JP2954811B2 - Document size detection mechanism of document reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document size detecting mechanism of a document reading device used for an image input device of a copying machine or a computer.

[0002]

[Prior art]

[Conventional Example] FIG. 5 is a schematic diagram of a document size detecting mechanism according to a conventional reflected light amount detecting method.

Conventionally, as a document size detecting mechanism used in a document reading device in a copying machine or the like, a device for detecting the magnitude of the amount of reflected light has been used. As shown in FIG. 5, an infrared light emitting diode (LE)
An original mounting table 3 (transparent glass plate) on which an original G is placed by a light emitting element 1 such as D) and a light receiving element 2 such as a phototransistor
It is installed under.

Here, when there is no document G on the document table 3, the light emitted from the light emitting element 1 is divided into light reflected on the document table 3 and light transmitted through the document table 3. Only the light reflected by the document table 3 enters the light receiving element 2.
At this time, the amount of light to the light receiving element 2 decreases.

On the other hand, when the document G is on the document table 3, the light transmitted through the document table 3 is reflected by the document G, so that the light reflected by the document table 3 Both of the light reflected by the original G are incident. At this time,
The light amount to the light receiving element 2 increases.

As described above, when the amount of reflected light is large, it is detected that "the document G as a reflective object exists" at the sensing position, and when the amount of reflected light is small, "the document G is not present".
And By installing a plurality of sensors for detecting the magnitude of the light amount, the document G can be placed at each sensing position.
The document G size is detected.

In the above conventional example, the original G is placed on the original placing table 3.
When the color of the original G is whitish, that is, a color having a high reflectance, the amount of light incident on the light receiving element 2 is greatly increased, so that the detection is easy.

However, if the color of the original G is a blackish color, that is, a color having a low reflectance, such as an original copied from a photograph, the amount of light incident on the light receiving element 2 does not increase so much. For this reason, the sensor may erroneously detect that the document G is absent even though the document G is present.

In addition, deterioration due to the change of the LED light amount with time,
If the LED light amount decreases due to a change in the ambient temperature, the frequency of erroneous detection of the size of the darker-colored original G may increase, or the size of the original G of a color whose reflectance is not so low may be erroneously detected. There is.

Therefore, the present applicant has proposed the color (reflectance) of an original.
In order to prevent the erroneous detection of the original size due to the above, a proposal as shown in FIGS.
No. 83489).

[Structure of Proposed Example] As shown in FIG. 6, the size detecting mechanism of the proposed example includes a plurality of size detection sensors 1 at a plurality of sensing positions of a document table 12 on which a document 11 is placed.
5, each of the size detection sensors 15 includes a light emitting element 32 for irradiating the original 11 with light, a light receiving element 33 for receiving light emitted from the light emitting element 32 and reflected by the original 11 on the original placing table 12, A signal processing circuit 35 for detecting an output signal of the element 33.

In FIG. 6, reference numeral 36 denotes an output signal detection circuit for detecting a photocurrent flowing through the PSD 33, and 37 denotes a drive circuit for driving the light emitting element 32.

In the proposed example, the optical axis CL1 of the light emitting element 32 is, as shown in FIG. 7, the light receiving element with respect to the original placing table 12 so as to reduce the direct influence of the specular reflection light on the original placing table 12. 33 is inclined to the opposite side.

In the proposed example, as the light receiving element 33,
As shown in FIGS. 8A and 8B, a semiconductor position detecting element (Position Sens) for detecting the spot position of the reflected light.
active Photodetector: PS
D), the presence / absence of the document 11 is detected as if distance measurement is performed, even if the light reflectance differs depending on the color of the document 11, thereby increasing the detection accuracy.

As shown in FIG. 8A, the PSD 33 is composed of a p ^- layer on the front surface of the silicon chip, an n ⁺ layer on the back surface, and an i-layer intermediate the three layers.
3 is irradiated with a light spot φ, the generated charges (carriers) are divided in the resistive layer (p ⁻ layer) in inverse proportion to the light incident position and the distance to the extraction electrodes A and B,
Currents I ₁ and I ₂ are extracted from the respective electrodes A and B. The PSD 33 detects the presence or absence of a document at a ratio of the currents I ₁ and I ₂ by simulating the distance measurement to the document.

The pseudo principle of the distance measuring operation of the PSD 33 will be described. As shown in FIG. 7, the light emitted by the light emitting element 32 is reflected by the document 11 through the irradiation lens 41, and enters the PSD 33 through the light receiving lens 42. The sensing position (light spot position) at which the reflected light M is incident on the PSD 33 changes depending on the distance L between the document 11 and the size detection sensor 15, and when the document 11 is farther (L becomes longer), the reflected light M1 becomes As shown by the dotted line in FIG. 7, PS
The spot position of the light incident on D33 also changes. PSD
When the spot position of the light changes incident to 33, the balance of the signal current I ₁ and I ₂ to be taken out from both ends of PSD33 changes accordingly.

The signal processing circuit 35 is a circuit for detecting the signal currents I ₁ and I ₂ from the PSD 33. By detecting the balance between the signal currents I ₁ and I ₂ , the original 11 and the size detection sensor 15 are detected. Can be detected, and the presence or absence of the document 11 can be detected.

Here, the principle of operation of the signal processing circuit 35 will be described with reference to FIGS. Now, as shown in FIG. 8A, the photocurrent I ₀ , the distance from the middle point of the electrodes A and B to the light incident point P is x, the resistance value from the incident position P to the electrode A is R ₀₁ , The resistance from the point of incidence P to the electrode B is R ₀₂ , the distance between the electrodes A and B is L, the resistance between the electrodes A and B is R _T , and the current drawn from the electrodes A and B is I ₁ , respectively. Assuming that I ₂ , currents I ₁ and I ₂ are represented by the following (1)
It is expressed by equation (2).

