrostatic latent image by the developing unit 14, and the toner image is formed (developed) on the photosensitive drum 11.

Subsequently, the operation control of superimposing the toner image formed on the photosensitive drum 11 of each color on the intermediate transfer belt 21 is executed. Specifically, a predetermined positive voltage is applied to the primary transfer roller 15 facing the photosensitive drum 11 via the intermediate transfer belt 21, and the toner image on the photosensitive drum 11 is statically transferred onto the intermediate transfer belt 21 in the primary transfer unit. Transfer electrically. By executing this operation for each color, a full-color (Y color + M color + C color + K color) unfixed toner image is formed on the intermediate transfer belt 21. The unfixed toner image is carried to the secondary transfer nip portion T2 by the rotational drive of the drive roller 22. The toner that cannot be transferred onto the intermediate transfer belt 21 by the primary transfer unit and remains on the photosensitive drum 11 is cleaned by a cleaning member (not shown).

Further, in parallel with the operation of forming the unfixed toner image on the intermediate transfer belt 21, the operation of feeding paper from the cassette 2 is executed. Specifically, one sheet of paper P is fed by the feeding roller 3 and the separating roller pair 4 in accordance with the image forming timing, and is conveyed to the resist roller pair 5. After that, the paper P is conveyed to the secondary transfer nip portion T2 in synchronization with the unfixed toner image on the intermediate transfer belt 21.

Subsequently, the operation control of transferring the unfixed toner image on the intermediate transfer belt 21 onto the paper P is executed. Specifically, at the timing when the unfixed toner image and the paper P are conveyed to the secondary transfer nip portion T2, the secondary transfer bias has a positive polarity opposite to the negative polarity of the toner charging polarity to the secondary transfer roller 25. Is applied to electrostatically transfer the unfixed toner image from the intermediate transfer belt 21 to the paper P (secondary transfer). That is, the unfixed toner image is transferred to one side of the paper P by sandwiching and transporting the paper P by the secondary transfer nip portion T2. The toner that cannot be transferred onto the paper P by the secondary transfer unit and remains on the intermediate transfer belt 21 is cleaned by the intermediate transfer belt cleaner 23.

<Voltage application to secondary transfer section>
FIG. 4 is a schematic diagram of an equivalent circuit of the secondary transfer unit. The power supply is connected to the secondary transfer roller 25. Let the resistance of the secondary transfer roller 25 be Rr. Let Rm be the resistance when a recording material such as paper passes through the secondary transfer nip portion T2. Let the resistance of the intermediate transfer belt 21 be Ri. These are in a state of being connected in series.
If the total combined resistance is R here,
R = Ri + Rm + Rr ... (Equation 1)
Will be. Further, the high voltage power supply 251 can arbitrarily set the bias voltage applied to the secondary transfer roller 25 as a load, and includes a measuring device 252 which is an ammeter.

Here, in order to transfer the toner from the intermediate transfer belt 21 to the paper, a predetermined charge transfer (current I) is sufficient. The image forming apparatus 1 of the present embodiment sets the applied voltage E at the time of image formation as follows in order to pass a predetermined current I (in this embodiment, the predetermined current I is 30 μA during image formation. Is set to be).
First, when the paper is not in the secondary transfer nip portion T2, a constant voltage is applied to measure the current. As a result, the combined resistance R (at this moment, R = Ri + Rr) of the intermediate transfer belt 21 and the secondary transfer roller 25 is obtained. Next, Rm is determined by comparing the relationship data between the paper and the resistance recorded in the memory in advance from the paper type set in advance by the user, and the combined resistance R (= Ri + Rm + Rr) including the paper is obtained. .. The applied voltage E (= I × R) is set from the combined resistance R thus obtained and the predetermined current I.

<Paper jam detection>
Here, the configuration of the paper jam detecting means J will be described. As described with reference to FIG. 2, the paper jam detecting means J described here is arranged in front of the secondary transfer nip portion T2 on the paper transport path Q. The paper jam detecting means J has a configuration called a flag type. Specifically, the flag portion is arranged so as to slightly penetrate the paper passing position. The flag part has a shaft and is movable, and when the paper passes, the flag part moves so as to be pushed down by the paper. A hole is provided in the flag portion, and a light emitting portion and a light receiving portion are provided so as to face the hole and sandwich the flag. When the paper does not pass through, the emitted light passes through the hole and reaches the light receiving portion, but when it passes through, it is shielded from light. This difference is used to detect the passage of paper.

Next, a method for detecting a paper jam will be described. The controller 100 grasps the size of the paper set in advance by the user. In this example, the size of the paper is set to A4, and it is assumed that it is 210 mm. Since the image forming apparatus 1 conveys the paper at a transport speed of 300 mm / s, it takes 0.7 s for the paper to pass through. Further, since the transport distance from the paper feed unit to the paper jam detecting means J is 30 cm, it takes 1.0 s from the start of transport until the paper reaches the paper jam detecting means J.

From this information, a judgment is made according to the case classification, for example, as follows.
If the paper jam detecting means J cannot detect the start of passing the paper even after 1.0 s from the start of paper transport, it is determined that the paper is jammed somewhere and the delay is determined. When the time from the start of detection of the paper by the paper jam detecting means J to the end of the detection is longer than 0.7 s, it is determined that the paper is retained in the paper jam detecting means J. On the contrary, if it is shorter than 0.7s, it is determined that the size of the set paper is set incorrectly.
In either case, the situation is notified to the user via the display unit or the like, and the image formation of the image forming apparatus 1 is stopped according to the situation. Then, after waiting for the user's action (removing the jammed paper or resetting the paper size), the image forming of the image forming apparatus is restarted.
The paper jam detecting means J is generally arranged approximately at the center of the direction perpendicular to the paper transport direction. This is to enable detection even when narrow paper is conveyed or when the user moves the paper to one side of the paper feed unit.

Next, the detection of missing paper (detection of residual paper pieces) in the transfer unit and the notification to the user will be described. FIG. 1 is a flowchart showing a process for executing a print job. This process is realized by the CPU 101 executing a program stored in the memory 102 or the like.
In this embodiment, as shown in FIG. 5 (1), the paper is divided into four parts vertically and horizontally with respect to the B5 (182 mm × 254 mm) size, which is often used for price tags used on distribution shelves. It is assumed that the thick paper has a basis weight of 128 g / m ² and has three perforations in each of the vertical and horizontal directions. The paper is conveyed with the upper side at the tip in FIG.

