JP2002193482A - Sheet feeding device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an accurate number of remaining loaded sheet materials not detectable by a remaining number detecting system by sensor shading. SOLUTION: Loading height detecting means 151 and 152 are provided for detecting that a loading height of loaded sheet materials 133 is a first height and a second height lower than the first height. A remaining number calculating means 103 is provided for counting the number of sheets fed outside after the loading height is detected to be the first height and until the loading height is detected to be the second height by the loading height detecting means, and calculating the number of remaining loaded sheet materials on the basis of a difference between the first and second heights and the counted number of sheet materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus which is attached to an image forming apparatus or the like and supplies a sheet material such as recording paper.

[0002]

2. Description of the Related Art The above-mentioned sheet feeding apparatus is provided, for example, in an image forming apparatus and has a function of feeding a recording sheet to an image forming section in the image forming apparatus.

FIG. 6 shows a schematic configuration for detecting the remaining number of recording sheets in the related art. In this figure, a pressure plate 157 in a cassette 131 which is a storage portion for recording sheets is provided.
The recording sheets 133 are stacked on top of each other. A spring 156 is arranged between the pressure plate 157 and the bottom surface of the cassette 131, and the recording sheet is pressed against a paper feed roller (not shown) by the urging force of the spring 156.

The actuator 138 operates according to the remaining number of the recording sheets 133, and when the recording sheets 133 become approximately ／ of the capacity of the cassette 131, a sensor 137 is provided.
Are shielded from light, and the capacity of the cassette 131 is almost 2/4.
When it becomes (1/2), the sensor 136 is shielded from light.
Further, when the capacity of the cassette 131 becomes approximately ほ ぼ, the sensor 135 is shielded from light, and
When 3 is completely gone, the sensor 134 is shielded from light. As described above, when the sensors 134 to 137 are shielded from light, the approximate remaining number of the recording sheets 133 is detected.

[0005]

However, the above-described method of detecting the number of remaining sheets by light blocking of the sensor cannot accurately detect the number of remaining recording sheets stacked in the cassette.

If the number of recording sheets initially loaded is set in a counter, and the number of sheets fed to an image forming unit or the like is sequentially counted down, it is possible to detect the accurate number of remaining sheets. It is not realistic, for example, that the operation of setting the number of stacked sheets is troublesome or that the number of sheets set and the actual number of stacked sheets must be matched.

Accordingly, an object of the present invention is to provide a sheet feeding apparatus capable of automatically detecting an accurate remaining number of stacked sheet materials.

[0008]

In order to achieve the above object, according to the present invention, the stacked height of a stacked sheet material is a first height and a second height which is lower than the first height. Loading height detecting means for detecting that the loading height has reached the second height after the loading height detecting means detects that the loading height has reached the first height. Counting the number of sheet materials fed to the outside until the sheet is detected, and based on the difference between the first and second heights and the counted number of sheet materials, And a remaining number calculating means for calculating the remaining number of materials.

The remaining number calculating means calculates the thickness of one sheet material from, for example, the difference between the first and second heights and the counted number of sheet materials.
The remaining number of sheet materials is calculated based on the thickness of the sheet and the second height.

[0010] This makes it possible to detect the accurate remaining number of stacked sheet materials without requiring an initial number of sheets to be set.

It is to be noted that the remaining sheet number information is output by subtracting the number of sheet materials fed to the outside after calculating the remaining number from the calculated remaining number of sheet members, thereby displaying the remaining sheet number. The sheet supply device may be sent to a host computer that manages an image forming apparatus or the like provided with the sheet supply device.

Further, as the loaded height detecting means, a means for optically detecting the distance to a member which moves according to the loaded amount of sheet material may be used.

[0013]

(First Embodiment) FIG. 1 shows a schematic configuration of a printer (image forming apparatus) provided with a sheet feeding device according to a first embodiment of the present invention.

In FIG. 1, reference numeral 100 denotes a printer main body;
102, an operation panel for operating the printer; 103, control of the entire printer and a host computer (not shown)
And a control unit (remaining number calculating unit) that controls image forming apparatus main body and sheet feeding apparatus while processing image data and the like supplied from the image forming apparatus.

Numeral 104 denotes a semiconductor laser light emitting element which irradiates a polygon mirror 105 with laser light in accordance with image data from the printer control unit 103. The laser light deflected by the rotation of the polygon mirror is further deflected by the fθ lens 106,
The light is reflected by the mirror 108 and the photosensitive drum 110 is horizontally scanned. Reference numeral 107 denotes a photodetector that detects a horizontal synchronizing signal of the image forming operation.

The horizontal scanning of the laser beam forms an electrostatic latent image on the photosensitive drum 110, and the developing unit 109 applies toner to the electrostatic latent image to develop the image into a visible image. .

The recording sheets 133 are stacked on the pressure plate 157 in the cassette 131 which is a storage section for the recording sheets (sheet material) 133. Pressure plate 157
A spring 156 is disposed between the recording sheet 133 and the bottom surface of the cassette 131.
The rotation of 4 causes the recording sheet 133 to be fed from the cassette 131 into the image forming apparatus main body.

