JPH03111925A - Method for detecting movement of speckle pattern and position specifying device using the same - Google Patents

Abstract

PURPOSE:To stabilize movement detecting operation even to a production error by restricting the average size of speckles on the light receiving face of a photodetector within a prescribed area and holding a detected moving ration at an almost fixed value. CONSTITUTION:Since the average size D of speckle patterns on the light receiving face of the photodetetor 2 is included within the prescribed area E, the moving ratio J detected by the photodetector 2 is held at the almost fixed value even if the average size of speckles is slightly changed. When the speckle pattern SP is moved in the arrow direction at a fixed velocity (v) in the case of using the photodetector 2 consisting of a pair of photodetecting elements 2a, 2b, signal intensity detected by one photodetecting element 2a positioned on the prestige in the moving direction of the speckle pattern is almost the same as the photodetecting element 2a positioned on the post stage in the moving direction before only a certain time tau.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a speckle pattern movement detection method for detecting movement information of a speckle pattern caused by scattering of coherent electromagnetic waves on a rough surface of an object, and a speckle pattern movement detection method using the same. This invention relates to the improvement of a position specifying device (a position specifying device useful for specifying a position on a display screen in a computer terminal, a workstation, a personal computer, etc., or specifying a position for various controlled objects).

[Conventional technology]

As an example of a conventional position specifying device for computer input, a so-called mouse is widely used because it is inexpensive, easy to operate, and has high position specifying accuracy.

The current mainstream mechanical mouse has a ball protruding from a part of the housing that can rotate in any direction, and the direction and amount of movement can be detected based on the direction and amount of rotation of this ball. , to specify the position to be specified.

[Problem to be Solved by the Invention 1] However, since such conventional mechanical mice utilize contact rotation of a mechanical ball, there are problems in terms of durability, and there are also problems with positional accuracy. There are limits to improvement.

An optical mouse that optically detects movement information in a non-contact manner has already been provided as a solution to the drawbacks of mechanical mice.

This type of optical mouse is disclosed in Japanese Patent Application Laid-Open No. 5710792, for example.
No. 9, as shown in Publication No. 57-207930,
It includes a main body in which a light source and a photodetector are housed,
Movement information is detected by moving the main body on a dedicated underlay stamped with a regular grid pattern and counting the number of grids on the dedicated underlay that it crosses during movement.

However, this type of optical mouse requires a special underlay, which not only limits the freedom of use, but also makes it unusable if the underlay gets dirty or damaged, which reduces its durability. Even points are not enough (, furthermore,
The resolution of movement information detection is determined by the fineness of the grid engraved on the dedicated underlay, so it is not easy to increase the resolution of movement information without increasing costs.

In order to solve these problems, the inventor of the present invention aims to reduce the cost of the device itself, improve operability and durability, and use a special underlay by detecting movement information of so-called speckle patterns. However, a position specifying device that can easily increase the resolution of movement information detection has already been provided (see Japanese Patent Application No. 116878/1983).

However, in such a position specifying device, the detection accuracy of speckle pattern movement information itself affects the position specification accuracy, but various optical system factors such as the length of the optical path and the position of the beam waist There are variations in the top,
If it fluctuates during use, the detection accuracy of the movement information of the speckle pattern will vary, which causes the problem that the position designation operation tends to become unstable.

Note that this problem is not limited to the mouse mentioned above.
Various devices (movement detection devices,
The same problem can occur in speed detection devices, etc.).

The present invention has been made from the above viewpoint, and provides a speckle pattern movement detection method that can improve speckle pattern movement detection accuracy, and a method for stabilizing position specifying operation using the same. A position specifying device is provided.

[Means to solve the problem]

0 Experimental analysis to solve the problem In order to solve the above problem, the present inventor focused on the average size of speckles among the properties of the speckles themselves that form the speckle pattern, and conducted the following experiment. I did it.

