JP2826214B2 - Paper size detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a size detecting device for detecting the size of a document and a sheet, that is, a size.

[0002]

2. Description of the Related Art As a device for detecting the size of a document or a sheet, for example, a guide member for guiding one side edge of the sheet is provided movably, and the movable guide member is moved in accordance with the sheet size. The size is detected by detecting the moving position of the guide member.

As means for detecting the moving position of the movable guide member, if the paper to be used is a standard size, a detection center such as a micro switch or a reed switch is provided at a position corresponding to the standard size, or an irregular size paper is provided. In the case of detecting the size of the movable guide member, for example, a detection element including a variable resistor that continuously changes the value according to the movement of the movable guide member is provided. As an apparatus for detecting the paper size by providing this variable resistor, for example, Japanese Patent Application Laid-Open No. 53-42
820 is disclosed. In this technique, the guide member is not moved according to the sheet size, but is displaced (depending on the cassette on which the slider of the variable resistor is mounted) in order to detect the size of the sheet stored in the cassette. Move). In this case, the cassette body is devised so that the slider can move according to the size of the paper stored in the cassette. As a result, the sizes of various types of paper, including the size of irregular-sized paper in the cassette, can be detected.

Therefore, the size of the original or paper can be easily detected based on the detection state and the detection output of the detection element.

[0005]

However, although the use of a sensing element having a continuously variable output is advantageous in that not only a fixed size but also an irregular size can be detected, the use of each variable element is advantageous. There is a problem of erroneous detection due to variation in resistance value of the resistor and variation in the arrangement position of the variable resistor. In other words, even with the same size, the output value does not become constant for each device due to the variation in the resistance value of each variable resistor, and the size may be erroneously detected, so that accurate size detection cannot be performed.

[0006] Therefore, in the variation of the position of the variable resistor, not in der Re if problems can be accurately positioned and arranged, it is possible to create as well the resistance change of all the things that match the variable resistor If there is no problem <br/>. However, complicated adjustments are required to increase the position accuracy, and even if the variable resistors have the same change in the resistance value, the cost and the like are increased due to problems such as yield.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a paper size detecting apparatus capable of always performing an accurate size detection regardless of a variation in a detecting element and a variation in an arrangement position thereof. .

[0008]

According to the present invention, there is provided a paper size detecting apparatus comprising: a movable member movable in accordance with the size of a sheet; a detecting element which continuously changes in accordance with a moving position of the movable member; Means for recognizing the paper size in accordance with the output value of the element, wherein the output value of the detection element at at least two different positions of the movable member is sampled, and the two points are sampled. Means for calculating a tilt between the two, correcting the value of the detection element corresponding to the position of the movable member from the calculated tilt data, and determining the size based on the corrected value.

Further, the paper size detecting device of the present invention is characterized in that a variable resistor whose resistance value changes continuously and linearly is used as the detecting element.

[0010]

According to the paper size detecting apparatus of the present invention, first, in order to grasp the characteristics of the detecting element, the output values of the detecting element corresponding to the moving position of the movable member are sampled, and this is sampled at at least two positions at different positions. Perform sampling with. The slope which is the characteristic of the detection element according to the sampled output values of these two points is calculated, and this is stored as a correction value.

When the size is detected, the output value obtained according to the moving position of the movable member by the detection element is corrected with the correction value to obtain a regular value, and the size is determined based on the corrected value. .

[0012]

Embodiments of the present invention will be described below. In particular, in the present embodiment, an apparatus for detecting the size of a document will be described. However, the present invention is not limited to this and can be applied to a paper size.

FIG. 1 is a block diagram of a paper size detecting apparatus according to the present invention, FIG. 2 is a flowchart showing a control procedure for pre-storing characteristics of the variable resistor in FIG. 1, and FIG. 3 is a size detecting apparatus according to the present invention. FIG. 4 is a perspective view of a sheet mounting portion of the apparatus, FIG. 4 is a cross-sectional view showing a part of an image forming apparatus provided with the size detecting device of the present invention, and FIG. 5 is a view showing characteristics of a variable resistor.

First, in FIG. 4, a document 1 is placed on a loading tray 2.
The original is sent out by a paper feed roller or the like (not shown), is transported to the position of the original drum 5 via the transport rollers 3 and 4, and is pressed against the transparent plate 6 by the original drum 5. At this time, light from a light source (not shown) disposed below the transparent plate 6 is irradiated, and the reflected light of the image of the document pressed against the transparent plate 6 is projected onto the photosensitive member via the optical system. , Or on a reading sensor such as a CCD. The document 1 is separated from the document drum 5 after reading the image, and is discharged via the transport roller 7.