Paper cassette 13 in printer body 100
The recording sheet 133 fed from the transport roller 11
9, 9, and 115, the toner image is conveyed to a position in front of the transfer unit having the photosensitive drum 110 and the like, and the toner image is transferred to the recording sheet 133 by the transfer unit.

The recording sheet 133 on which the toner image has been fixed by the fixing unit 111 is discharged to a discharge tray 113.

Note that sensors 126, 127, and 128 for detecting the conveyance of the recording sheet 133 are provided between the sheet feeding cassette 131 and the sheet discharging tray 113.

The sensor 128 is provided at a position where the recording sheet 133 is detected immediately after the feeding of the recording sheet 133 from the sheet feeding cassette 131 is started, and detects that the sheet feeding is started.

The sensor 127 is provided immediately before the transfer section, and is a sensor for judging whether the transfer has been started.

When the recording sheet fed from the sheet feeding cassette 113 is detected, the sensor 128 is turned on and the sensor 127 is turned on.
Is OFF, the recording sheet has not yet reached the transfer portion.

After the transfer unit, a sensor 126 for detecting that the recording sheet has passed the transfer unit is provided.
The arrangement interval of these sensors 126 and 127 is shorter than the shortest recording sheet length, and exists at a position where two sensors (127 and 128, 126 and 127) can be simultaneously turned on.

The transport rollers 115, 118, 119, and 120 provided closer to the sheet feeding cassette 113 than the transfer section are rollers that can rotate forward and reverse.

The printing operation of the printer configured as described above will be described. When an image signal is sent from the host computer to the printer, a printing operation is started, and a laser beam is horizontally scanned on the photosensitive drum 110,
An electrostatic latent image is formed. Then, the electrostatic latent image is developed by the developing unit 109.

On the other hand, in accordance with the timing at which the toner image developed by the developing unit 109 is transferred at the transfer portion,
The recording sheet 133 is conveyed from the sheet feeding device or the optional sheet feeding device in the printer main body 100 to the transfer unit through the selected sheet feeding port.

The toner image is fixed on the recording sheet on which the transfer is completed in the fixing unit 111,
It is discharged to 3.

FIG. 2 shows a schematic configuration of the remaining sheet number detecting unit provided in the sheet feeding apparatus. In this figure,
151 and 152 are micro displacement sensors (load height detecting means). These micro displacement sensors 151, 152
Is the position of the light-receiving element where the reflected light is detected by a plurality of light-receiving elements arranged so that different light-receiving elements are detected depending on the incident angle within the sensor and emitted from the LED and reflected by the object to be measured. Output a voltage value corresponding to. The distance from the object to be measured can be detected from the voltage values from the sensors 151 and 152.

The object to be measured by the micro displacement sensors 151 and 152 is a reflection plate 155 provided at an end of the pressure plate 157 in an inclined posture. The reflection plate 155 gradually rises together with the pressure plate 157 by the urging force of the spring 156 as the recording sheet 133 decreases. In addition,
The distance r between the micro displacement sensors 151 and 152 is set accurately.

Next, a sequence for detecting the remaining amount of sheets in the sheet feeding apparatus according to the present embodiment will be described with reference to a flowchart shown in FIG.

First, the process waits until the detection voltage level of the sensor 151 becomes 2.5 V or less, that is, until the reflection plate 155 (that is, the stacked height of the recording sheet 133) becomes the first height (S11).

The detection voltage level of the sensor 151 is 2.5 V
In the following cases, the counter for counting the number of recording sheets is reset (S12).

Next, when one recording sheet 133 is fed (S13), the above-mentioned counter is incremented by one (S14).

Next, the sheet feeding operation is performed until the detection voltage level of the sensor 152 becomes 2.5 V or less, that is, until the reflection plate 155 (that is, the stacked height of the recording sheet 133) becomes the second height. It repeats (S15).

The detection voltage level of the sensor 152 is 2.5 V
In the following case, the necessary value is substituted into the following equation 1 to calculate the normalized thickness of one recording sheet (S16).

Recording sheet thickness = distance r between sensor 151 and sensor 152 / counter value (Equation 1) Further, the remaining number of recording sheets 133 is calculated from the following Equation 2 (S17).

The number of remaining sheets = distance (second height) from sensor 152 to pressure plate 157 in the absence of sheet / recording sheet thickness (Equation 2) Then, the number of remaining sheets calculated in S17 is set in a counter (S18). ), And outputs the remaining sheet number information to the host computer (S19). The host computer controls the image forming apparatus based on the information on the number of remaining sheets, displays the number of remaining sheets, and issues a warning indicating that the number of remaining sheets is smaller than a predetermined number.

Further, each time one sheet is fed (S20),
The value of the counter is decremented by one (S21). Until the value of the counter becomes 0, that is, until there are no more recording sheets, the subtraction in S21 and the output of the remaining sheet number information obtained by this subtraction to the host computer are repeated (S22).

When the recording sheet 133 runs out, a predetermined process when there is no sheet is performed.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
1 illustrates a configuration of an image forming apparatus according to an embodiment. First
In the embodiment, two sensors 151 and 152 are used to detect the first and second sheet stacking heights. However, in the present embodiment, one micro displacement sensor 151 is used.
Only the first and second sheet stacking heights having different detection voltage levels are detected by using only the first and second sheet heights.

