JPH11249799A - Light scanning angle measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of dispersion in a light scanning angle per unit measuring time (one clock for measurement) when the shape of a scan mirror is distorted. SOLUTION: Concerning an instrument for finding a light scanning angle K by reflecting light from a light emitting element 17 on a scan mirror 23 and receiving the returned light through the reflection of the scan mirror 23 to a light receiving element 18, in this case, the instrument is provided with a rotating time measuring means 26 for measuring time (4T) required for one rotation of the scan mirror 23 and a 2-bit shift register 28 for finding one scanning period T by dividing the found measuring time with the number of reflection planes 4 (in the case of N=4) on the scan mirror 23. Even when one scanning period of each reflection plane is not equal because of the distortion in the shape of the scan mirror 23, since the time required for one rotation of the scan mirror is equal (Ta+Tb+Tc+Td=4T=fixed, for example), a maximum number Cm of one measured scanning period T(=4T/4) is fixed so that no dispersion occurs in the light scanning angle K(=π/Cm).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for irradiating an optical scanning area by reflecting light from a light emitting portion with a rotatable scan mirror, and returning light from the optical scanning area via reflection of the scan mirror. The present invention relates to an optical scanning angle measuring device that receives light at a light receiving unit and obtains an optical scanning angle K per unit measurement time (for example, per unit measurement clock) based on received light energy.

[0002]

2. Description of the Related Art The above-described optical scanning angle measuring device is, for example,
It is used in an optical scanning type touch panel as shown in FIG.
This optical scanning type touch panel is configured as follows, for example. Optical scanning units 11a, 1a, and 1b are provided on the upper corner and the lower corner of one side surface of the substrate 10 such as an optical filter.
On the front surface of the substrate 10, retroreflectors 12 are mounted on three sides excluding the mounting sides of the optical scanning units 11a and 11b. In the optical scanning unit 11a, as shown in FIG. 9, a fixed portion (not shown) of the unit support plate 13 is fixed to the substrate 10 with an adhesive or the like, and a substantially L-shaped support portion 14 integrated with the fixed portion is provided. Unit body 1 on top
5 is mounted and attached so that the angle can be adjusted. The unit main body 15 has a substantially L-shaped L-shaped groove 16 which is loosely fitted to the support portion 14 on the lower surface, and a light emitting element 17 such as a semiconductor laser device and a light receiving element 18 are housed therein, A refraction prism 20 for refracting a laser beam (hereinafter simply referred to as light) 19 output from the light emitting element 17;
A prism 22 having a half mirror 21 for transmitting the refracted light 19 and a scan mirror 23 are provided. The scan mirror 23 is rotatably provided by a pulse motor 24. The optical scanning unit 11b has the same configuration as the optical scanning unit 11a.

Each of the optical scanning units 11a and 11b operates as follows. Light 19 output from the light emitting element 17 is refracted by the refraction prism 20, passes through the half mirror 21 and the prism 22, and passes through the scan mirror 23.
And irradiates the retroreflector 12. In the retroreflector 12, the light returns substantially along the same optical path as the incident light, is reflected by the scan mirror 23, is reflected and refracted by the half mirror 21 of the prism 22, and is received by the light receiving element 18. Pulse motor 24
The rotation of the scan mirror 23 causes the light 19 to change the angle θ
(For example, about π radians (= 180 degrees)). When the object 25 is present in the optical scanning area, the object 25
As a result, the light 19 is blocked, so that the light scanning angle θ of the object 25 is obtained based on the received light energy of the light receiving element 18. By applying the optical scanning angles θa and θb of the object 25 obtained by the respective optical scanning units 11a and 11b to the principle of triangulation, the position coordinates of the object 25 on a coordinate plane formed on the substrate 10 are obtained. .

The light scanning angles θa, θ of the object 25 described above
b is obtained by the following equation (1). θa = Ka × (measured number of ta), θb = Kb × (measured number of tb) (1) In the equation (1), ta and tb are the light scanning units 11.
a, 11b represents a detection period required from the start of optical scanning to the detection of the object 25, comparing the received light energy of the light receiving element 18 with a preset threshold value, and obtaining the detected energy based on the comparison output. Can be The number of measurements of ta and tb represents the number of measurements of the measurement clock in the detection periods ta and tb. Further, Ka and Kb represent optical scanning angles per unit of measurement clock, and are obtained by the following equation (2). Hereinafter, Ka and Kb will be described as K for convenience of description. K = π / (maximum number of measurements in period T) (2) In equation (2), π (radian) represents the angle of one scanning cycle (π = 180 degrees), and period T is the scan mirror 2
A scanning period per reflection surface scanned by three rotations (hereinafter, referred to as a scanning period)
One scanning cycle), and the maximum number of measurements in the period T represents the maximum number of measurement clocks in the period T.

