JP2000327177A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing mis- detection of a sheet use-up judging means. SOLUTION: This image forming device is provided with a paper feeding device 19 for feeding sheets P housed in a paper feeding tray 27, a sheet use-up detecting means 33 for detecting no paper in the paper feeding tray 27, and a main control part for controlling the paper feeding operation of a paper feeding means according to the detected result of the sheet use-up detecting means 33, and an image is formed on the paper P fed from the paper feeding tray 27. The main control part invalidates the detected result of the sheet use-up detecting means 33 until the next paper can be fed from the time of the start of feeding of the paper P by the paper feeding device 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art Generally, in a sheet feeding device (sheet feeding means) of an image forming apparatus such as a copying machine, a printer, and a facsimile,
A paper end detecting means (paper out detecting means) for detecting that the paper in the paper feed tray has run out (hereinafter referred to as "paper end") is used.

As the paper end detecting means, for example, when the sheets stacked on the bottom plate of the paper feed tray are exhausted and the bottom plate is lowered, the filler is lowered by its own weight or a spring or the like to shield the photo interrupter. Some of them detect paper end.

[0004]

However, according to the above-mentioned technique, when the paper loaded on the paper feed tray is a paper having a high rigidity such as a thick paper or an envelope, the paper is fed by the rigidity of the paper. Sometimes, the paper itself pushed down the bottom plate, and the filler blocked the photo interrupter. If the filler blocks the photointerrupter, an erroneous detection occurs that the photointerrupter is detected as a paper end even though paper is stacked on the bottom plate. That is, there is a problem that erroneous detection of the paper end detecting unit due to the paper feeding operation by the paper feeding device occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of preventing erroneous detection of the paper-out detecting means.

[0006]

According to a first aspect of the present invention, there is provided a paper feed unit for feeding paper stored in a paper storage unit, and a paper out detection unit for detecting the absence of paper in the paper storage unit. An image forming apparatus for forming an image on a sheet fed from a sheet storage unit, the control unit controlling a sheet feeding operation of the sheet feeding unit in accordance with a detection result of the sheet out detecting unit. The means invalidates the detection result of the paper-out detecting means from the start of paper feeding by the paper feeding means until the next paper can be fed.

According to the first aspect of the present invention, while the paper is being fed (between the start of feeding the paper and the time when the next paper can be fed), the control means detects the paper-out detection means. Since the result is invalidated, even if the paper-out detecting means detects that there is no paper, the control means causes the paper-feeding operation to be performed as it is.

When the paper feeding operation by the paper feeding means is completed, the detection result of the paper out detecting means is validated. At this time, when the out-of-paper detecting unit detects out-of-paper, the control unit performs control such as stopping the paper feeding operation of the paper feeding unit. On the other hand, when the out-of-paper detecting means does not detect out-of-paper (when paper remains in the paper storage unit), for example, control such as continuing the paper feeding operation is performed.

The control means invalidates the detection result of the paper-out detecting means during paper feeding, thereby providing
It is possible to prevent erroneous detection of the out-of-sheet detecting unit due to the sheet feeding operation of the sheet feeding unit.

According to a second aspect of the present invention, there is provided a paper feed unit for feeding paper stored in a paper storage unit, a paper out detection unit for detecting the absence of paper in the paper storage unit, and a paper out detection unit. Control means for controlling the paper feeding operation of the paper feeding means in accordance with the detection result, and an image forming apparatus for forming an image on the paper fed from the paper storage unit. Paper type detection means for detecting the type of paper being fed, and the control means, when the paper type detection means detects a specific paper type, enables the next paper to be fed from the start of paper feeding by the paper feeding means. Until that time, the detection result of the paper-out detecting means is invalidated.

In the invention according to claim 2, for example,
Depending on the type of paper that is stored in the paper storage section, such as thick paper, some paper-out detectors can easily make false detections.
When the paper type detecting means detects a paper sheet (specific paper) such as thick paper which is likely to be erroneously detected, the control means invalidates the detection result of the paper-out detecting means during paper feeding.

