JP3423518B2 - Moisture content detection device / moisture content measurement method and moisture content measurement 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 moisture content detection device for detecting moisture content of a detection target, a moisture content measurement method for measuring moisture content of a measurement target, and a moisture content measurement device for carrying out this method.

[0002]

2. Description of the Related Art Water is contained in many things, and the physical and chemical properties of the material change depending on the "moisture content", that is, the "content of water content". In process control and the like, it is often necessary to detect and measure water content.

For example, a transfer paper on which a toner image is transferred in an electrophotographic image forming apparatus such as a copying machine, a printer or a facsimile changes its electric resistance due to its water content, so that a good toner image transfer is performed. The water content must be maintained in an appropriate area. The moisture content of the transfer paper is preferably 4 to 8%, and if it is 10% or more, the efficiency of transfer / separation of the toner image may decrease, a paper feed error may occur, wrinkles may occur in the fixing device, or the toner image may not be fixed. Become. Further, when the water content of the transfer paper is 2% or less, the electric charge applied to the transfer paper during the transfer is discharged between the transfer paper and the conductive member, which causes disturbance in the toner image.

[0004] Conventionally, a moisture content detecting device is "provided with a light emitting section for irradiating a detection target with light, a light receiving section for receiving reflected light from the detection target, and either the light emitting section side or the light receiving section side. A pair of detectors consisting of a filter and the filters of the detectors are configured to pass light of different wavelengths "or" a light emitting unit that irradiates the detection target with light and a reflected light from the detection target. It has a light receiving part that receives light and a filter that is inserted between the light emitting part and the light receiving part, and the filter is replaced every time measurement is performed with light of different wavelengths. "
There is.

However, the moisture content detecting device, in which the filter is replaced every time the measurement is performed, tends to take a long time for the measurement because the filter is replaced. The moisture-containing detection device in which the detection devices are provided in pairs requires parts of the detection devices in pairs, which increases cost due to an increase in the number of parts and is not suitable for downsizing of the device.

As a method of measuring the water content, infrared light having a wavelength that is easily absorbed by water and infrared light having a wavelength that is difficult to be absorbed by water are sequentially irradiated to the test object, and each infrared light There is a method of detecting the water content from the reflection intensity, and an apparatus for carrying out this method is also known (JP-A-55-29726,
JP-A-3-115838, JP-A-3-23114
No. 0).

Japanese Unexamined Patent Publication No. 55-29726 discloses that "the moisture content of a powder is measured using two different absorption wavelengths and a pair of comparison wavelengths, and the actual moisture content is calculated from a formula previously obtained from these measurement results. The method for determining the water content is disclosed in Japanese Patent Application Laid-Open No. 3-115838.
In the moisture content measurement using one infrared comparison wavelength, “either of the two infrared comparison wavelengths is set to a shorter wavelength side or a longer wavelength side than the infrared absorption wavelength, and the signal obtained by the two infrared comparison wavelengths is extrapolated. , A moisture measuring method for accurately measuring moisture content by correcting a signal component caused by factors other than moisture of a target substance included in a signal of an infrared absorption wavelength.

In the moisture content measuring method disclosed in each of the above publications, in order to obtain infrared light having different wavelengths for irradiating an object to be measured, light from a common light source is rotated in a "turret type sector having a plurality of filters". This is performed by separating the wavelengths, and since the apparatus includes a movable part, the size of the entire apparatus tends to increase, and it is difficult to increase the measurement speed.

Further, "preparatory operation such as zero-point calibration" is required before starting the measurement, and the measurement efficiency is poor.
Further, since invisible infrared light is used, it is not possible to visually confirm which part of the test object is irradiated with light, and the workability of measurement is poor.

[0010]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, it is an object of the present invention to detect a moisture content of a detection object in a non-contact manner and to stably detect the moisture content to be detected even if the environment changes. To do.

Another object of the present invention is to realize a method for measuring water content by near infrared light, which enables simple and quick measurement of water content with high accuracy (claim 1).

Another object of the present invention is to realize a moisture content measuring device using near infrared light capable of measuring moisture content easily and quickly with high accuracy (claims 2 to 6).

[0013]

First, a moisture content detecting device as a reference example will be described.

This moisture content detection device is a "moisture content detection device having a plurality of light emitting portions for sequentially irradiating light to be detected with different emission wavelengths and a light receiving portion for receiving reflected light from the detection object". It is characterized by the following points.

That is, "a plurality of light receiving signals are fetched from the light receiving portion based on the sequential light emitting operation of the plurality of light emitting portions, and the moisture content to be detected is determined based on a preset value by comparing the plurality of light receiving signals. It is equipped with a control unit that

That is, in the moisture content detection apparatus of the reference example, a plurality of light emitting units having different emission wavelengths sequentially irradiate the detection target with light, and the light receiving unit receives the reflected light from the detection target. The control unit takes in a plurality of light receiving signals from the light receiving unit based on the sequential light emitting operation of the plurality of light emitting units, and judges the moisture content of the detection target based on a preset value by comparing the plurality of light receiving signals. .

The "predetermined value" is information relating to the comparison between the received light signals and the water content, and information relating to the appropriate value range of the water content in the detection target.

The moisture content detecting device of the reference example has a plurality of light emitting portions and a light receiving portion.