(1) Experimental details When speckles of a predetermined size are moved under predetermined conditions, the movement information of this speckle pattern is processed by a processing system as appropriate, and based on this processed data, for example, the data is displayed on a personal computer. An experimental system (Figure 2) was constructed to move a cursor on the screen, and the cursor movement rate K (the ratio of the actual cursor movement amount to the rough surface movement amount for generating a moving speckle pattern) and speckle We investigated the relationship between the average size of

(2) Experimental system In FIG. 2, reference numeral 10 is a He-Ne laser, 11 is a condensing lens that condenses the beam Bm from the laser 10, and 1
2 is a rough moving plate that is irradiated with the laser beam Bm focused by the condenser lens 11 and moves by a predetermined amount xd in a predetermined direction (in this example, the X direction) at a predetermined speed v, i; 13 is scattered by the rough moving plate 12, and the moving speed V3
A detector consisting of a pair of photodiodes 13a and 13b arranged in parallel along the X direction to detect the speckle pattern SP moving by X at . (t ds
: Frequency 9M: Amplifier that amplifies the number of vibrations (number of signal peaks 1), 15 (specifically 15a).

15b) is a binarization circuit that binarizes the output from each amplifier 14 using an appropriate threshold value.

Further, 16 is a personal computer, which includes an arithmetic processing section 19 that performs arithmetic processing on how to move the cursor 18 on the display screen 17. This arithmetic processing unit 19 inputs the output from each binarization circuit 15, determines the direction of movement of the cursor 18 from the sign of the phase difference τ between the two, and changes the number of pulses of the binarization signal in the direction of movement. It is provided with an up/down counter that counts up or down accordingly, and moves the cursor 17 by N to a position according to the output of this counter.

(3) Experimental conditions In Figures 2 and 3, Laser beam wavelength λ: 632.8 nm Photodiode spacing: 0.3 mm Photodiode aperture size: 0.295 mm Radius of beam waist Bw ω. :9.7μm speckle rigidity η:
10 However, if the speckle translation distance is LT and the average speckle size is D, then η=L/D
...(1).

Here, as shown in FIG. 4, the speckle translation distance L1 refers to the spatial cross-correlation function γ(×
) (x is the spatial shift amount) (speckle movement amount x C0<X, <X2 <X3 <X (<X5
] is the peak height of the cross-correlation function of the stationary speckle, γ,. The amount of speckle movement when the value becomes 1/e (e: base of natural logarithm) is N, Takai,
T, Iwai & T, Asakura, Applie
d 0ptics Vo122 No. 1 (1983)
Pages 170-177' Correlation dis
tance of dynamic speckles'
), when the speckle moves without deformation LT=
(2), and when the speckles are only deformed and do not move, it is LT-0. Therefore, the speckle rigidity η obtained by normalizing the speckle translation distance L1 by the speckle average size D serves as an index indicating the difficulty of speckle deformation.

According to the above literature, in the case of Gaussian speckle that occurs when a so-called Gaussian beam is scattered by unevenness that is sufficiently deeper than the wavelength, the speckle of the diffraction field (scattering in free space without going through an imaging system) is The speckle translation distance LT is L = (1 + R / ρ) ω ... (
2) However, R is the distance from the rough moving plate 12 to the detection surface position of the speckle pattern SP, and ρ is the rough moving plate 12
The radius of curvature of the wavefront of the laser beam Bm in is the radius of curvature of the wavefront of the laser beam Bm, and ω is the spot radius of the laser beam Bm on the rough moving plate 12.

Further, the average speckle size D corresponds to the average speckle radius, and is expressed as D=λR/πω (3).

Therefore, by substituting equations (2) and (3) into equation (1), η=(1+R/ρ)ω/(λR/πω)=(πω2/λ
) (1/R+1/ρ)...(4) Here, +1/R
1< 11/ρ That is, IRI > Iρ1...
Assuming (5), the above equation (4) becomes ηtransport πω2/(λρ) (4').

Also, the beam waist B narrowed down by the condensing lens 11
Z is the distance from w to the rough moving plate 12.

a=πω. '/λ, then ω=ωo v' (1+ (z/a) 2) ...(
6) o=z [1+ (a/z) ” ] River (7
), and by substituting equations (6) and (7) into equation (4') above, xωo
! z fl + (z/a) ” ]η = λ a2 [1+ (z/a) 2] = z /
a −λz/(πω.)2ocz... (
8) Here, assuming that 2 above is sufficiently large, (a/
z)"< 1, and considering the above equation (7), the above equation (5) holds because normally 1, ol ζlzl
, IRI > lzl - (9).