[0005]

In the apparatus shown in FIG.
If the shape of the scan mirror 23 is distorted, there is a problem that the value of the optical scanning angle K varies depending on the reflection surface. For example, a scan mirror 2 having four reflection surfaces
In the case of No. 3, since the cross-sectional shape is ideally a square as shown in FIG. 10A, the rotation angle φ of the scan mirror 23 and the reflection surfaces A,
One scanning cycle Ta, Tb, Tc, T for B, C, D
The relation with d is Ta = Tb as shown in FIG.
= Tc = Td = T. For this reason, the denominator of Equation (2) (the maximum number of measurements in the period T) is calculated for each of the reflection surfaces A, B, C, and D.
, And there is no variation in the value of the optical scanning angle K.
On the other hand, if the scan mirror 23 is distorted and the cross-sectional shape is distorted into a rhombus as shown in FIG. 11B, the relationship between the rotation angle φ and one scanning cycle Ta, Tb, Tc, Td is shown in FIG. 11 (b), Ta, Tb, Tc, T
d is not equal. For this reason, the denominator of Equation (2) (the maximum number of measurements in the period T) is not the same for each of the reflection surfaces A, B, C, and D, and the value of the light scanning angle K varies. The case where the scan mirror 23 is distorted and the cross-sectional shape is distorted into a rhombus as shown in FIG. 11C is the same as the case of FIG. 11B. In FIG. 10, reference numeral 23 a denotes a rotation axis of the scan mirror 23, and in FIGS. 10 and 11, a, b, c, and d denote primary reflected lights from the respective reflection surfaces A, B, C, and D of the scan mirror 23. Represents the distortion of the scan mirror 23, and in FIG. 11, X represents the appearance information of the object 25 in each one scanning cycle Ta, Tb, Tc, Td.

In the apparatus shown in FIG. 8, when the number of revolutions of the motor 24 for rotating the scan mirror 23 changes due to fluctuations in the supply voltage, changes in the ambient temperature, aging, etc.
There is a problem that the optical scanning angle K per unit of measurement clock changes, and accurate angle calculation cannot be performed. For example,
In the case of the scan mirror 23 having four reflection surfaces, the motor 24
When the primary reflected lights a, b, c, and d of the scan mirror 23 when the rotation speed of the motor 24 is a standard value are represented by (a) in FIG. 12 (one scanning cycle = T), the rotation speed of the motor 24 is the standard value. The primary reflected lights a, b, c, and d when smaller are changed as shown in FIG. 3B (one scanning cycle = T1), and T1> T, so that the denominator of equation (2) ( The primary reflected light a, b, c, and d when the light scanning angle K is reduced and the rotation speed of the motor 24 is larger than the standard value is as shown in FIG. (1 scanning cycle = T
2) Since T2 <T, the denominator of the equation (2) (period T2
(The maximum number of measurements) decreases and the light scanning angle K increases, and an error occurs in the light scanning angle by an angle corresponding to these changes.

The present invention has been made in view of the above-mentioned problems, and provides an optical scanning angle measuring device capable of preventing a variation in a required optical scanning angle K from occurring when a shape of a scan mirror is distorted. The purpose is to do. Another object of the present invention is to provide an optical scanning angle that can maintain a desired optical scanning angle K even when the rotation speed of a motor that rotates a scan mirror changes due to a change in supply voltage, a change in ambient temperature, aging, and the like. It is to provide a measuring device.

[0008]

According to a first aspect of the present invention, a light from a light emitting unit is reflected by a rotatable scan mirror to irradiate an optical scanning area, and light returned from the optical scanning area is scanned by the scan mirror. A rotation time measuring means for measuring a time required for one rotation of a scan mirror in an apparatus which receives light at a light receiving portion via reflection of light and obtains an optical scanning angle K per unit measurement clock based on received light energy; A division means for dividing the measurement time obtained by the rotation time measurement means by the number N of reflection surfaces of the scan mirror (N is an integer of 3 or more) to obtain one scanning cycle, and one scanning cycle obtained by the division means. The optical scanning angle K is obtained based on

Even if one scanning cycle on each reflecting surface of the scanning mirror is not equal due to distortion of the shape of the scanning mirror (for example, when the number of reflecting surfaces is four) (for example, Ta ≠ T)
b ≠ Tc ≠ Td), if the rotation number of the scan mirror is constant, the time required for one rotation of the scan mirror is equal (for example, Ta + Tb + Tc + Td = 4T = constant). Therefore, the time tr required for one rotation of the scan mirror measured by the rotation time measuring means becomes constant (for example, tr = 4T).
= Constant), one scanning period T (= tr /
N) is also constant (N is a value specific to the scan mirror,
For example, 4). A value Cm obtained by dividing this one scanning cycle T by a certain measurement unit time (one cycle of a unit measurement clock) is 1
As is apparent from equation (2), the light scanning angle (a constant value determined by the structure of the device, for example, π radian) in one scanning period T is divided by Cm, so that the light scanning angle becomes the maximum number of measurements in the scanning period T. K is required.

According to a second aspect of the present invention, in the first aspect of the present invention, in order to simplify the configuration of the rotation time measuring means, the rotation time measuring means generates and outputs a measuring clock. Optical scanning start detecting means for detecting optical scanning start information on each reflecting surface of the scan mirror based on the light receiving energy of the light receiving section; and a frequency dividing the optical scanning start information detected by the optical scanning start detecting means by N And a counter for counting a measurement clock in one cycle of the optical scanning start information obtained by the frequency dividing means.
The dividing means divides the count value of the counter by N to obtain the maximum measured number Cm in one scanning cycle T.

According to a third aspect of the present invention, in order to simplify the configuration of the frequency dividing means and the dividing means,
The frequency dividing means is constituted by a frequency dividing circuit (M is a positive integer) which divides the optical scanning start information detected by the optical scanning start detecting means by (2 to the power of M). It is configured by an M-bit shift register that shifts the data by M digits to the right and makes it 1 / (2M).