First, when the print job is started in response to an instruction from the user, the CPU 101 starts feeding thick paper from the feeding unit (step S101). Almost at the same time, the CPU 101 starts forming an image on the photosensitive drum 11 (step S102).
Before the thick paper reaches the secondary transfer nip portion T2, the CPU 101 applies a bias voltage previously set to match the paper for 128 g / m ² to the secondary transfer roller 25 via the high voltage power supply 251. (Step S103). At the same time, the CPU 101 measures the current using the measuring device 252 (step S104).
Here, normally, the output is performed without a paper jam (Y in step S105), and the measured current is normal (Y in step S106), so that the print job ends as it is.

FIG. 6A shows the measured current at this time by the broken line 6a. In the graph of FIG. 6A, the horizontal axis is the time from the start of paper feeding, and the vertical axis is the current measured by the measuring device 252 on the secondary transfer roller 25. In order to show the relative relationship between the time of the graph and the position of the paper, the paper shown in FIG. 5 (1) and its transport direction are shown below the graph of FIG. This graph shows that the paper rushes into the secondary transfer nip portion 4T2 at 1.3 s and finishes passing at 2.0 s after 0.7 s.

Since it is necessary for the paper to reach a predetermined voltage when passing through the secondary transfer nip portion T2, the bias voltage is started to be applied at a predetermined value as described above immediately before the paper enters (here,). , Bias voltage is 1200V). At this time, the combined resistance R is composed of the resistance Ri of the intermediate transfer belt 21 and the resistance Rr (20 MΩ) of the secondary transfer roller, and the current value rises to 60 μA (= 1200 V / 20 MΩ). When the paper rushes in here, the resistance Rm (20MΩ) of the paper is added and the combined resistance R increases (40MΩ), and the current value reaches the target value of 30μA (= 1200V / 40MΩ) during image formation. return. Further, when the paper passes through the secondary transfer nip portion T2, the current value rises to 60 μA again, but becomes 0 μA by stopping the application of the bias voltage almost at the same time.

Next, a case where all 1/4 of the rear end of the paper (i to iv in the figure) with respect to the transport direction, which is shown in FIG. 5 (1), is missing in the image forming apparatus 1 will be described. In this case, the measured current is as shown by the solid line 6b in FIG. 6A.
If the paper is missing at the bent portion (3 → 4 → 5 or 6 → 7 → 8 → 5 in FIG. 2) immediately after the paper feeding portion, the paper jam detecting means J requires a paper passing time of 0.7 s. However, the paper is detected only at 3/4 times (0.525s) of that. Therefore, the CPU 101 determines that a paper jam has occurred due to a size setting error (N in step S105 of FIG. 1), displays a paper jam in the UI section (step S107), and cancels the print job. The current detected at this time is the same as that in the case where the paper is not in the secondary transfer nip portion T2 in the last 1/4 as shown by the solid line 6b in FIG. 6A. This is because the combined resistance R becomes R = Ri + Rr (20 MΩ) as in the case where the paper does not rush into the secondary transfer nip portion T2 because the paper is missing and does not exist in the last 1/4.

Next, a case where a part (only i in the figure) of the rear end of the paper is missing with respect to the transport direction as shown in FIG. 5 (1) will be described. In this case, the measured current value is as shown by the solid line 6c in FIG. 6B.
Since the paper jam detecting means J is provided in the central portion as shown by the arrow portion in FIG. 5, it cannot detect the omission and it is determined that there is no paper jam (Y in step S105 of FIG. 1). ). Here, the current transition when passing through the secondary transfer nip portion T2 is as shown by the solid line 6c in FIG. In the last 1/4 missing portion, the resistance Rm of the paper becomes 3/4 times (20 → 15 MΩ), so that the combined resistance R also decreases. That is, due to the relationship of I = E / R, the solid line 6c is higher than the broken line 6a, which is the normal current value, and becomes 37.5 μA.
In this embodiment, since the threshold value is set to 35 μA in advance (details will be described later), it is determined that the paper is missing because the current is higher than the threshold value (N in step S106 of FIG. 1). Then, it is displayed that there is a possibility that a missing piece of paper remains in the UI unit 50 (step S108). Specifically, as shown in FIG. 7, a warning is notified to the user as a UI display. At the same time, stop the print job once. When the user presses the OK button after confirmation, the print job is restarted. As a result, even if a piece of paper remains in the image forming apparatus 1, the user can always check it.

Next, the above-mentioned current threshold value will be described. In this embodiment, as described above, the current is 60 μA when the paper is not passed and 30 μA when the paper is passed in the normal state. Generally, most of the price tags used in distribution are divided into four parts. Therefore, if the 1/4 portion is missing, it can be calculated in advance that the current will be about 37.5 μA as shown below.
60μA-{(60μA-30μA) x (1-1 / 4)}
In addition, the threshold value is set to 35 μA, which is slightly lower than 36.5 μA, in consideration of the occurrence of an error of about ± 1 μA including runout due to the intermediate transfer belt 21 and the secondary transfer roller 25 and electrical noise. do.

Here, the case where the current measurement at the time of non-passing paper is performed in front of the tip of the paper has been described, but the current measurement may be performed in advance, for example, when the power of the image forming apparatus is turned on.
Further, here, the case where the current measurement during paper passing is performed on the tip side of the paper has been described, but the averaged current values when the paper is constantly fed from the same paper feed unit is stored. , The threshold value may be set based on the value.
Further, since the front end side of the paper may be missing, the current may change contrary to the state shown in FIG. In consideration of such a case, it is determined that the current exceeds the threshold value in step S106 of FIG. 1 when there is a difference of a predetermined value or more (for example, 2 μA or more) at the timing assumed to be during paper passing. You may.

Here, the case of a full-color image forming apparatus consisting of four colors of YMCK having an intermediate transfer belt has been described, but the image forming apparatus is not limited to this configuration. For example, the image forming apparatus may be provided with a direct transfer portion of a full-color image forming apparatus having a transfer belt for directly transferring from the photosensitive drum 11 to paper, or a transfer portion of a monochrome image forming apparatus having one color of K.
Further, although the case of the multifunction printer having the image reader 40 has been described here, it may be a single function printer that outputs only an image.
Further, here, the case where the presence or absence of paper loss is determined by the change in the current flowing through the load when a predetermined bias voltage is applied has been described, but the change in the voltage applied to the load by passing a predetermined bias current is described. You may judge whether or not the paper is missing.