[0019]

(Equation 1)

The surface resistance layer ^- so (p layer) of the distribution of the specific resistance _{R i} is uniform as shown in FIG. 8 (B), the resistance _R 01, R
₀₂ is proportional to the distance from the incident position P to the electrodes A and B, and is expressed by the following equation.

[0021]

(Equation 2)

When this is substituted into the equations (1) and (2), the currents I ₁ and I ₂ extracted from the electrodes A and B are as follows.

[0023]

(Equation 3)

Here, when the ratio of the sum and difference of the currents I ₁ and I ₂ is calculated, the following equation is obtained.

[0025]

(Equation 4)

As described above, when the PSD is used as the light receiving element 33, the position information can be directly obtained as an output.

FIG. 9 shows an example of the signal processing circuit 35 for processing the signal currents I ₁ and I ₂ of the PSD 33. In Figure _9, R 1 ~R ₇ is _resistance, P 1 to P ₅ denotes an amplifier.
The signal currents I ₁ and I ₂ of the PSD 33 are converted into voltages V ₀₁ and V ₀₂ by the current-voltage conversion circuit unit 35a. V ₀₁
Is V ₀₁ = R ₁ × I ₁ , and V ₀₂ is V ₀₂ = R ₁ × I ₂ . Next, the subtraction of _{V 02} and _{V 01} at subtraction circuit portion _35b, to obtain an output voltage _{V 0A} corresponding to I 2 -I _{1. V0A} is represented by the following equation.

[0028]

(Equation 5)

Further, V ₀₁ and V
₀₂ is added. In FIG. 9, V ₀₃ is represented by the following equation.

[0030]

(Equation 6)

Then, the output V _0B corresponding to I ₁ + I ₂
Can be obtained. V _0B is represented by the following equation.

[0032]

(Equation 7)

[0033] By processing the _{V 0A} and _{V 0B} a microcomputer or the _like, obtains the _V 0A _/ V _{0B. V0A} /
V _0B is represented by the following equation.

[0034]

(Equation 8)

Therefore, (I ₂ −I ₁ ) / (I ₁ + I
₂ ) corresponds to the position of the light incident on the PSD 33 as described above, and the spot position of the light incident on the PSD 33 can be found from (I ₂ −I ₁ ) / (I ₁ + I ₂ ).

If the spot position of the light incident on the PSD 33 is known, the distance between the size detection sensor 15 and the document 11 can be known as described above.

As described above, the signal current I of the PSD 33
_By processing ₁ and I ₂ in the signal processing circuit 35,
The distance between the size detection sensor 15 and the document 11 can be detected.

Here, in order to explain the detection level of the signal processing circuit 35, an outline of the distance characteristic of the output of the size detection sensor 15 is shown in FIG. In FIG. 10, the vertical axis is PSD33.
The ratio of the _two light output currents I ₁ and I ₂ of FIG.
It is a distance from 1 and it can be seen that both are in inverse proportion. Here, even if the reflectance of the document 11 changes and, for example, the reflectance becomes １ ／, both I ₁ and I ₂ are 1
/ 2, so that the ratio between I ₁ and I ₂ does not change. That is, regardless of the reflectance of the document, an output corresponding to the distance to the document can be obtained by the photoelectric size detection sensor.

When the size of the document 11 is detected by the size detection sensor 15 and the document cover is closed, the light of the light emitting element 32 is reflected not only on the surface of the document 11 but also on the surface of the document cover. In some cases, it may be difficult for the PSD 33 to distinguish between the document cover and the document 11. Therefore, the size detection operation may be performed, for example, at the moment immediately before the worker moves the upper cover (document cover) by a predetermined angle to close the document cover to bring the document cover to the closed position.

As described above, by using the size detection sensor 15 and the signal processing circuit 35, when the output of the PSD 33 changes in accordance with the presence or absence of the original, the presence or absence of the original can be accurately identified regardless of the reflectance of the original. Therefore, the original size can be accurately detected without depending on the reflectance of the original.

Here, the photoelectric size detection sensor 1 is actually
FIG. 11 shows data obtained by detecting the presence / absence of a document in the copying machine at No. 5. In FIG. 11, θ represents the light emitting element 3 as shown in FIG.
The angle between the optical axis No. 2 and the normal line of the document table 12 (glass plate). That is, for example, the data of θ = 0 ° indicates that the optical axis of the light emitting element 32 is set to the original table 1 as an original reading apparatus.
This is the data when oriented vertically to 2. Document table 12
When there is no, even if the color (reflectance) of the original is changed, a constant output is obtained.

However, when paper is placed on the document table 12, the output changes due to the reflectance of the paper. When paper is not placed on the document table 12 alone, the output further changes. doing. The reason is as follows.

FIG. 12 is a schematic diagram when the size detection sensor 15 is used for detecting the presence or absence of an original in a copying machine, and FIG. 13 is a schematic diagram of the directivity characteristics of the size detection sensor 15 for the LED light.

As the signal processing circuit 35, a circuit having another circuit structure may be used as shown in FIG.
In this circuit, 51 is a logarithmic conversion circuit section, 52 is a differential amplifier circuit section, 53 and 54 are log diodes, and outputs V ₀₁ and V ₀₂ are represented by the following equations. Here, k is the Boltzmann constant, T is the absolute temperature (° K), and q is the amount of electron charge.

