JP5499578B2 - Paper feeding device, image forming apparatus, and remaining paper amount detection method - Google Patents

Description

  The present invention relates to a sheet feeding device that supplies a sheet-like recording medium such as paper, transfer paper, or OHP sheet to the subsequent stage, and an image forming apparatus such as a copying machine, a printer, a facsimile, a plotter, or a digital multi-function peripheral equipped with the sheet feeding device. And a sheet remaining amount detection method executed by the sheet feeding device.

  In recent years, in image forming apparatuses such as printers, copiers, and facsimiles, operations such as increasing the number of sheets that can be stacked, reducing the number of sheets set by the user, or enabling detection of the remaining amount of sheets in multiple stages, etc. Many functions for improving the performance have been demanded.

With the remaining amount detection that detects the remaining amount detection of the conventional paper in multiple stages,
1) A plurality of sensors for detecting the position of the shielding plate are provided so that the shielding plate rises in conjunction with the upward movement of the paper, and the paper loading amount is detected by the number of sensors shielded by the shielding plate. thing,
2) An encoder is provided in the rotating part of the ascending motor for the ascending movement of the paper, the slit of the encoder is measured by a sensor, and the paper loading amount is detected from the number of pulses (rotation angle, moving amount) from the sensor,
3) A stepping motor is used as the ascending motor, and the paper loading amount is detected from the number of motor drive pulses (rotation angle, movement amount).
Etc. have been proposed.
Specifically, for example, the inventions described in Patent Documents 1 to 3 are known. Among them, Patent Document 1 (Japanese Patent No. 4015860) discloses a bottom plate that is provided in a sheet feeding cassette so as to be movable up and down, and that raises the bottom plate when the sheet feeding cassette is mounted, while being detached. Lifting and lowering means that pivots so as to lower the bottom plate, and a surface that extends in a fan shape in a direction orthogonal to the pivot axis of the lifting and lowering means in conjunction with the rotation of the lifting and lowering means Remaining amount detecting means having an outer peripheral protruding surface protruding from the periphery in the insertion direction of the paper feed cassette and a notch provided in the outer peripheral protruding surface, and detecting positions of the outer peripheral protruding surface and the notch A plurality of sensors provided at predetermined positions for outputting ON / OFF according to the rotation of the remaining amount detecting means, and the ON output from the plurality of sensors when the rotation of the remaining amount detecting means stops. / Based on off combination There is disclosed a sheet remaining amount detecting device, comprising: a determination unit that determines a remaining sheet amount, and disposed so that at least one of the plurality of sensors is always turned on when the sheet feeding cassette is mounted. .

  In Patent Document 2 (Japanese Patent Laid-Open No. 2000-118792), a sheet is supported on a bottom plate of a sheet feeding cassette, and the sheet is pressed against a sheet feeding roller by raising a sheet feeding side end of the bottom plate. A sheet remaining amount detecting device used in a sheet feeding device that rotates the sheet feeding roller to feed the sheet, and includes a first actuator having a first protrusion that rotates depending on the presence or absence of the sheet, and a height of the bottom plate A second actuator having a second projecting portion that rotates according to the height, and a plurality of projecting portion detecting means disposed on the pivot trajectories of the first and second projecting portions, respectively. , At least a part of the rotation trajectory of the second protrusion is made coincident, and the remaining amount and presence / absence of the sheet in the sheet cassette can be detected by using the detection information of the protrusion by the protrusion detection unit. Disclosed paper remaining amount detection device is disclosed To have.

  Further, Patent Document 3 (Japanese Patent Application Laid-Open No. 2000-16639) discloses a driving means for raising a bottom plate of a paper feed cassette loaded with paper, and the bottom plate is raised so that the uppermost surface of the paper starts a predetermined paper feed. In the image forming apparatus including the paper surface detecting means for detecting the arrival at the position and the cassette set detecting means for detecting whether or not the paper feed cassette is set in the apparatus main body, from the time when the remaining amount detection is turned off. Each time a sheet is fed from the sheet cassette, the number of sheets fed is counted, and the count is set to one of preset values among several types of setting values for detecting the remaining amount of paper in multiple stages. An image forming apparatus including a control unit that estimates the remaining amount of paper when a value reaches is disclosed.