Here, the paper jam detecting means J is arranged in front of the secondary transfer nip portion T2, but may be arranged behind or both. In that case, the user may be notified of the possibility of missing paper only when the paper jam is not detected.
The high-voltage power supply and measuring means used in this embodiment are generally possessed by an image forming apparatus for adjusting and setting a high voltage at the time of image formation. Therefore, there is no need to add or change the device again, and it can be handled only by software, so that the cost increase can be minimized. In addition, since no special equipment is required, it can be deployed in a wide variety of models.

<Example 2>
In this embodiment, the paper chipping detection (paper piece residue detection) in the cleaning device (intermediate transfer belt cleaner 23) and the fixing device (fixing unit 30) will be described. The description of the same configuration and function as in the first embodiment will be omitted.

Here, as shown in FIG. 5 (2), in order to use the printed photograph without borders, a case where pre-perforated paper is used is taken as an example. This paper has a cutout portion of 2 sheets in the center and 2 sheets in the upper and lower parts, for a total of 4 sheets. Due to the arrangement, the paper jam detecting means J arranged in the center cannot detect the paper jam even if the paper is missing.
That is, if the paper is missing immediately after the paper is pulled out of the secondary transfer nip portion T2 due to the pressing for sandwiching by the secondary transfer nip portion T2, the secondary transfer nip portion T2 is normal, and therefore, in Example 1. Paper loss cannot be detected by the method described.

This will be described with reference to FIG. In the image forming apparatus, the missing paper may adhere to the intermediate transfer belt 21, and the adhered paper may invade the intermediate transfer belt cleaner 23. As described above, a high voltage bias voltage is applied to the intermediate transfer belt cleaner 23 as a load. Specifically, 2000V is applied at a constant voltage. A measuring device 232, which is an ammeter, is also arranged in the high voltage power supply 231.
Therefore, when the paper invades the intermediate transfer belt cleaner 23 and stays there, the current changes as shown in FIG. Here, the horizontal axis of FIG. 8 is the time from the start of feeding, and the vertical axis is the measured current. In order to show the position of the paper and the timing of measurement, the shape and the transport direction of the paper shown in FIG. 5 (2) are shown below the graph of FIG. Here, since it is known in advance that the variation in the current in the steady state is about ± 0.5 μA, the threshold value at which the abnormal state can be detected is set to +1.0 μA. Further, in order to accurately grasp that the paper is missing, the time from when the paper enters the secondary transfer section to when the paper passes through and the time when the missing paper will reach the intermediate transfer belt cleaner 23 are taken into consideration. The timing (detection section) for determining whether the current exceeds the threshold value is determined. Here, the current was 15.5 μA before the paper detection section. From this, the threshold value is set to 16.5 μA. Then, when the current rises to 17.5 μA during the detection section of the paper, the threshold value is exceeded and it is determined that the paper is missing.
Although the cleaner facing the intermediate transfer belt 21 of the color machine has been described here, the same configuration may be obtained on the photosensitive drum 11 of the monochrome machine.

In addition, the paper may be missing in the fixing unit 30 and the paper may adhere to the fixing device. As described in the first embodiment, a high voltage bias voltage is applied to the fixing unit 30 in order to prevent the toner from electrically adhering to the fixing unit 30. A measuring device 302, which is an ammeter, is also arranged in the high voltage power supply 301. Therefore, similar to the case where the paper is missing in the intermediate transfer belt cleaner 23, when the threshold value of the predetermined current is exceeded at the timing when the paper passes, it can be determined by the fixing device that the paper is missing.

<Example 3>
In this embodiment, the notification to the user of the remaining portion of the missing piece of paper will be described. The description of the same configuration and function as in the first or second embodiment will be omitted.
A method of notifying the user of the remaining portion of the piece of paper will be described with reference to FIG.
As described in Examples 1 and 2, in the image forming apparatus 1 of the present embodiment, the secondary transfer nip portion T2, the intermediate transfer belt cleaner 23, and the fixing unit 30 each detect paper loss (paper piece residue). Detection) is possible. The missing part is determined from the combination of these detection results.
When the missing paper is detected by the secondary transfer nip portion T2, it is determined that there is a gap between the paper feed roller 3 and the secondary transfer nip portion T2 in FIG. 2 (region A). If T2 does not detect the missing paper and the intermediate transfer belt cleaner 23 detects it, it is determined that the paper is missing on the transfer unit 20 (region B). If the secondary transfer nip portion T2 does not detect the omission but the fixing unit 30 detects the omission, it is determined that the omission is in the fixing unit 30 (region C).

In this embodiment, based on these judgments, as shown in FIG. 9, the UI unit 50 indicates that the paper may be missing and which part of the paper should be removed. (The example of FIG. 9 shows a case where there is a possibility that the paper is missing in the area A).
This makes it easier for the user to find the missing paper and further reduces the possibility of the missing piece of paper remaining.

Although the case where the missing place of the paper is specified by the detection by the high voltage is described here, the missing place of the paper may be specified in combination with other detection means such as a sensor for transporting the paper.
Further, as in Example 1 or Example 2, the case where the paper is completely missing has been described in this embodiment, but the mount and the label on the surface are separated, for example, as in the case of label paper, and the separated portion is used. You may judge the omission by detecting the high pressure change of.

<Example 4>
Example 4 describes an example of detecting the missing of the paper according to the output value (change in the surface characteristic or the thickness) of the media sensor that measures the surface characteristic and the thickness of the paper.

<Media sensor>
FIG. 28 shows the configuration of the media sensor ME. As shown in FIG. 28, the media sensor ME includes an ultrasonic sensor and an optical sensor.
An ultrasonic sensor including an ultrasonic transmitter 610 and an ultrasonic receiver 620 is a sensor that detects the thickness of paper. The ultrasonic transmitter 610 is arranged on the right door side of the image forming apparatus 1 main body, and the ultrasonic receiver 620 is arranged on the image forming apparatus 1 main body side.
The optical sensor including the LED 810 and the light receiving sensor 820 is a sensor for detecting the surface roughness of the paper. Both the LED 810 and the light receiving sensor 820 are arranged next to the ultrasonic receiver 620.