[0045]

(Equation 9)

Then, the output V ₀ from the inside of the amplifier circuit section 52 is output.
Is represented by the following equation.

[0047]

(Equation 10)

With this circuit, an output corresponding to log (I ₁ / I ₂ ) can be obtained. _{I 1} / I ₂ is, PS
D corresponds to the spot position of light incident on D
From (I ₁ / I ₂ ), the spot position of the light incident on the PSD can be determined. When the spot position of the light incident on the PSD 33 is known, the distance between the size detection sensor 15 and the document 11 can be detected as described above.

[Operation of Proposed Example] First, when the document 11 is not on the document table 12, the LED light is divided into light reflected on the document table 12 and light transmitted through the document table 12. The reflected light is specularly reflected by the document table 12, so that the light reflected by the document table 12
The light incident on the SD 33 is only light having an angle indicated by the beam A in FIG. In this case, the spot position of the light incident through the lens 42 in front of the PSD 33 is
Is the same as the spot position at the point X in FIG. 12, and the output is that the output ratio is longer than the actual distance to the document table 12 at the output ratio in FIG.

Next, the white original 11 is placed on the original placing table 12.
, The beam B besides the reflected light by the beam A
Irradiates the original 11 through the original mounting table 12 and the original 1
Part of the light diffusely reflected at 1 enters the PSD 33 via the lens 42 as spot light. Although the correct distance information can be obtained from the reflected light from the beam B, there is also the distance information from the reflected light from the beam A that the distance is longer. The output value is output. That is, the output is shifted to an output smaller than the correct output of the data (θ = 0 °) when white paper is placed on the original mounting table 12 in FIG.

Further, when the white original on the original placing table 12 is changed to a paper having a low reflectance, such as a gray original or a black original, the amount of light reflected by the beam B shown in FIG. As described above, the output is shifted to the output at a longer distance due to the reflected light by the beam A.

However, in FIG. 11, even in black paper having a low reflectance, which is the most difficult to detect, there is a clear difference in output as compared with the case where there is no original and only the original table 12 is used. Even if the LED light quantity changes due to the deterioration of the LED as the light emitting element 32 and the change in the ambient temperature, the PSD
33 obtained by the reflected light of the beams A and B incident on
Since the ratio of the light output currents I ₁ and I ₂ of the SD 33 does not change, the detection accuracy does not deteriorate due to the output change due to the LED deterioration and the temperature change. The original size can be detected with high accuracy.

Further, the presence or absence of a document is detected with high accuracy,
In order to accurately detect the document size, the angle of the size detection sensor 15 may be changed so that the LED beam optical axis is inclined in the direction indicated by + θ in FIG.

The reason is that the directivity of the LED light is
Since the relative intensity distribution as shown in FIG. 13 is shown, by changing the angle of the size detection sensor 15 in the + θ direction, the PSD 33 reflects specularly from the surface of the document table 12.
The amount of light incident on the document table 12
This is because the amount of shift of the distance measurement output to the long distance side due to the specular reflected light from the surface is reduced.

As shown in FIG. 11, actual measurement data when the angle of the size detection sensor is changed in the + θ direction is θ = + 1.
Θ = 0 at any of 0 °, + 15 °, and + 20 °
°, the difference between the output when only the document table 12 is placed and the output when the document 11 is placed on the document table 12 is larger, making it easier to detect the presence or absence of the document 11. The document size can be reliably detected.

The installation position of the size detection sensor 15 in the proposed example is arranged, for example, as shown in FIG. Here, three sensors of the first sensor 15a, the second sensor 15b, and the third sensor 15c are used. Table 1 shows the relationship between the sensor output and the document size in this case.

[0057]

[Table 1]

As described above, by using the distance measurement type sensor as the document size detection sensor, the size of the black-colored document having low reflectance is not erroneously detected.
Higher accuracy can be achieved.

[0059]

In the proposed example shown in FIG. 6, erroneous detection of the document size due to the color (reflectance) of the document can be prevented. However, the output between the individual sensors 15 varies due to variations in the position of the light receiving element 33 and the front lens 42 of the light receiving element on the assembly. Therefore, for example, it is necessary to correct and adjust output variations in a circuit such as by operating a variable resistor (VR).

In view of the above problems, the present invention provides a variable resistor (VR) for correcting and adjusting characteristic variations of individual sensors.
It is an object of the present invention to provide a document size detecting mechanism of a document reading apparatus which does not require an operation for adjusting the document size.

[0061]

As shown in FIG. 1, a means for solving the problem according to the first aspect of the present invention includes a transparent document table 12 on which a document 11 is placed, and a document 11 on the document table 12.
An exposure unit 13 for exposing the document 11 from below the document table 12, a reading unit 14 for reading light emitted from the exposure unit 13 and reflected by the document 11 on the document table 12, and A plurality of size detection sensors for detecting the size of the document 11 on the document table 12 and detecting the size of the document by detecting the presence or absence of the document at a plurality of sensing positions. Fifteen
And a size determination circuit 60 that determines the size of the document 11 based on a signal from each of the size detection sensors 15 when the upper lid 58 is tilted by a certain angle, wherein each of the size detection sensors 15 A light emitting element 32 for irradiating the original 11 with light, and a light receiving element 3 for receiving light emitted from the light emitting element 32 and reflected by the original 11 on the original placing table 12
3 and a signal processing circuit 35 for detecting an output signal of the light receiving element 33. The light receiving element 33 is a position detecting element in which a ratio of a pair of currents changes due to a change in a spot position when the light is received as reflected light. The size determination circuit 60 includes a storage unit 62 in which document presence data Dt1 serving as a reference for determining the presence or absence of a document on the document table 12 is stored in advance, and the upper lid 58 is tilted by a predetermined angle. The state of the document stored in the storage unit 62 based on the inclination timing signal from the inclination state detecting means 63 and the inclination timing signal from the inclination state detecting means 63. A comparison unit 64 that compares the time data Dt1 with the time data Dt1; and, based on the comparison result of the comparison unit 64, the presence or absence of a document at the position where the size detection sensors 15 are arranged. Sectional, and further a determination section 65 determines the size of the document 11, the determination unit 65, in which a control circuit unit 66 for driving and controlling the comparison unit 64 and the storage unit 62 is provided.