  There are a wide variety of techniques for detecting the remaining amount in the paper feeding device. However, since each technique has merits and demerits, various techniques have been proposed according to the purpose and application. Among these, the technique described in Patent Document 1 is configured to detect the remaining amount of paper with a member having a notch in the outer shape coaxially with the rotation shaft accompanying the rise of the bottom plate, and the displacement sensor. Since a sensor dedicated to the remaining amount detection is necessary and expensive, and additional components are required, it cannot be applied to a low-cost apparatus.

  In the technique disclosed in Patent Document 2, the remaining amount of paper is detected in multiple stages by ON / OFF of a composite signal using a paper presence / absence detection sensor and another sensor. A sensor dedicated to the remaining amount detection is required, and only three-step detection of whether there is a large amount of paper, an intermediate level remaining, or no paper is available, and lacks accuracy.

  Furthermore, in the technique described in Patent Document 3, a sensor is provided in the middle of whether the amount of paper stacked on the bottom plate is large or small, and the remaining amount is estimated by counting according to the number of times the paper is passed after the middle. However, there remains a problem that a sensor dedicated to detecting the remaining amount of paper is separately required, and the remaining amount estimation by counting the number of times of passing of paper lacks certainty. That is, the inventions described in Patent Documents 1-3 also have room for improvement in terms of detection accuracy and device cost.

  Accordingly, the problem to be solved by the present invention is to enable detection of the remaining amount of paper in almost real time without causing an increase in parts.

In order to solve the above-mentioned problem, the present invention raises the paper feed side end of the bottom plate on which the paper is placed to press the paper against the paper feed roller, before the roller abuts the paper. A sheet feeding device having a sheet feeding section that rotates the roller in the sheet feeding direction to feed the sheet, and is located downstream of the sheet feeding section in the sheet conveying direction and detects the leading edge of the sheet; Driving means for pressing and separating the roller for each sheet, and a preset timing before the timing when the maximum number of sheets placed on the bottom plate come into contact with the roller. Calculating means for calculating a remaining amount of paper based on a time Tn from when the detecting means is fed by the roller until the leading edge of the paper is detected, and the calculating means comprises:
The time from the start of paper feeding until the leading edge is detected by the detecting means is t1,
T0 is the time from when the bottom plate starts to rise to the pressure contact when the paper is fully loaded.
N, the maximum number of sheets loaded
N, the number of sheets passed from the maximum loading
Δt / N is the delay in the bottom plate rise time for each sheet of paper
When
The time that the detection means detects after the leading edge of the nth sheet from the maximum stacking capacity receives a paper feed command
Tn = t0 + t1 + nΔt / N
And a separate sheet remaining amount table that stores the relationship between the number of sheets when the maximum number of sheets is loaded, the rotation angle of the bottom plate, the rotation speed of the bottom plate, the movement speed of the sheet, and the conveyance mode with respect to the sheet type. And calculating the remaining amount of paper .

In the embodiment described later, the bottom plate is denoted by reference numerals 1 and 2, and the sheet feeding side end is the rotation center 1-a, 2-
At the end away from a, the paper feed roller is the pickup roller R2 or the paper feed roller R1, the paper feed unit is the main body paper feed unit PS1 and the manual paper feed unit PS2, and the detection means is the registration sensor S3. The drive means is a drive mechanism (not shown), the preset timing before the timing of contacting the roller is B2, and the timing when the detection means is fed by the roller to detect the leading edge of the paper is B5, B6. to, the calculating means CPU 111, the use Kamizanryou table in the storage unit 170, images forming apparatus to the printer 100, corresponding.

  According to the present invention, it is possible to detect the remaining amount of paper substantially in real time without causing an increase in parts.