As shown in FIG. 2, the media sensor ME (first media sensor ME1) is arranged downstream of the pre-registration sensor R and upstream of the intermediate transfer belt 21. Further, if necessary, as shown in FIG. 2, the second media sensor ME2 may be arranged downstream of the fixing unit 30.
Further, as shown in FIG. 16, the main scanning direction position of the media sensor ME is arranged at a position close to the center of the paper.

With reference to FIG. 26, the operation of the optical sensor that detects the surface roughness of the paper by the media sensor ME will be described.
The LED light emission control unit 710 transmits an ON / OFF signal to the LED 810 based on the signal from the controller 100, and causes the LED 810 to emit light. Then, in synchronization with the ON / OFF information of the pre-registration sensor R, the light receiving sensor 820 receives the light reflected on the paper, and the light receiving signal is transmitted to the light receiving calculation unit 720. The light receiving calculation unit 720 amplifies and integrates the received signal and outputs it to the controller 100. The controller 100 converts the signal received from the light receiving calculation unit 720 into the surface roughness of the paper.

Next, the operation of the ultrasonic sensor that detects the thickness of the paper by the media sensor ME will be described with reference to FIG. 27.
The ultrasonic transmission control 510 transmits an ON / OFF signal to the ultrasonic transmitter 610 based on the signal from the controller 100, and emits ultrasonic waves from the ultrasonic transmitter 610. Then, in synchronization with the ON / OFF information of the pre-registration sensor R, the ultrasonic receiver 620 receives the signal and transmits the received signal to the ultrasonic reception calculation unit 520. The ultrasonic reception calculation unit 520 amplifies and integrates the received signal and outputs it to the controller 100. The controller 100 converts the signal received from the ultrasonic wave reception calculation unit 520 into the thickness of the paper.

<Sensor before cash register>
As shown in FIG. 2, the pre-registration sensor R is located between the confluence of the cassette 2 and the multi-tray 6 and the resist roller pair 5, and is in contact with the paper from the back side of the paper.
Further, as shown in FIG. 16, the pre-registration sensor R is installed at the same position as the loop sensor L in the main scanning direction. In the case of this embodiment, the pre-registration sensor R is arranged at a position 10 mm from the center of the image toward the front of the main body.

The pre-registration sensor R has a configuration called a flag type. Specifically, the flag portion is arranged so as to slightly penetrate the paper passing position. The flag part has a shaft and is movable, and when the paper passes, the flag part moves so as to be pushed down by the paper. A hole is provided in the flag portion, and a light emitting portion and a light receiving portion are provided so as to face the hole and sandwich the flag. When the paper does not pass through, the emitted light passes through the hole and reaches the light receiving portion, but when it passes through, it is shielded from light. This difference is used to detect the passage of paper.

<Missing detection by media sensor>
Next, the detection of missing paper by the media sensor ME and the notification to the user will be described.
In this embodiment, as shown in FIG. 12A, a case where a medical band is used as the paper will be described as an example.
As shown in FIG. 13 (a), the medical band has a three-layer structure of a surface layer, an adhesive layer, and a release layer in the surrounding regions shown by a, b, c, and d in FIG. 12 (a). ing.

Further, as shown in FIG. 13 (b), the region shown by e in FIG. 12 (a) of the medical band has a two-layer structure of a surface layer and a release layer, and has no adhesive layer. Further, in order to attach the medical band to the wrist after cutting it, cuts as shown in X1 and X2 in FIG. 13B are made along the outer shape of the medical band, and the medical band is further removed from the surrounding area. It has an easy structure. FIG. 13 (c) shows a state in which a part of the medical band is missing. When the medical band is missing, a release layer is exposed, as shown in FIG. 13 (c).
As the material of the above-mentioned surface layer, a resin such as cellulose or paper is used. As the adhesive component of the adhesive layer, a material obtained by synthesizing a component such as urethane, acrylic, or silicon from a natural material such as starch or natural rubber is used. A silicon-based or non-silicon-based material is used as the release agent for the release layer.

Next, using the flowchart of FIG. 10, missing detection and notification to the user when a print job is executed using a medical band as paper will be described. FIG. 10 is a flowchart showing a process for executing a print job. This process is realized by the CPU 101 executing a program stored in the memory 102 or the like.

First, the user confirms the status of the medical band to be used (step S1001). Next, the user sets the medical band in the multi-tray 6 (step S1002). Next, upon receiving an instruction from the user, paper feeding is started (step S1003).
After that, it is detected that the medical band has passed the pre-registration sensor R (step S1004). Next, it is detected that the medical band has passed through the media sensor ME (step S1005).
Almost at the same time that the medical band passes through the media sensor ME, image formation on the photosensitive drum 11 starts (step S1006). After that, fixing (step S1007) and paper ejection (step S1008) are performed.
Normally, there is no abnormal signal from the sensor, it is determined that no piece of paper remains (Y in step S1009), and the print job ends as it is.

Here, a method of determining the presence or absence of a piece of paper remaining in step S1009 of FIG. 10 and identifying a portion where the piece of paper remains will be described with reference to FIG.
In the table of FIG. 11, "paper status confirmation" indicates the result of the user confirming the paper status in step S1001 of FIG. Further, "media sensor (ME) detection" indicates the result of the media sensor ME confirming the paper status in step S1005 of FIG.

No. 11 in FIG. In the case of 1, since there is no omission in the "paper status check", it means that the user has checked the paper status and confirmed that there is no problem. Further, since the "media sensor (ME) detection" is also "no omission", it means that the media sensor ME has detected that there is no omission. Therefore, NO. In the case of 1, it means that there is no paper chipping as a whole.
No. 11 in FIG. In the case of 2, it is "no omission" in "paper status confirmation", but it is "missing" in "media sensor (ME) detection". This indicates that there was no paper missing when the multi-tray 6 was set, and the paper was missing between the multi-tray 6 and the media sensor ME.

First, the NO. The actual sensor output in the case of 1 will be described as an example.
In this case, when the user confirms the medical band in step S1001 of FIG. 10, there is no omission, and the media sensor ME does not detect the omission in step S1005. Therefore, the output of the media sensor ME in step S1005 is as shown in FIG.

As shown in FIG. 17, the surface roughness output of the media sensor ME is 1.0 μm, which shows a constant value. Further, the thickness output of the media sensor ME is 150 μm, which shows a constant value.
When the surface roughness output of the media sensor ME and the paper thickness output of the media sensor ME are constant and are predetermined values, it is determined that there is no omission. In this embodiment, if the change Δ of the surface roughness is less than 0.2 μm and the change of the thickness is less than 20 μm, it is judged that there is no omission.
No. 11 in FIG. In the case of 1, since there is no omission in step S1001 and there is no omission in step S1005, it is determined that there is no omission as a whole.

