JP3631325B2 - 3D image input device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a three-dimensional image input apparatus using a two-dimensional image sensor capable of simultaneously inputting a two-dimensional distance image and its luminance image.
[0002]
[Prior art]
As a conventional technique for simultaneously inputting a two-dimensional distance image and its luminance image, for example, there is a “two-dimensional distance sensor” as proposed in Japanese Patent Application No. 7-146949. Next, a conventional technique proposed in the above application will be described. FIG. 4 is a block diagram showing a two-dimensional distance sensor (three-dimensional image input device) proposed in the above application. In FIG. 4, 101 is a sensitivity modulation driving unit for modulating the sensitivity of the two-dimensional image sensor 103, 102 is a two-dimensional image sensor driving unit, 104 is a control signal generator, 105 is a signal processing unit, and 106 is a light source 109. An optical band filter that transmits only the wavelength of the emitted light, 107 is an imaging optical system, 108 is a light source driving unit that modulates the light source 109, and 110 is a subject (target object). As the two-dimensional image sensor 103 capable of sensitivity modulation, for example, there is a CMD (Charge Modulation Device) image sensor.
[0003]
Next, the operation of the three-dimensional image input apparatus having such a configuration will be described with reference to the timing chart shown in FIG. In FIG. _S Is the measurement start pulse, Φ _SM Is a pulse that modulates the light receiving sensitivity of the two-dimensional image sensor 103, Φ _LD Is the pulse that drives the light source 109, Φ _ref Is returned from the light source 109, reflected by the subject 110 at a finite distance and imaged on the light receiving surface of the two-dimensional image sensor 103, Φ _RD Is a read drive pulse group for reading data from the two-dimensional image sensor 103, Φ _DATA Represents data (signal charge) read from the two-dimensional image sensor 103. Time t in FIG. ₀ , All the signal charges of the two-dimensional image sensor 103 are discarded in advance, and the time t ₀ Measurement start pulse Φ _S Enters. With this as a starting point, the distance measuring apparatus starts to operate. On the other hand, the control signal Φ from the control signal generator 104 in a state where the light source 109 is OFF. _LD As a result, the light source driving unit 108 starts luminance modulation of the light source 109, and the sensitivity modulation driving unit 101 of the two-dimensional image sensor 103 also controls the control signal Φ from the control signal generator 104. _SM Thus, the sensitivity modulation of the two-dimensional image sensor 103 is started at the same frequency as the luminance modulation.
[0004]
This three-dimensional image input apparatus performs distance measurement by synchronizing the luminance modulation of the light source and the sensitivity modulation of the two-dimensional image sensor. To further simplify the description, the luminance modulation and the sensitivity modulation are performed with a period Tf. , And the lowest level of the modulated luminance is set to 0, the highest level of the modulated sensitivity is set to 1, and the lowest level is set to 0. In addition, the sensitivity level in a state having sensitivity when sensitivity modulation is not performed is defined as 1. The luminance modulation referred to here means controlling the charge accumulation of the two-dimensional image sensor 103 by turning on and off the light source 109 at a certain set frequency. On the other hand, sensitivity modulation refers to changing the sensitivity of the two-dimensional image sensor 103 at a certain set frequency.
[0005]
Next, how to obtain the distance information and the operation of the 3D image input apparatus will be described together. Considering the subject 110 1 at a distance z, the light projected from the light source 109 travels the distance z, is projected and reflected on the subject 110 1, travels the distance z again, and forms an image on the two-dimensional image sensor 103 1. Is done. Incident light from the subject 110 1 at this distance z is expressed by the following equation (1). _d Only after the light emission from the light source 109 is incident on the two-dimensional image sensor 103.
t _d = (2 × z) / c (1)
Where c is the speed of light. For this reason, the ratio η of the number of signal charges that can be generated in the pixel portion of the two-dimensional image sensor 103 during one luminance modulation period is as follows if the subject at the distance z = 0 is normalized to η = 1. It is represented by Formula (2).