According to a fourth aspect of the present invention, in order to simplify the configuration of the rotation time measurement means, the rotation time measurement means generates a measurement clock and outputs the measurement clock.
Optical scanning start detecting means for detecting optical scanning start information relating to each reflecting surface of the scan mirror based on the light receiving energy of the light receiving section, and a measuring clock in each cycle of the optical scanning start information detected by the optical scanning start detecting means And an adding means for adding N times of the count value of this counter corresponding to one rotation of the scan mirror.

According to a fifth aspect of the present invention, the light from the light emitting section is reflected by a rotatable scan mirror to irradiate the light scanning area, and the light returned from the light scanning area is received via the reflection of the scan mirror. In a device that receives light at a unit and obtains an optical scanning angle K per unit of measurement clock based on received light energy, a measurement clock creation circuit that creates and outputs a measurement clock, Optical scanning start detecting means for detecting optical scanning start information on each reflection surface of the scan mirror, and means for keeping the optical scanning angle K constant based on the measuring clock and the optical scanning start information. It is characterized by.

Even if the number of revolutions of the motor for rotating the scan mirror changes due to fluctuations in the supply voltage, changes in the ambient temperature, aging, etc., the means for keeping the optical scanning angle K per unit measurement clock constant. The light scanning angle K is kept constant. For this reason, even if the number of rotations of the motor changes, the required light scanning angle K can be kept constant.

According to a sixth aspect of the present invention, in accordance with the fifth aspect of the present invention, the optical scanning angle K is kept constant in order to keep the optical scanning angle K constant by controlling the number of revolutions of the motor for rotating the scan mirror. A standard value register for preliminarily setting a standard value corresponding to the standard rotation speed of the motor for rotating the scan mirror, and a counter for counting a measurement clock in one cycle of the optical scanning start information detected by the optical scanning start detecting means. And a motor that compares the count value of this counter with a standard value of a standard value register, and decreases the motor speed when the count value is larger than the standard value, and increases the motor speed when the count value is smaller than the standard value. It is composed of rotation speed control means.

According to a seventh aspect of the present invention, in the fifth aspect, the frequency of the measurement clock can be varied by the measurement clock generation circuit in order to keep the optical scanning angle K constant by controlling the frequency of the measurement clock. And a means for holding the optical scanning angle K constant, a standard value register in which a standard value corresponding to the standard rotational speed of the motor for rotating the scan mirror is set in advance, and a light detected by the optical scanning start detecting means. A counter for counting the measuring clock in one cycle of the scanning start information, and comparing the counted value of the counter with a standard value of a standard value register. If the counted value is larger than the standard value, the clock frequency of the measuring clock generating circuit is reduced. And a clock frequency control means for increasing the clock frequency of the measurement clock generation circuit when the count value is smaller than the standard value.

According to an eighth aspect of the present invention, in order to simplify the configuration of the measurement clock generation circuit, the measurement clock generation circuit is constituted by a voltage controlled oscillator.

According to a ninth aspect of the present invention, there is provided the second aspect of the present invention.
In the invention of 5, 6, 7 or 8, in order to simplify the configuration of the optical scanning start detecting means, the optical scanning start detecting means includes a current / voltage conversion circuit for converting a current flowing through the light receiving section into a voltage, An A / D conversion circuit that samples the output voltage of the current / voltage conversion circuit with the clock of the measurement clock generation circuit and converts it into a digital signal; and the primary reflection of the scan mirror from the output signal of the A / D conversion circuit And a primary reflected light separation circuit that separates a signal corresponding to light and outputs it as light scanning start information.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical scanning angle measuring device according to the present invention will be described below with reference to FIG. In FIG. 1, the same parts as those in FIGS. FIG.
, 12 is a retroreflector, 17 is a light emitting element, 18
Is a light receiving element, 19 is light from the light emitting element 17, 23 is a scan mirror having four reflecting surfaces (when N = 4), a square cross section, and 24 is a motor (for example, a pulse motor). 26 is a rotation time measuring means for measuring the time required for one rotation of the scan mirror 23, 28 is a 2-bit shift register as dividing means, and 30 is an MPU (microprocessor unit).

The rotation time measuring means 26 includes a VCO (voltage controlled oscillator) 32 as an example of a measuring clock generating circuit for generating and outputting a measuring clock, an optical scanning start detecting means 34, and a frequency dividing means. Frequency divider circuit 3 as an example
5 and a counter 36. The light scanning start detecting means 34 converts a current corresponding to the light receiving energy of the light receiving element 18 into a voltage and outputs the voltage. The current / voltage converting circuit 38 converts the output voltage of the current / voltage converting circuit 38 into a digital signal. A / D (analog / digital) conversion circuit 40 for converting and outputting, and this A / D conversion circuit 4
A primary reflected light separation circuit 42 that separates a signal corresponding to the primary reflected light (maximum received energy) of the scan mirror 23 from the output signal of 0 and outputs optical scanning start pulses Pa, Pb, Pc, and Pd; It is composed of The divide-by-4 circuit 35 is formed by combining D-type flip-flops 37 and 39 as shown in FIG. 2, and outputs light scanning start pulses Pa, Pb, Pc and Pd output from the primary reflected light separation circuit 42. The frequency is divided by 4 and output. The counter 36 counts the measuring clock of the VCO 32 in one cycle of the optical scanning start signal obtained by the divide-by-4 circuit 35.