Next, the NO. The actual sensor output in the case of 2 will be described as an example.
In this case, when the user confirms the medical band in step S1001, there is no omission, and in step S1005, the media sensor ME detects the omission. When the medical band is missing, the release layer is exposed as shown in FIG. 13 (c).

FIG. 18 shows the output when the medical band passes through the media sensor ME in a state where the medical band is missing as shown in FIG. 12 (b). Since the surface roughness of the release layer of the medical band is 1.5 μm, which is coarser than the surface roughness of the surface layer of the medical band of 1.0 μm, the output of the surface roughness of the media sensor ME is convex (Fig.). See Part A of 18). Here, the difference Δ in surface roughness is 0.5 μm, and in this embodiment, if the difference Δ in surface roughness is 0.2 μm or more, it is detected as an abnormality, and therefore it is determined that there is a defect.
Further, the thickness of only the release layer lacking the medical band is 50 μm, which is thinner than the thickness of the entire paper of the medical band of 150 μm, so that the output of the surface thickness of the media sensor ME is concave (FIG. 18). See part B). Here, the thickness difference Δ is 100 μm, and in this embodiment, if the thickness difference Δ is 20 μm or more, it is detected as an abnormality, so that it is determined that there is a gap.

In this embodiment, after the user confirms that the medical band is not missing and sets it in the multi-tray 6, it is detected that the band is missing at the position of the media sensor ME. Therefore, the media sensor ME is detected from the multi-tray 6. It is determined that the medical band was missing between them.
In the case of a multi-layered paper as in this embodiment, the outer shape of the paper does not change even if a part of the paper is missing. If the outer shape does not change, the mechanical sensor determines that there is no abnormality, and it is not possible to detect a part of the paper that is missing.
However, since the media sensor ME can detect changes in surface roughness and changes in thickness even when the outer shape of the paper does not change, it is possible to detect missing paper in a multilayer structure. Further, the media sensor ME can more accurately determine the presence or absence of omission by simultaneously detecting the change in surface roughness and the change in thickness.

<Residual display of paper pieces>
In this embodiment, when the missing paper is detected, in the flowchart of FIG. 10, it is determined that there is a missing paper in step S1009 (N), and it is indicated that a piece of paper may remain in step S1010. Is done.
Specifically, as in the first embodiment, as shown in FIG. 7, a warning is notified to the user. At the same time, the print job is temporarily stopped. Then, after the user confirms the warning, the user presses the OK button to restart the print job. As a result, even if a piece of paper remains in the image forming apparatus, the user can always check it.

<Notification of residual location>
Next, a method of notifying the user of the remaining portion of the missing piece of paper will be described with reference to FIG. 24.
In this embodiment, it is possible to detect a missing portion of a piece of paper from the detection result of the media sensor ME. For example, when the user installs the medical band on the multi-tray, there is no omission, and the media sensor ME detects the omission, so that it can be seen that the omission has occurred between the multi-tray 6 and the media sensor ME.
In this way, it is possible to identify the presence or absence of paper missing and the residual portion from the output of the media sensor ME.

Based on these judgments, as shown in FIG. 24A, the UI unit 50 indicates that the paper may be missing and in which portion the piece of paper to be removed remains.
In FIG. 24A, part A represents a region from the cassette 2 or the multi-tray 6 to the media sensor ME. Further, the portion B represents an area from the media sensor ME to the output tray 9 including the transfer unit 20.
In this embodiment, the missing paper can be detected in the region between the multi-tray 6 and the media sensor ME, and this region corresponds to part A in the figure of FIG. 24 (a). Therefore, when the missing paper is detected in the A part, as shown in Fig. 24 (a), "There is a possibility that a piece of paper remains in the A part of the device. After checking, click" OK ". Is displayed.

<Example 5>
<Missing detection by two media sensors>
In this embodiment, missing detection and notification to the user when two media sensors are used will be described.
The first media sensor ME1 is arranged between the pre-registration sensor R and the transfer unit 20, and the second media sensor ME2 is arranged downstream of the fixing unit 30.
In this embodiment, as shown in FIG. 12A, a case where a medical band is used as a paper will be described as an example. The medical band is the same as in Example 4.

Next, using the flowchart of FIG. 14, missing detection and notification to the user when a print job is executed using a medical band using two media sensors will be described. FIG. 14 is a flowchart showing a process for executing a print job.

First, the user confirms the status of the medical band to be used (step S1101). Next, the user sets the medical band in the multi-tray 6 (step S1102). Next, upon receiving an instruction from the user, paper feeding is started (step S1103).

After that, it is detected that the medical band has passed the pre-registration sensor R (step S1104). Next, it is detected that the medical band has passed through the first media sensor ME1 (step S1105).
Image formation on the photosensitive drum 11 starts almost at the same time as the medical band passes through the first media sensor ME1 (step S1106). After that, fixing (step S1107) is performed.
Next, it is detected that the medical band has passed through the second media sensor ME2 (step S1108). After that, paper ejection (step S1109) is performed.
Normally, there is no abnormal signal from each media sensor, it is determined that no piece of paper remains (Y in step S1110), and the print job ends as it is.

Here, a method of determining the presence or absence of a piece of paper remaining in step S1110 of FIG. 14 and identifying a portion where the piece of paper remains will be described with reference to FIG.
In the table of FIG. 15, “paper status confirmation” indicates the result of the user confirming the paper status in step S1101 of FIG. Further, the "media sensor 1 (ME1) detection" is the result of the first media sensor ME1 confirming the paper status in step S1105 of FIG. 14, and the "media sensor 2 (ME2) detection" is the second step S1108. The result of checking the paper condition by the media sensor ME2 of the above is shown.

No. 15 in FIG. In the case of 1, since there is no omission in the "paper status check", it means that the user has checked the paper status and confirmed that there is no problem. Further, since "media sensor 1 (ME1) detection" and "media sensor 2 (ME2) detection" are also "no omission", the first media sensor ME1 and the second media sensor ME2 detect that there is no omission. It means that you did. Therefore, NO. In the case of 1, it means that there is no paper chipping as a whole.