To summarize the above, the rough surface is far from the beam waist Bw, and compared to the distance 2 between the beam waist Bw and the rough surface,
When the distance R between the rough surface and the detection surface is sufficiently long, it can be said that the speckle rigidity η is proportional to the above Z.

In addition, in this experiment, the speckle average size D
is expressed by the above equation (3).

Here, assuming that the above Z is sufficiently large, 1((λ2
/πω. ')2...(10).

Therefore, from equations (6) and (10), ω-. (λ2/πω.′) =λ2/πω. ...(11) holds true.

Therefore, by substituting this equation (11) into the above equation (3), we get D! =t(λR/π) (πω./λ2)=Rω.

/2　　　　　　...(12) is approximated.

In summary, when the rough surface is far from the beam waist Bw, the average speckle size D is proportional to the distance R between the rough surface and the detection surface, regardless of the wavelength λ, and the distance between the beam waist) Bw and the rough surface 2. It can be said that it is inversely proportional.

In this experiment, by appropriately adjusting R and z based on equations (3) and (4) above, the speckle rigidity η was uniquely set, and the numerical value of the average speckle size D was variably set. did.

(4) Experimental Results The relationship between the average speckle size D and the cursor movement rate is shown in FIG.

According to the same figure, the average speckle size D is 0 to 600μ.
It is understood that the cursor movement rate tends to increase proportionally up to approximately m, but the cursor movement rate remains approximately constant from around the point where the average speckle size D exceeds 600 μm.

This means that if the average speckle size D is preset in the region E exceeding 600 μm, even if the average speckle size D changes slightly for some reason, the cursor movement rate K will change accordingly. It means there is no.

0 Theoretical analysis for problem solving (1) Basic model system FIG. 6 is a model of the experimental system shown in FIG.

In addition, in the subsequent analysis, the speckle pattern SP
When considering only the amount of movement without considering the direction of movement, there is no essential difference from using only one photodiode as a detector. In addition, speckle deformation is considered to be negligible.

By doing so, in theoretically analyzing the model system, it becomes possible to make the movement information of an undeformed image equivalent to that detected by a spatial filter. In order to apply the speed measurement method using a spatial filter, in the analysis, instead of the cursor movement amount, speckle movement amount, and rough surface movement amount, we consider the cursor speed, speckle speed, and rough surface speed, respectively. , if the amount of movement is required, the velocity is integrated over time.

In the figure, the cursor speed p is as follows: p=-v, (13) However, K=: -K2, K, (14).

Here, K: Cursor movement rate: 1: Speckle speed/Rough surface speed ratio (referred to as speckle movement rate) K2: Average frequency of detector signal/Speckle speed ratio: 3: Cursor speed/Detector signal ratio Represents the ratio of average frequencies.

Furthermore, by integrating the above equation (13), the following equation for the cursor movement amount N can be found.

1'J = K-x a...(
15) However, X is the amount of movement of the rough surface.

(2) Each coefficient of the cursor movement rate (2-a) Regarding Kl and Kj, the speckle movement rate K is, due to the characteristics of dynamic speckle, in the case of Gaussian speckle, it is usually expressed by the following formula % formula % (16) Equation (9) above 1ρl = lzl, IRI>l
Considering z, the above equation (16) is approximated as K,=1+R/z=R/z (17).

That is, under the above approximation, the speckle movement rate is proportional to the distance R from the rough surface to the detection surface and inversely proportional to the distance 2 from the beam waist Bw to the rough surface, without being influenced by the wavelength.

Further, K3 is a constant determined by the computer interface, etc.

(2-b) Regarding K2, 2 represents the characteristic of the detector as a spatial filter.

Now, if we do not consider the deformation of speckles, then the velocity V,
According to the theory of velocity detection using a spatial filter, the output of the detector placed inside the speckle is W (fd,) = Φ (L, / v -) ・Ω (fd
−/v, )...(18) It is expressed as follows.