The "plurality of light emitting parts" have different emission wavelengths, and are for sequentially irradiating the detection target with light. "The spectral emission intensity is 1.45 .mu.m on the long wavelength side of the spectral sensitivity of the light receiving part." And a “light emitting portion having a peak of spectral emission intensity on the short wavelength side of the spectral sensitivity of the light receiving portion”.

The "light receiving section" receives the reflected light from the detection target.

"Each light emitting portion in the plurality of light emitting portions" and the light receiving portion are arranged at a predetermined angle, and the outputs of the plurality of light emitting portions and the light receiving portion, that is, "emission intensity of each light emitting portion and light receiving output of the light receiving portion". Can be set by external input.

That is, the plurality of light emitting portions having different emission wavelengths are
A light emitting part having a peak of spectral emission intensity at 1.45 μm on the long wavelength side of the spectral sensitivity of the light receiving part and a light emitting part having a peak of spectral emission intensity at the short wavelength side of the spectral sensitivity of the light receiving part, for example 0.80 μm or less. And has a function of sequentially irradiating the detection target with light. The light receiving unit and the plurality of light emitting units are arranged at a “predetermined angle”, the light receiving unit receives the reflected light from the detection target, and the outputs of the plurality of light emitting units and the light receiving units can be set by an external input.

The method for measuring water content according to claim 1 is that "transfer paper as a measurement object is used for measuring two or more kinds of near-infrared light having wavelengths or wavelength ranges different in water absorption. , A transfer paper on which a toner image is transferred in an electrophotographic image forming apparatus such as a facsimile) is sequentially irradiated, and reflected light from the measurement target is converted into a detection signal by a light receiving unit to measure the moisture content in the measurement target. It is a method of measuring water content as data "and is characterized by the following points.

Two light emitting sources are used, and each of these two light emitting sources emits "near infrared light of a predetermined wavelength or wavelength range". The two types of near-infrared light emitted from these two light-emitting sources have different "absorbance" by water.

Near-infrared light emitted from each of the two light-emitting sources is applied to the transfer paper which is the object to be measured, and each reflected light from the object to be measured is "single light-receiving means" by a transparent condensing optical system. Is focused on. The output of the light receiving means is intermittently taken in, and the two light emitting sources emit light sequentially in synchronization with the taking in of the output of the light receiving means.

In this way, as the detection signal of the light receiving means, the detection signal PD ₀ when none of the light emitting sources is emitting light and the jth (1≤j≤2) th light emitting source emits light. (1 + 2) detection signals due to the detection signal: PD _j are generated repeatedly n (≧ 2) times, and the resulting n · (1 + 2) detection signals are used as data. The water content in the measurement target is detected by the data processing.

That is, as the detection signal of the light receiving means, the detection signal when no light emitting source is emitting light: PD ₀
And a detection signal when the j-th (1 ≦ j ≦ 2) light emitting source emits light: PD _j and (1 + 2) detection signals are repeatedly generated for a predetermined n (≧ 2) times. , PD1 = PD ₁ −PD ₀ , PD2 = PD ₂ −P for each iteration
D ₀ is calculated to obtain n sets of PD1 and PD2.
Average value for a pair of PD1 and PD2: PD _1n = ΣPD1
/ N, PD _2n = ΣPD2 / n, and P
X = PD _1n / PD _2n is calculated from D _1n and PD _2n , and the moisture content in the transfer paper is compared by comparing and comparing the calculation result: X and the moisture content in a predetermined table with the above calculation result: X. Is detected.

A moisture content measuring apparatus according to a second aspect is an apparatus for performing the method according to the first aspect, which comprises two light emitting sources, a single light receiving means, and a condensing optical system. It has a control processing means and a display means.

Each of the "two light emitting sources" emits near-infrared light having a predetermined wavelength or wavelength range, and two kinds of near-infrared light emitted from two light-emitting sources are mutually emitted. "Absorption" by water is different. Then, these two light emitting sources are arranged so that the near-infrared light from each light emitting source is applied to the transfer paper to be measured.

The "single light receiving means" is composed of two kinds of infrared light.
It is a means for commonly receiving the reflected light from the measurement object.

The "light-collecting optical system" is transparent and collects each reflected light from the object to be measured on the light receiving means.

The "control processing means" detects, as the detection signal of the light receiving means, the detection signal when no light emitting source emits light: PD ₀ and the jth (1≤j≤2) light emitting source. Detected signal when PD is emitting light: PD _j and (1+
2) The two light emitting sources are synchronized with the capture of the output of the light receiving means while controlling the capture of the output of the light receiving means intermittently so as to repeatedly generate a predetermined number of detection signals n (≧ 2) times. Then, light emission is sequentially controlled, data processing is performed using the obtained n · (1 + 2) detection signals as data, and the moisture content in the measurement target is detected.

The "display means" displays the water content detected by the control processing means.

The above-mentioned control processing means is "PD1 = PD ₁ -P according to the detection signal: PD ₀ , PD _j every n times.
Compute D ₀ , PD2 = PD ₂ −PD ₀ to obtain n sets of PD
1 and PD2 are obtained, and the average values for these n sets of PD1 and PD2 are: PD _1n = ΣPD1 / n, PD _2n = ΣPD2 /
n is _calculated , and X = PD _{1n is calculated} from these PD _1n and PD _2n.
/ PD _2n is calculated, and the table that predetermines the relationship between the calculation result: X and the moisture content is compared with the calculation result: X to detect the moisture content in the measurement object, and regress with respect to X. It has a function of performing a distributed calculation and correcting the proportional relationship between X and the data in the table.