η = 1− (2 × t _d ) / Tf (2)
In other words, when the output of the pixel is measured, as shown in the equation (2), from the known period Tf and the measured η, t _d Further, if (1) is used, the distance z to the subject 110 can be calculated by the following equation (1) ′.
z = (c × t _d ) / 2 (1) '
[0006]
At the end of the signal accumulation period Ta 1, each pixel portion on the two-dimensional image sensor 103 has a period during which the brightness of the return light from the light source 109 during the signal accumulation period Ta and the sensitivity of the two-dimensional image sensor 103 are set. The signal charge generated at the time that overlaps the existing period is accumulated. The signal charge accumulated in the two-dimensional image sensor 103 is read out during the period Ra. The signal charge read here is read as Ha. This signal charge Ha is expressed by the following equation (3).
Ha (x, y) = (k / 2) · η (z) · I (x, y) · Ta (3)
Here, k is a proportionality constant related to luminance modulation, and is modulated with a duty of 50%, so it is multiplied by 1/2.
η (z); term related to sensitivity modulation
I (x, y): The intensity of reflected light from the subject, and this I (x, y) includes the influence of the illuminance of the light source that decreases according to the distance to the subject.
[0007]
After the signal accumulation period Ta is completed as described above, the two-dimensional image sensor 103 is driven to read out these signal charges and store them in a memory (not shown) provided in the signal processing unit 105. Simultaneously with or after reading, the signal charge of each pixel is cleared. Next time t ₁ Again, the control signal Φ from the control signal generator 104 _LD Thus, the light source driving unit 108 starts luminance modulation of the light source 109, and the sensitivity modulation driving unit 101 enables signal charges to be accumulated while maintaining the sensitivity of the two-dimensional image sensor 103 (FIG. 5, period). Tb). At this time, the signal accumulation periods Ta and Tb are set to be equal. This is because information on the distance to the subject is calculated by comparing the signal charges in the signal accumulation periods Ta and Tb later. In the period Tb, since sensitivity is not modulated and the sensitivity is constant (normal imaging mode), the factor accompanying the sensitivity modulation in the equation (3) is a constant, and the state having this sensitivity is defined as 1. Therefore, when the period Tb ends, the signal charge represented by the following equation (4) is accumulated in each pixel portion of the two-dimensional image sensor 103.
Hb (x, y) = (k / 2) · I (x, y) · Tb (4)
[0008]
At the end of period Tb, time t ₁ Similar to the previous operation, the two-dimensional imaging device 103 is driven in the period Rb to read out these signal charges as Hb, and the end of the signal accumulation period Ta 1 in the memory (not shown) provided in the signal processing unit 105 1 is completed. The information (signal charge) represented by the equation (4) is stored in a memory different from the one written after. Then time t ₂ Previously, the signal charge of the two-dimensional image sensor 103 was discarded, and the time t ₂ Measurement start pulse Φ _S Entered, time t ₀ Ranging starts in the same way as in. This time t ₀ To t ₂ This is one cycle of distance measurement, and actual distance measurement is performed by repeating this procedure. Thus, two-dimensional imaging is performed from the signal charge Ha represented by the expression (3) and the signal charge Hb represented by the expression (4) stored in the memory (not shown) provided in the signal processing unit 105. The ratio of the signal charge Ha 1 at the time of sensitivity modulation driving to the signal charge Hb at the time of normal driving of the element 103 is obtained by the following equation (5).
η = {Ha (x, y) / Ta} / {Hb (x, y) / Tb} (5)
From this signal charge ratio η and the known Tf, t _d T was obtained here. _d Is substituted into the equation (1) ′, the distance z to the subject 110 is obtained.
[0009]
[Problems to be solved by the invention]
By the way, when the distance is measured by the conventional three-dimensional image input device (two-dimensional distance sensor), the distance range z that can be measured is t _d The condition of ≦ (Tf / 2) must be satisfied. Therefore, the following equation (6) is obtained from the equation (1) ′.
z ≦ (c × Tf) / 4 (6)
Therefore, in order to expand the distance measurement range, it is necessary to increase the luminance modulation period Tf (lower the luminance modulation frequency). In order to improve distance measurement accuracy, it is necessary to reduce the luminance modulation period Tf (increase the luminance modulation frequency). This shows that the distance measurement accuracy and the distance measurement range are not compatible.