According to a second aspect of the present invention, the control circuit section 66 is configured to control the drive of the storage section 62 when the power of the document reading apparatus is turned on. Symbol before when closed state is one that is configured to store to the storage unit 62 the measurement result Vo of each size detection sensor 15 as the original chromatic time data Dt1.

[0063] according to item (1) above third aspect, before
The state in which the upper cover 58 is closed is detected by the size detection sensor 15.

[0064] The present invention SUMMARY According to claim 4, before
A state in which serial upper lid 58 is closed, is intended to test knowledge by the inclination state detecting means 63.

According to a fifth aspect of the present invention, there is provided the control circuit section 66 in which the document presence data Dt in the storage section 62 is stored.
1 is provided, and a timing input terminal 68 for inputting the update timing of the data updating means 67 is provided.

A sixth aspect of the present invention provides a control circuit unit comprising: an update mode for updating the document presence data Dt1 when the upper cover is closed; and an update mode for updating the original presence data when the upper cover is open. A mode switching unit 69 is provided for switching to a determination mode for determining the document size.

[0067]

According to the first aspect of the present invention, first, the measurement result Vo of each size detection sensor 15 is temporarily stored in the storage unit 62 as the document presence data Dt1.
Later, the original 11 is placed on the original placing table 12 and the
Is closed, the exposure unit 13 irradiates the original 11 with light, and the reflected light is read by the reading unit 14.

At this time, while closing the upper lid 58, the upper lid 5 is closed.
8, the inclination state detecting means 63 detects this, and based on the timing signal, the measurement result Vo at that time and the document presence data Dt1
Are compared with each other to determine the document size. Thereby, the determination of the measurement result Vo of each size detection sensor 15
Relative to the absolute reference value, it can be performed relatively, and there is no need to consider output variations between the individual sensors 15 due to variations in the position of the light receiving element 33 and the light receiving element front lens 42 on the assembly.

When a position detecting element is used as the light receiving element 33, a change in spot position when light is received as reflected light is detected by a change in a ratio of a pair of currents, thereby affecting the color (reflectance) of the original. The original size can be accurately detected without receiving the original.

According to the second aspect, when the upper cover 58 of the original reading device is actually closed when the power of the original reading device is turned on,
By storing the document presence data Dt1 in the storage unit 62 at that time, automation and efficiency of the storage operation are achieved.

Further, by using a position detecting element as the light receiving element 33, it is possible to detect whether or not the upper cover 58 is closed in exactly the same manner as detecting the presence or absence of the document 11. Therefore, it is possible to prevent an increase in the number of parts
You.

According to the fourth aspect, an increase in the number of components is prevented by detecting the closed state of the upper lid 58 by using the inclined state detecting means 63.

According to the fifth aspect, by inputting the update timing signal from the timing input terminal 68, the original data Dt1 in the storage unit 62 can be arbitrarily changed when the original data Dt1 does not match the actual environment. to correct.

In the sixth aspect, the mode is switched to the update mode when the upper lid 58 is in the closed state, and the measurement result Vo of the size detection sensor 15 at that time is updated in the storage section 62 as the document presence data Dt1. When the upper cover 58 is in the open state, the mode is switched to the determination mode, and the document size is determined. Therefore, the document presence data Dt in the storage unit 62
By repeatedly updating 1, the output change of the size detection sensor 15 due to the environmental change is corrected, and the comparison of the document size can be always performed based on the new document presence data Dt1.

[0075]

【Example】

(First Embodiment) FIG. 1 is a schematic view of a document reading apparatus and a size detection mechanism according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the vicinity of an inclination detecting unit of the document reading apparatus. However, in the following description, members having the same functions as those of the above-described proposal are denoted by the same reference numerals.

The document reading apparatus according to the present embodiment is used in a general copying machine. As shown in FIG. 1, a document placing table 12 for placing a document 11 and a document on the document placing table 12 are provided. An upper cover (document cover) 58 for holding the document 11, an exposure unit 13 for exposing the document 11 from below the document table 12, and a document 11 emitted from the exposure unit 13 and placed on the document table 12.
An optical system 14 as a reading unit that reads light reflected by
A size detection mechanism for detecting the size of the document 11.

As shown in FIG. 1, the original placing table 12 is made of a conventional transparent glass plate on which an original 11 having a maximum size of A3 can be placed.

The upper lid 58 is for preventing disturbance light from entering the document table 12 and is supported on one side of the document table 12 so as to be rotatable around a horizontal axis 59 as shown in FIG. Is done. On the lower surface of the upper lid 58, a resin sheet (not shown) having a light scattering property similar to a paper material is provided.
The reason for providing the resin sheet is to make the optical system 14 and the size detection mechanism recognize as if there is a document even if there is no document when the upper lid 58 is closed.

As the exposure section 13, a general one in which a plurality of light sources 22 are arranged in a row on a substrate 21 and the light from the light sources 22 is irradiated to the original table 12 side by a lens 23 is used. You.