Here, tF(fd=) is the time-frequency power spectrum of the output signal of the detector, Φ(ξ) is the spatial-frequency power spectrum of the speckle, Ω(ξ) is the spatial-frequency power spectrum of the detector, and f ds is the time-frequency power spectrum of the detector. Frequency and ξ indicate spatial frequencies, respectively.

According to equation (18), the overlap between the time-frequency power spectrum of the speckle and the time-frequency power spectrum of the detector is obtained as the output signal of the detector.

Therefore, as shown in FIG. 7, if the size of the speckle S is sufficiently larger than the aperture d of the detector 13,
In other words, as shown in FIG. 8, if the spread of the spatial frequency power spectrum Φ (ξ) of the speckle is sufficiently smaller than the spread of the spatial frequency power spectrum Ω (ξ) of the detector, the output of the detector 13 is The signal is determined by the speckle velocity V and the speckle spatial frequency power spectrum Φ(ξ), and not by the detector spatial frequency power spectrum.

Then, Φ(ξ) can be found as follows.

Φ(ξ) =a+exp(-82D21ξ12)...
(19) However, in the above equation (19), the maximum value (correlation peak value) is normalized to be 1, and al+82 is a constant.

Therefore, the spread of the spatial frequency power spectrum of speckles is proportional to 1/D, and as a result, the spread of the time frequency power spectrum of the output signal of the detector is proportional to v,/D.

Therefore, K2 is: K2 = f as / V - "l / D
...(20). However, f ds is the time average of fa+.

Then, by substituting the above-mentioned equation (12) into this equation (20), K2(X:Z/Rωo - (21) is established.

(3) Conclusion When the cursor movement rate K is calculated based on the coefficients of the cursor movement rate detailed in (2) above, the result is as follows.

That is, from equations (14), (17), and (21), K=to, -2　・K3 ” (R/z) (Z/Rω.)・K.

-K3/ω. It becomes (22).

Here, K3. Since ω0 is a constant, it can be said that the cursor movement rate is constant.

In summary, it has been theoretically supported that when the average size D of speckles is sufficiently larger than the aperture size d of the detector 13, the cursor movement rate is kept constant.

◎Summary of the Invention The present inventor has devised the present invention through the above-mentioned experimental and theoretical analysis.

That is, as shown in FIG. 1(a), the method for detecting movement of a speckle pattern according to the present invention optically detects movement information M of a speckle pattern SP generated by scattering of a coherent electromagnetic wave Bm against a rough object surface 1. When detecting with the photodetector 2, the average size D of speckles in the speckle pattern SP on the light-receiving surface of the photodetector 2, relative movement information of the photodetector 2 with respect to the object rough surface 1, and the photodetector 2
The average size D of the speckles is set within a range E in which the detected movement rate J is kept substantially constant in relation to the detected movement rate J indicating the ratio to the output movement information of be.

In such a method invention, the movement information M of the speckle pattern SP is not limited to only the movement amount, but broadly includes movement speed, movement acceleration, etc. Therefore, in addition to the position specifying device described below, this method invention can be applied to other speed detecting devices such as movement amount detecting devices and speed sensors that are necessary for controlling the position of self-propelled carts, etc. Can be mentioned.

In addition, the speckle pattern SP is shown in Fig. 1(a).
As shown in , only speckles in the so-called diffraction field without an imaging system, which are caused by scattering on the object's rough surface 1, are targeted, and the scattered light on the object's rough surface 1 is imaged on a predetermined part using an imaging lens. What is caused by so-called image field speckles is not a target because the speckle velocity/rough surface velocity (corresponding to 1 above) is different from the above-mentioned one.

Furthermore, the photodetector 2 may be selected as appropriate as long as it can detect the movement information of the speckle pattern SP, and the signal processing system from the photodetector 2 may also be a target device. You may change the design as appropriate.

Here, regarding the photodetector 2, from the viewpoint of easy real-time processing and accurate determination of the movement information M including the positive and negative of the movement direction of the speckle pattern SP, it is difficult to perform real-time processing as shown in FIG. As shown in FIG.
), it is preferable to configure so that the phase difference τ between the output signals from a pair of photodetecting elements 2 a and 2 b is detected.