[0010]
As described above, since the conventional three-dimensional image input device (two-dimensional distance sensor) proposed in the previous application is a single light source, it is impossible to achieve both distance measurement accuracy and distance measurement range. For example, if the luminance modulation frequency of the light source is 10 MHz, the distance measurement possible range is 7.50 m from the equation (6). If the distance measurement is performed with 8-bit gradation (256 gradations), the distance measurement range 7 When .50 m is divided into 256 gradations, the distance measurement range (resolution) for one gradation is 2.9 cm. On the other hand, if the luminance modulation frequency of the light source is 100 MHz, the distance measurement range per luminance modulation period is reduced to 0.75 m, so the distance measurement range per gradation in an 8-bit gradation is 0.29 cm. Become. In other words, this is equivalent to an improvement in resolution by one digit.
[0011]
The present invention has been made to solve the above-mentioned problems in the previously proposed two-dimensional distance sensor (three-dimensional image input device), and provides a three-dimensional image input device capable of satisfying both distance measurement accuracy and distance measurement range. The purpose is to do.
[0012]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a light source that projects a light beam whose luminance is modulated at a predetermined frequency, duration, and repetition time onto a target object, and a target object that is illuminated with the light beam from the light source. An imaging optical system that forms an image of the image, a two-dimensional imaging device that is installed on the imaging surface of the imaging optical system and capable of modulating the sensitivity of photoelectric conversion, and an electrode terminal that determines the sensitivity of the imaging device A drive unit that modulates at the frequency; and a reading unit that extracts a signal corresponding to the signal charge generated in each pixel of the image sensor; and the two-dimensional distance information of the target object is the signal charge of the two-dimensional image sensor In the three-dimensional image input apparatus obtained from the above distribution, the light beam from the light source is composed of light beams having a plurality of wavelengths having different luminance modulation frequencies.
[0013]
In this way, the light beam from the light source is configured with a plurality of wavelengths having different luminance modulation frequencies, and an optical distributor for distributing the light beam is provided, and a plurality of light beams that respectively receive the divided light beams. By providing the two-dimensional imaging element, it becomes possible to perform three-dimensional imaging with different luminance modulation frequencies simultaneously and in parallel. Thereby, it is possible to improve the distance measurement accuracy without changing the time required for the distance measurement, and without reducing the distance measurement range.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments will be described. FIG. 1 is a block configuration diagram showing an embodiment of a three-dimensional image input apparatus according to the present invention. In this embodiment, two types of light sources are used to simplify the description. The three-dimensional image input apparatus of this embodiment is different from the previously proposed one shown in FIG. 1 in that two types of light sources having different light wavelengths and luminance modulation frequencies are used, and these two light sources are returned from the subject. This is the point where light is observed simultaneously. Of the two types of light sources, one light source has a predetermined light wavelength and a luminance modulation period, and the other light source has a light wavelength different from that of the one light source. The modulation period is set short (the luminance modulation frequency is high).
[0015]
When the distance is measured first, the distance range z that can be measured is t _d Although it has been stated that the condition of ≦ (Tf / 2) must be satisfied, the reason for this will be described first. As described in the conventional example shown in FIG. 4, during distance measurement, each pixel portion on the two-dimensional image sensor 103 has a period (in the signal accumulation period Ta) with the brightness of the return light from the light source 109 ( Φ _ref During which the two-dimensional image sensor 103 is sensitive (Φ _SM The signal charges generated during the overlapping period of (ON period) are accumulated. Therefore, t _d Is 0 ≦ t _d In the period of ≦ (Tf / 2), the signal charge Ha accumulated in the two-dimensional image sensor 103 is t _d If it is defined that Ha = 1 when t = 0, t _d Φ with increasing _ref And Φ _SM Since the overlapping period of the ON period decreases, the value of Ha decreases and t _d When Ha == (Tf / 2), Ha = 0. On the other hand, (Tf / 2) <t _d <For the period of Tf, t _d Signal charge Ha starts to increase again at the boundary of Ha = 0 when == (Tf / 2), and t _d Φ with increasing time _ref And Φ _SM Since the overlapping period of the ON period increases, the value of Ha increases and t _d = Ha when Tf = 1 (t _d = 0) (equivalent to when 0). Since the distance information of this distance measurement is calculated from the accumulated signal charge, (Tf / 2) <t _d Even if the accumulated signal charge during the period of <Tf is used as the distance measurement data, 0 ≦ t _d It is not possible to determine whether or not it is obtained during the period of ≦ (Tf / 2). Therefore, the expression (6) that defines the distance range z that can be measured includes t _d The condition of ≦ (Tf / 2) is included.