Thus, in the first embodiment, it is necessary to accurately position the two sensors 151 and 152 in order to make the distance r between the sensors and the installation angle highly accurate. It is only necessary to accurately position one sensor 151, and it is not necessary to form an angle for the sensor 151.

FIG. 5 is a sequence flowchart for detecting the remaining amount of sheets in the sheet feeding apparatus according to the present embodiment.

First, the process waits until the detection voltage level of the sensor 151 becomes 0.5 V or less, that is, until the reflection plate 155 (that is, the stacked height of the recording sheet 133) becomes the first height (S51).

When the detected voltage level becomes 0.5 V or less, the counter for counting the recording sheets 133 is reset (S52).

Next, when one recording sheet 133 is fed (S53), the above-mentioned counter is incremented by 1 (S54).

Next, the sheet feeding operation is performed until the detection voltage level of the sensor 151 becomes 4.5 V or less, that is, until the reflection plate 155 (that is, the stacked height of the recording sheet 133) becomes the second height. It repeats (S55).

When the detected voltage level is equal to or lower than 4.5 V, the necessary value is substituted into Expression 1 to calculate the thickness of one recording sheet as in the first embodiment (S56).

Further, the remaining number is calculated from Expression 2 (S
57).

Then, the number of remaining sheets calculated in S57 is set in a counter (S58), and the information on the number of remaining sheets is output to the host computer (S59). The host computer controls the image forming apparatus based on the information on the number of remaining sheets, displays the number of remaining sheets, and issues a warning indicating that the number of remaining sheets is smaller than a predetermined number.

Further, each time one sheet is fed (S60),
The value of the counter is decremented by one (S61). Until the value of the counter becomes 0, that is, until there are no more recording sheets, the subtraction in S61 and the output of the remaining sheet number information obtained by this subtraction to the host computer are repeated (S62).

When the recording sheet 133 runs out, a predetermined process when there is no sheet is performed.

In each of the above embodiments, a sheet supply device provided in a printer has been described. However, the present invention is not limited to an image forming apparatus other than a printer (such as a copying machine or a facsimile) or a sheet supply apparatus other than an image forming apparatus. The present invention can also be applied to a sheet feeding device used for various necessary devices.

[0054]

As described above, according to the present invention,
The accurate remaining number of the stacked sheet materials can be detected without the necessity of setting an initial number of sheets.

If the number of remaining sheet materials is subtracted from the calculated number of remaining sheet materials and the number of sheet materials fed to the outside is subtracted from the calculated number of remaining sheet materials, the remaining sheet information may be output. The sheet can be sent to a host computer which manages an image forming apparatus provided with the sheet supply device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a printer according to a first embodiment of the invention.

FIG. 2 is a schematic configuration diagram of a remaining sheet number detection unit in a sheet supply device provided in the printer.

FIG. 3 is a flowchart illustrating a sequence of the sheet feeding apparatus.

FIG. 4 is a schematic configuration diagram of a remaining sheet number detection unit in a sheet supply device provided in a printer according to a second embodiment of the present invention.

FIG. 5 is a flowchart illustrating a sequence of a sheet feeding apparatus according to the second embodiment.

FIG. 6 is a schematic configuration diagram of a conventional recording material remaining number detection unit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Image forming apparatus main body 111 Fixing device 112 Discharge roller 113 Discharge tray 115 Transfer roller before transfer 116 Transfer roller before fixing 117, 118, 119, 120 Transport roller 124 Feed roller 126 Recording paper detection sensor after transfer 127 Recording before transfer Paper detection sensor 128 Paper feed start detection sensor 131 Paper feed cassette 151, 152 Micro displacement sensor 155 Reflector 157 Pressure plate

Claims (5)

[Claims] 1. A stack height detecting means for detecting that the stack height of stacked sheet materials has reached a first height and a second height lower than the first height, and a stack height. After detecting that the stacking height has reached the first height by the detecting means, the sheet material fed to the outside before the detection of having reached the second height is detected. A counting means for counting the number of sheets and calculating a remaining number of the stacked sheet materials based on the difference between the first and second heights and the counted number of sheet materials. Sheet feeding device. 2. The remaining number calculating means calculates the thickness of one sheet material from the difference between the first and second heights and the counted number of sheet materials, and calculates the calculated thickness of one sheet material. The sheet feeding apparatus according to claim 1, wherein the remaining number of sheet materials is calculated based on the thickness of the sheet material and the second height. 3. The remaining sheet number calculating means outputs sheet remaining number information obtained by subtracting the number of sheet members fed to the outside after calculating the remaining number from the calculated remaining number of sheet members. The sheet feeding device according to claim 1. 4. The apparatus according to claim 1, wherein the stack height detecting means optically detects a distance between the stack member and a member that moves in accordance with the stack amount of the sheet material. The sheet supply device described in him. 5. An image forming apparatus comprising the sheet feeding device according to claim 1, wherein an image is formed on a sheet supplied from the sheet feeding device.