The 2-bit shift register 28 shifts the count value of the counter 32 by two digits to the right to make it 1/4,
The count value Cm of the measurement clock in one scanning cycle T is output. This count value Cm corresponds to the maximum number of measurements in the denominator period T in equation (2).

The MPU 30 is calculated according to the formulas (2) and (1).
Is calculated. That is, the light scanning angle π in one scanning period T
(Radian) is divided by the value Cm output from the 2-bit shift register 28 to obtain an optical scanning angle K per unit measurement clock (= π / Cm). The scanning angle θ of the object is obtained by multiplying the number of measurements in the detection period t until the detection of the object 25. The number of measurements in the detection period t includes a comparison output signal of a comparator (not shown) that compares the output voltage of the voltage / current conversion circuit 38 with a reference voltage, and light scanning start pulses Pa, Pb, It is calculated by the MPU 30 based on Pc and Pd.

Next, the operation of FIGS. 1 and 2 will be described with reference to FIGS. 3 and 10. For convenience of explanation, a case where the cross section of scan mirror 23 is distorted in a rhombus shape as shown in FIG. 10B and one scanning cycle on each reflection surface of scan mirror 23 is not equal (Ta （Tb ≠ Tc ≠ Td) explain.

The current / voltage conversion circuit 38 includes the light receiving element 18
Converts the current corresponding to the received light energy into a voltage,
The D conversion circuit 40 converts the output voltage of the current / voltage conversion circuit 38 into a digital signal, and the primary reflected light separation circuit 42
A scanning start pulse Pa as shown in FIG. 3B corresponding to the primary reflected light from the output signal of the A / D conversion circuit 40,
Pb, Pc, and Pd are separated and output to the divide-by-4 circuit 35. For comparison, the scan mirror 23 is shown in FIG.
Shows a case where the cross section of the sample is an ideal square without distortion. 3A and 3B, the scanning start pulses Pa and P
b, Pc, and Pd are primary reflected lights a, from the respective reflecting surfaces A, B, C, and D of the scan mirror 23 in FIGS.
X represents signals corresponding to b, c, and d, and X represents FIG.
2, one scanning cycle Ta, Tb, Tc, Td
, Represents the detection information of the object 25, and t represents a detection period from the start of scanning to the time of detection of the object 25. Since the rotation speed of the scan mirror 23 is constant, the detection period t is constant.

When a signal as shown in FIG. 3B is input to the divide-by-4 circuit 35, an optical scanning start signal having a period of 4T as shown in FIG. 3D is output from the output side. That is, CK of the D-type flip-flop 37 of the divide-by-4 circuit 35
When a signal as shown in FIG. 3B is inputted to the terminal, the scanning start pulses Pa, Pb, P as shown in FIG.
c and Pd output a signal which is inverted by two and which is inverted at a time delayed by a certain time from the rise due to the rising edge operation of Pd.
Since the signal is input to the K terminal, the D-type flip-flop 39
A light scanning start signal having a period of 4T obtained by dividing the input signal by 4 is output from the Q2 terminal of FIG.

The counter 36 counts the measuring clock output from the VCO 32 during the period 4T based on the scanning start signal having the period 4T as shown in FIG. The 2-bit shift register 28 shifts the count value of the counter 36 two places to the right,
Then, the maximum measurement number Cm in one scanning cycle T is output. The MPU 30 divides the scanning angle π in one scanning period T, which is previously set in a register (not shown) or receives a set value, by the maximum measurement number Cm output from the 2-bit shift register 28 (Equation (2) ) Is calculated, and the light scanning angle K per unit measurement clock is obtained. MP
U30 further multiplies the optical scanning angle K by the number of measurements in the detection period t (performs the calculation of Expression (1)) to obtain the scanning angle θ of the object 25. The detection period t is calculated by the MPU 30 based on the comparison signal of the comparator for comparing the output voltage of the current / voltage conversion circuit 38 with the reference voltage and the scanning start pulses Pa, Pb, Pc, Pd.

In the embodiment shown in FIG. 1, the frequency dividing means is constituted by a divide-by-four circuit, and the dividing means is shifted by two digits to the right to make it a quarter corresponding to this. However, the present invention is not limited to this, and the frequency dividing means divides the optical scanning start information by (2 to the power of M) (M is a positive integer, M in the example of FIG. 1). = 2), and the dividing means shifts to the right by M digits (2 to the power of M) in response to this.
(In the example of FIG. 1, it is set to １).

In the above embodiment, the rotation time measuring means comprises a VCO, an optical scanning start detecting means, a frequency dividing means and a counter, and the dividing means shifts the count value of the counter by M digits to the right (2 Has been described as an M-bit shift register that is 1 / (Mth power), but the present invention is not limited to this. The rotation time measuring means measures the time required for one rotation of the scan mirror. The dividing means only needs to divide the measurement time obtained by the rotation time measuring means by the number N of reflection surfaces of the scan mirror (N = 4 in FIG. 1) to obtain one scanning cycle T.

