JPH06336352A - Residual sheet of paper detecting device - Google Patents

Abstract

PURPOSE:To reduce a cost of manufacture by markedly decreasing a number of ports of a CPU while displaying residual sheets of papers, received into a paper loader, accurated detected without being influenced by a thickness of paper. CONSTITUTION:In a residual sheet of paper detecting device for contactlessly detecting residual sheets of paper S in a casing 2 for loading a plurality of sheets of papers received, a detector, constituted of a light emitting part 20 comprising a light emitting element 21 and a projection lens 22 and a light receiving part 30 comprising a distance measuring light receiving element 31 and a condensing lens 32, is arranged in the upward of the casing 2, and outgoing light from the light emitting element 21 of the light emitting part 20 is projected by the projection lens 22 and applied to the uppermost surface of the paper A loaded in the casing 2. Reflected light from the uppermost surface of the paper S is condensed by the condensing lens 32 of the light receiving part 30 to be incident upon the distance measuring light receiving element 31 as a spot beam, to convert incoming light into an electric signal, and by calculating a current value change followed up to displacement of the residual sheets of papers, a number of residual sheets of the papers S in the casing 2 is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to recording sheets stacked and accommodated in a sheet feeding cassette of an image forming apparatus such as a copying machine or a printer, and sheets of originals or the like stacked and accommodated in a document tray of an automatic document feeder. The present invention relates to the remaining amount detecting device.

[0002]

2. Description of the Related Art Conventionally, in copying machines, printers, etc.,
Recording paper is stored in a paper feed cassette and fed one by one for copying or printing. When copying or printing progresses and the recording paper in the paper feed cassette is completely exhausted, the detector is activated, and a recording paper supply signal is issued to stop the copying or printing operation. However, when a large number of copies are to be made, it is necessary to remove the paper feed cassette from the copying machine or the main body of the printing machine and check the remaining amount.
If the recording paper in the cassette runs out during copying, when the recording paper is replenished and the copying is restarted, the actual number of copies before that is invalidated, and the continuous copying operation is restarted from the beginning. There is an inconvenience that it will end up. Japanese Patent Laid-Open No. 56-118616 proposes one of the means for detecting and displaying the remaining amount of recording paper stored in a conventional cassette. This is to convert the change in the number of recording papers in the cassette into the amount of rotation, convert the amount of rotation into an electric signal with a potentiometer and display it on the meter. However, there is a malfunction due to poor contact of the contact of the potentiometer, and it has been practically difficult to use.

As another method, according to the proposal of Japanese Utility Model Laid-Open No. Sho 56-130943, a movable recording paper is mounted which swings upward with one end as the recording paper in the cassette decreases. A mirror is provided on the back surface of the bottom plate, a projector for irradiating the mirror to the main body of the apparatus, and a photoelectric converter for changing the amount of light received by changing the reflection position of the mirror as the movable bottom plate swings are provided. The amount is connected to an ammeter and the remaining amount is displayed on the meter. However, in this proposal, there are drawbacks such that the mirror causes a detection error due to adhesion of dust, the adjustment of the mounting position of the mirror is troublesome, and the detection device is expensive.

Further, as another optical non-contact sheet remaining amount detecting device, in parallel with a perpendicular line to the sheet surface in the cassette,
The height of the uppermost surface of the stacked sheets is detected by disposing a light emitting section on one side so as to sandwich the sheets in the cassette and a light receiving section having a large number of light receiving elements arranged on the other side according to the sheet stacking amount. According to this method, a large number of light receiving elements must be provided in the light receiving section, only resolution of the arrangement pitch interval of the light receiving sections can be obtained, and it is impossible to detect a small number of remaining sheets. Further, since a large number of light receiving elements are required, there is a drawback that the manufacturing cost becomes high.

[0005]

SUMMARY OF THE INVENTION The present invention enables highly accurate detection and display of the remaining amount of paper by detecting the height of the uppermost surface of the paper stacked and accommodated in the cassette one by one. That is the purpose.

[0006]

SUMMARY OF THE INVENTION A paper remaining amount detecting device of the present invention which achieves the above object, is a paper remaining amount for non-contact detection of the remaining amount of paper in a housing for accommodating and accommodating a plurality of sheets. In the detection device, a detection device composed of a light emitting portion including a light emitting element and a light projecting lens, and a light receiving portion including a distance measuring light receiving element and a condenser lens is arranged above the housing,
Light emitted from the light emitting element of the light emitting unit is projected by the light projecting lens to irradiate the uppermost surface of the stacked paper in the housing, and the reflected light on the uppermost surface of the paper is collected by the condenser lens of the light receiving unit. By condensing and making it enter the distance measuring light receiving element as a spot light beam, converting the incident light into an electric signal, and calculating the current value change by following the displacement of the remaining amount of paper,
The number of remaining sheets of paper in the housing is detected.

