JPH0524710A - Paper size detector - Google Patents

Abstract

(57) [Summary] [Purpose] To detect the paper size in detail and prevent erroneous detection. [Structure] A movable guide 12 is moved according to a sheet to be placed on a placing tray 2, and a resistance value of a variable resistor 13 connected to the movable guide 12 is changed according to a moving amount of the movable guide 12. It changes, and the paper size is detected according to this resistance value. In this case, a value corresponding to the resistance value at different moving positions of the movable guide 12 is sampled, and the characteristic of the resistance change of the variable resistor 13 is stored as a correction value based on the sampled value. The signal that changes according to the amount of movement of the movable guide 12 is corrected to detect the size. [Effect] It is possible to prevent the erroneous detection of the size due to the variation of the variable resistor and the variation of the arrangement position of the resistor.

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 sizes of originals and sheets, that is, the sizes.

[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 movably provided, and the movable guide member is moved in accordance with the sheet size so that the movable member can be moved. The size is detected by detecting the moving position of the guide member.

As a means for detecting the moving position of the movable guide member, if the paper to be used has 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 used. In the case of detecting the size including the above, for example, a detecting element by a variable resistor that continuously changes the value according to the movement of the movable guide member is provided. An apparatus for detecting the paper size by providing this variable resistor is, for example, Japanese Patent Laid-Open No. 53-42.
There is one disclosed in Japanese Patent No. 820. In this technique, the guide member is not moved according to the size of the sheet, but in order to detect the size of the sheet stored in the cassette, the slider of the variable resistor is displaced according to the cassette mounted. To move). In this case, the cassette body side is devised so that the slider can be moved according to the size of the paper stored in the cassette. As a result, it is possible to detect the sizes of various types of paper, including the size of irregular-sized paper in the cassette.

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

[0005]

However, although it is advantageous to detect not only a fixed size but also an irregular size by using a sensing element whose output is continuously variable, each sensing element is variable. There is a problem of erroneous detection due to variations in resistance value of resistors and variations in arrangement position of the variable resistors. That is, even with the same size, the output value may not be 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 the size cannot be accurately detected.

Therefore, the variation in the arrangement position of the variable resistors does not cause any problem as long as they can be accurately arranged and arranged, and it is possible to make the resistance values of all the variable resistors to be the same. The problem goes away. However, in order to improve the positional accuracy, it is necessary to make a troublesome adjustment, and even if each variable resistor is made to have the same resistance value change, there is a problem such as a yield and the cost is increased.

In view of the above points, it is an object of the present invention to provide a paper size detection apparatus which can always perform accurate size detection regardless of the dispersion of the detection element and the dispersion of the arrangement position thereof. .

[0008]

SUMMARY OF THE INVENTION A sheet size detecting apparatus according to the present invention includes a movable member that moves according to the size of a sheet, a detection element that continuously changes according to the moving position of the movable member, and the detection unit. A paper size detection device comprising a means for recognizing the paper size according to an output value of an element, wherein output values of the detection element at at least two different positions of the movable member are sampled, and the two points are sampled. It is characterized in that it further comprises means for calculating an inclination between the two, correcting the value of the detection element according to the position of the movable member from the calculated inclination data, and discriminating the size based on the correction.

Further, the paper size detecting device of the present invention is characterized in that a variable resistor whose resistance value continuously changes 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 value of the detecting element is sampled according to the moving position of the movable member, and this is sampled at at least two different positions. Sampling with. The inclination, which is the characteristic of the detection element, is calculated according to the output values sampled at these two points, and this is stored as a correction value.

When performing size detection, the output value obtained according to the moving position of the movable member by the detection element is corrected by the correction value to obtain a normal value, and the size determination is performed based on this value. .

[0012]

EXAMPLES Examples of the present invention will be described below. Particularly, in the present embodiment, an apparatus for detecting the size of a document will be described, but 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 device according to the present invention, FIG. 2 is a flowchart showing a control procedure for pre-storing the characteristics of the variable resistor in FIG. 1, and FIG. 3 is a size detecting according to the present invention. FIG. 4 is a perspective view of a sheet placing portion in the apparatus, FIG. 4 is a sectional view showing a part of an image forming apparatus provided with the size detecting device of the present invention, and FIG.