1 is a schematic configuration diagram illustrating a paper feeding device and a paper feeding conveyance path of a printer according to an embodiment of the present invention. FIG. 10 is a schematic configuration diagram illustrating an operation of the manual sheet feeder in a state where sheets are stacked. 6 is a timing chart illustrating the operation timing of each unit in a paper feeding operation. It is a figure which shows the relationship between the time Tn calculated | required by the number of paper passing, and a calculation. It is a figure which shows the example of the table used when calculating time Tn. FIG. 2 is a block diagram illustrating an outline of a control configuration of a printer according to the present embodiment.

  According to the present invention, the remaining amount of paper can be detected in real time almost without any increase in parts by using the detection time timing of a sensor that is originally installed. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram illustrating a paper feeding device and a paper feeding conveyance path of a printer according to an embodiment of the present invention. Arrows A1, A2, and A3 in the figure indicate the sheet conveyance path. The sheet feeding unit is composed of a main body sheet feeding unit PS1 on the left side and a manual sheet feeding unit PS2 on the right side.

  The main body sheet feeding portion PS1 includes a bottom plate 1 that swings about a rotation center 1-a, a sheet feeding roller R1 that is disposed at an end of the bottom plate 1 opposite to the rotation center 1-a, and a sheet feeding roller R1 position. A conveyance path A2 from the registration roller pair R4 position to the registration roller pair R4 position, a conveyance path A1 that leads from the registration roller pair R4 position through the transfer roller R5 to the paper discharge port, and an elastic member 3 that constantly elastically urges the bottom plate 1 toward the paper feed roller R1. And a sensor filler (hereinafter simply referred to as a sensor) S1 for detecting paper on the bottom plate 1.

  Similarly, the manual sheet feeding portion PS2 includes a bottom plate 2 that swings about the rotation center 2-a, a pickup roller R2 that is disposed at the end opposite to the rotation center 2-a of the bottom plate 2, and a pickup roller. Paper feed roller R3 located on the downstream side in the paper conveyance direction, conveyance path A3 from the paper feed roller R3 position to the registration roller pair R4 position, elastic member 4 that constantly elastically urges the bottom plate 2 toward the pickup roller R2, and the bottom plate 2 A sensor filler (hereinafter simply referred to as a sensor) S2 for detecting the upper sheet is provided. The separation members 7 and 5 are in sliding contact with the paper feed rollers R1 and R3, respectively, to separate the multi-feed paper and feed only the paper on the side in contact with the paper feed rollers R1 and R3. It is like that. The transfer roller R5 has a nip between the transfer belts 6 and transfers an image on the transfer belt 6 to a sheet passing between the nips.

  That is, in the example of FIG. 1, a so-called print head that forms or prints an image on a sheet by the transfer belt 6 and the transfer roller R5 is configured. Since this print head presupposes a so-called electrophotographic image forming section, an example using the transfer belt 6 is given. However, there are monochrome and full-color image forming sections, not the transfer belt 6. Even when a transfer drum is used and when a transfer drum is used, there are monochrome and full-color ones. Furthermore, as a method other than the electrophotographic method, a droplet discharge type print head such as an ink jet method or a gel jet method may be used. In the present invention, the printing method of the printer is not limited.

  In the paper feeding device configured in this way, for example, when paper is transported from the manual paper feeding unit PS2, the paper is placed on the bottom plate 2 and is urged by the elastic member 4 in the direction of the pickup roller R2. Then, the uppermost sheet is brought into pressure contact with the pickup roller R2. At this time, every time a sheet is fed, the bottom plate 2 is swung around the rotation center 2-a by a one-rotation clutch such as a gear or a cam or a driving mechanism such as a stepping motor, and repeatedly raises and lowers the stacked sheets.

  The sheet pressed against the pickup roller R2 reaches the nip between the sheet feeding roller R3 and the separation member 5 that is in sliding contact with the sheet feeding roller R3 by the rotation of the pickup roller R2, and is separated into one sheet. The separated sheet is conveyed along the conveyance path A3 to the registration roller pair R4, and after correcting the skew of the sheet at the nip position with the registration roller pair R4, the image on the transfer belt 6 is timed. It is sent out and reaches the transfer roller R5 and the transfer belt 6 on the downstream side. The toner image sent from the developing unit is transferred to the sheet at the nip between the transfer roller R5 and the transfer belt 6, and further, the sheet is discharged through a fixing unit and a sheet discharge unit (not shown) downstream.