No. 15 in FIG. In the case of 2, it is "no omission" in "paper status confirmation", but it is "missing" in "media sensor 1 (ME1) detection" and "media sensor 2 (ME2) detection". This indicates that there was no paper missing when the multi-tray 6 was set, and the paper was missing between the multi-tray 6 and the first media sensor ME1.
No. 15 in FIG. In the case of 3, "no omission" is obtained in "paper status confirmation" and "media sensor 1 (ME1) detection", but "missing" is obtained in "media sensor 2 (ME2) detection". This indicates that there was no omission between the first media sensor ME1 from the time of setting in the multi-tray 6, and there was a omission between the first media sensor ME1 and the second media sensor ME2.

Next, the NO. The actual sensor output in the case of 1 will be described as an example.
In this case, when the user confirms the medical band in step S1101 of FIG. 15, there is no omission, the first media sensor ME1 does not detect the omission in step S1105, and the medical band is shown in FIG. 12 (a). It is in the state shown in. Then, in step S1108, the second media sensor ME2 detects the omission, and the medical band is in the state as shown in FIG. 12 (b).

Therefore, the output of the first media sensor ME1 in step S1105 is as shown in FIG. As shown in FIG. 17, the output of the first media sensor ME1 in step S1105 has a surface roughness output of 1.0 μm and shows a constant value. Further, the surface thickness output is 150 μm and shows a constant value.
When the surface roughness output and the surface thickness output of the first media sensor ME1 are constant and are predetermined values, it is determined that there is no omission. Also in this embodiment, if the change Δ of the surface roughness is less than 0.2 μm and the change of the thickness is less than 20 μm, it is judged that there is no omission.

Further, the output of the second media sensor ME2 in step S1108 is as shown in FIG. Since the surface roughness of the release layer of the medical band is 1.5 μm, which is coarser than the surface roughness of the surface layer of the medical band of 1.0 μm, the output of the surface roughness of the second media sensor ME2 is shown in FIG. As shown in part A, it has a convex shape. Here, the difference Δ in surface roughness is 0.5 μm, and in this embodiment, if the difference Δ in surface roughness is 0.2 μm or more, it is detected as an abnormality, so that it is determined that there is a defect.
Further, since the thickness of only the release layer lacking the medical band is 50 μm, which is thinner than the thickness of the entire paper of the medical band of 150 μm, the output of the surface thickness of the second media sensor ME2 is B in FIG. As shown by the part, it has a concave shape. Here, the thickness difference Δ is 100 μm, and in this embodiment, if the thickness difference Δ is 20 μm or more, it is detected as an abnormality, so that it is determined that there is a gap.
In this embodiment, it can be specified that the medical band is missing between the first media sensor ME1 and the second media sensor ME2 based on the output result of each media sensor as described above.

<Residual display of paper pieces>
In the present embodiment, when the missing paper is detected, in the flowchart of FIG. 14, it is determined that there is a missing paper in step S1110 (N), and it is indicated that a piece of paper may remain in step S1111. Is done.
Specifically, as in the fourth embodiment, as shown in FIG. 7, a warning is notified to the user. At the same time, the print job is temporarily stopped. Then, after the user confirms the warning, the user presses the OK button to restart the print job. As a result, even if a piece of paper remains in the image forming apparatus, the user can always check it.

<Notification of residual location>
Next, a method of notifying the user of the remaining portion of the missing piece of paper will be described with reference to FIG. 24.
In this embodiment, it is possible to detect the missing portion of the paper from the detection results of the first media sensor ME1 and the second media sensor ME. For example, the first media sensor ME1 did not detect the omission, and the second media sensor ME2 detected the omission, so that the omission occurred between the first media sensor ME1 and the second media sensor ME2. I understand.
In this way, it is possible to identify the presence or absence of paper missing and the residual portion from the outputs of the two media sensors.

Based on these judgments, as shown in FIG. 24B, the UI unit 50 indicates that the paper may be missing and in which portion the piece of paper to be removed remains.
In FIG. 24B, part A represents a region from the cassette 2 or the multi-tray 6 to the first media sensor ME1. Further, the portion B represents an area from the first media sensor ME1 to the paper ejection tray 9 including the transfer unit 20.
In this embodiment, the missing paper can be detected in the region between the first media sensor ME1 and the second media sensor ME2, and this region corresponds to part B in the figure of FIG. 24 (b). do. Therefore, when the missing paper is detected in the B part, as shown in Fig. 24 (b), "There is a possibility that a piece of paper remains in the B part of the device. After checking, click" OK ". Is displayed.

<Example 6>
<Missing detection by two line sensors>
In this embodiment, missing detection and notification to the user when two line sensors LN having a detection area along the main scanning direction (width direction) of the paper are used will be described.
The reason for using the line sensor LN is that the media sensor ME can measure the surface roughness and thickness of the paper with high accuracy, but as shown in FIG. 16, the media sensor ME is located at the substantially center position of the image. This is because the determination can be made only in a narrow range in the main scanning direction of the image. (If a plurality of media sensors ME are used, it is possible to make a judgment even in a wider range.)
Therefore, in this embodiment, a line sensor LN capable of measuring the surface roughness of the paper up to the equivalent of the paper width is used so that the entire main scanning direction of the paper can be confirmed. In this way, by making it possible to confirm the entire area of the main scanning direction by the line sensor LN, it is possible to detect the omission even when the edge of the paper such as the label paper is missing.

The line sensor LN has a configuration in which a sensor capable of detecting surface roughness, such as the media sensor ME described in the fourth and fifth embodiments, is continuously connected in the main scanning direction up to the width of the paper. Further, the positions where the first line sensor LN1 and the second line sensor LN2 are arranged are the same as those of the first media sensor ME1 and the second media sensor ME2 in the fifth embodiment.

In this embodiment, as shown in FIG. 19, a case where a label paper is used as the paper will be described as an example.
Using the flowchart of FIG. 22, missing detection and notification to the user when a print job is executed using the label paper using the two line sensors LN will be described. FIG. 22 is a flowchart showing a process for executing a print job.

First, the user confirms the status of the label paper to be used (step S1201). Next, the user sets the label paper in the multi-tray 6 (step S1202). Next, upon receiving an instruction from the user, paper feeding is started (step S1203).