In this case, when detecting -dimensional movement information, one set of photodetecting elements 2 a,
For example, two or three sets of photodetecting elements 2a, 2b may be used so that the straight lines connecting the photodetecting elements 2a, 2b are perpendicular to each other. This makes it possible to detect two-dimensional or three-dimensional movement information.

Furthermore, the processing system for processing the output signal from the photodetector 2 consisting of the pair of photodetecting elements 2 a and 2 b may be selected as appropriate, but the obtained phase difference τ
From the viewpoint of reducing the influence of errors caused by the irregularity of the speckle pattern SP, a plurality of sets of photodetecting elements 2a and 2b are used per one dimension, and each set of photodetecting elements 2a , 2b, each phase difference τ obtained from
or take the average of a pair of photodetecting elements 2a, 2b.
It is preferable to adopt a configuration in which the time average of the phase difference τ obtained from τ is taken or a combination of both is used.

Further, the invention of a position specifying device using the speckle pattern movement detection method described above includes a movable body 3 movable with respect to the rough surface 1 of the object, and a movable body 3 that An electromagnetic wave source 4 that is incorporated in the movable body 3 and irradiates a coherent electromagnetic wave Bm from a predetermined portion of the movable body 3 to the rough surface 1 of the object; and speckles that are incorporated in the movable body 3 and that are generated from the rough surface 1 of the object due to the irradiation of the electromagnetic wave Bm. A photodetector 2 that detects relative movement information of the pattern SP with respect to the movable body 3, an average size D of speckles in the speckle pattern SP on the light-receiving surface of the photodetector 2, and an object rough surface of the photodetector 2. In the relationship with the detection movement rate J indicating the ratio of the relative movement information with respect to 1 and the output movement information of the photodetector 2, the average size D of the speckles is within a range E where the detection movement rate J is kept approximately constant. A speckle size setting means 5 is provided for setting a speckle size, and a position to be specified is specified based on relative movement information detected by the photodetector 2.

In such a device invention, the photodetector 2 may be appropriately selected as described in the method invention, and the output signal detected by the photodetector 2 may be selected as appropriate. The location of the processing system may be selected as appropriate, such as external equipment, the movable body 3, or equipment connected to external equipment, but from the perspective of sharing it with various external devices, it is best to place it within the movable body 3. It is preferable to provide a signal processing system.

Further, as the speckle size setting means 5, as long as the average size D of speckles can be arbitrarily set, a lens that narrows down the electromagnetic wave Bm directed from the electromagnetic wave source 4 toward the object rough surface 1 may be appropriately selected. , appropriately selecting the distance between the object rough surface 1 and the photodetector 2.

[Effect]

In the above-mentioned technical means, according to the method invention shown in FIG. The detection movement rate J by the detector 2 is kept substantially constant even with slight variations in the average size of speckles.

In particular, a set of photodetecting elements 2a as shown in FIG. 1(b)
, 2b (the spacing between their centers is g), the speckle pattern SP (assumed to be extremely small in deformation) now moves in the direction of the arrow at a constant speed V. If so, the signal intensity detected by one of the photodetecting elements 2a located at the front stage in the moving direction will be τ for a certain period of time.
This is approximately the same as the photodetecting element 2b located at the rear stage in the moving direction of the isperacle pattern.

In this case, as shown in FIG. 1(c), the time variation curve of the output signals of the pair of photodetecting elements 2a and 2b is as follows:
They are similar to each other and shifted by a phase difference τ, and the phase difference τ
is determined by τ=g/v.

Therefore, from the information on the phase difference τ, the speckle pattern S
It is possible to determine whether the moving direction of the spec pattern SP is positive or negative from each movement information of P, for example the sign of τ, and from its absolute value it is possible to determine the magnitude of the movement speed V. Furthermore, the rise of the output signal, By counting the falling edges, the amount of movement of the speckle pattern SP can be determined.