A document detection sensor (microswitch) 8 and a transport roller 7 disposed between the transport rollers 3 and 4
Document detection sensor (micro switch) placed after
9 detects the leading edge and the trailing edge of the document,
A signal for controlling the driving of the fourth and the seventh is output.

When the original 1 is placed on the loading tray 2 and is detected by a sensor 10 (micro switch) arranged below the tray 1, for example, the copying machine main body enters a standby state. In this state, if a print start is instructed, one sheet is fed by the feed roller, and the original 1 is transported by the transport roller 3. Original document 1 sensor is original detection sensor 8
Is detected, the document 1 is once stopped from being transported (stop of the transport roller 3), and after synchronizing with the copying machine main body, transport is started again (driven by the transport roller 3). The document is sent to the original drum 5 via the original. At this time, as described above, the original 1 is pressed against the transparent plate 7 and the image is sequentially formed on the photoconductor at the same time as being conveyed. If the sensor 8 detects the trailing edge of the original document while forming the image of the original document 1, the feeding of the next original document is started. Stopped. When the image formation of the previous original 1 is completed, the original 1 is separated from the original drum 5 and discharged through the conveying roller 7, and when the trailing end is detected by the sensor 9, the next standby state is established. The conveyance of the document is started, and the same operation as described above is repeated.

The size of the original 1 placed on the original tray 2 is detected, and the copying machine main body controls image formation and selects a paper size to be used in accordance with the size.
As shown in FIG. 3, the document tray 2 is provided with regulation guides 11 and 12 for regulating both sides of the document. The regulation guide 12 is a movable guide that can move in the width direction of the document 1. This configuration is a well-known mechanism and its details are omitted. The movable guide 12 regulates both sides of the original 1 that is movable and placed according to the size of the original 1 with the guide 11,
The document is guided in a regular state.

A variable resistor 13 for detecting the size of the original 1 to be placed is connected to the movable guide 12. The variable resistor 13 has a slider 14 connected to a protruding portion 12-1 formed integrally with the movable guide 12. Therefore, the slider 14 moves in accordance with the moving position of the movable guide 12, so that the resistance value of the variable resistor 13 changes and the size of the document, that is, the size of the document can be detected.

The size of the original can be detected in accordance with the resistance value of the variable resistor 13. This is the size detection in the width of the original. For example, the sensor 8 detects the leading end of the original in the direction in which the original is transported. The size detection can be performed according to the time from when the detection is performed to when the rear end is detected. If the leading edge of the original placed on the loading tray 2 is regulated, like the movable guide 12 and the variable resistor 13 described above, the movable guide for regulating the trailing end of the original 1 is moved in the transport direction of the original. May be provided so as to be movable along, and the size may be detected by changing the resistance value according to the movement.

FIG. 1 is a block diagram relating to size detection according to the present invention. The resistance value R0 of the variable resistor 13 is divided by the resistance R1 of the control section 21 to be converted into a voltage value V1, and the voltage value is converted to a voltage value V1. V1 is input to the CPU 22. CP
U20 is equipped with an analog port, and detects the potential difference between ground (GND) and the reference voltage VREF, for example, by 256.
The input voltage V1 is compared via an analog port to which level the potential corresponds to. Thus, the size is determined by associating one of the 256 levels. As described above, the slider 1 having the variable resistance value 13
The resistance value corresponding to the moving position (sliding position) of No. 4 is converted to the voltage V1 and this is read by the CPU 22 via the analog port.

Accordingly, by moving the movable guide 12 in accordance with the size, particularly the width, of the document 1 placed on the document tray 2, the voltage V1 corresponding to the moving position is adjusted by the CPU 22.
The size according to the value of the voltage V1 is determined.

The voltage V1 of the variable resistor 13 varies depending on the device due to the variation due to the resistance value of the variable resistor 13 and the variation in the mounting position of the variable resistor 13, and the size cannot be accurately determined.

Therefore, in the present invention, in the simulation mode as an initial adjustment, the relationship between the actual sliding position of the movable guide 13 and the voltage V1 at that time is sampled at a plurality of points, and the voltage V1 obtained by the sampling is varied. A slope, which is a characteristic of the resistor 13, is obtained and stored as a correction value. Based on the correction value, by calculating the actual moving position by the voltage V1 which is output in accordance with the movement position of the movable guide 12, to determine the size. Thereby, the variable resistor 1
3 is prevented from being erroneously detected due to a variation in 3 or a variation in the arrangement position of the variable resistor 13.