As the optical system 14, a general one comprising a photoreceptor 24 and a selfoc lens 25 for guiding the light reflected on the document table 12 to the photoreceptor 24 is used.

As shown in FIG. 1, the size detecting mechanism detects a document at a plurality of sensing positions to detect the size of the document, and a plurality of size detecting sensors 15 for detecting the size of the document. And a size determination circuit 60 for determining the size of the document 11 based on the signal from each of the size detection sensors 15.

Each of the size detection sensors 15 is connected to the original 11
A light-emitting element 32 for irradiating light, a light-receiving element 33 for receiving light emitted from the light-emitting element 32 and reflected by the original 11 on the original mounting table 12, and an output signal of the light-receiving element 33 to determine whether the original 11 is present. And a signal processing circuit 35 for detection. The installation position of the size detection sensor 15 is arranged as shown in FIG.

As shown in FIG. 1, the light emitting element 32 uses an infrared light emitting diode (LED) similar to that of the proposed example, and is driven by a drive circuit 37. In front of the light emitting element 32,
An irradiation lens 41 is provided. The optical axis of the light emitting element 32 is
As shown in FIG. 7, the document table 12 is inclined to the opposite side of the light receiving element 33 with respect to the document table 12 so as to reduce the influence of specular reflection light on the document table 12.

As the light receiving element 33, the same semiconductor position detecting element (PSD) that detects the spot position of the reflected light as in the proposed example shown in FIGS. Thereby, even if the light reflectance differs depending on the color of the document 11, the presence or absence of the document 11 is detected as if the distance measurement is performed.
The detection accuracy has been improved. Also, as the light receiving element 33, PS
Since D is used, even if the object placed on the document table 12 is different from the document 11, the presence or absence of the object can be detected regardless of the material. Utilizing this, the light receiving element 3
Reference numeral 3 also serves as closed state detecting means 61 for detecting a state in which the upper cover 58 of the document reading apparatus is closed. FIG.
Reference numeral 42 denotes a light receiving lens.

The signal processing circuit 35 is the same as the proposed example,
The one shown in FIG. 9 or FIG. 14 is used. As the size determination circuit 60, a general microcomputer chip or the like having a CPU, a ROM, and a RAM is used, and the closed state detection means 6 which also serves as the light receiving element 33 is used.
1, a storage unit 62 in which original document presence data Dt1 serving as a criterion for judging the presence or absence of an original on the original mounting table 12 is stored, and a tilt state detection for detecting a state in which the upper lid 58 is tilted by a certain angle. Means 63 and, based on the tilt timing signal from the tilt state detecting means 63, the measurement result Vo of each size detection sensor 15 is converted to original document presence data Dt.
A comparing unit 64 for comparing the size of the original 11 with the first comparing unit 64;
The control unit 66 includes a control circuit 66 that controls the driving of the determination unit 65, the comparison unit 64, and the storage unit 62.

When the upper lid 58 is closed, when the closed state detecting means 61 (that is, the light receiving element 33) receives the reflected light from the upper lid 58 and outputs an ON signal, the storage section 62 stores the current state. The measurement result Vo of each size detection sensor 15 is stored as original document presence data Dt1.

The document presence data Dt1 means “output signal data of the light receiving element 33 when there is a document”. However, in practice, even when the original 11 is not placed when the upper lid 58 is closed,
Since a resin sheet having a light scattering property similar to that of the paper material is provided, the light receiving element 33 recognizes as if there is a document by the light reflected on the resin sheet. Therefore, regardless of whether or not the original 11 is actually placed, the measurement result Vo when the upper lid 58 is closed is simply represented by the original presence data D.
It can be stored as t1.

As shown in FIG. 2, an existing position sensor such as a micro sensor using an actuator, a reflection type photo interrupter, or a proximity sensor is used for the tilt state detecting means 63, and is disposed near the horizontal axis 59 of the upper lid 58. Is done. The inclination angle of the upper lid 58 to be detected is set to 20 to 30 degrees. This is because the detection timing of the document size is determined by the upper cover 5
This is because an attempt is made to adjust just before the closing of 8.

The comparing section 64 is provided with an inclination detecting means 63.
When it is determined that the upper lid 58 is tilted by a certain angle based on the tilt timing signal from the CPU, the document presence data Dt1 already stored in the storage unit 62 is read, and the document presence data Dt1 and the size detection sensor 15 are read. Measurement result Vo
Compare with This comparison is performed for each of the plurality of size detection sensors 15.

The determination unit 65 determines that the comparison result of the comparison unit 64 is “new measurement result Vo by the size detection sensor 15”.
If the difference between the original document presence data Dt1 and the original document presence data Dt1 exceeds a predetermined allowable range, it is determined that the original 11 is not present at the sensing position of the size detection sensor 15, and the If the difference between the new measurement result Vo and the document presence data Dt1 is within a certain allowable range, it is determined that "the document 11 is present" at the sensing position of the size detection sensor 15. This judgment,
The determination is performed for each of the plurality of size detection sensors 15 and the combination of the presence or absence of the
Is determined.

The control circuit section 66 drives and controls the circuits 35 and 37 of each size detection sensor 15, the storage section 62, the comparison section 64, the determination section 65 and the like based on the input of the timing signal from the document reading apparatus. Is what you do. In FIG. 1, reference numeral 68 denotes a timing input terminal to which a timing signal transmitted from the document reading device is input.

