JPH06194910A - Paper size detector - Google Patents

Abstract

PURPOSE:To stably detect the size of a paper in simple structure. CONSTITUTION:A detecting means composed of a light source 4 and a light receiving part 5 is provided on the side of a chute 2 guiding the carrying of the paper 1 and an optical axis 3 is set in a direction perpendicular to the X-direction of carrying the paper. Plural filters, for instance, three filters 6 turned/driven in response to the passing of the paper 1, intercepting the optical axis 3 and detecting paper sizes A, B and C, are arranged on the optical axis. A part or all of plural filters are turned and located in the optical axis according to the size of the paper 1 passing the chute, to detect the size of the paper 1 by light quantity detected by the light receiving part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet size detecting device which is provided in a sheet conveying path of an image forming apparatus and detects the amount of light received according to the sheet size.

[0002]

2. Description of the Related Art Various proposals have heretofore been made for an image forming apparatus for detecting the size and position of a sheet such as a document conveyed in a sheet conveying path. For example, the proposal described in JP-A-60-4956 discloses
A metal detection sensor is provided on one side of the document transport path, and a metal member protruding to and retractable from the document transport path is provided on the opposite side. Then, by moving the metal member away from the metal detection sensor by the document conveyed on the document conveyance path, the output voltage of the metal detection sensor is lowered and the presence of the document is detected.

Further, the proposal disclosed in Japanese Patent Laid-Open No. 62-49344 discloses that a large number of sensors are provided on a document table to detect the size of a document. Further, in the proposal disclosed in Japanese Patent Laid-Open No. 63-280569, an original cover is colored with a specific color, and an optical filter for cutting the reflected light from the original cover at the time of position detection is provided to accurately detect the end of the original. It is configured to be possible.

[0004]

However, Japanese Unexamined Patent Application Publication No. Sho 6
The proposal described in Japanese Unexamined Patent Publication No. 0-4956 is for detecting the presence / absence of a document, not for detecting the size of the document. Further, the document size can be detected by providing a plurality of pairs of metal detection sensors and metal members, but the structure becomes complicated and the cost becomes high. In addition, JP-A-62
According to the proposal disclosed in Japanese Patent Publication No. 49434/1992, since a large number of sensors are provided, the wiring of the harness is complicated, and dust such as paper dust is easily attached to the light receiving portion, and stable size detection cannot be performed. Further, the proposal disclosed in Japanese Patent Laid-Open No. 63-280569 is to identify a document and a document cover, and there is a problem that no particular consideration is given to simplification of the structure. An object of the present invention is to provide a paper size detection device capable of stable size detection with a simple structure.

[0005]

In order to achieve the above-mentioned object, the present invention according to claim 1 is a paper size detection device for detecting the size of the paper, which is provided in a paper conveyance path of an image forming apparatus. In the apparatus, a detection means including a light emitting portion and a light receiving portion provided on an optical axis in a direction perpendicular to the sheet conveying direction, and a plurality of emission energy attenuating filters according to the sheet size are provided on the optical axis. And a luminescence energy attenuating means which is provided so as to be retractable therein and which responds to a sheet passing through a sheet conveying path having the detecting means and projects the luminescence energy attenuating filter into the optical axis. The sheet size is detected based on the amount of light incident on the light receiving section through.

[0006]

According to the above construction, one or a plurality of filters are provided on the optical axis according to the size of the sheet to be conveyed, by the filter provided at the position corresponding to the size in the width direction of plural kinds of sheets. Located in. Therefore, the number of filters located on the optical axis changes depending on the size of the paper, and the physical quantity such as the amount of light emitted from the light source and incident on the light receiving part changes.Therefore, it is necessary to detect the paper size based on the detected physical quantity. You can

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the paper size detecting device of the present invention will be described below with reference to the drawings. FIG. 1 shows the positional relationship between sensors and filters for various paper sizes. Chutees 2a and 2b forming a pair for guiding the sheet 1 are provided on the conveyance path of the sheet 1. Further, a light source 4 and a light receiving unit 5 having an optical axis 3 perpendicular to the conveying direction X of the sheet 1 are provided on the side of one chute 2a so as to face each other. Further, a plurality of, for example, three filters 6a, 6b, 6c are provided on the optical axis 3 on the chute 2a so as to be rotatable in a direction perpendicular to the optical axis 3, respectively. Further, on the conveying path, the papers 1a, 1b, 1c having three kinds of widths A, B, C are provided.
, The filter 6a is arranged within the width A of the sheet 1a, the filter 6b is arranged between the width A and the width B, and the filter 6c is arranged between the width B and the width C. The filters 6a, 6b, 6c have a characteristic of attenuating the amount of light incident on the light receiving section 5.