The control means invalidates the detection result of the paper-out detecting means during paper feeding, so that
It is possible to prevent erroneous detection of the out-of-sheet detecting unit due to the sheet feeding operation of the sheet feeding unit.

According to a third aspect of the present invention, there is provided a paper feed unit for feeding paper stored in a paper storage unit, a paper out detection unit for detecting the absence of paper in the paper storage unit, and a paper out detection unit. A control unit for controlling a sheet feeding operation of the sheet feeding unit according to the detection result, wherein the image forming apparatus forms an image on a sheet fed from the sheet storage unit, and detects a sheet size. The control unit includes a detecting unit that detects when the paper size detecting unit detects a specific paper size from the start of paper supply by the paper supply unit until the next paper can be supplied. The detection result of the means is invalidated.

According to the third aspect of the invention, generally,
The paper size (specific paper size) for postcards and envelopes is
Because the paper out detection means is thick paper that can easily be misdetected,
By detecting the paper size, the paper-out detecting means can determine the paper which is likely to be erroneously detected, and the paper caused by the paper feeding operation of the paper feeding means with a simple configuration and without adding a memory resource or the like. Erroneous detection of the cut detection means can be prevented.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment will be described in detail with reference to the accompanying drawings. FIG. 1 is a configuration diagram schematically showing an image forming apparatus to which the present invention is applied. First, the configuration and operation of the image forming apparatus will be schematically described.
As shown in FIG. 1, the image forming apparatus 1 has a photosensitive drum 3 as an image carrier on which an electrostatic latent image corresponding to image information is formed on the surface (peripheral surface).

A charging roller 5 for charging the surface of the photosensitive drum 3 is provided around the photosensitive drum 3, and a light image data is applied to the photosensitive drum 3 after the charging process by irradiating the photosensitive drum 3 with light image data. Optical unit 7 for forming an electrostatic latent image on the surface of
A developing device 11 having a developing roller 9 for visualizing an electrostatic latent image formed on the photosensitive drum 3 as a toner image;
A transfer roller 13 for transferring the toner image on the photosensitive drum 3 to the paper P; and a cleaning blade 1 for cleaning the photosensitive drum 3 after the transfer process in preparation for the next image forming process
5 is disposed.

Below the image forming apparatus 1, there is provided a paper feeder (paper feed means) 19 for feeding paper P to the image forming apparatus main body (this will be described later). Further, the paper P fed from the paper feeding device 19 is provided in the image forming apparatus main body.
Roller pair 21 which sends the toner image between the photosensitive drum 3 and the transfer roller 13 at a predetermined timing, and a fixing / fixing unit which fixes (performs a fixing process) the toner image transferred to the paper P by the transfer roller 13 23, and a discharge tray 25 for receiving the sheet P on which the fixing process has been performed. Reference numeral 12 in the drawing indicates a manual paper feed tray.

In such a configuration, first, the sheet feeding device 19
The sheet P fed from the printer is transported by the registration roller pair 21 between the photosensitive drum 3 and the transfer roller 13 at a predetermined timing. During this time, the photosensitive drum 3 is rotationally driven by a motor 63 (see FIG. 4), the surface of the photosensitive drum 3 is uniformly charged by the charging device 2, and the photosensitive drum 3 receives laser light from the laser optical system 4 and rests on the surface. An electrostatic latent image is formed.

The electrostatic latent image is visualized as a toner image by the toner supplied from the developing device 11, and the visualized toner image is transferred to the paper P by the transfer roller 13. Then, the toner image transferred to the paper P is fixed by applying heat and pressure in the fixing unit 23, and is discharged onto the discharge tray 40 by the discharge roller pair 34. The toner remaining on the photosensitive drum 3 after image formation is scraped off by the cleaning blade 15 of the cleaning device 17 and removed.