Further, according to the position specifying device invention shown in FIG. 1(d),
An electromagnetic wave Bm is irradiated from an electromagnetic wave source 4 such as a laser to the rough surface 1 of the object, and the movable body 3 moves at a speed V, U, with respect to the rough surface 1 of the object.
If the object's rough surface 1 moves by a distance U, the object rough surface 1 will move relative to the movable body 3 by an amount U at a speed V.

At this time, the speckle pattern SP scattered by the rough object surface 1 moves on the light receiving surface of the photodetector 2 at a speed of V and U as the rough object surface 1 moves relative to each other.

move proportionally.

Therefore, the photodetector 2 has the speckle pattern S.
By detecting the movement information of P at a predetermined detection movement rate J, the relative movement amount of the object rough surface 1 is indirectly detected, and the position of the designated object is determined based on this detection information. It is specified.

At this time, the speckle size setting means 5 sets the average size of the speckles on the light receiving surface of the photodetector 2 within the predetermined area E, so that the detection movement rate J by the photodetector 2 is the average size of the speckles. It remains approximately constant even with slight variations in size.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

9 and 10 show the present invention applied to a computer input mouse.

In the figure, reference numeral 30 denotes a rough surface of the object, 31 a movable housing having a sliding pressing pad 32 at the bottom, 33 a semiconductor laser as an electromagnetic wave source housed in the movable housing 31 and irradiating a laser beam Bm; 34 is a plastic lens that guides the beam Bm from the semiconductor laser 33 to the irradiation area Q of the object rough surface 30 at a predetermined spot radius ω;
A condensing lens such as a Fresnel lens, 35 is a reflection mirror that appropriately reflects the reflected beam from the object rough surface 30 in order to ensure the optical path length of the detection optical system, and 36 is disposed at the end of the optical path of the detection optical system. Detector 37 detects movement information of the speckle pattern SP generated in the reflected beam from the object rough surface 30; 37 is a signal processing system that converts the output signal from the detector 36 into a movement control signal for computer input; 38 Reference numeral 39 indicates an input switch for performing a position designation operation, and 39 indicates a connection harness to an external device (not shown).

In this embodiment, the detector 36 is particularly
As shown in FIG. 1, light-receiving cells 36a to 36d made of photodiodes are arranged side by side in the X direction, which is the movement reference direction, and spaced apart by a predetermined distance along the X direction.

In this case, the condenser lens 34 is used to obtain an appropriate radius ω0 of the beam waist Bw, which is the beam waist radius ω. , the distance Z between the beam waist t-Bw and the object rough surface 30 and the distance R between the object rough surface 30 and the detector 36 are determined by
The average size of speckles on d is set to be five times the aperture area of each of the light receiving cells 36a to 36d.

Further, the signal processing system 37 includes light receiving cells 36a arranged in parallel in the X direction, particularly as shown in FIG.

It is comprised of an X component signal processing system 37x that processes signals from 36b, and a y component signal processing system 37Y that processes signals from light receiving cells 36a and 36C arranged in parallel in the X direction.

In this embodiment, the signal processing system 37 includes a corresponding set of light receiving cells 36a, 36b, or 36a.

An amplifier 41 that amplifies the output of 36c, and this amplifier 41
It consists of a cut filter 42 that removes DC components, noise, and high frequency components of the output of the cut filter 42, and a binarization circuit 43 that binarizes the output of the cut filter 42 with a threshold value of 0.

Furthermore, in this embodiment, the signal from the signal processing system 37 is input to the arithmetic processing section 51 in the computer 50, and this arithmetic processing section 51 converts the X component of the output from the binarization circuit 43,
Phase difference in the X direction τ8. τ.

The direction of movement is determined from the sign of , the number of pulses of the binary signal is counted up or down depending on the direction of movement, and based on this count value, the relative movement of the speckle pattern SP with respect to the object rough surface 3o is determined. The information is determined and the cursor 53 on the display screen 52 is moved in accordance with this movement information.
The location has been determined.

Next, the operation of the position specifying device according to this embodiment will be explained.

Now, the laser beam Bm irradiated from the semiconductor laser 33
reaches the detector 36 after being reflected by the rough surface 30 of the object, and a speckle pattern S is formed on the detector 36.
P is occurring.