"Single light receiving means" in claims 1 and 2
Needless to say, it must be sensitive to all of these two types of near-infrared light, because it receives two types of near-infrared light having different wavelengths or wavelength regions.

As described above, in the moisture content measuring apparatus according to the second aspect of the invention, two light emitting sources are used.

One of the two light emitting sources is a "light emitting element having a spectral emission intensity peak at 1.45 μm" and the other is a "light emitting element having a spectral emission intensity peak in the near infrared region of 1.4 μm or less. It can be said (Claim 3). In the case of the invention according to claim 3, the two light emitting sources can be housed in the same resin case and arranged in the "central part of the condensing optical system" (claim 4).

In the moisture content measuring apparatus using near infrared light according to any one of claims 2 to 4, the transparent condensing optical system may be a "silicon lens" (claim 5). Alternatively, it may be a "hologram lens" (claim 6).

The above-mentioned "silicon-based lens" may be a normal lens or a "Fresnel lens" in its form. "Hologram lens" is 2
It may be multiple-recorded so that near-infrared light of a certain wavelength range is condensed at the position of a single light-receiving means, or the lens is divided into two areas, and each area is near a predetermined wavelength. The infrared light may be configured to be condensed at a single light receiving unit position.

In the method and apparatus for measuring water content according to any one of claims 1 to 6, the plural kinds of near-infrared light with which the object to be measured is irradiated are sequentially emitted from different light emitting sources so that the irradiation timing and the wavelength can be changed. Are sequentially shifted. Further, during the measurement, the output of the light receiving means: PD _{0 in} a state where no light emitting source emits light is generated as data.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a form of a moisture content detection device of a reference example. The illustrated form is an example of a moisture content detection device used in an image forming apparatus or the like. This water content detection device 1
Is a detection device 5 having light emitting units 2 and 3 each composed of a light emitting diode (hereinafter abbreviated as an LED) and a light receiving unit 4, a light emission drive circuit 6, an amplifier circuit 7, a control unit 8, an input unit 9, an output unit 10, and The display unit 11 is provided, and the moisture content of the detection target 12 placed at the detection position is from high moisture content: 100% to low moisture content: 4
Detect up to%. Hereinafter, for the sake of concreteness of the description, the “transfer paper” to which the toner image is to be transferred is assumed as the detection target 12.

As shown in FIG. 2, the LEDs 2 and 3 have different spectral emission intensities, the LED 2 has a peak of the spectral emission intensity at 1.45 μm, and the LED 3 has a spectral emission intensity at 0.80 μm or less, for example 0.72 μm. With the peak of. Of the light emitting units 2 and 3, the light emitting unit that emits light in the comparative wavelength band may be a light emitting unit having a peak of spectral emission intensity at 0.60 to 0.80 μm. The light receiving part 4 is composed of an "InGaAs-based light receiving element" and has a thickness of 0.6 to 1.7 .mu.m as shown in FIG.
It has "spectral sensitivity" in m.

As shown in FIG. 1, the LEDs 2 and 3 have an optical axis (direction in which the intensity of the radiated light flux is maximum) which is to be detected 12.
Is arranged so as to be “substantially symmetric” with respect to the normal line of the detection surface at, and the light receiving unit 4 forms an angle of 10 to 40 degrees with the optical axes of the LEDs 2 and 3 on the normal line of the detection surface of the detection target 12. It is placed in such a position.

The LEDs 2 and 3 are alternately driven by the light emission drive circuit 6, irradiate the detection target 12 with light, and the light receiving section 4 receives the reflected light from the detection target 12. The output signal of the light receiving unit 4 is amplified by the amplifier circuit 7 and input to the control unit 8.

The "detection position (position where the detection target 12 is arranged)" in the embodiment shown in FIG. 1 is a "predetermined reference that is predetermined as a reference prior to the detection of the water content of the detection target 12." A reference plate or a sensing object having water content is placed, the light emission drive circuit 6 alternately drives the LEDs 2 and 3, and L is set based on the set value from the control unit 8.
The light amount of the EDs 2 and 3 is controlled. The light from the LEDs 2 and 3 is applied to the “reference plate or the detection object”, and the reflected light is received by the light receiving unit 4.

The output signal of the light receiving section 4 is amplified by the amplifier circuit 7 and input to the control section 8. The control unit 8 controls the output signal of the amplification circuit 7 to correspond to a set value (the above “predetermined reference moisture content”) preset in the control unit 8.
(The output value of 1) and the light amount of the LEDs 2 and 3 are variably controlled so that the value input from the amplifier circuit 7 to the control unit 8 becomes equal to the set value.

As another method, the "amplification factor" of the amplifier circuit 7 is variably adjusted by the control unit 8 while keeping the light emission amounts of the LEDs 2 and 3 constant, and the output signal of the amplifier circuit 7 becomes equal to the set value. The amplification factor may be set as described above.