Next, features of the present invention will be described. FIG.
FIG. 3 is a configuration diagram schematically showing a sheet feeding device, and FIG. 3 is a cross-sectional view showing a state in which an actuator shields a paper end sensor.

As shown in FIG. 2, the paper supply device 19 includes a paper supply tray (paper storage section) 27 for storing paper P, a bottom plate 29 provided on the paper supply tray 27 for loading paper P, and a bottom plate 29. And a paper-out detecting means 33 for detecting that the paper P stored in the paper feed tray 27 has run out.

The bottom plate 29 is a portion on which the sheets P stored in the sheet feed tray 27 are stacked, and can swing up and down around a fulcrum 35 in the figure. The leading end of the bottom plate 29 in the sheet feeding direction is connected to a cassette arm 39 by a tension spring 37. The sheet feed tray 27 is
The cassette arm 39 is lifted by a guide block (not shown) of the main body base portion, and the upper surface of the paper P stacked on the bottom plate 29 is maintained at a constant height by a tension spring 37 connected to the bottom plate 29. Is to be held. In FIG. 2, the paper P is omitted.

Further, a hole 29a (see FIG. 3) is formed in the bottom plate 29, and the paper out detecting means 33 is located above the hole 29a. Out of paper detecting means 33
Is a paper end sensor 41 and an actuator 43
And detects that the paper stored in the paper feed tray 27 has run out (that is, that the paper P stacked on the bottom plate 29 has run out).

In the present embodiment, the paper end sensor 41 uses a transmission type photo sensor, and the paper end sensor 41 is a shielding member 47 of the actuator 43.
(See FIG. 3), the absence of paper is detected.

The actuator 43 has a support member 45 and a shielding member 47. When the paper P is stacked on the bottom plate 29, as shown in FIG. 2, the support member 45 is lifted by the paper P, and the shielding member 47 is located at a position where the paper end sensor 41 is not shielded. . On the other hand, when the paper P on the bottom plate 29 runs out, as shown in FIG. 3, the support member 45 falls into the hole 29a formed in the bottom plate 29, so that the shielding member 47 shields the paper end sensor 41. ing.

The paper feed roller 31 abuts on the uppermost paper of the paper P stacked on the bottom plate 29, and feeds the uppermost paper of the paper P by its rotation. A friction pad 49 is arranged near the paper feed roller 31, and the paper P fed by the paper feed roller 31 is separated and sent out one by one by the friction pad 49.

In the vicinity of the paper feed roller 31, a paper feed sensor 42 (see FIG. 4) for detecting the paper P to be fed is disposed. While receiving the detection signal from the printer, the paper feeder 19 is determined to be feeding paper. That is, when the sheet feeding sensor 42 detects the leading end of the sheet P, it is determined that the sheet feeding is started, and when the sheet feeding sensor 42 detects the trailing end of the sheet P, it is determined that the sheet feeding is completed.

FIG. 4 is a block diagram showing a control system of the image forming apparatus. As shown in FIG. 4, the control of the entire image forming apparatus 1 is performed by a main control unit (control unit) 55. The main control unit 55 includes a controller 57 that issues an instruction for image formation, various sensor units 5 such as a temperature detection sensor that detects a fixing temperature of the paper end sensor 41, the paper feed sensor 42, or the fixing unit 23 described above.
9, an optical unit 7, a fixing unit 23, a charging roller 5 and a developing device 1 on the photosensitive drum 3 for forming an image.
A high-voltage unit 61 for applying a high-voltage system load (bias) to one or the like is connected. Further, a motor 63 for driving the photosensitive drum 3, the paper feed roller 31 and the like is connected to the main control unit 55 via a driver 65.

When the paper feed sensor 42 is detecting the paper P (when the paper feeder 19 is feeding paper), the main control unit 55 outputs a signal (from the paper end sensor 41 of the paper out detecting means 33). (Detection result) is invalidated, and even if the paper end sensor 41 receives a signal indicating that the paper is out of paper during paper feeding, control such as stopping the paper feeding operation of the paper feeding device 19 is performed. Not to be.