In this state, when the movable housing 31 is moved on the object rough surface 30, the detector 36
The speckle pattern SP on each of the light receiving cells 36a to 36d moves. The X-direction component of the movement of this speckle pattern SP corresponds to a set of three
6a, 36b, and the X direction component of the movement of the speckle pattern SP is detected by a pair of light receiving cells 36a, 36c arranged in parallel along the X direction.

Here, since the detection operations for each movement component of the speckle pattern SP are substantially the same, the movement detection operation for the X-direction component will be described below.

That is, in FIG. 12, when the speckle pattern SP moves from the light receiving cell 36a to the light receiving cell 36b,
The output signal of the light receiving cell 36a varies according to the movement of the speckle pattern SP.

At this time, if the deformation of the speckle pattern SP can be ignored, the adjacent light-receiving cell 36b has approximately the same form as the output signal of the light-receiving cell 36a for a time τ, as shown in FIG. 13(a). You will get a delayed signal.

This output signal is input to the X component signal processing system 37x,
After being amplified by the amplifier 41, as shown in FIG. 13(b), the cut filter 42 converts the signals into m and n signals that cross the 0 line, and then as shown in FIG. 13(c). Then, the binarization circuit 43 converts m, n with the 0 line as a reference.
It is converted into two systems of binary signals. The binarized signal is then input to the arithmetic processing section 51.

In this case, the time delay τ is determined by the light receiving cell 36.
It is determined by the distance between a and 36b and the moving speed of the speckle pattern SP, and it is possible to determine whether the moving direction of the speckle pattern SP is positive or negative depending on the sign of τ8.

The number of peaks of the output signal of 36b is the same as that of each light receiving cell 36a.

In order to correspond to the number of speckle grains passing over 36b, by counting the number of teeth, it is possible to detect the magnitude of the movement of the speckle pattern SP, and from this, movement information can be obtained. be able to. The arithmetic processing unit 51 described above determines the moving direction and moving amount of the speckle pattern SP based on the above-described principle, and thereby sets the moving direction and moving amount of the cursor 53.

This arithmetic processing unit 5] is exactly the same as a conventional mechanical mouse or optical mouse, and this type of arithmetic processing unit 51 is usually incorporated into the interface of the computer 50.
The binarized signal in this embodiment can be directly input into a conventional mouse interface.

In evaluating the performance of the mouse according to this example, we investigated the changes in the cursor movement rate when the mouse according to the example was moved under certain conditions, and found that the cursor movement rate was approximately constant. It has been confirmed that it can be maintained.

Furthermore, in this embodiment, the detector 36 includes a plurality of sets of light receiving cells (not shown) in the X direction and in the X direction.
If the signal processing unit 37 can average the phase difference information based on the output from each set, it is possible to reduce the variation in the phase difference information based on the irregularity of the speckle pattern SP. It is possible.

〔Effect of the invention〕

As explained above, according to the speckle pattern movement detection method according to claim 1, the average size of the speckles on the light receiving surface of the photodetector is within a predetermined area, and the detection by the photodetector The movement rate can be kept almost constant even with slight variations in the average size of speckles, so even if the various constants of the optical system vary due to manufacturing errors in the movement detection device or change due to use, Also, the movement detection operation can be stabilized.

In particular, according to the method for detecting movement of a speckle pattern according to claim 2, temporal fluctuations of the speckle pattern are detected by at least one set of photodetecting elements arranged in parallel in the moving speckle pattern, and Since the movement information of the speckle pattern can be detected through simple processing such as determining the phase difference between the speckle patterns, real-time processing is easy, and various movement information including the movement direction of the speckle pattern can be easily obtained.

Further, according to the position specifying device according to claim 3, the relative movement information of the speckle pattern generated from the rough surface of the object with respect to the rough surface of the object is detected and the position to be specified is specified. It eliminates the need to use an underlay, which makes it easier to operate, and reduces the durability of conventional mechanical mice due to mechanically moving parts, and prevents use when the dedicated underlay becomes dirty or damaged. There are no more restrictions on
The durability of the device itself can be further improved, and
By appropriately setting the optical system harammeter between the electromagnetic wave source and the photodetector without being affected by the grid density of the dedicated underlay, it is possible to increase the resolution of movement information detection and improve position specification accuracy. be able to.