Generally, the power supply O of the original reading apparatus is
At N, the upper lid 58 is often closed. For this reason, it is desirable to store the document presence data Dt1 in the storage unit 62 when the document reading device is started up. Therefore, the document reading apparatus is configured to automatically transmit a timing signal to the timing input terminal 68 when the power is turned on. In particular, when the power of the document reading apparatus is turned on, it is preferable that the control circuit 66 drives the closed state detecting means 61 (that is, the light receiving element 33) and the storage 62.

For the same reason, the document presence data Dt1 once stored in the storage unit 62 can be updated at the time of resetting the document reading device or any other timing desired by the operator. It is configured as follows. That is,
The control circuit unit 66 may be provided with a data update unit 67, and the timing signal may be input from the timing input terminal 68 to update the document presence data Dt1 in the storage unit 62 as needed.

In the above configuration, first, the power of the document reading device is turned on. At this time, a timing signal is automatically sent to the timing input terminal 68, and the control circuit 66 drives the closed state detecting means 61 (that is, the light receiving element 33) and the storage 62. From this point on, the light emitting element 32 continues to emit light until the power of the document reading apparatus is turned off.

If the upper cover 58 is closed when the power of the document reading device is turned on, the measurement result Vo of the size detection sensor 15 is converted to the document based on a signal from the closed state detecting means 61 (that is, the light receiving element 33). It is stored in the storage unit 62 as the presence data Dt1. It should be noted that even if no original is actually placed when the upper lid 58 is closed,
Since a resin sheet having a light scattering property similar to that of a paper material is provided on the lower surface of the sheet, the light receiving element 33 recognizes as if there is a document by the light reflected by the resin sheet. Accordingly, the measurement result Vo at the time when the upper lid 58 is closed can be simply stored as the document presence data Dt1 regardless of whether or not the document is actually placed.

On the other hand, the upper cover 5
8 is not closed, the closed state detecting means 61
The signal from the light receiving element 33 transmits to the control circuit 66 that the upper lid 58 is not closed. Since the measurement result Vo of the size detection sensor 15 at this time is meaningless even if it is stored in the storage unit 62, the control circuit unit 66
The measurement result Vo is not transmitted to the storage unit 62. Thereafter, the control circuit unit 66 continues to drive the closed state detecting means 61 (that is, the light receiving element 33) and the storage unit 62, or regularly drives them at regular time intervals.
8 is closed, the measurement result Vo at that time is stored in the storage unit 62 as the document presence data Dt1.

Next, after the upper cover 58 is opened and the document 11 is placed on the document table 12, the upper cover 58 is closed and the document 11 on the document table 12 is pressed. During the operation of closing the upper cover 58, the upper cover 58
When the angle reaches an angle of up to 30 degrees, the control circuit unit 66 receives the measurement result Vo from each size detection sensor 15.

Here, when the document 11 is located at a predetermined sensing position of the size detection sensor 15, the light emitted from the light emitting element 32 is reflected by the document 11, so that the reflected light enters the light receiving element 33 and the signal The output signal of the light receiving element 33 is detected by the processing circuit 35. Then, the signal processing circuit 35
Outputs the measurement result Vo to the control circuit unit 66.

On the other hand, when the document 11 is not at the sensing position of the size detection sensor 15, the light emitted from the light emitting element 32 passes through the document table 12 and passes upward without change, so that the reflected light is received. It does not enter the element 33. Then, the signal processing circuit 35 outputs the absence of the output signal from the light receiving element 33 to the control circuit unit 66 as the measurement result Vo.

Here, the light reflectance may vary depending on the color of the document 11, but by using a position detecting element for detecting the spot position of the reflected light as the light receiving element 33,
The presence or absence of the document 11 can be detected by the ratio of a pair of currents that changes depending on the position of the light receiving spot. Since the ratio of the pair of currents does not change even if the reflectance of the document decreases, the detection is compared to simply detecting the light amount. Accuracy can be improved. These detection operations are performed for each size detection sensor 15.

Next, the control circuit section 66
The new measurement result Vo for each size detection sensor 15 from No. 5 is transmitted to the comparison unit 64. The comparison unit 64 compares the measurement result Vo with the document presence data Dt1 already stored in the storage unit 62 for each size detection sensor 15.

On the basis of the result of comparison by the comparing section 64,
The determination unit 65 determines the presence or absence of a document at the position where each size detection sensor 15 is disposed, and further determines the size of the document 11. Then, the determination result information is transmitted to another operation mechanism such as a scale ratio of the document reading device and a securement of a read data area. Thereafter, the document 11 is exposed from below the document table 12 by the exposure section 13, and light emitted from the exposure section 13 and reflected by the document 11 on the document table 12 is read by the reading section 14.

As described above, by using the PSD as the light receiving element 33, the presence / absence of the document, that is, the size of the document can be accurately detected without being affected by the color (reflectance) of the document 11.

The original data Dt1 is stored in the storage unit 62.
Is stored, and the measurement result Vo from each size detection sensor 15 is stored.
Is compared with the document presence data Dt1, the document size is determined. Therefore, an operation for adjusting the output variation between the individual sensors is not required, and the document size detection mechanism has an automatic correction function. be able to. That is, even if an erroneous detection of the presence or absence of a document may occur due to an environmental change such as an ambient temperature, the output Vo when the document is present is stored again to eliminate the erroneous detection in a later operation. Becomes possible.