  Similarly, in the case of paper feed from the main body feed PS1, the paper placed on the bottom plate 1 passes through the nip of the feed roller R1, the registration roller pair R4, the transfer roller R5 and the transfer belt 6 and is discharged from the paper discharge port. Is done.

  In a series of transport operations, the sensors S1 and S2 detect the ON / OFF state of the sensor based on the presence or absence of paper on the bottom plates 1 and 2, and when it is determined that there is no paper, it is determined that the set paper has run out. Cancels the printing operation. A registration sensor filler (hereinafter referred to as a unit registration sensor) S3 detects ON / OFF when the leading edge of the sheet contacts and rotates, and is measured as information on the sheet conveyance timing, and the sheet does not perform a predetermined conveyance operation. If it is detected, it is determined that the jam has occurred and the printing operation is stopped.

  FIG. 2 is a schematic configuration diagram illustrating the operation of the manual sheet feeder in a state where sheets are stacked, and FIG. 3 is a timing chart illustrating the operation timing of each unit in the sheet feeding operation. 2A shows a case where the number of stacked sheets is minimum (0), FIG. 2B shows a case where the number of stacked sheets is maximum, and in FIG. 2, P is a stacked sheet, and F0 is a standby position for raising and lowering the bottom plate. Represents.

When the sheet feeding device receives a sheet feeding command, the pickup roller R2 starts to rotate (FIG. 3: B1), and at the same time, the bottom plate 2 starts a lifting operation to start the sheet feeding operation from the standby position F0 (FIG. 3). 3: B2). At this time, the rotation angle from the standby position F0 to the pressure contact (B3) to the pickup roller R2 when the number of sheets is 0 is θ1 [deg], and the rotation angle when the number of sheets is maximum is θ2 [deg]. deg], the smaller the number of sheets, the larger the rotation angle. That is,
θ1> θ2
It becomes.

On the other hand, when the rotation speed of the bottom plate 2 is set to A [rpm], the pressure contact (FIG. 3) from the bottom plate rising start (FIG. 3: B2) to the pickup roller R2 when the number of sheets is 0 and when the number of sheets is maximum. : B3, B4) as Δt (FIG. 3: B4-B3)
Δt = (θ1−θ2) / 6A [sec] (1)
Holds. Since the conveyance of the sheet is started from the moment when it is brought into pressure contact with the already rotating pickup roller R2 (FIG. 3: B3, B4), Δt [sec] is greater when the number of sheets is maximum than when the number of sheets is zero. It will start as soon as possible (FIG. 3: B3).

Assuming that the paper conveyance start position is constant, the conveyance distance from the standby position until the registration sensor S3 is turned ON is L, and the paper movement speed is V, the time t1 from the paper supply start to the registration sensor S3 ON (FIG. 3)
t1 = L / V [sec] (2)
It becomes. Assuming that the number of sheets when the maximum number of sheets is stacked is N, and the time from the start of raising the bottom plate 2 to the pressure contact when N sheets are stacked is t0, time t0 (FIG. 3: B3-B2) is
t0 = θ2 / 6A [sec] (3)
It becomes. Δt / N [sec] for each sheet of paper
The time Tn for detecting the ON (FIG. 3: B5, B6) of the registration sensor S3 after the leading edge of the nth sheet passing from the maximum stacking of the sheets after receiving the sheet feeding command is
Tn = t0 + t1 + nΔt / N [sec] (4)
It becomes.

Solving equation (4) for n: n = (Tn−t1−t0) N / Δt [sheet number] (5)
The remaining paper amount Nz at this time is Nz = N−n
= N- (Tn-t1-t0) N / .DELTA.t
= N (1− (Tn−t1−t0) / Δt) [sheets] (6)
It becomes.