For example, as shown in FIG.
The following addition function, division function, and multiplication function are provided, and the addition function, the VCO 32, the optical scanning start detection means 34, the counter 36a, and the reflection surface number register 4 are added.
4 may constitute a rotation time measurement means, and the division function and the reflection surface number register 44 may constitute a division means. The reflection mirror 44 includes the scan mirror 23.
The number of reflection surfaces N (for example, N = 4) is set. Addition function: Adds the count value of the counter 36a N times according to the value N set in the reflection surface number register 44. N = 4
In the case of (3), the counter 36a is
Scanning start pulses Pa, Pb, Pc, Pd output from
In one cycle Ta, Tb, Tc, Td, the counting clock of the VCO 32 is counted, and these counted values are added. Division function: The addition value obtained by the addition function is divided by N of the value set in the reflection surface number register 44 to obtain the maximum measurement number Cm in one scanning cycle T. In the case of N = 4, the maximum value Cm in one scanning cycle T is obtained by dividing the added value by four. Division function: As in the case of FIG. 1, the light scanning angle K is obtained by dividing the scanning angle π of one scanning cycle T by the maximum measurement number Cm obtained by the division function. Multiplication function: As in the case of FIG. 1, the light scanning angle K obtained by the division function is multiplied by the number of measurements in the detection period t, and the object 2
5 is obtained.

FIG. 5 shows another embodiment of the present invention. The same parts as those in FIGS. 1 and 4 are denoted by the same reference numerals, and the description thereof is omitted. In FIG. 5, reference numeral 50 denotes a standard value register for setting a standard value corresponding to the standard rotation speed of the motor 24 for rotating the scan mirror 23. Reference numeral 52 denotes motor rotation speed control means. The means 52 and the counter 36a constitute a means for keeping the scanning angle constant.

The motor rotation speed control means 52 includes a DC power supply 54 for variably supplying a drive voltage to the motor 24 to change the rotation speed, a D / A (digital / analog) conversion circuit 56, and an MPU 30b. Consisting of this M
The PU 30b has the following comparison control function, and FIG.
The same division function and multiplication function as the functions provided to the MPU 30a are provided. Comparison control function: The count value of the counter 36a is compared with the standard value of the standard value register 50, and when the count value is larger than the standard value, the DC power supply 54 Is output, and when the count value is smaller than the standard value, a control signal for increasing the rotation speed of the motor is output to the DC power supply 54 via the D / A conversion circuit 56. .

Next, the operation in the case of FIG. 5 will be described. When the rotation speed of the motor 24 that rotates the scan mirror 23 changes due to a change in the supply voltage, a change in the ambient temperature, an aging, etc., the motor 2
The number of rotations is controlled so that the number of rotations becomes the number of rotations corresponding to the standard value of the standard number of rotations register 50. That is, the motor 2
When the number of rotations of the scanning start pulse No. 4 increases from the standard number of rotations, the scanning start pulses Pa, Pb, P
Since one scanning cycle Ta, Tb, Tc, Td of c and Pd is shorter than one scanning cycle T when the rotation speed of the motor 24 is a standard value (Ta = Tb = Tc = Td <T), the counter 36a Is smaller than the standard value of the standard value register 50, and the motor 2 is controlled by the comparison control function of the MPU 30b.
4 is reduced. When the number of rotations of the motor 24 decreases below the standard number of rotations, the operation of the motor 24 is reversed, and
The rotation speed of the motor 24 is increased by the comparison control function of 30b. Since the rotation speed of the motor 24 is maintained at the standard rotation speed by such rotation speed control, the division function of the MPU 30b divides the scanning angle π of one scanning cycle T by the count value Cm of the counter 36a to obtain the light scanning angle. K is required. Further, the multiplication function of the MPU 30b multiplies the optical scanning angle K by the number of measurements in the detection period t, and
Is obtained.

In the embodiment shown in FIG. 5, the case where the means for keeping the light scanning angle K constant is constituted by a standard value register, a counter and a motor speed control means has been described. The present invention is not limited to this, as long as the optical scanning angle K is kept constant based on the measuring clock generated by the measuring clock generating circuit (for example, VCO) and the optical scanning start information detected by the optical scanning start detecting means. Good.

For example, as shown in FIG. 6, a measuring clock generating circuit is provided with a VC capable of changing the frequency of the measuring clock.
The means formed by O32a and holding the optical scanning angle K constant is constituted by the standard value register 50, the counter 36b, and the clock frequency control means 58. The counter 36b includes:
Optical scanning start pulse P detected by optical scanning start detecting means 34
One cycle of each of a, Pb, Pc, and Pd Ta, Tb, Tc, T
The measurement clock output from the VCO 32a at d is counted. The clock frequency control means 58 includes an LPF (low-pass filter) 60, a D / A conversion circuit 56a,
The MPU 30c is provided with the following comparison control function and the same division function and multiplication function as those provided to the MPU 30a in FIG. Comparison control function: The count value of the counter 36b is compared with the standard value of the standard value register 50, and when the count value is larger than the standard value, the D / A conversion circuit 56a and the LPF 6
0, a control signal for decreasing the clock frequency is output to the VCO 32a. When the count value is smaller than the standard value, the D / A conversion circuit 56a and the LPF 60
A control signal for increasing the clock frequency is output to the VCO 32a through the VCO.

Next, the operation in the case of FIG. 6 will be described with reference to FIG. For convenience of explanation, when the rotation speed of the motor 24 is the standard rotation speed corresponding to the standard value of the standard register 50,
As shown in FIGS. 7A and 7B, one scanning cycle is T
(= Ta = Tb = Tc = Td), the clock frequency of the VCO 32a is F, the detection period required from the start of scanning in each scanning cycle to the detection of the object 25 is t, and the rotation speed of the motor 24 is a standard rotation. When the number of rotations is smaller than the number, T1, F1, and t1 are set as shown in (c) and (d) of the figure. When the rotation number of the motor 24 is larger than the standard number of rotations, (e) and (f) of the figure. ), T2, F2, and t2.