Further, the remaining paper amount detecting device of the present invention is characterized in that the light emitting element is an infrared light emitting diode.

Further, the remaining paper amount detecting device of the present invention is characterized in that the distance measuring light receiving element is a one-dimensional semiconductor detecting element.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet remaining amount detecting device of the present invention will be described below with reference to an embodiment shown in the accompanying drawings.

FIG. 1 is a front sectional view showing a state in which a sheet feeding cassette is mounted in a sheet feeding section of an image forming apparatus such as a copying machine, and FIG. 2 is a side sectional view of the sheet feeding cassette and the sheet remaining amount detecting apparatus. .

A sheet placing plate 3 in a housing 2 of a sheet feeding cassette 1
A large number of sheets S are stacked and placed on the upper surface of. When this paper feed cassette 1 is attached to the paper feed unit 10 of the image forming apparatus main body, a part of the side wall of the housing 2 of the paper feed cassette 1 becomes a driven unit (not shown) in the paper feed cassette storage unit of the paper feed unit 10. The push-up lever 11 of the paper feeding section 10 is operated via the above. That is, by the driven means rotating the rotating shaft 12,
The push-up lever 11 fixed to the rotary shaft 12 is swung counterclockwise around the rotary shaft 12 as shown in the drawing, and the push-up lever 11 is rotated.
The tip member 13 attached to the tip of the sheet presses the bottom surface side of the paper loading plate 3 in the paper feed cassette 1 and pushes it up, and the paper loading plate 3 is a fulcrum shaft portion 2A provided at the bottom of the housing 2. And swings in the clockwise direction in the figure to move up.

The sheets S stacked on the sheet placing plate 3 are
When the uppermost surface of the sheet is pressed against the peripheral surface of the feed roller 14 of the sheet feeding unit 10 with a predetermined pressure, the ascending drive of the sheet placing plate 3 is stopped and the pressure contact is maintained.

Then, in response to a paper feed signal from the main body of the image forming apparatus, the feed roller 14 of the paper feed section 10 is rotated, the upper sheet S is fed, and the separation roller 15 and the double feed prevention roller 16 are fed.
Only the uppermost one sheet S is fed to the image forming section by the separating action of the above.

When the sheet S is continuously fed by the input of the sheet feed signal and the number of sheets in the sheet placing plate 3 and the housing 2 decreases, the driving means is driven to push up the lever.
11 is rotated upward to press the sheet bundle against the delivery roller 14 at a constant pressure.

The uppermost layer surface of the bundle of sheets placed on the bottom surface 2B of the housing 2 excluding the sheet placing plate 3 of the sheet feeding cassette 1 gradually descends following the sheet feeding.

Above the bottom surface 2B of the housing 2, a light emitting section 20 including a light emitting element 21 such as an infrared light emitting diode and a light projecting lens 22, a distance measuring light receiving element 31 and a condenser lens 32 are provided. The detection device including the light receiving unit 30 is unitized and fixed to a holding unit (not shown) of the paper feeding unit 10.

The light emitted from the light emitting element 21 of the light emitting section 20 is converged by the light projecting lens 22 to become convergent light, which is applied to the uppermost surface of the stacked sheets S in the paper feed cassette 1. The reflected light on the uppermost surface of the sheet is condensed by the condenser lens 32 and is incident on the distance measuring light receiving element 31 as a spot light beam. The distance measuring light receiving element 31 is an optical sensor that converts an incident spot light flux into an electric signal and detects a one-dimensional position of the incident spot light flux.

FIG. 2 shows the principle of detection of the remaining amount of stacked sheets by the detection device composed of the light emitting section 20 and the light receiving section 30. The changes L _{1 to} L _{2 in the} remaining amount of paper are measured by using the principle of triangulation.

The range of distance to be measured is L ₁ mm to L ₂ mm
And the distance between the optical axes of the light projecting lens 22 and the condenser lens 32 (base line length) is B mm, and the focal length from the condenser lens 32 to the light receiving surface of the light receiving element 31 is f, then The distance changes x ₁ and x ₂ of the spot light on the light receiving surface are x ₁ = B · f / L ₁ x ₂ = B · f / L ₂ . In this way, spots are obtained at the positions of x ₁ and x ₂ , and photocurrents I ₁ and I ₂ are obtained, respectively.

FIG. 3 is a block diagram of the arithmetic / control circuit of the remaining paper amount detecting device, and FIG. 4 is a characteristic diagram of the output current value I and the distance x by the detecting device.