According to the position specifying device according to claim 3, the average size of speckles is set in a predetermined area by the speckle size setting means, so that the movement rate of the position specifying member with respect to fluctuations in the average size of speckles is Since fluctuations are avoided, it becomes possible to perform a position specifying operation with a constant movement rate at all times, and accordingly, a stable position specifying operation can be performed.

[Brief explanation of drawings]

FIG. 1(a) is an explanatory diagram showing the principle of the speckle pattern movement detection method according to the present invention, and FIGS. 1(b) and (c) are explanatory diagrams showing one embodiment of a photodetector and an explanation of its detection operation. 1(d) is an explanatory diagram showing the schematic configuration of a designated device according to the present invention, FIG. 2 is an explanatory diagram showing the experimental system conducted in devising this invention, and FIG. Figure 2 is a detailed view of the ■ part in Figure 2, Figure 4 is an explanatory diagram showing the concept of speckle translation distance, and Figure 5 shows the relationship between the average speckle size and cursor movement rate determined in the experimental system of Figure 2. Graph diagram showing,
FIG. 6 is an explanatory diagram modeling the experimental system of FIG. 2, FIG. 7 is a schematic explanatory diagram showing the relationship between speckles and a detector according to this invention, and FIG. 8 is a space of speckles according to this invention. 9 is a graph showing the relationship between the frequency power spectrum and the spatial frequency power spectrum of the detector; FIG. 9 is an explanatory diagram showing an embodiment of the mouse to which the present invention is applied; FIG.
The figure is a partially cutaway bottom view, FIG. 11 is an explanatory diagram showing the configuration of the detector according to the embodiment, FIG. 12 is a block diagram showing the signal processing system of the detector according to the embodiment, and FIG. 13 is the signal processing. 3 is a timing chart showing the operation timing of the system. [Explanation of symbols] SP... Speckle pattern Bm... Electromagnetic wave M... Movement information j... Object rough surface 2... Photodetector 2 a, 2 b... Photo detection element 3. ...Movable body 4...Electromagnetic wave source 5...Speckle size setting means

Claims (1)

[Claims] 1) Speckle pattern (SP) caused by scattering of coherent electromagnetic waves (Bm) on the rough surface of an object (1)
When detecting the movement information (M) with the photodetector (2), a speckle pattern (
SP), the detection movement rate (D) which indicates the ratio of the relative movement information of the photodetector (2) with respect to the rough object surface (1) and the output movement information of the photodetector (2);
J), the average size of the speckles (
D) A method for detecting movement of a speckle pattern. 2) The photodetector (2) has at least one set of photodetecting elements (2a, 2b) arranged in parallel per dimension, and the photodetector (2) has at least one set of photodetecting elements (2a, 2b) arranged in parallel per dimension.
A method for detecting movement of a speckle pattern, characterized in that a phase difference (τ) between output signals from a and 2b) is detected. 3) A movable body (3) that is movable with respect to the rough object surface (1), and a coherent electromagnetic wave that is incorporated in this movable body (3) and is transmitted from a predetermined part of the movable body (3) to the rough object surface (1). (Bm)
an electromagnetic wave source (4) that irradiates an electromagnetic wave (Bm) that is incorporated into the movable body (3);
a photodetector (2) that detects relative movement information of a speckle pattern (SP) generated from the object rough surface (1) with respect to the movable body (3) when irradiated with the object; and a light-receiving surface of the photodetector (2). The speckle pattern above (
SP), the detection movement rate (D) which indicates the ratio of the relative movement information of the photodetector (2) with respect to the rough object surface (1) and the output movement information of the photodetector (2);
J), speckle size setting means (5) for setting the average size (D) of the speckles within a range in which the detection movement rate (J) is kept substantially constant; A position specifying device characterized in that a position to be specified is specified based on relative movement information detected by a device (2).