Motor 24 for rotating scan mirror 23
Clock frequency control means 58 controls the clock of VCO 32a so that the count value of counter 36b becomes equal to the standard value of standard value register 50, when the rotation speed of power supply changes due to supply voltage fluctuation, change in ambient temperature, aging, and the like. The frequency is controlled. That is, when the rotation speed of the motor 24 is the standard rotation speed, the count value of the counter 36b is equal to the standard value of the standard value register 50, so that the clock frequency F of the VCO 32a does not change. When the rotation speed of the motor 24 becomes smaller than the standard rotation speed, one scanning period T1 of each of the scanning start pulses Pa, Pb, Pc, and Pd output from the scanning start detection means 34 becomes the standard as shown in FIG. Since the rotation speed becomes longer than the period T, the count value of the counter 36b becomes T1 / T times the standard value unless the clock frequency of the VCO 32a changes. Therefore, the counter 36
The clock frequency control means 58 controls the count value of b to be equal to the standard value so that the clock frequency of the VCO 32a becomes F1 (= F × T / T) times T / T1 times F, as shown in FIG. T1 <F) and the counter 36
The count value of b is held at the standard value. Therefore, the optical scanning angle K per unit measurement clock (= π / maximum number of measurements in the period T1) is also kept the same as in the case of the standard rotation speed, and the scanning angle θ1 of the object 25 (= K × ( The number of measurements during the period t1)) is also the scanning angle θ (= K ×
(The number of measurements in the period t)). That is,
(The number of measurements in the period t1) = F1 × t1 = (F × T / T1)
× (t × T1 / T) = F × t = (the number of measurements in the period t), so that θ1 = θ. When the rotation speed of the motor 24 becomes larger than the standard rotation speed, each one scanning period T2 of the scanning start pulses Pa, Pb, Pc, and Pd output from the scanning start detection means 34 becomes the standard as shown in FIG. Since the rotation speed is smaller than the period T, the count value of the counter 36b becomes T2 / T times the standard value unless the clock frequency of the VCO 32a changes. For this reason, the clock frequency control means 58 for controlling the count value of the counter 36b to be equal to the standard value causes the clock frequency of the VCO 32a to become F / T2 times T / T2 times F, as shown in FIG.
(= F × T / T2> F), and the count value of the counter 36b is held at the standard value. Therefore, the optical scanning angle K per unit of measurement clock (= π / maximum number of measurements in the period T2) is kept the same as in the case of the standard rotation speed, and the scanning angle θ2 of the object 25 (= K × ( The number of measurements during the period t2) is also the scanning angle θ (= K ×
(The number of measurements in the period t)). That is,
(The number of measurements in the period t2) = F2 × t2 = (F × T / T2)
× (t × T2 / T) = F × t = (measured number of period t), so that θ2 = θ.

In the above-described embodiment, the case where the measurement clock generating circuit is formed by the VCO has been described. However, the present invention is not limited to this, and any circuit that generates and outputs a measurement clock may be used.

In the above embodiment, the case where the optical scanning start detecting means is constituted by a current / voltage converting circuit, an A / D converting circuit and a primary reflected light separating circuit has been described, but the present invention is not limited to this. Instead, any device may be used as long as it detects the light scanning start information on each reflection surface of the scan mirror based on the light receiving energy of the light receiving element.

[0039]

According to the first aspect of the present invention, the light from the light emitting section is reflected by the rotatable scan mirror to irradiate the light scanning area, and the light returned from the light scanning area is reflected by the scan mirror. In a device that receives light at a light receiving section and obtains an optical scanning angle K per unit measurement clock based on received light energy, the time required for one rotation of the scan mirror is determined by the number of reflection surfaces N of the scan mirror (for example, N = 4). , The one scanning cycle T is obtained, so that when the shape of the scan mirror is distorted, it is possible to prevent the required light scanning angle K from varying. That is,
If the number of rotations of the scan mirror is constant, the time tr required for one rotation of the scan mirror is constant (for example, tr = 4T = constant), even if the shape of the scan mirror is distorted, and one scanning cycle obtained by the dividing means. T (= tr / N) is also constant. The value Cm (maximum number of measurements in one scanning cycle) obtained by dividing this one scanning cycle T by a certain measurement unit time (one cycle of the measurement clock) is also constant, so that the optical scanning angle in one scanning cycle (device structure) The light scanning angle K obtained by dividing a constant value determined by (for example, π radian) by Cm is also constant.

According to a second aspect of the present invention, in the first aspect of the present invention, the rotation time measuring means comprises a measuring clock generating circuit, an optical scanning start detecting means, a frequency dividing means and a counter, and the dividing means counts the count value of the counter. Is divided by N to obtain one scanning cycle T, so that the configuration of the rotation time measuring means can be simplified.

According to a third aspect of the present invention, in the second aspect of the present invention, the frequency dividing means divides the optical scanning start information detected by the optical scanning start detecting means by (2 to the power of M). Frequency dividing circuit), and the dividing means calculates the count value of the counter as M
Since it is constituted by an M-bit shift register (for example, a 2-bit shift register) which shifts one digit to the right (2 to the power of M), the configuration of the frequency dividing means and the dividing means can be simplified.