After that, it is detected that the label paper has passed through the pre-registration sensor R (step S1204). Next, it is detected that the label paper has passed through the first line sensor LN1 (step S1205).
Image formation on the photosensitive drum 11 starts almost at the same time as the label paper passes through the first line sensor LN1 (step S1206). After that, fixing (step S1207) is performed.
Next, it is detected that the label paper has passed through the second line sensor LN2 (step S1208). After that, paper ejection (step S1209) is performed.
Normally, there is no abnormal signal from each sensor, it is determined that no piece of paper remains (Y in step S1210), and the print job ends as it is.

Here, a method of determining the presence or absence of a piece of paper remaining in step S1210 of FIG. 22 and identifying a portion where the piece of paper remains will be described with reference to FIG. 23.
In the table of FIG. 23, "paper status confirmation" indicates the result of the user confirming the paper status in step S1201 of FIG. Further, "line sensor 1 (LN1) detection" is the result of the first line sensor LN1 confirming the paper condition in step S1205, and "line sensor 2 (LN2) detection" is the second line in step S1208. The result of checking the paper condition by the sensor LN2 is shown.

No. 23 in FIG. In the case of 1, since there is no omission in the "paper status check", it means that the user has checked the paper status and confirmed that there is no problem. Further, since "no omission" is also obtained in "line sensor 1 (LN1) detection" and "line sensor 2 (LN2) detection", the first line sensor LN1 and the second line sensor LN2 detect that there is no omission. It means that you did. Therefore, NO. In the case of 1, it means that there is no paper chipping as a whole.

No. 23 in FIG. In the case of 2, "no omission" is obtained in "paper status confirmation", but "line sensor 1 (LN1) detection" and "line sensor 2 (LN2) detection" are "missing" in front of the main body. This is because there was no paper missing when the paper was set in the multi-tray 6, the paper was missing between the multi-tray 6 and the first line sensor LN1 on the front side of the main body, and the paper passed through the second line sensor LN2 with the missing. Is shown. That is, it indicates that the paper was missing on the front side of the main body between the multi-tray 6 and the first line sensor LN1.
No. 23 in FIG. In the case of 3, it is indicated that the sensor is missing from the multi-tray 6 to the first line sensor LN1 on the back side of the main body.

No. 23 in FIG. In the case of 4, "no omission" is obtained in "paper status confirmation" and "line sensor 1 (LN1) detection", but "line sensor 2 (LN2) detection" is "missing" in front of the main body. This indicates that it was missing on the front side of the main body between the first line sensor LN1 and the second line sensor LN2.
No. 23 in FIG. In the case of 5, it is shown that the sensor is missing from the back side of the main body between the first line sensor LN1 and the second line sensor LN2.

Next, as an example, the NO. The actual sensor output in the case of 4 will be described.
In this case, when the user confirms the label paper in step S1201 of FIG. 22, there is no omission, the first line sensor LN1 does not detect the omission in step S1205, and the label paper is shown in FIG. 19 (a). It is in such a state. Then, in step S1208, the second line sensor LN2 detects the omission, and as shown in FIG. 19B, the label paper is in a state where a part of the rear end is missing.

Therefore, the output of the first line sensor LN1 in step S1205 is as shown in FIG.
20 (b) shows the paper in the α and β parts of the first line sensor LN1 when the label paper passes through the first line sensor LN1 without any omission as shown in FIG. 19 (a). The output in the traveling direction (secondary scanning direction of the line sensor) is shown. As shown in FIG. 20 (b), both the α part output and the β part output show 1.0 μm. Here, since there is no omission of the label paper, the output of the first line sensor LN1 remains constant at 1.0 μm in both the α portion and the β portion from the front end of the image to the rear end of the image.

FIG. 20 (c) shows the output in the main scanning direction of the line sensor in the γ portion and the ε portion of the first line sensor LN1. As shown in FIG. 20 (c), it is shown that both the γ part output and the ε part output are constant values at 1.0 μm.
In this embodiment, when the change Δ of the surface roughness is less than 0.2 μm, it is judged that there is no omission.

Further, the output of the second line sensor LN2 in step S1208 is as shown in FIG.
FIG. 21B shows the output in the paper advancing direction (secondary scanning direction of the line sensor) in the α portion and the β portion of the second line sensor LN2. Since the label paper is not peeled off in the α part, the α part output shows a constant value of 1.0 μm. On the other hand, in the β portion, as shown in FIG. 21A, the label paper is peeled off at the rear end of the paper, and the release paper appears at the uppermost portion. Therefore, the surface roughness is 1 in the peeled portion. It will be 5.5 μm. (See part A in FIG. 21 (b)).
Since the surface roughness of the label paper is 1.0 μm and the surface roughness of the release paper is 1.5 μm, the difference Δ of the surface roughness is 0.5 μm. In this embodiment, if the difference Δ of the surface roughness is 0.2 μm or more, it is detected as an abnormality, and therefore it is determined that there is a lack from the output of the second line sensor LN2.

Next, the output of the second line sensor LN2 in the main scanning direction is shown in FIG. 21 (c).
As shown in FIG. 21 (a), since the label paper is not missing in the γ portion, the output in the γ portion shows a constant value of 1.0 μm. On the other hand, in the ε part, a part of the front side of the label paper is missing and the release paper appears on the uppermost surface, so that the output of the ε part is as high as 1.5 μm on the front side (B in FIG. 21 (c)). See section).
Since the surface roughness of the label paper is 1.0 μm and the surface roughness of the release paper is 1.5 μm, the difference Δ of the surface roughness is 0.5 μm. As described above, in the present embodiment, if the difference Δ of the surface roughness is 0.2 μm or more, it is detected as an abnormality, so that it is determined that there is a lack from the output of the second line sensor LN2.

In the above example, in step S1201, the user confirms that the label paper is not missing and sets it in the multi-tray 6. After that, in step S1205, there is no omission at the position of the first line sensor LN1, and in step S1208, the omission is confirmed at the position in front of the second line sensor LN2. From this, it means that the label paper is missing at the front position between the first line sensor LN1 and the second line sensor LN2.
As described above, in this embodiment, it is possible to specify that the label paper is missing between the first line sensor LN1 and the second line sensor LN2. Further, since the line sensor LN is located on the entire surface of the paper in the main scanning direction perpendicular to the transport direction of the main body, it is possible to detect at which position in the main scanning direction of the label paper the chipping has occurred.