The moisture content detection is preferably performed in an environment where the influence of ambient light, particularly near infrared light, is small. When there is a possibility of being affected by ambient light, the outer shape around the moisture content detection device 1 is used. Place a protective member such as a case.

FIG. 3 is a flow chart showing the procedure of moisture content detection in the embodiment of FIG. 1, and the flow chart of FIG. 4 is shown in FIG.
3 shows a part of the flow chart of FIG. The control unit 8 in FIG. 1 is configured by using a microcomputer. In FIG. 3, when the power is turned “on” (step 21), the controller 8 carries out an initial setting process of the moisture content detection device (step 22).

The control unit 8 checks the operation start signal (start power-on signal) input from the outside through the input unit 9 (step 23). When the operation start signal is input, the light emission drive circuit 6 turns on the LEDs 2 and 3. Light is emitted alternately (step 24). The light from the LEDs 2 and 3 is applied to the detection target 12, and the reflected light is received by the light receiving unit 4. The output signal of the light receiving unit 4 is amplified by the amplifier circuit 7 and input to the control unit 8.

The control unit 8 samples and reads the output signal (PD data) of the amplifier circuit 7 based on the alternate light emission operation of the LEDs 2 and 3, and stores it in the internal memory (step 25). That is, first, the light from the LED 2 is detected 12
The reflected light from the detection target 12 is received by the light receiving unit 4. The output signal of the light receiving unit 4 is amplified by the amplifier circuit 7, sampled and read by the control unit 8, and stored in the memory as measurement data: A. next,
The light from the LED 3 is applied to the detection target 12, and the light reflected by the detection target 12 is received by the light receiving unit 4. The output signal of the light receiving unit 4 is amplified by the amplifier circuit 7, sampled and read by the control unit 8, and stored in the memory as measurement data: B.

The control unit 8 checks "whether the output signal of the amplifier circuit 7 is read for the second time" (step 2).
6) When the reading of the output signal of the amplifier circuit 7 corresponding to the alternate light emission operation of the LEDs 2 and 3 is completed twice, data comparison is performed (step 27).

The "data comparison" of step 27 in FIG. 3 is performed in the procedure shown in FIG. That is, the control unit 8
"Check measurement data stored in memory: A, B" in step 271 of FIG.
If B does not exist, "abnormality display" is displayed on the display unit 11 (step 274). If there are measurement data A and B, the control unit 8 "compares the measurement data: A and B" (step 272).

"Measurement data:
A set value that defines "quotient of A and measured data: B: correspondence between A / B and moisture content" is set as a table or an arithmetic expression, and the control unit 8 controls the above quotient: A / B and set value. The moisture content of the detection target 12 is judged by comparison with or calculation with and the “judgment result” is stored in the storage unit.

In the memory of the control unit 8, information for judgment (appropriate value range of moisture content in the transfer paper which is the detection target 12, for example, 4 to 8% described above) is set as a preset value in advance.

The control unit 8 sets the "predetermined range (for example, 4 to 8% above)" in which the determination result (the water content corresponding to the quotient: A / B) stored in the memory at step 273 is set as the set value. It is determined whether or not it is within the range), and if it is not within the range, an abnormal display is performed.When the abnormal display is performed, the moisture content of the transfer paper as the detection target 12 is not suitable for the transfer of the toner image.

Instead of the set value, a set value (for example, 5 to 10%) can be set externally from the input unit 9 (see FIG. 1). In this way, inputting the set value from the outside through the input unit 9 is performed when correcting the determination value due to the difference in the amount of reflected light due to the difference in the type of the detection target 12 or when an arbitrary moisture content in the detection target is corrected. This is effective when determining the state of the detection target with.

In this case, the control unit 8 determines that the moisture content of the detection target 12 is 5% or more and 10% or less based on the determination information (setting value or setting value input from the outside) from the determination result stored in the memory. Whether or not it is within a predetermined range is determined by determining whether or not there is, and the determination result is output to the outside through the output unit 10 according to an instruction input from the outside through the input unit 9. If the moisture content of the detection target 12 is not within the predetermined range, the control unit 8 displays the display unit 11 in step 274.
Causes "abnormality display" to be performed.

The control section 8 proceeds from step 27 to step 28 in FIG. 3 and judges whether or not there is a new input of the above-mentioned set value or the above-mentioned set value from the outside through the input section 9, and the set value is set. Is input, the judgment value is corrected to the input set value, and if the set value is input, the set value is corrected to the "newly input set value" (step 29). .

Next, the control unit 8 judges "whether an output or display instruction is input from the outside through the input unit 9" (step 30), and when the output or display instruction is input, Outputs the determination result, the setting information, the setting value, and the like through the output unit 10 according to the instruction, or the display unit 11
(Step 31).

The control unit 8 further determines "whether or not the power is turned off", and repeatedly executes the above-described operation at a preset operation cycle until the power is turned off, and the detection target stored in the storage unit is detected. The determination result of moisture content 12 is updated to the latest one (step 32).

The control unit 8 removes noise due to "light intensity deterioration and dirt" of the light emitting units 2 and 3 and "component sensitivity variation" of the light receiving unit 4, etc., and is set in advance from an externally set value or internally set. Based on the control content, the adjustment control of the light amount of the light emitting units 2 and 3 is performed as described above.