According to the fourth aspect of the present invention, since the rotation time measuring means is constituted by a measuring clock generating circuit, an optical scanning start detecting means, a counter and an adding means, the structure of the rotating time measuring means can be simplified.

According to a fifth aspect of the present invention, the light from the light emitting section is reflected by the rotatable scan mirror to irradiate the light scanning area, and the light returned from the light scanning area is received through the reflection of the scan mirror. In a device that receives light at a unit and obtains an optical scanning angle K per unit of measurement clock based on received light energy, a measurement clock creation circuit that creates and outputs a measurement clock, An optical scanning start detecting means for detecting optical scanning start information on each reflection surface of the scan mirror; and a means for keeping the optical scanning angle K constant based on the measuring clock and the optical scanning start information. The optical scanning angle K per unit of measurement clock is kept constant even if the rotational speed of the motor rotating the motor changes due to fluctuations in the supply voltage, changes in the ambient temperature, aging, etc. Since such optical scanning angle K is kept constant by means of, it is possible to hold the optical scanning angle K the rotational speed of the motor is also determined by constantly changing.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the means for maintaining the optical scanning angle K constant includes a standard value in which a standard value corresponding to the standard rotational speed of the motor for rotating the scan mirror is preset. A value register, a counter for counting a measuring clock in one cycle of the optical scanning start information detected by the optical scanning start detecting means, and comparing the counted value of the counter with a standard value of a standard value register, and determining the counted value as a standard value. When the motor speed is larger than the standard value, the motor speed is decreased, and when the count value is smaller than the standard value, the motor speed is increased. The optical scanning angle K can be kept constant by controlling the motor rotation speed to a standard value by the motor rotation speed control means even if it changes due to changes, aging and the like. .

According to a seventh aspect of the present invention, in the fifth aspect of the present invention, in order to keep the optical scanning angle K constant, the measuring clock generating circuit is formed so that the frequency of the measuring clock can be changed, Means for holding K constant, a standard value register for pre-setting a standard value corresponding to the standard rotation speed of the motor for rotating the scan mirror, and one cycle of the optical scanning start information detected by the optical scanning start detecting means. A counter that counts the clock for measurement, and compares the count value of this counter with the standard value of the standard value register. If the count value is larger than the standard value, the clock frequency of the clock generation circuit for measurement is reduced, and the count value becomes the standard value. When it is smaller, the clock frequency control means for increasing the clock frequency of the measurement clock generation circuit is used, so that the number of rotations of the motor may vary with the supply voltage. Changes in ambient temperature, be varied by aging or the like, can be allowed to coincide with the standard value of the count value of the counter in the frequency control of the measuring clock by the clock frequency control means for holding the optical scanning angle K constant.

According to an eighth aspect of the present invention, in the seventh aspect of the present invention, since the measurement clock generation circuit is constituted by a voltage controlled oscillator, the configuration of the measurement clock generation circuit can be simplified.

The ninth aspect of the present invention provides the second aspect of the present invention.
In the invention of 5, 6, 7 or 8, the optical scanning start detecting means is constituted by a current / voltage conversion circuit, an A / D conversion circuit and a primary reflected light separation circuit, so that the configuration of the optical scanning start detecting means can be simplified. can do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of an optical scanning angle measuring device according to the present invention.

FIG. 2 is a block diagram showing a specific example of a divide-by-4 circuit 35 in FIG. 1;

FIG. 3 is a timing chart for explaining the operation of FIG. 2;

FIG. 4 is a block diagram showing a main part of a second embodiment of the optical scanning angle measuring device according to the present invention.

FIG. 5 is a block diagram showing a third embodiment of the optical scanning angle measuring device according to the present invention.

FIG. 6 is a block diagram showing a fourth embodiment of the optical scanning angle measuring device according to the present invention.

FIG. 7 is a timing chart for explaining the operation of FIG. 6;

FIG. 8 is a plan view of an optical scanning type touch panel which is an example of an application example of the present invention.

FIG. 9 is a side view showing an attached state of the optical scanning unit in FIG.

FIG. 10 shows a state where the shape of the scan mirror is distorted (b).
It is explanatory drawing which showed (c) in comparison with the ideal shape state (a).

FIG. 11A shows the shape of the scan mirror in FIG.
It is explanatory drawing of the primary reflected light in the case of (b).

FIG. 12 is an explanatory diagram of primary reflected light when the rotation speed of the motor that rotates the scan mirror is the standard rotation speed, is smaller than the standard rotation speed, and is larger than the standard rotation speed.

[Explanation of symbols]