First, referring to FIG. 4, the original 1 is placed on the loading tray 2.
The sheet is placed on the sheet, is fed out by a sheet feeding roller (not shown), is conveyed to the position of the original drum 5 via the conveying 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) arranged below the transparent plate 6 is irradiated, and reflected light of the image of the original pressed against the transparent plate 6 is projected onto the photoconductor through the optical system. , Or a CCD or other reading sensor. The original document 1 is separated from the original document drum 5 after the image is read, and is ejected via the conveyance roller 7.

A document detecting sensor (micro switch) 8 arranged between the above-mentioned conveying rollers 3 and 4, and a conveying roller 7.
Document detection sensor (micro switch) placed after the
9 detects the leading edge and the trailing edge of the document, and detects the respective conveyance rollers 3,
A signal for driving and controlling 4, 7 is output.

The original 1 is placed on the placing tray 2, and if it is detected by the sensor 10 (micro switch) arranged under the original tray 2, for example, the main body of the copying machine enters a standby state. In this state, if a print start is instructed, one sheet is fed by the sheet feed roller, and the original 1 is conveyed by the subsequent conveyance roller 3. Document detection sensor 8 at the leading edge of document 1
If the document 1 is detected by, the conveyance of the original 1 is once stopped (the conveyance roller 3 is stopped), the conveyance is restarted (driven by the conveyance roller 3) after synchronizing with the main body of the copying machine, and the conveyance roller 4 is moved. It is sent to the document drum 5 via the. At this time, as described above, the original 1 is pressed against the transparent plate 7 and its images are sequentially formed on the photoconductor at the same time as being conveyed. If the rear edge of the original is detected by the sensor 8 during the formation of the image of the original 1, the feeding of the next original is started, and if the front edge of the next original is detected by the sensor 8, the position is set to that position. Be stopped. When the image formation of the original 1 is completed, the original 1 is separated from the original drum 5 and ejected through the conveying roller 7, and when the rear end is detected by the sensor 9, the next original waiting 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 main body of the copying machine controls the image formation and selects the paper size to be used according to the size.
As shown in FIG. 3, the document tray 2 is provided with regulation guides 11 and 12 that regulate both sides of the document, and the regulation guide 12 is a movable guide that can move in the width direction of the document 1. This structure is a well-known mechanism, and its details are omitted. The movable guide 12 regulates both sides of the document 1 which is moved and placed according to the size of the document 1 with the guides 11,
The manuscript is guided in a proper state.

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

The document size can be detected according to the resistance value of the variable resistor 13, but this is size detection in the width of the document, and in the size in the direction in which the document is conveyed, for example, the sensor 8 detects the leading edge of the document. The size can be detected according to the time from when the trailing edge is detected. If the leading edge of the original placed on the loading tray 2 is restricted, the movable guide that restricts the rear end of the original 1 is used in the original conveyance direction, as in the movable guide 12 and the variable resistor 13 described above. The size may be detected by being provided so as to be movable along with, and configured so that the resistance value changes according to this movement.

FIG. 1 is a block diagram relating to the size detection of 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 thereof is converted. V1 is input to the CPU 22. CP
U20 is equipped with an analog port, and the potential difference between the ground (GND) and the reference voltage VREF is, for example, 256.
The voltage is divided into stages, and a comparison is made as to which stage the voltage V1 input corresponds to the potential through the analog port. Thereby, the size is determined by associating with one of 256 levels. As described above, the slider 1 with the variable resistance value 13
The resistance value corresponding to the moving position (sliding position) of 4 is converted into the V1 voltage, which is read by the CPU 22 via the analog port.

Therefore, when the movable guide 12 is moved in accordance with the size, particularly the width of the document 1 to be placed, the voltage V1 corresponding to this moving position is taken into the CPU 22, and the value of the voltage V1 is obtained. The corresponding size will be determined.

The variable resistor 13 cannot be accurately determined in size because the voltage V1 varies from device to device due to variations in the resistance value of the variable resistor 13 and variations in the mounting position of the variable resistor 13.