  Therefore, if the time Tn which is a variable is measured from the equation (6), the remaining amount of paper for each sheet can be estimated. Here, by suppressing the remaining amount detection accuracy to a step-by-step detection of the remaining amount of paper instead of every single sheet, it is possible to allow variation in the position of the sheet that occurs during conveyance, and to achieve a lower cost.

  Further, if the measurement start timing of the time Tn is a certain time before the timing when the maximum loaded paper is pressed against the pickup roller R2, there is no need to be particularly concerned with the start of the bottom plate ascent.

  Here, for example, when the paper is thick and strong, or the paper has a rough surface and a high friction coefficient, the variation in the measurement time Tn increases. In this case, a relay roller R6 shown in FIG. 1 is provided in the middle of the registration sensor S3 from the paper feeding unit to strengthen the conveyance force. As a result, the variation in time Tn can be suppressed and the remaining sheet detection accuracy can be kept high.

Further, in the pickup roller R2 in FIG. 2, an end guide 8 is provided on the end side (upstream side in the transport direction) of the bottom plate 2, and after the nth sheet is sent out, it is rotated in the direction opposite to the transport direction. As a result, the (n + 1) th sheet that has been taken forward by the friction force to the nth sheet can be returned to the original standby position. As a result, it is possible to always keep the sheet feeding start position constant, and as a result, it is possible to keep the remaining sheet detection accuracy high. In addition, in order to further improve the detection accuracy of the remaining amount of paper,
-Increase the resolution of the resist sensor S3 itself,
-Decrease the rotation speed of the bottom plate 2 as much as possible,
There are methods.

  FIG. 4 is a diagram showing the relationship between the number of sheets to be passed and the time Tn obtained by the above equation (4). After the paper is fed, for example, when it is caught by a joint between parts or a burr due to molding failure, or the leading edge of the set paper is originally broken, the arrival at the registration sensor S3 may be suddenly delayed. A predetermined variation threshold value is set for as many consecutive Tn values as possible immediately before the determination is made only by the information of the k-th sheet that causes such an irregular operation. If the threshold value is exceeded, the remaining paper amount information is cleared and the time is measured again. As a result, it is possible to prevent erroneous detection of the remaining amount of paper due to an irregular transport operation.

  Specifically, in FIG. 4, the points indicated by hatched circles are the kth Tn (k) where a sudden paper delay has occurred. At this time, the standard deviation σn of the parameter 3 of Tn−1 and Tn−2 immediately before Tn is taken. At this time, the following condition is set as the predetermined variation threshold σa.

[conditions]
Tn is reset when σn ≧ σa When σn <σa Tn = (Tk−2 + Tk−1 + Tk) / 3 (7)
As a result, the remaining paper amount Nz is calculated by substituting the time Tn into the equation (6).

  In this case, the standard deviations σk, σk + 1, σk + 2 calculated using Tk shown in FIG. 4 exceed the predetermined variation threshold σa, and are reset. Thereafter, the value after σk + 3 falls below σa, Tn is determined, and the remaining amount of paper is calculated. By this measure, it is possible to prevent erroneous detection of the remaining amount of paper due to a sudden paper delay Tk. Further, the remaining amount detection accuracy can be changed by adjusting the parameter and the threshold value σa. Thus, the possibility of erroneous detection is reduced even when a sheet is being fed or when a user replenishes a bundle of sheets after a predetermined number of printing operations have been completed.

  Moreover, when the average value of a plurality of values is taken as in Expression (7), the displacement of the detected remaining amount becomes smooth. Further, instead of detecting the remaining amount one by one, the maximum number of stacked sheets N is divided into a plurality, and the remaining amount of paper Nz is detected step by step to lower the resolution, thereby preventing erroneous detection without increasing physical accuracy. it can.

  If the sensors S1 and S2 for detecting the presence or absence of the paper shown in FIG. 1 are installed, the remaining amount of paper up to the final paper is judged by the registration sensor S3, and only the final paper is detected by the sensors S1 and S2. As described above, it is possible to reliably prevent a jam after the sheet has run out without increasing the accuracy of the remaining sheet detection as necessary by separating the roles of the sensors.