(Second Embodiment) In the first embodiment, the size detection sensor 1 when the upper cover is closed when the power of the document reading apparatus is turned on.
5 is stored as the document presence data Dt1, but if the power of the document reading device is turned ON by mistake when the upper cover is opened, the data is updated by an operation such as pressing a reset button. There is a need to do. In addition, the present applicant has proposed a method that can be easily performed by applying an erasing current to the EEPROM when erasing and rewriting stored data by using the EEPROM (Japanese Patent Application No. Hei 5-3160). In this method,
Since an EEPROM is required in addition to the microcomputer, the size and cost of the system are increased, and the output of the size detection sensor 15 when the original is present and when there is no original before the copier is shipped.
There is a problem that it is necessary to store the information in the EPROM in advance.

Therefore, in the size detecting mechanism of the original reading apparatus of this embodiment, as shown in FIG. 3, the control circuit 66 instructs the control circuit 66 to close the upper cover 58 based on the upper cover open / close signal from the closed state detector 61. The original document presence data Dt1
Mode switching means 69 for switching between an update mode for updating the document size and a determination mode for determining the document size when the upper lid 58 is open. In the update mode, when the upper lid 58 is in the closed state, the data updating means 67
Is operated to change the original document presence data Dt1 stored in the storage unit 62 to the latest value.

In the above configuration, when the power of the document reading apparatus is turned on, if the upper cover 58 is closed, a closing signal from the closed state detecting means 61 is input from the mode switching signal terminal 70 to the control circuit section 66, The mode is switched to the update mode by the mode switching means 69. Then, the measurement result Vo of each size detection sensor 15 at this time is stored in the storage unit 62 as the document presence data Dt1.

On the other hand, when the power of the document reading apparatus is turned on,
When the upper cover 58 is closed for the first time, the measurement result Vo of the size detection sensor 15 at that time is set to the original presence data D, as in the first embodiment.
It is stored in the storage unit 62 as t1.

Next, when the upper lid 58 is opened, an open signal from the closed state detecting means 61 is input to the control circuit section 66 via the mode switching signal terminal 70, and the mode is switched to the determination mode by the mode switching means 69. Then, the document table 12
After the original 11 is placed on the document, the upper lid 58 is closed.

During the operation of closing the upper lid 58, the upper lid 5
When the angle between the document 8 and the document table 12 reaches 20 to 30 degrees, the control circuit 66 receives the measurement result Vo from each size detection sensor 15, performs a size detection operation, and
1 is determined.

When the upper cover 58 is closed until it comes into contact with the document table 12, the mode is switched again to the update mode, and the measurement result Vo of the size detection sensor 15 at that time is returned.
Is updated as the document presence data Dt1. Thereafter, every time the upper lid 58 is opened and closed, the document presence data Dt1
And the determination of the document size is repeated.

As described above, by opening and closing the upper lid 58,
When the upper cover 58 is closed, the document presence data Dt1 is updated, and when the upper cover 58 is open, the document size can be determined. Therefore, the original data D
Since the output change of the size detection sensor 15 due to an environmental change such as an ambient temperature change can be corrected without performing an operation such as pressing a reset button at the time of updating t1, the document size can be compared and determined based on the latest data. Thus, the detection accuracy of the document size is improved. In addition, since there is no need to use an EEPROM, it is not necessary to store the output data of the size detection sensor 15 before shipping the copying machine without increasing the size and cost of the system.

Note that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention.

For example, in the first and second embodiments, when the power of the document reading apparatus is turned on, the closed state detecting means 61 is driven,
Although it was detected whether or not the upper cover 58 of the document reading device was closed, the power of the document reading device was turned on regardless of this.
At times, the measurement result Vo may be forcibly stored in the storage unit 62 as the document presence data Dt1. In this case, the upper lid 5
Even if the power is turned on with 8 open,
In the first embodiment, after the upper lid 58 is closed and the reset button is pressed, the data updating unit 67 of the control circuit 66 updates the original presence data Dt1 in the storage unit 62 to the correct content (the state in which the upper lid is closed). At any time. Further, in the second embodiment, by opening / closing the upper lid 58, the document presence data Dt1 can be updated, so that no major problem occurs.

In the first embodiment, the light receiving element 33 is used as it is as the closed state detecting means 61.
The tilt state detecting means 63 may be used as it is.

Furthermore, the position of the size detection sensor is
Although the setting is made as shown in FIG. 15, the setting may be made as shown in FIG. 4, for example, or another arrangement may be used.

In the above-described embodiment, the original size detecting mechanism using the PSD has been described. However, the present invention may be applied to a conventional original size detecting mechanism based on a reflected light amount detecting system. Further, although the description has been made by taking the document reading device of the copying machine as an example, the invention may be applied to other devices such as an image input device of a computer.

[0118]

As is apparent from the above description, according to the first aspect of the present invention, the measurement result of each size detection sensor is temporarily stored in the storage unit as the document presence data, and the data is stored when the upper cover is inclined to a certain angle. Since the document size is determined by relatively comparing the measurement result with the data with the document, the variation in the characteristics of the light emitting element and the light receiving element is smaller than when determining by comparing with the absolute reference value. There is no need to consider. Therefore, an operation for adjusting the output variation between the individual size detection sensors is not required, and the document size detection mechanism can be provided with an automatic correction function. Even if an erroneous detection of the presence or absence occurs, by storing the output when the document is present again, it is possible to eliminate the erroneous detection in a later operation. Therefore, it is possible to save labor for adjusting work such as adjusting the variable resistance.

Further, since the position detecting element is used as the light receiving element, a change in the spot position when the light is received as reflected light can be detected by a change in a ratio of a pair of currents. In comparison, the document size can be accurately detected without being affected by the color (reflectance) of the document.

According to the second aspect, the power supply O of the document reading apparatus is
At the time of N, the document presence data can be stored in the storage unit only when the upper cover of the document reading device is actually closed,
It is possible to prevent the measurement result when the upper lid is opened from being stored in the storage unit, and it is possible to automate and improve the efficiency of the storage operation.