Next, the operation of the first embodiment will be described based on the above configuration and the flowchart of FIG. FIG. 5 is a flowchart illustrating control by the main control unit.

As shown in FIG. 5, in step S1, before the paper is fed by the paper feeding device 19, it is determined whether or not the paper P is present on the bottom plate 29 (whether or not it is the paper end). In step S1, when the main control unit 55 receives a signal from the paper end sensor 41 of the paper out detecting unit 33, it determines that there is no paper P on the bottom plate 29 (determines that the paper is end), and outputs the signal. If not received, it is determined that there is a sheet P on the bottom plate 29. If there is no paper P on the bottom plate 29 (on the paper feed tray 27), the process proceeds to step S
In step S3, for example, the paper feeding operation of the paper feeding device 19 is stopped, or a paper end process such as turning on a lamp for urging replenishment of the paper P is performed. I do. On the other hand, if there is a sheet P on the bottom plate 29, the process proceeds to step S2.

In step S2, it is determined whether or not sheet feeding has started. In step S2, when a signal from the paper feed sensor 42 is received (when the paper feed sensor 42 detects the leading edge of the paper P), it is determined that paper feeding has been started, and the process proceeds to step S4.

In step S4, the main control unit 55
Is the paper end sensor 41 of the paper out detecting means 33
Is invalidated (the paper end detection signal is masked), and the process proceeds to step S5. In this step S4, after the paper feed is started, the paper end sensor 4
Even if 1 detects no paper, its detection signal (detection result)
Has been disabled.

In step S5, it is determined whether or not the sheet feeding has been completed. In this step S5, the paper feed sensor 4
When there is no signal from the second sheet (after the trailing edge of the sheet P has passed), it is determined that the sheet feeding has been completed, and the process proceeds to step S6.

In step S6, the main control unit 55
Enables the detection signal from the paper end sensor 41 (by unmasking the paper end detection signal),
Proceed to step S7.

In step S7, after the paper is fed by the paper feeding device 19, it is determined whether or not there is a paper on the bottom plate 29 (whether or not it is a paper end). In step S7, the same control as in step S1 is performed. That is, the main control unit 5
5 is a paper end sensor 4 of the paper out detecting means 33
1 is received, it is determined that there is no sheet P on the bottom plate 29, and if no signal is received, the bottom plate 2 is not received.
It is determined that there is a sheet P in 9.

If there is no paper P on the bottom plate 29 (on the paper feed tray 27), the process proceeds to step S9, for example,
9, a paper end process such as stopping a paper feeding operation or turning on a lamp for urging the replenishment of the paper P is performed.
7 stands by without the paper P. On the other hand, if there is a sheet P on the bottom plate 29, the process proceeds to step S8 to prepare for the next sheet feeding (next sheet feeding ready).

In the first embodiment, the sheet feeding device 19
During the feeding of the paper P by the main control unit 55,
Since the detection result of the paper end sensor 41 of the paper out detecting means 33 is invalidated, erroneous detection of the paper out detecting means 33 due to the paper feeding operation of the paper feeding device 19 can be prevented.

That is, when the paper feeding device 19 feeds thick paper or the like, the bottom plate 29 is pushed down by the stiffness of the thick paper, and the shielding member 47 of the actuator 43 is moved to the paper end sensor 4.
1 may be blocked. In this case, if the main control unit 55 validates the detection result of the paper-out detecting means 33, the main control unit 55 determines that there is no paper P on the bottom plate 29 even if there is a paper P on the bottom plate 29. Erroneous detection such as erroneous detection occurs. On the other hand, in the present embodiment, the detection result of the out-of-paper detecting means 33 is invalidated during paper feeding.
Erroneous detection can be prevented.

Next, other embodiments will be described. In the description, portions having the same functions and effects as those described above are denoted by the same reference numerals, and detailed description of those portions is omitted. I do.