FIG. 5 shows an example of the characteristics of the variable resistor 13 assuming that the resistance value changes linearly and continuously as the slider 14 moves. In FIG. 5, the slide position (the slide position of the movable guide 12)
And the voltage V1 at that time. Therefore,
If the slide position is S, the maximum size of the document width (MA
X), the circuit is configured so that the movable guide 12 moves at the maximum and the value of the variable resistance value 13 becomes MAX. Therefore, the slide position Sma when the maximum original is detected is detected.
The voltage V1 input by the CPU 22 at the time of x is the maximum value V1m
ax. Then, when the minimum document is detected, the slide position is Smin, and the voltage at that time is V1min.

As shown in FIG. 5, the slope a, the slide position S, and the output voltage V1 at that time in the characteristics of the variable resistor 13 have the relationship of V1 = aS. Therefore, the slope a is calculated by the following equation: a = (V1max−V1min) / l where l is obtained by 1 = Smax−Smin.

Therefore, the size of the original at the slide position of the movable guide 12 is the slide position S at that time.
Is input, the slide position S is determined by S = V1 / a + Smin,
In addition, the size of the document corresponding to the slide position S can be determined.

A simulation mode for performing the sampling for calculating the gradient a will be described with reference to the flowchart of FIG. First, the copying machine main body is set to the simulation mode in response to a specific key operation provided on the operation panel 23 arranged on the copying machine main body. That is, the key input from the operation panel 23 is
By inputting to 2, the CPU executes control according to the input state, and by inputting a key operation related to the simulation mode, the CPU is set to that mode. In particular, if the key operation on the operation panel 23 is related to copying, control for copying is performed according to a procedure programmed in the ROM 24 in accordance with a copying command, and data necessary for the control is stored in the RAM 25. Let it.

Therefore, if a simulation mode for performing sampling is set, control is performed according to a program in the ROM 24. First, in step F1, the control waits for input of V1max. That is, the movable guide 12
Is moved to the maximum state, as shown in FIG. 1, the maximum of V1 corresponding to the maximum resistance value at that time is increased by the CPU 22.
Is input to At this time, after the movable guide 12 is moved to the maximum, the input key of the operation panel 23 is operated to set the V1max.
Is stored in the designated area of the RAM 25 (F2).
This is stored as the voltage V1 when the position S of the movable guide 12 is the maximum size.

Next, in step F3, an input state of V1min is waited. Similarly, the movable guide 12 is moved to the minimum document position, and the input key of the operation panel 23 is operated, so that V1min at that time is stored in a predetermined area of the RAM 25.

The above voltage is Oite sampled slide position according to the maximum and minimum document size as V1
max and V1min are stored. The slope a is calculated from this value according to the above-described equation, and the slope a is also stored in a predetermined area of the RAM 25.

In this manner, the specification of the variable resistor 13 (including the variation in the resistance value and the variation in the arrangement position of the resistor 13) is stored, and the variable resistor 13 is generated at the position in the movable guide 12 based on the stored value. Correcting the voltage V1 enables normal size detection. That is, the movable guide 1
The moving position of the movable guide 12 is calculated from the voltage V1 generated when the moving member 2 is moved by the formula of S = V1 / a + Smin, whereby the document size can be determined. In particular, even if the arrangement position of the variable resistor 13 is slightly shifted, since the voltage V1min corresponding to Smin corresponding to the minimum size is stored, accurate size detection can be performed without any problem.

[0032]

As described above, according to the present invention, the detecting element
Not only variations in the characteristics of the element itself, but also
Accurate use regardless of the disposition of the paper tray
The paper size can be detected.

[Brief description of the drawings]

FIG. 1 is a block diagram relating to size detection of the present invention.

FIG. 2 is a control flowchart at the time of sampling according to the present invention;

FIG. 3 is a perspective view of a document placement unit for size detection according to the present invention.

FIG. 4 is a cross-sectional view showing a document feeder provided with the size detection of the present invention.

FIG. 5 is a diagram showing one characteristic of a variable resistor according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Document 2 Document loading tray 12 Movable guide 13 Variable resistor 14 Slider R0 Resistance value of variable resistor

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B65H 7/02 B65H 1/00 501 G03B 27/62 G03G 15/00 514

Claims (2)

(57) [Claims] A movable member movable in accordance with the size of the paper placed on the paper tray , and a detection element provided in the paper tray and continuously changing in accordance with the moving position of the movable member. And a means for recognizing the paper size in accordance with the output value of the detection element, wherein the paper size detection device comprises: a detection unit for detecting the paper size in at least two different positions obtained by moving the movable member. An output value is sampled, a slope between the two points is calculated, and a storage unit that stores the calculated tilt data, and an output value of the detection element corresponding to a position of the movable member is stored in the storage unit. Means for performing size determination based on a value corrected by the inclination data, and a sheet size detection device. 2. The paper size detecting device according to claim 1, wherein said detecting element is a variable resistor which is continuously variable, and calculates a slope of a resistance value of said variable resistor which is linearly converted. apparatus.