  As described above, depending on the type of paper, the transport speed at the front end of the paper may change even in the same transport path. Also, depending on the apparatus, the conveyance speed is often set individually for the paper thickness (basis weight). Therefore, if a numerical value table supplementary for measuring the time Tn is prepared for the paper type to be passed in advance, the accuracy of detecting the remaining amount of paper to be fed is improved.

  For example, even when the maximum stacking height is the same, if the sheet thickness is different, the number N of sheets at the maximum stacking changes. Further, depending on the paper, the stacking height may be limited, and the rotation angle θ2 of the bottom plate 2 at the time of maximum stacking may also change. In addition, when the paper conveyance load is high, the paper movement speed V may be individually set because the conveyance speed may be lowered. When the moving speed V is changed, the bottom plate ascent speed is often changed in the same manner, so that the rotational speed A of the bottom plate 2 is also set individually. The rotation angle θ1 and the transport distance L are usually constant values regardless of the paper type. FIG. 5 shows an example of an individual setting table based on the above.

  In this table, the relationship among the number of sheets N at the time of maximum loading, the rotation angle θ2 of the bottom plate at the maximum loading, the rotation speed A of the bottom plate, the movement speed V of the sheet, and the conveyance mode is set for the sheet type. . With regard to the paper types, the maximum number N of sheets that can be stacked is the individual value, and the rotation speed θ2 is common to the sheets (a) and (b) for the sheets (a) to (d). This indicates that the maximum loading height is the same. Note that the conveyance distance L from the standby position to turning on the registration sensor S3 and the rotation angle θ1 from the standby position F0 to the pressure contact with the pickup roller R2 when the number of sheets is 0 are the sheet type (sheet thickness). Therefore, it is a fixed value (a constant value) according to the model of the paper feeding device.

  As for the rotation speed A and the movement speed V, two modes of mode (1) for paper (a) and (b) and mode (2) for paper (c) and (d) are set as the transport modes. For example, the mode of thick paper (c) and (d) is less than the thin paper (a) and (b), while the transport speed V and the bottom plate raising speed A are halved. In many cases, a plurality of setting values are set depending on the conveyance performance of the apparatus, such as the maximum loading height is different between c) and (d). Therefore, if such a setting table is prepared for a paper type expected in advance, the remaining paper amount Nz can be calculated using the equations (1) to (6).

  Even if such a table is prepared, when a new paper type that does not exist in the assumed table is passed, a new value is obtained based on the measured value of the time Tn when the paper is passed and information on the maximum number N of sheets loaded. Create a numerical table in the table so that it can be reflected. For this reason, in this embodiment, the CPU 111 of the control unit 110 shown in FIG.

  That is, FIG. 6 is a block diagram showing an outline of the control configuration of the printer according to the present embodiment. In FIG. 1, the printer 100 according to the present embodiment includes a paper feed unit 120, an image forming unit 130, a paper discharge unit 140, an operation display unit 150, an external I / F unit 160, and a storage unit 170. The control configuration is controlled by the control unit 110. The sheet feeding unit 120 includes the main body sheet feeding unit PS1 and the manual sheet feeding unit PS2 illustrated in FIG. 1, and the image forming unit 130 includes image forming elements including the transfer belt 6 illustrated in FIG. The paper discharge unit 140 discharges the paper on which the image is fixed on the paper to the outside of the apparatus or a post-processing device on the downstream side, on the downstream side of the transfer roller R5 in the transport direction and downstream of the fixing unit (not shown). The operation display unit 150 is a user interface of the printer 100, and receives operation instructions from the user and displays soft keys and messages on the screen. The external I / F is an interface that is connected to a control unit 110 to which a PC (personal computer), a scanner, and the like (not shown) are connected. The storage unit 170 is a memory for storing image data and the table, and a mass storage device such as an HDD is used. Note that a flash memory such as a DRAM can be used for the table.

  The control unit 110 includes a CPU 111, a ROM 112, and a RAM 113, receives sensor signals from each unit, and controls each unit based on the input signals and operation signals. The control is executed by the CPU 111. The CPU 111 develops a program stored in the ROM 112 in the RAM 113, and executes processing defined by the program while using the RAM 113 as a work area and a data buffer.