Further, by using the position detecting element as the light receiving element, it is possible to detect whether or not the upper cover is closed in the same manner as detecting the presence or absence of a document. Therefore, an increase in the number of parts can be prevented. Alternatively, even when used as it is inclined obliquely state detection means to detect whether the lid is closed, thereby preventing an increase in the number of parts.

According to the fifth aspect, since the control circuit section is provided with data updating means for updating the document presence data in the storage section, the document presence data in the storage section does not match the actual environment. If, for example, an update timing is input from a timing input terminal, this data can be arbitrarily corrected.

According to the sixth aspect, the update of the document presence data and the determination of the document size can be repeatedly performed by the opening / closing operation of the upper cover. When the document size is determined, the new document presence data and the size detection sensor are always updated. Comparison with the measurement result is possible. Therefore, an output change of the size detection sensor due to a change in environment such as a change in ambient temperature can be corrected, so that erroneous detection of the presence or absence of a document can be prevented, and there is an excellent effect that the accuracy of document size detection is improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a document reading apparatus and a size detection mechanism according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the vicinity of an inclination detecting unit of the document reading apparatus.

FIG. 3 is a schematic diagram of a document reading apparatus and a size detection mechanism according to a second embodiment of the present invention.

FIG. 4 is a diagram showing an example of a mounting position of a size detection sensor.

FIG. 5 is a diagram showing a general size detection sensor.

FIG. 6 is a schematic diagram of a size detection mechanism of the proposed example.

FIG. 7 is a schematic diagram of a size detection sensor.

8A is a diagram illustrating an operation principle of a PSD as a light receiving element, and FIG. 8B is a distribution diagram of a specific resistance of a surface resistance layer of the PSD.

FIG. 9 illustrates an example of an internal configuration of a signal processing circuit.

FIG. 10 is a diagram illustrating output characteristics of a size detection sensor with respect to a distance from a document.

FIG. 11 is a diagram illustrating output characteristics of a size detection sensor with respect to an optical axis and a color of a document.

FIG. 12 is a diagram showing a detection operation of a size detection sensor.

FIG. 13 is a diagram showing light directivity characteristics of a size detection sensor.

FIG. 14 is a diagram showing another example of the internal configuration of the signal processing circuit.

FIG. 15 is a diagram showing an example of a mounting position of a size detection sensor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 document 12 document placing table 13 exposure unit 14 reading unit 15 size detection sensor 32 light emitting element 33 light receiving element 35 signal processing circuit 58 top cover 60 size determination circuit 61 closed state detection means 62 storage unit 63 tilt state detection means 64 comparison unit 65 determination Section 66 control circuit section 67 data updating means 68 timing input terminal 69 mode switching means Dt1 original data

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-284752 (JP, A) JP-A-2-167536 (JP, A) JP-A-1-238941 (JP, A) JP-A-62 83605 (JP, A) JP-A-4-172441 (JP, A) JP-A-3-1127 (JP, A) JP-A-5-19378 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) G03B 27/62

Claims (6)

(57) [Claims] A transparent document table for mounting the document, an upper cover for pressing the document on the document table, an exposure section for exposing the document from under the document table, and an emission section from the exposure section. A reading unit for reading light reflected by the document on the document table, wherein the size of the document on the document table is detected, and the document is read at a plurality of sensing positions. A plurality of size detection sensors for detecting the presence or absence and detecting the size of the document, and a size determination circuit for determining the size of the document based on a signal from each of the size detection sensors when the top cover is inclined by a certain angle. A light-emitting element for irradiating a document with light; a light-receiving element for receiving light emitted from the light-emitting element and reflected by the document on the document table; and an output signal of the light-receiving element. detection A position detection element that changes a ratio of a pair of currents due to a change in a spot position when the spot is received as reflected light, and the size determination circuit includes: A storage unit for storing in advance the presence / absence data serving as a criterion for determining the presence / absence of the original, an inclination state detection means for detecting a state in which the upper cover is inclined by a certain angle, and an inclination state detection means. A comparison unit that compares the measurement result of each size detection sensor with the document presence data already stored in the storage unit based on the tilt timing signal, and based on the comparison result of the comparison unit, A judging unit for judging the size of the document by judging the presence or absence of the document at the position where the size detection sensor is arranged; A document size detecting mechanism for the document reading device, wherein the document size detecting mechanism includes a path portion. 2. The original size detecting mechanism according to claim 1, wherein the control circuit is configured to drive and control the storage unit when the power of the original reading device is turned on. when the closed state of the upper lid
Document size detection mechanism before SL document reading apparatus characterized by being configured to store to the storage unit the measurement results as the original chromatic time data in each size detection sensor. 3. A state in which the closing of the upper cover, the document size detection mechanism of the document reading apparatus of the previous SL size detection sensor according to claim 2, wherein the sensing by the light receiving element. 4. The method of claim 2 the closed state of the upper lid, characterized that you detected by the inclination state detecting means
Document size detection mechanism of the document reading device described in the above. 5. The document size detecting mechanism according to claim 2, wherein the control circuit unit is provided with data updating means for updating the document presence data in the storage unit. A document size detecting mechanism for a document reading apparatus, comprising a timing input terminal for inputting an update timing. 6. An original size detecting mechanism according to claim 1, wherein said control circuit includes an update mode for updating said document presence data when said upper lid is closed, and said upper lid is opened. A document size detecting mechanism for a document reading apparatus, comprising: a mode switching unit for switching to a determination mode for determining a document size in a state.