As shown in FIG. 2, the filter 6 is rotatably supported by a bearing 7 provided on the chute 2a, and one end of the filter 6 penetrates a slit (not shown) formed in the chute 2a. Then, the actuator 8 projecting into the transport path is integrally provided. Actuator 8
The filter 6 when it is inactive when it extends to block the chute.
Is in a retracted position off the optical axis. On the other hand, when the actuator is pushed by the paper, the filter 6 moves to the optical axis position.

When the sheet 1 passes through the chutes 2a and 2b, the actuator 8 of the filter 6 within the width of the sheet 1
Is pushed in the direction of arrow a in the figure, the filter 6 is rotated around the bearing 7 in the direction of arrow b, and the filter 6 moves from the retracted position to the optical axis position shown in FIG. The filter 6 outside the conveyance of the sheet 1 is in the retracted position shown in FIG. 2B because the actuator 8 is not pushed.

A reflection type sensor 9 is arranged within the minimum width A of the sheet 1, and light emitted from a light source (not shown) provided in the sensor 9 illuminates the sheet 1 and reflected light from the sheet 1 is not shown. The light receiving section receives light. Then, the length of the sheet 1 in the transport direction can be detected by measuring the time during which the light receiving section detects the reflected light.

Next, the operation of the above embodiment will be described. Paper 1
Only the filter 6a is positioned on the optical axis 3 when the sheet a is conveyed. Similarly, on paper 1b, filters 6a and 6b are located on optical axis 3, and on paper 1c, filters 6a and 6b.
And 6c are located on the optical axis 3. When the number of filters located on the optical axis changes, the amount of light detected by the light receiving unit 5 changes. Therefore, the size of the sheet 1 in the width direction can be detected from the amount of received light by previously setting the relationship between the light amount and the sheet size.

According to this embodiment, the paper size can be detected by the sensor consisting of a pair of the light source 4 and the light receiving section 5, so that the structure is simplified and the wiring can be minimized. Moreover, since the light source 4 and the light receiving unit 5 can be arranged at a position away from the conveyance position of the sheet 1, dust such as paper dust is unlikely to adhere, the light source 4 and the light receiving unit 5 are less contaminated, and stable size detection is possible. Become. In this embodiment,
The filter is rotated by the operation of the actuator and positioned on the optical axis. However, the rotation of the actuator is changed into a linear motion, and the filter is reciprocated between the retracted position and the optical axis position. It doesn't matter.

In the above embodiment, the case where the light quantity of the light incident on the light receiving section 5 is changed by the combination of the three filters 6 has been described, but the light source 4 having a plurality of kinds of wavelengths is used.
In the case of using the above, the light receiving portion may be provided with one capable of discriminating light rays of a plurality of types of wavelengths, and the three filters 6 may be configured to block light rays of three or less wavelengths. For example, the filter 6a has a wavelength of 400 nm or less, the filter 6b has a wavelength of 500 nm or less, and the filter 6c has a wavelength of 6 nm or less.
Blocks rays below 00 nm. Then, the light source 4 emits a light beam having a wavelength of 300 nm to 600 nm, and the light receiving unit 5
By detecting the wavelength of the light beam received by, the paper size can be identified by associating the paper size registered in advance with the wavelength of the light beam. It should be noted that the number of types of sheets 1 and the number of filters 6 shown in each of the above-described examples are one example, and are not limited to three.

[0014]

As described above, according to the present invention,
Since a filter for attenuating emission energy, which is positioned in response to the paper being conveyed, is provided on the optical axis of one set of detecting means, the wiring process of the detecting means is reduced, and moreover, it is perpendicular to the paper conveying direction. Since it is arranged at a position deviated from the conveyance path in the direction, contamination can be reduced and stable paper size detection can be performed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of an embodiment of a paper size detection device of the present invention.

FIG. 2 is an explanatory diagram showing the operation of the filter of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 paper, 3 optical axes, 4 light source (light emitting means), 5 light receiving portion (light receiving means) 6 light emission energy attenuation filter

Claims (1)

[Claims] 1. A paper size detecting device provided in a paper carrying path of an image forming apparatus for detecting the size of the paper, wherein a light emission provided on an optical axis perpendicular to a carrying direction of the paper. Section and a light receiving section, and a plurality of filters for attenuating emission energy according to the size of the sheet are provided so as to be retractable in the optical axis, and respond to a sheet passing through a sheet conveying path including the detecting section. And a light emission energy attenuating unit for projecting the light emission energy attenuating filter in the optical axis, and detecting the paper size from the amount of light incident on the light receiving unit through the light emission energy attenuating unit. .