The above-described form is used for detecting the moisture content of the sheet (transfer sheet) in the image forming apparatus to detect the moisture content of the sheet having high reflectance. When detecting the moisture content of an object having a low reflectance, the light amounts of the light emitting units 2 and 3 and the output of the light receiving unit 4 can be adjusted and set to values that can be handled by the control unit 8. The image forming apparatus can control the measurement target (for example, “change the transfer voltage depending on the moisture content”) based on the detection result (the determination result) in the above-described embodiment.

The above-described form is a form of a reference example, in which a plurality of light emitting portions 2 and 3 having different emission wavelengths for sequentially irradiating the detection target 12 with light and the reflected light from the detection target 12 are received. In the moisture-containing detection device 1 having the light receiving section 4, a plurality of light receiving signals: A and B are fetched from the light receiving section 4 based on the sequential light emitting operations of the plurality of light emitting sections 2 and 3, and a plurality of light receiving signals: A and B. The control unit 8 that determines the moisture content of the detection target 12 based on the preset value (set value) from the comparison
Since only one light receiving unit 4 is required for a plurality of light emitting units 2 and 3, it is possible to reduce the size and cost, and it is possible to accurately detect the moisture content of the detection target without contact. Can be detected. It should be noted that the detection target may be paper or cloth having an electric charge.

In the above embodiment, a plurality of light emitting portions 2 and 3 having different emission wavelengths for sequentially irradiating the detection target 12 with light are provided.
And a plurality of light emitting units 2 and 3 having a peak of spectral emission intensity at 1.45 μm on the long wavelength side of the spectral sensitivity of the light receiving unit 4. And a light emitting section having a peak of spectral emission intensity at 0.72 μm on the short wavelength side of the spectral sensitivity of the light receiving section 4, and the plurality of light emitting sections 2 and 3 and the light receiving section 4 are arranged at a predetermined angle. At the same time, since the outputs of the plurality of light emitting units 2 and 3 and the light receiving unit 4 can be set by an external input, the light amount of the light emitting units 2 and 3 and the output of the light receiving unit 4, the difference in the density / reflected light amount of the detection target 12, etc. It is possible to correct the information according to the external input, to improve the measurement noise and error, the measurement accuracy, and the resolution, and to detect the moisture content of the detection target in a stable and non-contact manner even if the environment changes. it can.

In the above embodiment, the light emitting units 2 and 3 that irradiate the detection target 12 with light, the light receiving unit 4 that receives the reflected light from the detection target 12, and the light receiving units 2 and 3 receive light based on the light emitting operation. The light receiving signal is fetched from the unit 4 and stored in the storing means, and the controller 8 for judging the water content of the detection target 12 based on the preset value from the light receiving signal stored in the storing means.
Since it is provided with, it becomes possible to automatically measure the moisture content of the detection target, and it becomes possible to control the control target based on the measured value.

FIG. 5 shows another form. In this embodiment, in the above-described embodiment, the detection device 5 has an LED 2 having a peak of spectral emission intensity at 1.45 μm, and 0.6 to 1.7 μm.
The LED 2 is driven by the light emission driving circuit 6 and the output signal of the light receiving unit 4 is amplified by the amplifier circuit 7.

The control unit 8 stores the signal sampled and read from the amplifier circuit 7 in the storage unit as the measurement data A, and the detection target 12 is detected based on the preset value from the measurement data A in the storage unit. Judge the water content.

The embodiment shown in FIG. 5 is effective when there is no change in the detection distance to the detection target 12 and the amount of light emitted from the light emitting section 2 and does not require very high accuracy.
Therefore, the cost of parts can be reduced and the size of the detection device 5 can be reduced.

In the above embodiment, the object to be detected may be something other than paper, such as cloth or toner.

FIG. 6 is a diagram for explaining one embodiment of a “moisture content measuring device” using near infrared light according to claims 1, 2, 3, and 5. That is, in (a) schematically showing the embodiment, the water content measuring device 1A is a device for measuring the water content of the measurement target 13, and includes the light emitting section 14, the light emission drive circuit 37, the light receiving element 35, and the amplification circuit. 38, transmissive condensing optical system 34, control unit 120, input unit 9A, output unit 10
A and the display unit 11A. The measurement target 13 is the “transfer paper”.

The light emitting section 14 has two components as shown in FIG.
It has LEDs 141 and 142 as one light emitting source. Figure 6
As shown in (c), the LED 141 has a spectral emission intensity c-1 having a peak at 1.45 μm, and the LED 142 has
Spectral emission intensity having a peak in the near infrared region of 1.4 μm or less, for example, spectral emission intensity c− having a peak at 1.3 μm
It has a spectral emission intensity c-2 having a peak at 5 or 0.8 μm or less (claim 3). The LED 141 is an "InP-based LED" and realizes the above-described spectral emission intensity c-1.

As shown in FIG. 6B, the two light emitting elements LED141 and 142 in the light emitting section 14 are housed in the "same resin case" together with the common cathode 140, and as shown in FIG. As shown in the drawing, it is arranged in the central portion of the condensing optical system 34 (claim 4), and the driving lead wires 32, 3 are provided.
By passing a drive current by 3, it is possible to emit light independently of each other.