11a, 11b: optical scanning unit, 12: retroreflector, 17: light emitting element, 18: light receiving element, 19: light output from light emitting element 17, 23: scan mirror,
23a: rotation axis of scan mirror 23, 24: motor, 25: target object, 26: rotation time measuring means, 2
8. 2-bit shift register (an example of division means)
0, 30a, 30b, 30c... MPU (microprocessor), 32, 32a... VCO (an example of a measurement clock generation circuit), 34... Optical scanning start detecting means 35.
Frequency dividing circuit (an example of frequency dividing means), 36, 36a, 36b
... Counter, 37, 39 ... D-type flip-flop,
38: current / voltage conversion circuit, 40: A / D conversion circuit,
42: Primary reflected light separation circuit, 44: Reflection surface number register, 50: Standard value register, 52: Motor rotation speed control means, 54: DC power supply with variable voltage, 56, 5
6a: D / A conversion circuit, 58: clock frequency control means, 60: LPF, A, B, C, D: reflection surface of scan mirror 23, a, b, c, d: scan mirror 2
, VC, primary reflected light from each reflective surface of No. 3, F, F1, F2,.
O32, 32a clock frequency, Pa, Pb, P
c, Pd: scanning start pulse by primary reflected light a, b, c, d (an example of scanning start information), T, T1, T2 ... one scanning cycle, t, t1, t2 ... from scanning start to object detection , X... Object 25 in each scanning cycle
Appearance information.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Toshiyuki Kishi 1116, Suenaga, Takatsu-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu General Limited (72) Inventor Fumihiko Nakazawa 4-1-1, Kamidadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Inside the corporation

Claims (9)

[Claims] An optical scanning area is radiated by reflecting light from a light emitting section with a rotatable scan mirror, and light returned from the optical scanning area is received by a light receiving section via reflection of the scan mirror. A rotation time measuring means for measuring a time required for one rotation of the scan mirror, and a measuring time obtained by the rotation time measuring means. Dividing means for dividing by the number N of reflecting surfaces of the scan mirror (N is an integer of 3 or more) to obtain one scanning cycle, and the light scanning angle K is calculated based on the one scanning cycle obtained by the dividing means.
An optical scanning angle measurement device that calculates 2. A rotation time measuring means, comprising: a measuring clock generating circuit for generating and outputting a measuring clock; and a light for detecting optical scanning start information on each reflecting surface of a scan mirror based on light receiving energy of a light receiving section. Scanning start detection means,
The optical scanning start information detected by the optical scanning start detecting means is represented by N
Frequency dividing means for dividing the frequency; and a counter for counting the clock of the measuring clock generating circuit in one cycle of the optical scanning start information obtained by the frequency dividing means. The dividing means counts the count value of the counter to N 2. The optical scanning angle measuring device according to claim 1, wherein one scanning cycle is obtained by dividing by one. 3. The frequency dividing means divides (2 to the power of M) the optical scanning start information detected by the optical scanning start detecting means (M is a positive integer), and the dividing means divides the count value of the counter by M. 3. The optical scanning angle measuring device according to claim 2, wherein the optical scanning angle measuring device is an M-bit shift register that shifts the digit right by one and sets it to (1 / M). 4. A rotation time measuring means, comprising: a measuring clock generating circuit for generating and outputting a measuring clock; and a light for detecting optical scanning start information on each reflecting surface of a scan mirror based on light receiving energy of a light receiving section. Scanning start detection means,
1 of the light scanning start information detected by the light scanning start detecting means.
A counter for counting the clock of the measurement clock generation circuit in a cycle; and an adding unit for adding N times of the count value of the counter corresponding to one rotation of the scan mirror, and the dividing unit is obtained by the adding unit. 2. The optical scanning angle measuring device according to claim 1, wherein one scanning period is obtained by dividing the added value by N. 5. An optical scanning area is radiated by reflecting light from a light emitting section with a rotatable scan mirror, and light returned from the optical scanning area is received by a light receiving section via reflection of the scan mirror. A device for calculating an optical scanning angle K per unit measurement time based on received light energy, a measuring clock generating circuit for generating and outputting a measuring clock, and each of the scan mirrors based on the received light energy of the light receiving unit. Optical scanning comprising: optical scanning start detecting means for detecting optical scanning start information on a reflection surface; and means for holding the optical scanning angle K constant based on the measuring clock and the optical scanning start information. Angle measuring device. 6. A means for maintaining the optical scanning angle K constant, wherein a standard value register for preliminarily setting a standard value corresponding to a standard rotation speed of a motor for rotating a scan mirror is detected by an optical scanning start detecting means. A counter for counting the measuring clock in one cycle of the optical scanning start information, and comparing the count value of the counter with the standard value of the standard value register, and when the count value is larger than the standard value, reducing the rotation speed of the motor. 6. The optical scanning angle measuring device according to claim 5, further comprising: motor rotation speed control means for increasing the rotation speed of the motor when the count value is smaller than a standard value. 7. The measurement clock generating circuit is formed such that the frequency of the measurement clock is variable, and the means for keeping the optical scanning angle K constant is a standard value corresponding to the standard rotation speed of a motor for rotating the scan mirror. A counter for counting a measurement clock in one cycle of the optical scanning start information detected by the optical scanning start detecting means;
The count value of this counter is compared with the standard value of the standard value register. When the count value is larger than the standard value, the clock frequency of the measurement clock generation circuit is decreased. When the count value is smaller than the standard value, the measurement clock is used. 6. The optical scanning angle measuring device according to claim 5, further comprising clock frequency control means for increasing a clock frequency of the creation circuit. 8. The optical scanning angle measurement device according to claim 7, wherein the measurement clock generation circuit is a voltage controlled oscillator. 9. An optical scanning start detecting means, comprising: a current / voltage conversion circuit for converting a current flowing through a light receiving section into a voltage;
A that converts the output voltage of the voltage conversion circuit into a digital signal
And a primary reflection light separation circuit for separating a signal corresponding to the primary reflection light of the scan mirror from the output signal of the A / D conversion circuit and outputting the signal as optical scanning start information. The optical scanning angle measuring device according to 2, 3, 4, 5, 6, 7, or 8.