Therefore, in the present invention, in the simulation mode as the initial adjustment, the relationship between the actual slide position of the movable guide 13 and the voltage V1 at that time is sampled at a plurality of points, and is varied from each voltage V1 obtained by the sampling. The slope, which is the characteristic of the resistor 13, is obtained and stored as a correction value. Based on this correction value, the actual moving position can be calculated by the voltage V1 output according to the moving position of the movable guide 12,
Determine the size. This prevents erroneous detection due to variations in the variable resistor 13 and variations in the arrangement position of the variable resistor 13.

FIG. 5 shows an example of the characteristic of the variable resistor 13 in which the resistance value changes linearly and continuously with the movement of the slider 14. In FIG. 5, the slide position (slide position of the movable guide 12)
And the voltage V1 at that time. Therefore,
If the slide position is S, the maximum document width (MA
In the case of (X), the movable guide 12 moves at the maximum and the variable resistance value 13 is set to MAX. Therefore, the slide position Sma at the time of detecting the maximum document is Sma.
The voltage V1 input by the CPU 22 when x is the maximum value V1m
It becomes ax. Then, when the minimum document is detected, the slide position becomes Smin, and the voltage at that time becomes V1min.

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

Therefore, the document size at the slide position of the movable guide 12 is the slide position S at that time.
By inputting the value of the voltage V1 at, the slide position S is obtained by S = V1 / a + Smin,
Moreover, the document size according to the slide position S can be determined.

The simulation mode in which sampling is performed to calculate the slope 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
By inputting 2, the CPU executes control according to the input state, and by inputting the 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 involves copying, the control for copying is performed according to the copying command according to the procedure programmed in the ROM 24, and the data necessary for the control is stored in the RAM 25. Let

Therefore, if the simulation mode for sampling is set, control is performed according to the program in the ROM 24. First, in step F1, the input of V1max is awaited. That is, the movable guide 12
Is moved to the maximum state, the maximum value of V1 corresponding to the maximum resistance value at that time is set to the CPU 22 as shown in FIG.
Entered in. At this time, by operating the input key of the operation panel 23 after the movable guide 12 is moved to the maximum, 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, the input state of V1min is awaited. Similarly, by moving the movable guide 12 to the minimum document position and operating the input key of the operation panel 23, V1min at that time is stored in a predetermined area of the RAM 25.

As described above, the voltage V1m sampled at the slide position for the maximum and minimum document sizes
ax and V1min are stored. From this value, the slope a is calculated according to the above-mentioned equation, and R
It is stored in a predetermined area of the AM 25.

In this way, the specification of the variable resistor 13 (including the variation of the resistance value and the variation of the arrangement position of the resistor 13) is stored, and occurs at the position in the movable guide 12 based on the stored value. The voltage V1 can be corrected to perform regular size detection. That is, the movable guide 1
The moving position of the movable guide 12 is calculated from the voltage V1 generated when 2 is moved by the formula S = V1 / a + Smin, and the size of the document can be determined by this. In particular, even if the arrangement position of the variable resistor 13 is slightly shifted, the accurate size detection can be performed without problems because the voltage V1min corresponding to Smin corresponding to the minimum size is stored, for example.

[0032]

As described above, according to the present invention, an accurate size can be detected regardless of variations in the resistance value of the variable resistor and variations in the arrangement position.

[Brief description of drawings]

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

FIG. 2 is a control flowchart for sampling according to the present invention.

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

FIG. 4 is a cross-sectional view showing a document feeder including a size detection device according to the present invention.

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

[Explanation of symbols]

1 manuscript 2 Document tray 12 Movable guide 13 Variable resistor 14 Slider Resistance value of R0 variable resistor

Claims (2)

[Claims] 1. A movable member that moves according to the size of a sheet, a detection element that continuously changes according to the moving position of the movable member, and the sheet size is recognized according to the output value of the detection element. A sheet size detecting device including means, sampling output values of the detecting element at at least two different positions of the movable member, calculating an inclination between the two points, and calculating the calculated inclination data. A storage unit that stores the output value of the detection element according to the position of the movable member, and a unit that determines the size based on a value that is corrected by the tilt data stored in the storage unit. Paper size detection device. 2. The paper size detection according to claim 1, wherein the detection element is a variable resistor that is continuously variable, and the slope of the resistance value that is linearly converted by the variable resistor is calculated. apparatus.