When the LED 141 is made to emit light, the above "1.
Near-infrared light having “spectral emission intensity having a peak at 45 μm” is applied to the measurement target 13 as indicated by the solid line in FIG. Further, when the LED 142 is caused to emit light, near-infrared light having the above-mentioned “spectral emission intensity having a peak in the near-infrared region of 1.4 μm or less (for example, spectral emission intensity c-5)” is shown in FIG. The measurement target 13 is irradiated as indicated by the broken line. The transparent condensing optical system 4 is a "silicon lens".
(Claim 5).

The "light receiving means" is the light receiving element 35 and the amplifier circuit 3.
The light receiving element 35 is arranged at a position where each reflected light from the measurement target 13 is condensed by the condensing optical system 34. The two types of reflected light (indicated by a solid line and a broken line) from the measurement target 13 have different wavelength regions from each other, so that the converging positions are slightly deviated from each other due to the “chromatic aberration” of the condensing optical system 34. In the vicinity of the condensing position of each reflected light, it is arranged at an appropriate position where each reflected light can be commonly received.

In this embodiment, the light receiving element 35 has the "I
As shown in FIG. 6C, the photodetector is an “nGaAs type” and has substantially uniform spectral sensitivity c-3 in the near infrared region of the wavelength region of 0.6 to 1.7 μm.

The output of the light receiving element 35 is amplified by the amplifier circuit 38, converted into a digital signal by the A / D converter 121 of the control unit 120, taken in through the I / O port 122, and stored as data in the RAM of the memory 124. Remembered.
The "capturing of the output of the light receiving means" is controlled by the CPU 123 and is performed "intermittently".

The CPU 123 also uses the I / O port 122.
The lead wires 32, 33 are driven by the light emission drive circuit 37 via
Via the two light sources in the light emitting part, that is, the LED 14
The blinking of 1,142 is controlled. The control unit 120, the light emission drive circuit 37, the input unit 9A, and the output unit 10A constitute "control processing means".

The display section 11A constitutes "display means" and displays the measured value as the processing result by the control processing means.
The display means can be configured as a "display and / or printer" or "voice display"
It is also possible to adopt a configuration for performing.

The moisture content measurement will be described below with reference to the "time chart" shown in FIG. 7 and the "flow charts" shown in FIGS. As shown in FIG. 8, when the power is turned “on” (step 81), the CPU 123 (FIG. 6A) follows the “initial setting program” stored in the ROM of the memory 124 to “initialize” the device. Setting processing (self-probing whether or not each part of the apparatus moves properly) is performed (step 82). The result of the desired setting process is displayed on the output unit 10 as “measurable” or “abnormal”.

When the initial setting process is completed and the state is "measurable", the measurement target 13 is set and the input unit 9
When execution is instructed by A (execution key of keyboard, measurement button, etc.), as shown in FIG. 8, this signal is determined as a "start signal" and measurement is started (step 8).
3).

Referring to the time chart of FIG. 7, when the measurement is started by the start signal, the CPU 123 takes in the output of the light receiving means (the signal obtained by amplifying the output of the light receiving element 35 by the amplifier circuit 38) in accordance with the "measurement program", and outputs the detection signal. :
It is stored in the RAM of the memory 124 as PD ₀ (see FIG. 8).
84).

Subsequently, the CPU 123 intermittently captures the output of the light receiving means, and sequentially causes the LEDs 141 and 142, which are the light emitting sources, to emit light in synchronization with the capture (steps 85 and 87 in FIG. 8). The output of the light receiving means when the LED 141 emits light is used as a detection signal: PD ₁
The output of the light receiving means when 2 emits light is a detection signal: PD ₂
Is taken in as. The signal “1 time” is emitted n times in synchronization with the light emission timing of the LED 142.

As shown in FIG. 8, detection signals: PD ₁ , P
Immediately after D ₂ is taken in, the previously taken in detection signal: PD ₀ is subtracted (steps 86 and 88 in FIG. 8: data read / calculation).

Thus, the calculation result: PD1 = PD ₁
-PD ₀ , PD ₂ = PD ₂ -PD ₀ are obtained, and these operation results: PD _{1 and} PD ₂ are stored in the RAM together with the signal n times: “1 time”. The above process is repeated a predetermined number of times (for example, 10 times).

In FIG. 7, the PD signal is a signal representing "timing of taking in light receiving means". Further, the signal “2 times, 3 times, ..., N times” is sequentially generated for each repetition.

Three detection signals: PD ₀ , PD ₁ and PD ₂ are obtained as data for each one of the n times of the iterative process, and n times of these, ie, “3n” are obtained in the n times of repetition.
Will be obtained. When the repetition of n times is completed, the RAM of the memory 124 stores “calculation result: n PD1 and calculation result: PD2 n” obtained from the 3n pieces of data.

Then, as shown in FIG. 8, the calculation result: P
Calculate D1 and PD2 respectively: ΣPD1 / n, ΣPD
"Average" by 2 / n, and the result is PD
_1n , PD _2n, and calculation for these: PD _1n / P
_D2n is executed (step 90). This operation: PD
The result of _{1 n 2} / PD _{2 n} (hereinafter, referred to as X) includes information on the water content of the measurement target 13.

In the ROM of the memory 124 of the control unit 120, the "relationship between X and the moisture content (%)" that has been experimentally determined in advance is stored as a "table", and the calculation result: X is the above. The “moisture content” in the measurement target 13 is determined by comparing and comparing with the contents of the table (step 91 in FIG. 8: data comparison).