Each of the photocurrents I ₁ and I ₂ is converted into a voltage and output, and then amplified by an amplifier Amp to obtain C
Calculation processing is performed by the PU.

In the CPU, the distance x of the spot light on the light receiving surface of the light receiving element 31 is calculated by the following equation.

X = K│I ₁ + I ₂ │ / │I ₁ -I ₂ │where K is a constant determined by the optical system.

In FIG. 4, the remaining amount data at the position on the light receiving surface is x ₁ , the data when one sheet is discharged from this state is x ′, and the remaining amount data at the position (data of 0 sheet) is x. When _2, the residual paper count Z in the housing 2 of the cassette 1 by the following equation of Z = | x ₂ + x represented by _{| '| / | x 1 -x} '. Here, | x ₁ −x ′ | indicates the thickness of one sheet.

The number Z of remaining sheets calculated by the CPU is displayed by the LED or the like of the display device 33.

An infrared LED is used as the light emitting element 21 of the signal source light source, and a one-dimensional semiconductor position detecting element (PS) using a visible light cut type window material is used as the light receiving element 31.
D) was used. Alternatively, the light emitting element 21 of the signal source light source may be pulsed to remove the stationary ambient light component. Further, both the light projecting lens 22 and the condenser lens 32 are aspherical lenses whose spherical aberration is corrected, and it is preferable that the lens be a bright lens having a small F value (focal length / aperture). The light emitting unit 20 shown in FIGS. 2 and 3 is arranged vertically above the paper S, but the present invention is not limited to this, and the light is projected from obliquely above the paper surface. You may make it receive the reflected light.

FIG. 5 is a block diagram showing an embodiment in which the sheet remaining amount detecting device of the present invention is applied to an automatic document feeder 40.

The original document D placed on the original document placing portion 41 is fed out by rollers 42A, 42 arranged at the bottom of the original document placing portion 41.
B is fed to the bottom by B, sequentially fed from the lowermost original D, and passed through a separating means 43 to a platen glass 44 and a conveyor belt.
45 is sent to the transport unit where it is pressed.

Also in such a document feeding device of the document bottom feed type, a margin is provided by using the remaining paper amount detecting device in which the uppermost surface of the document stack descending following the feeding of the document D has the same configuration as described above. By detecting the copy, the number of remaining documents can be detected and displayed easily and accurately.

[0030]

As described above, according to the remaining paper amount detecting device of the present invention, the number of CPU ports can be greatly reduced, and the manufacturing cost can be reduced. Further, regardless of the thickness of the sheets, if the sheets are of the same quality, the excellent effect that the remaining amount of the sheets accommodated in the sheet stacking device can be accurately detected and displayed.

[Brief description of drawings]

FIG. 1 is a front cross-sectional view of a paper feed cassette mounted in a paper feed unit of an image forming apparatus such as a copying machine.

FIG. 2 is a side sectional view of the paper feed cassette and the remaining paper amount detection device.

FIG. 3 is a block diagram of a calculation / control circuit of the remaining paper amount detection device.

FIG. 4 is a characteristic diagram of an output current value and a distance by the remaining paper amount detection device.

FIG. 5 is a configuration diagram of an embodiment in which the sheet remaining amount detecting device of the present invention is applied to an automatic document feeder.

[Explanation of symbols]

 1 Paper feed cassette 2 Housing 3 Paper loading plate 10 Paper feed section 11 Push-up lever 20 Light emitting section 21 Light emitting element (infrared LED) 22 Light emitting lens 30 Light receiving section 31 Distance measuring light receiving element (PSD) 32 Light condensing Lens 33 Display device 40 Automatic document feeder 41 Document stacking area D Original S Paper Z Paper remaining number of sheets

Claims (3)

[Claims] 1. A sheet remaining amount detecting device for detecting the remaining amount of sheets in a casing for accommodating and accommodating a plurality of sheets in a non-contact manner. The sheet remaining amount detecting device comprises a light emitting element and a light projecting lens above the casing. A detector including a light emitting unit, a distance measuring light receiving element, and a light receiving unit including a condenser lens is arranged, and light emitted from the light emitting element of the light emitting unit is projected by the light projecting lens, It irradiates the uppermost surface of the stacked paper inside the body, collects the reflected light on the uppermost surface of the paper by the condenser lens of the light receiving section and makes it enter the distance measuring light receiving element as a spot light beam, and the incident light is an electric signal. The remaining paper amount detecting device is characterized by detecting the remaining number of papers in the housing by calculating the change in the current value following the displacement of the remaining papers. 2. The sheet remaining amount detecting device according to claim 1, wherein the light emitting element is an infrared light emitting diode. 3. The sheet remaining amount detecting device according to claim 1, wherein the distance measuring light receiving element is a one-dimensional semiconductor position detecting element.