FIG. 6 is a block diagram showing a control system according to the second embodiment. In the second embodiment, the main control unit 55 includes a paper type detection unit 67 that detects the type of the paper P stacked on the bottom plate 29. In the present embodiment, the controller 57 is provided with an input unit 58 in which buttons indicating the type of paper P loaded on the bottom plate 29, such as thick paper, an envelope, and a postcard, are provided. Is pressed, the paper type detecting means 67 detects the type of the paper P stacked on the bottom plate 29.

FIG. 7 is a flowchart showing control by the main control unit according to the second embodiment. As shown in FIG. 7, in step S20, it is determined whether the paper P stacked on the bottom plate 29 of the paper feed tray 27 is a thick paper. In this step S20, the cardboard is loaded (set) on the bottom plate 29, and the input unit 58 of the controller 57 is set.
Is pressed, the paper type detecting means 67 detects this. Then, the main control unit 55
When receiving the detection signal from the paper type detecting means 67, it is determined that the paper P is a thick paper, and the process proceeds to step S4. On the other hand, if the paper P is a type other than the thick paper, the process proceeds to step S7. In the second embodiment, it goes without saying that in each step other than step S20, the same control as in the above-described first embodiment is performed.

In the second embodiment, like thick paper,
Depending on the type of paper stored in the paper feed tray 27, the paper-out detecting means 33 may easily make an erroneous detection. Numeral 55 invalidates the detection result of the paper-out detecting means 33 during paper feeding, and has the same effect as the above-described first embodiment.

FIG. 8 is a schematic diagram showing a sheet feeding device according to the third embodiment, and FIG. 9 is a block diagram showing a control system according to the third embodiment. In the third embodiment, as shown in FIG. 8, the sheet feeding device 19 has a sheet size detecting unit 34 for detecting a sheet size (sheet size, size, etc.).

The paper size detection means 34 has a size switching dial 51 and a size detection switch 53.
The size of the paper P loaded on the bottom plate 29 is detected. The size switching dial 51 is provided with a projection (not shown) corresponding to each size.
3, each size is detected.

As shown in FIG. 9, the paper size detecting means 34 is connected to the above-described paper type detecting means 67. The size of the envelope or postcard is previously input to the paper type detection means 67 as a specific paper size. When the paper size detection means 34 detects the size of the envelope or postcard, the paper type detection means 67 Is detected as thick paper.

FIG. 10 is a flowchart showing control by the main control unit according to the third embodiment. As shown in FIG. 10, in step S30, the paper feed tray 27
It is determined whether the size of the paper P stacked on the bottom plate 29 is the size of a postcard or an envelope.

In this step S30, a postcard or an envelope is loaded on the bottom plate 29, and the size switching dial of the paper size detecting means 34 is adjusted to a postcard or an envelope. Upon detection, the paper type detecting means 67 detects that the paper P stacked on the bottom plate 29 is a thick paper. When the main control unit 55 receives the detection signal from the paper type detection unit, it determines that the paper P is a thick paper and proceeds to step S4. On the other hand, if the paper P is of a type other than the thick paper (other than a postcard or an envelope), the process proceeds to step S7.
In the third embodiment, it goes without saying that the same control as in the above-described second embodiment is performed in steps other than step S30.

In the third embodiment, when the size of the sheet P is a postcard or an envelope size, the sheet size detecting means 33 recognizes (determines) the sheet size as a thick sheet which is easily erroneously detected. It is possible to determine the type of the paper P based on the paper size, and to prevent erroneous detection of the paper-out detecting means 33 due to the paper feeding operation of the paper feeding device 19 with a simple configuration and without adding memory resources and the like. be able to.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the second embodiment, the paper-out detecting means 33 uses the thick paper as the paper that is likely to be erroneously detected. However, the present invention is not limited to this. Should be fine.