This "data comparison" is shown as a flow chart in FIG. 9 (a). First, it is determined whether or not it is a detection output (step 911), and then the above X = PD _1n.
/ PD _2n is compared with the moisture content data in the table (step 912). It is determined whether or not the result is an appropriate value (within range) as the water content (step 91).
3) If it is within the range, the water content in the table corresponding to X is specified by "% display". This moisture content is displayed on the display unit 1 which is "display means" as shown in the flow chart of FIG.
1A (FIG. 6 (a)) (step 95 in FIG. 8). The water content may be output to the output unit 10A as needed.

In FIG. 9A, if the detection output is not output or if the output is not within the above range, "abnormality display" is performed (step 914). In this case, "abnormal" means that when the reflected light cannot be received because the distance between the measurement target and the light emitting source is not appropriate, or when the ambient light is strong and the light receiving state of the light receiving element 35 is saturated, the measurement ( It is conceivable that the detection signal greatly changes due to a change in the distance relationship between the measurement target and the light emitting source (during repeating n times).

Although the abnormal display is displayed on the output unit 10A, this display may be displayed by an acoustic display such as a buzzer or together with the acoustic display.

In the above description, the data comparison is performed according to the table that gives the "correspondence relationship between X and moisture content", but as shown in FIG. 10, the relationship between moisture content and X (a large number of reference moisture content contents is used). According to the experimentally set correspondence between X and X) (see FIG. 10 for example) set by regression analysis.
Is stored as an arithmetic expression and the calculated value:
When X is obtained, this X may be substituted into the above formula to obtain the water content by calculation. When there are a plurality of types of measurement targets, the above table or arithmetic expression is prepared for each type of measurement target.

The water content of the measurement object is "4% or less or 10
In some cases, the control target is controlled according to an instruction value such as "% or more". Also, as a result of measuring the water content of the measurement target, when it seems that an error occurs in the proportional relationship between “X” and the comparison value (data in the table) in the data comparison (condensing optical system, light emitting source, light receiving element May occur due to dirt, etc.).

In the latter case, step 93 in FIG.
Data (shown in detail in FIG. 9B) from the input section:
Regression variance calculation is performed on X to "correct proportionality"
Is performed (step 933 in FIG. 9B). In the former case, the instruction value is input from the input unit 9A as “external input” (step 931 in FIG. 9B), for example, 10 ≧
If X ≧ 4 (data coincidence) is not satisfied, "abnormality display" is performed (step 934 in the figure).

The "external input" is also used to specify the measurement target species when there are a plurality of measurement targets. The input unit 9A can be used also as an input for storing a plurality of measurement data in the memory 124, and the output unit 10A can be used as an output unit for overwriting similar data and a change state due to environmental fluctuation of a measurement target.

The moisture content of the measurement target is affected by ambient light, the temperature of the measurement target and the temperature of the measurement environment, etc. Preliminary adjustments (zero-point calibration, etc.) had to be performed, and the measurement efficiency was poor.

In the invention described in claims 1 to 6, the detection signal: PD ₀ of the light receiving means in the "state where the object to be measured is not illuminated by the light emitting source" is detected during measurement. Detection signal: P
The influence of ambient light, the influence of temperature, and the like are included in D _j as information, and the influence of ambient light or temperature can be automatically removed by subtracting PD ₀ from the detection signal: PD _j . Therefore, in the present invention, there is no need for pre-adjustment such as 0-point calibration.

In addition, since n groups are detected with "PD ₀ , PD _j " as a data group in the detection signal and the moisture content is measured by processing these data, the ambient light and the measurement environment change with time. However, it is possible to perform accurate and appropriate measurement. The number of repetitions: n is set so that the measurement accuracy matches the "required accuracy".

Further, a light-emitting source that emits near-infrared light having a short wavelength is on the short wavelength side of the spectral emission intensity c-2, as shown by the broken line spectral emission intensity c-4 in FIG. 6C. When the "visible region" has a spectral emission intensity (broken line portion), the "irradiated portion of the measurement target" can be visually confirmed by the visible light component during measurement.

In the above embodiment, the two light emitting parts are housed in the same container, but FIG. 10 (a: plan view, b: side view).
LED1 which is two light emitting elements like the embodiment shown in FIG.
41 and 142 may be separately provided. 6 and 11
In the above, the light emitting portion is arranged in the central portion of the condensing optical system 4,
Not limited to this, each light emitting unit may be arranged at an appropriate position, and for example, near infrared light may be radiated to the measurement target in an oblique direction.

It should be additionally noted that it is possible to use a third light source having a spectral emission intensity in the visible region instead of the light source having a spectral emission intensity in the "visible region".

[0103]

As described above, according to the invention described in claims 1 to 6, in the method or apparatus for measuring water content,
Simple and quick accurate moisture content measurement can be realized for the transfer paper to be measured.

[Brief description of drawings]

FIG. 1 is a block diagram showing a form of a reference example.

FIG. 2 is a diagram showing spectral characteristics of a light emitting unit and a light receiving unit in the form of FIG.

FIG. 3 is a flowchart showing an operation flow of the configuration shown in FIG.