  As described above, since the CPU 111 has a function for creating a new table, a table for calculating the remaining amount N of paper for a new paper type is created whenever necessary. As a result, all types of paper used can be handled. For example, when passing a new paper type, a mode for detecting the remaining amount of paper is prepared, and the paper is loaded on the bottom plate up to the maximum stacking height to perform the paper passing operation. At this time, the number of sheets to be passed through to the final sheet is N, and the Tn of the final sheet is Tn (min) according to FIG. 3. Therefore, from the t0, t1, and Δt determined by the transport mode, the above-described formula (6) Thus, the remaining paper amount Nz can be estimated.

  The remaining paper amount detection information obtained in this way is displayed on the operation display unit 150 of the printer 100 and / or the screen of a personal computer that issues a print instruction, thereby allowing the user to recognize the remaining paper amount. It becomes possible. As a result, it is possible to prompt the user to set the paper before it runs out of paper.

As described above, according to the present embodiment,
1) The registration sensor S3 is fed by the pickup roller R2 from the preset timing B2 before the timing B3 when the maximum number of sheets placed on the bottom plate 2 come into contact with the pickup roller R2, and detects the leading edge of the sheet. Since the remaining amount of paper is calculated on the basis of the time Tn until it is done, the remaining amount of set paper can be detected in real time without newly adding parts.
2) Since the relay roller R6 is provided in the middle of the registration sensor S3 from the paper feeding unit to enhance the conveying force, variation in the moving speed of the leading edge of the paper can be suppressed and the remaining amount of paper can be detected accurately.
3) By moving the pickup roller R2 in the reverse direction, it is possible to prevent the trailing paper from being taken out by the preceding paper, and the remaining amount can be detected more accurately.
4) For a plurality of continuous times Tn, when the predetermined variation σa is exceeded, the remaining paper amount information is once cleared, and when the subsequent continuous recording is less than the predetermined variation σa, the remaining amount of paper is Therefore, even if the paper behavior is suddenly disturbed, erroneous detection of the remaining amount of paper can be prevented.
5) It is possible to prevent erroneous detection by dividing the maximum amount of paper into a plurality of pieces and detecting the remaining amount of paper step by step and lowering the resolution of the remaining amount detection.
6) Since sensors S1 and S2 for detecting the presence or absence of paper on the bottom plate are provided in addition to the registration sensor S3, jamming due to running out of paper can be reliably prevented while detecting the remaining amount.
7) An individual sheet remaining amount table (FIG. 5) relating to a plurality of sheet types is further provided in advance, and when calculating the time Tn, the calculation is performed with reference to the sheet remaining amount table. The remaining amount can be accurately detected with respect to the selected paper type.
8) The time Tn is measured for the paper type to be used, and a new table of remaining paper amount for the paper type is newly created and reflected in the remaining paper amount information. Detection can be performed accurately.
9) Since the user can recognize the remaining amount of paper via the operation display unit 150, the user can replenish paper before running out of paper, and the work efficiency of printing can be improved.
There are effects such as.

  It should be noted that the present invention is not limited to this embodiment, and various modifications are possible, and all technical matters included in the technical idea of the invention described in the scope of claims are the subject of the present invention. .

Japanese Patent No. 4015860 JP 2000-118792 A JP 2000-16639 A

1, 2 Bottom plate 1-a, 2-a Rotation center 8 End fence 100 Printer 111 CPU
150 Operation Display Unit 170 Storage Unit PS1 Main Body Paper Feed Unit PS2 Manual Paper Feed Unit R1 Paper Feed Roller R2 Pickup Roller R6 Relay Roller S1, S2 Sensor S3 Registration Sensor

Claims (10)