In this embodiment, erroneous detection caused by the bottom plate 29 being pushed down by the stiffness of thick paper or the like is prevented.
Even when the bottom plate 29 is lowered due to the deterioration of 7,
Erroneous detection during paper feeding can be prevented.

Further, in the present embodiment, the detection result of the paper-out detecting means 33 is invalidated from the start of sheet feeding to the end of sheet feeding. Until the next paper can be fed,
The detection result of the paper out detecting means 33 may be invalidated,
In this case, the same operation and effect can be obtained.

[0053]

According to the first aspect of the present invention, the control means invalidates the detection result of the paper-out detecting means during paper feeding, thereby causing the paper feeding operation of the paper feeding means. It is possible to prevent erroneous detection of the paper-out detecting means.

According to the second aspect of the present invention, when the paper type detecting means detects a sheet (specific paper) which is likely to be erroneously detected, the control means sets the detection result of the paper out detecting means during paper feeding. Is invalidated, it is possible to prevent erroneous detection of the paper-out detecting means due to the paper feeding operation of the paper feeding means.

According to the third aspect of the present invention, by detecting the paper size, the paper-out detecting means can determine the paper which is likely to be erroneously detected, with a simple configuration and without adding a memory resource or the like. It is possible to prevent erroneous detection of the out-of-sheet detecting unit due to the sheet feeding operation of the sheet feeding unit.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an image forming apparatus to which the present invention is applied.

FIG. 2 is a configuration diagram schematically showing a sheet feeding device.

FIG. 3 is a cross-sectional view illustrating a state in which the actuator shields the paper end sensor.

FIG. 4 is a block diagram illustrating a control system of the image forming apparatus.

FIG. 5 is a flowchart illustrating control by a main control unit.

FIG. 6 is a block diagram illustrating a control system according to a second embodiment.

FIG. 7 is a flowchart illustrating control by a main control unit according to the second embodiment.

FIG. 8 is a configuration diagram schematically showing a sheet feeding device according to a third embodiment.

FIG. 9 is a block diagram showing a control system according to a third embodiment.

FIG. 10 is a flowchart illustrating control by a main control unit according to a third embodiment.

[Explanation of symbols]

 1 Image Forming Apparatus 19 Paper Feeding Device (Paper Feeding Unit) 27 Paper Feeding Tray (Paper Storage Unit) 33 Out of Paper Detecting Unit 34 Paper Size Detecting Unit 55 Main Control Unit (Control Unit) 67 Paper Type Detecting Unit

Claims (3)

[Claims] A sheet feeding unit for feeding a sheet stored in a sheet storage unit; a paper out detection unit for detecting the absence of a sheet in the paper storage unit; and a paper supply in accordance with a detection result of the paper out detection unit An image forming apparatus for forming an image on a sheet fed from a sheet storage unit, the control unit comprising: An image forming apparatus, wherein the detection result of the paper-out detecting means is invalidated until the next sheet can be fed. 2. A paper feeding unit for feeding paper stored in a paper storage unit, a paper out detection unit for detecting the absence of paper in the paper storage unit, and a paper supply in response to a detection result of the paper out detection unit. An image forming apparatus for forming an image on a sheet fed from a sheet storage unit, the control unit controlling a sheet feeding operation of the unit, and a sheet for detecting a type of the sheet stored in the sheet storage unit. When the paper type detection unit detects a specific paper type, the control unit runs out of paper from the start of paper supply by the paper supply unit until the next paper can be supplied. An image forming apparatus for invalidating a detection result of a detection unit. 3. A paper feeding unit for feeding paper stored in a paper storage unit, a paper out detection unit for detecting the absence of paper in the paper storage unit, and a paper supply in accordance with a detection result of the paper out detection unit. An image forming apparatus for forming an image on a sheet fed from a sheet storage unit, comprising: a sheet size detecting unit for detecting a sheet size; Disables the out-of-paper detection means from the start of paper supply by the paper supply unit to the next paper supply when the paper size detection unit detects a specific paper size. An image forming apparatus.