FIG. 4 is a flowchart showing in detail a part of the flowchart of FIG.

FIG. 5 is a schematic view showing another characteristic example of another reference embodiment.

FIG. 6 is a diagram for explaining an example of an embodiment of the moisture content measuring apparatus according to claims 1, 2, 3, and 5.

FIG. 7 is a time chart of moisture content measurement in the embodiment of FIG.

FIG. 8 is a flowchart showing a procedure for measuring water content in the embodiment shown in FIG.

9 is a flowchart showing details of a part of the flowchart shown in FIG. 8. FIG.

FIG. 10 is a diagram for explaining an example of an arithmetic expression of water content.

FIG. 11 is a diagram for explaining a characteristic portion of another embodiment of the invention according to claim 5;

[Explanation of symbols]

1 Moisture content measuring device 2,3 light emitting part 4 Light receiving part 5 Detector 6 Light emission drive circuit 7 amplification circuit 8 control unit 12 detection target

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 PATOLIS

Claims (6)

(57) [Claims] 1. A transfer paper as a measurement object is sequentially irradiated with two types of near-infrared light having wavelengths or wavelength ranges different in water absorption, and reflected light from the measurement object is converted into a detection signal by a light receiving means. A method for measuring the moisture content as data on the moisture content of a measurement target, in which two types of near-infrared light are transferred from two emission sources, which are the measurement targets.
Together so as to irradiate the transfer paper, the light reflected by the measurement target so as to condense the single light receiving means by the transmission of the light converging optical system, while intermittently receives the output of the light receiving means, the 2 pieces <br/> emitting source by causing sequentially emit light in synchronism with the incorporation of, as a detection signal of the light receiving means, any of the detection signal in the state in which the light emitting source also not emitting light: a PD _0, the j
Detection when the (1 ≦ j ≦ 2) th light-emitting source emits light
Signal: PD _j and (1 + 2) detection signals
Is repeated n (≧ 2) times, and at each repetition
To, Starring the _{PD1 = PD 1 -PD 0, PD2} = PD 2 -PD 0
Then, n sets of PD1 and PD2 are obtained, and an average value for these n sets of PD1 and PD2: PD _1n =
ΣPD1 / n, PD _2n = ΣPD2 / n, and
PD _1n, the PD _2n, calculating the X = PD _1n / PD _2n
Calculation result: A table that predetermines the relationship between X and moisture content
And the above calculation result: X are compared and detected to detect the moisture content in the measurement target. 2. A transfer paper as a measurement target is sequentially irradiated with two types of near-infrared light having wavelengths or wavelength ranges having different absorptions by water, and reflected light from the measurement target is converted into a detection signal by a light receiving means. A device for measuring moisture content as data concerning the moisture content of a measurement target, which has two wavelengths or wavelength ranges with different water absorptions.
Single for receiving the two light emitting source for irradiating the transfer paper is a near-infrared light seeds are separately emitted to the measuring object, the two infrared light, the light reflected by the transfer sheet to be measured One light receiving unit, a transmissive condensing optical system for converging each reflected light from the measurement target on the light receiving unit, and a state in which none of the light emitting sources emit light as a detection signal of the light receiving unit. Detection signal at the time of: PD ₀ and the j-th (1
The light receiving means so as to generate (1 + 2) detection signals by the detection signal: PD _j when the ≦ j ≦ 2) -th light emitting source is emitting light, for a predetermined n (≧ 2) times. While intermittently controlling the output of the above, the two light emitting sources are sequentially controlled to emit light in synchronization with the above capturing, and data processing is performed using the obtained n · (1 + 2) detection signals as data, and measurement is performed. It has a control processing means for detecting the water content in the object and a display means for displaying the water content detected by this control processing means, and the control processing means performs the detection operation every n times.
Output signal: by _{PD 0, PD j, PD1 =} PD 1 -PD 0,
PD2 = PD ₂ −PD ₀ is calculated to obtain n sets of PD1 and PD
2 is obtained, and the average value is P for these n sets of PD1 and PD2: P
Obtain D _1n = ΣPD1 / n, PD _2n = ΣPD2 / n
Therefore, by these PD _1n and PD _2n , X = PD _1n / PD
_2n is calculated, and the calculation result: X and moisture content are determined in advance.
Measured by comparing and comparing the above table and the above calculation result: X
Along with the function of detecting the water content in the target , regression calculation is performed on X to obtain the X and the table.
A moisture content measuring device using near-infrared light, which has a function of correcting a proportional relationship with data in a bull . 3. A moisture content measuring apparatus according to claim 2, wherein, among the two light-emitting sources, one light emitting source is a light emitting element having a peak of spectral luminous intensity 1.45 .mu.m, the other light emitting source An apparatus for measuring moisture content by near infrared light, which is a light emitting element having a peak of spectral emission intensity in the near infrared region of 1.4 μm or less. 4. The near-infrared device according to claim 2 , wherein two light emitting sources are housed in the same resin case and arranged in the center of the condensing optical system. Moisture content measuring device by light. 5. The moisture content measuring apparatus according to claim 2, 3 or 4, wherein the transparent condensing optical system is a silicon lens. 6. The moisture content measuring apparatus according to claim 2, 3 or 4 or 5, wherein the transparent condensing optical system is a hologram lens.