By raising the paper feed side end of the bottom plate on which the paper is placed, the paper is pressed against a paper feed roller, and the roller is rotated in the paper feed direction before the roller contacts the paper. A paper feeding device having a paper feeding unit for feeding paper,
Detection means for detecting the leading edge of the paper in the downstream portion of the paper feeding direction in the paper feeding direction;
Driving means for pressing and separating the roller for each sheet when feeding the sheet;
The time Tn from when the detection unit is fed by the roller to detect the leading edge of the sheet from the preset timing before the timing when the maximum number of sheets placed on the bottom plate contact the roller is reached. A computing means for computing the remaining amount of paper based on;
Equipped with a,
The computing means is
The time from the start of paper feeding until the leading edge is detected by the detecting means is t1,
T0 is the time from when the bottom plate starts to rise to the pressure contact when the paper is fully loaded.
N, the maximum number of sheets loaded
N, the number of sheets passed from the maximum loading
Δt / N is the delay in the bottom plate rise time for each sheet of paper
When
The time that the detection means detects after the leading edge of the nth sheet from the maximum stacking capacity receives a paper feed command
Tn = t0 + t1 + nΔt / N
And a separate sheet remaining amount table that stores the relationship between the number of sheets when the maximum number of sheets is loaded, the rotation angle of the bottom plate, the rotation speed of the bottom plate, the movement speed of the sheet, and the conveyance mode with respect to the sheet type. And calculating the remaining amount of paper. The sheet feeding device according to claim 1,
A paper feeding device comprising one or more paper transport rollers downstream from the rollers and upstream from the detection means . The sheet feeding device according to claim 1 or 2,
Means for moving the next sheet in the direction opposite to the conveying direction after feeding the sheet by the roller ;
A restricting means for restricting the position in the moving direction of the paper moved in the reverse direction;
A paper feeding device comprising: The sheet feeding device according to any one of claims 1 to 3,
The computing means once clears the remaining sheet information when the predetermined variation for a plurality of consecutive times Tn exceeds a predetermined variation, and the sheet when a plurality of subsequent recordings are less than the predetermined variation. A sheet feeding device that reflects a calculation result of a remaining amount . The sheet feeding device according to any one of claims 1 to 4,
The paper feeding device is characterized in that the computing means divides the maximum paper loading capacity into a plurality of parts and detects the remaining paper quantity step by step . The sheet feeding device according to any one of claims 1 to 5,
In addition to the detecting means, a paper feeding device comprising paper presence / absence means for detecting the presence / absence of paper on the bottom plate . The sheet feeding device according to any one of claims 1 to 6,
The computing means is
Measure the time Tn for the paper type to be used,
A sheet feeding device that newly creates a table of remaining sheet amounts for the sheet types . The sheet feeding device according to any one of claims 1 to 7,
A sheet feeding device comprising: means for causing an operator to recognize the determined remaining sheet amount based on the remaining sheet amount calculated by the calculating unit. An image forming apparatus comprising the paper feeding device according to claim 1 . By raising the paper feed side end of the bottom plate on which the paper is placed, the paper is pressed against a paper feed roller, and the roller is rotated in the paper feed direction before the roller contacts the paper. A method for detecting a remaining amount of paper in a paper feeding device having a paper feeding unit for feeding paper ,
Detection means for detecting the leading edge of the paper in the downstream portion of the paper feeding direction in the paper feeding direction;
One or more paper transport rollers provided downstream of the rollers and upstream of the detection means;
Driving means for pressing and separating the roller for each sheet when feeding the sheet;
With
The time from the start of paper feeding until the leading edge is detected by the detecting means is t1,
T0 is the time from when the bottom plate starts to rise to the pressure contact when the paper is fully loaded.
N, the maximum number of sheets loaded
N, the number of sheets passed from the maximum loading
Δt / N is the delay in the bottom plate rise time for each sheet of paper
When
Time that the detecting means detects after the leading edge of the nth sheet from the maximum stacking capacity receives a paper feed command
Tn = t0 + t1 + nΔt / N
And a separate sheet remaining amount table that stores the relationship between the number of sheets when the maximum number of sheets is loaded, the rotation angle of the bottom plate, the rotation speed of the bottom plate, the movement speed of the sheet, and the conveyance mode with respect to the sheet type. And calculating the remaining amount of paper .

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