<Residual display of paper pieces>
In this embodiment, when the missing paper is detected, in the flowchart of FIG. 22, it is determined that there is a missing paper in step S1210 (N), and there is a display that there is a possibility that a piece of paper remains in step S1211. It will be done.
Specifically, as in the fifth embodiment, as shown in FIG. 7, a warning is notified to the user. At the same time, the print job is temporarily stopped. Then, after the user confirms the warning, the user presses the OK button to restart the print job. As a result, even if a piece of paper remains in the image forming apparatus, the user can always check it.

<Notification of residual location>
Next, a method of notifying the user of the remaining portion of the missing piece of paper will be described with reference to FIG. 25.
In this embodiment, it is possible to detect the missing portion of the paper from the detection results of the two line sensors LN. For example, the first line sensor LN1 did not detect the omission, and the second line sensor LN2 detected the omission, so that the omission occurred between the first line sensor LN1 and the second line sensor LN2. I understand.
In this way, it is possible to identify the presence or absence of paper missing and the residual portion from the outputs of the two line sensors LN.

Based on these judgments, as shown in FIG. 25, the UI unit 50 indicates that the paper may be missing and in which portion the piece of paper to be removed remains.
The difference between the UI display of FIG. 25 and the UI display of FIG. 24 is that in the UI display of FIG. 25, the position where the paper is missing in the main scanning direction perpendicular to the transport direction of the main body is displayed. Is.

Part A (front or rear) in FIG. 25 represents a region from the paper feed unit (cassette 2 or multi-tray 6) to the first line sensor LN1 on the front side or the back side of the main body. Part B (front or rear) represents a region from the first line sensor LN1 to the second line sensor LN2 on the front side or the back side of the main body. The C portion (front or rear) represents an area from the second line sensor LN2 to the output tray 9 portion on the front side or the back side of the main body.
The example of the UI display of FIG. 25 shows the case where the paper is missing in the B portion (front and back) between the first line sensor LN1 and the second line sensor LN2. Then, "There is a possibility that a piece of paper remains in the B part of the device. After checking, click" OK ". Message is displayed.

In this embodiment, the first line sensor LN1 and the second line sensor LN2 are used to detect the missing paper, but the type, combination, and number of sensors are not limited to this. Further, by installing a plurality of sensors of the same type in a direction perpendicular to the transport direction (main scanning direction), the detection accuracy in the main scanning direction can be improved.
Further, in this embodiment, it is assumed that the surface roughness measuring portion (LED and the light receiving portion) of the media sensor ME is extended in the main scanning direction as the line sensor LN, but the thickness detection sensor (ultrasonic sensor) The same effect can be obtained by arranging a plurality of the above in the main scanning direction.

Further, in this embodiment, the case where the medical band or the label paper is peeled off is taken as an example, but when printing is performed with the sticky note or the sticker attached to the paper and the sticky note or the sticker is peeled off in the machine, the media sensor is also used. It is possible to detect omission from the output result of the line sensor.
In this way, it is possible to detect whether or not a part of the multi-layered paper is missing and the missing position based on the output result of the media sensor or the line sensor.

<Other Examples>
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.
Further, the present invention may be applied to a system composed of a plurality of devices or a device composed of one device.
The present invention is not limited to the above-mentioned examples, and various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention. That is, all the configurations in which the above-mentioned configuration example and the modification thereof are combined are included in the present invention.

1 Image forming device 2 Paper feed cassette 6 Multi-tray 9 Paper output tray 30 Fixing device 50 User interface part ME media sensor LN line sensor

Claims (9)

A transport means for transporting the recording material along the transport path,
A transfer means for transferring an image to the recording material conveyed by the transfer means, and a transfer means.
A first measuring means for measuring a current flowing through the transfer means when a bias voltage is applied to the transfer means, or a voltage applied to the transfer means when a bias current is applied to the transfer means.
A residue detecting means for detecting the presence or absence of a piece of paper missing from the recording material remaining in the transport path based on the voltage or current measured by the first measuring means.
A notification means for notifying the user of the detection result by the residual detection means, and
An image forming apparatus characterized by having. A transport means for transporting the recording material along the transport path,
A transfer means for transferring an image to the recording material conveyed by the transfer means, and a transfer means.
A fixing means for fixing the image transferred by the transfer means to the recording material, and a fixing means.
A second measuring means for measuring a current flowing through the fixing means when a bias voltage is applied to the fixing means, or a voltage applied to the fixing means when a bias current is passed through the fixing means.
A residue detecting means for detecting the presence or absence of a piece of paper missing from the recording material remaining in the transport path based on the voltage or current measured by the second measuring means.
A notification means for notifying the user of the detection result by the residual detection means, and
An image forming apparatus characterized by having. A transport means for transporting the recording material along the transport path,
A transfer means for transferring an image to the recording material conveyed by the transfer means, and a transfer means.
A cleaning means for cleaning the developer remaining on the transfer means, and a cleaning means.
A third measuring means for measuring the current flowing through the cleaning means when a bias voltage is applied to the cleaning means, or the voltage applied to the cleaning means when a bias current is passed through the cleaning means.
A residue detecting means for detecting the presence or absence of a piece of paper missing from the recording material remaining in the transport path based on the voltage or current measured by the third measuring means.
A notification means for notifying the user of the detection result by the residual detection means, and
An image forming apparatus characterized by having. The image forming apparatus according to any one of claims 1 to 3, wherein the first to third measuring means measures a current flowing when the bias voltage of a constant voltage is applied. A transport means for transporting the recording material along the transport path,
A transfer means for transferring an image to the recording material conveyed by the transfer means, and a transfer means.
A fourth measuring means for measuring at least one of the surface characteristics or the thickness of the recording material to which the image is transferred by the transfer means.
A residue detecting means for detecting the presence or absence of a piece of paper missing from the recording material remaining in the transport path based on the surface characteristics or the thickness measured by the fourth measuring means.
A notification means for notifying the user of the detection result by the residual detection means, and
An image forming apparatus characterized by having. The image forming apparatus according to claim 5, further comprising two or more of the fourth measuring means. The image forming apparatus according to claim 5 or 6, wherein the fourth measuring means can measure at least one of the surface characteristics or the thickness over the entire area of the recording material in the main scanning direction. The image forming apparatus according to any one of claims 5 to 7, wherein the recording material has a multilayer structure. The image forming apparatus according to any one of claims 1 to 8, wherein the notification means notifies the residual portion of the recording material detected by the residual detecting means.

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