[0016]
Even when the following equation (7) is satisfied, the detected signal charge is repeated in the above cycle.
t _d ≦ (n · Tf) + (Tf / 2) (7)
However, n is a positive integer. However, in reality, in the formula (7), when n is 1 or more, the intensity of the return light from the subject becomes weaker in proportion to the square of the distance. .
[0017]
Next, a specific configuration of the embodiment shown in FIG. 1 will be described. In FIG. 1, reference numeral 1 denotes a half mirror for forming two imaging surfaces of return light (reflected light) from an object, and reference numerals 2 and 3 denote wavelength bands of light sources whose luminance is modulated by removing the influence of background light. The first and second optical bandpass filters that transmit only light in the vicinity of the reflected light wavelength, 4 and 5 are the first and second two-dimensional image sensors, and 6 is the sensitivity of the two-dimensional image sensors 4 and 5. Sensitivity modulation drive unit for modulation, 7 is a two-dimensional image sensor drive unit, 8 is a control signal generator, 9 is a signal processing unit, 10 is a light source drive unit, 11 is an illumination device equipped with light sources 11a and 11b, 12 Indicates an imaging optical system, and 13 indicates a subject (target object). The first band pass filter 2 is set to transmit only the wavelength of light from the light source 11a, and the second optical band pass filter 3 is set to transmit only the wavelength of light from the light source 11b.
[0018]
The difference between this embodiment and the previously proposed one shown in FIG. 4 is that, as described above, two types of light sources are used, and the subject of the light source 11b having a light wavelength and a luminance modulation frequency different from those of the light source 11a. 13 is configured such that the return light from 13 is simultaneously observed with the return light from the subject 13 of the light source 11a. Next, when two types of light sources are used, different light wavelengths and luminance modulation frequencies are set. Describe the reason. The reason for using different luminance modulation frequencies is to achieve both the distance measurement range and the distance measurement accuracy. Next, the reason for using different light wavelengths will be described. This is due to measurement system limitations. When two types of light (modulated light) emitted from the illumination device 11 return from the subject 13, the light is distributed by the half mirror 1 before entering the first and second two-dimensional imaging elements 4 and 5. The light received by the first and second two-dimensional image sensors 4 and 5 by the optical bandpass filters 2 and 3 respectively installed on the front surfaces of the first and second two-dimensional image sensors 4 and 5. Select only ingredients. Thus, in order to enable separation of light having different modulation frequencies, it is necessary to use light sources having different light wavelengths.
[0019]
Next, the operation of the three-dimensional image input apparatus configured as described above will be described with reference to the timing chart shown in FIG. First, the operation timing will be described only in the measurement system that measures the return light from the subject 13 in the light source 11a. In FIG. _S Is the measurement start pulse, Φ _SM1 Is a pulse that modulates the sensitivity of the first two-dimensional image sensor 4, Φ _LD1 Is a pulse for driving the light source 11a, Φ _ref1 Is returned from the light source 11a, reflected by the subject 13 at a finite distance, and imaged on the light receiving surface of the first two-dimensional image sensor 4 via the half mirror 1, Φ _RD1 Is a read drive pulse group for reading the accumulated signal charge from the first two-dimensional image pickup device 4, Φ _DATA1 Represents the accumulated signal charge read from the first two-dimensional image sensor 4.
[0020]
Next, the operation of the measurement system for observing the return light from the subject 13 by the light source 11a will be described. In order to simplify the description here, the luminance modulation and the sensitivity modulation are performed by a rectangular wave having a period Tfg and a duty of 50%, and the lowest level of the modulated luminance is zero and the lowest level of the modulated sensitivity. Is assumed to be set to zero sensitivity. Also, the sensitivity level in the state where the sensitivity is obtained when the sensitivity is not modulated is defined as 1.
[0021]
First, time t ₀ Then, all the signal charges of the first two-dimensional imaging device 4 are discarded in advance, and the time t ₀ Measurement start pulse Φ _S Enters. With this as a starting point, the distance measuring apparatus starts to operate. The light source 11a is in the OFF state, and the control signal Φ from the control signal generator 8 _LD1 Thus, the light source driving unit 10 starts luminance modulation of the light source 11a. Further, the sensitivity modulation driving unit 6 of the first two-dimensional image pickup device 4 is also controlled by the control signal Φ from the control signal generator 8. _SM1 Thus, the sensitivity modulation driving of the first two-dimensional image sensor 4 is started at the same frequency as the luminance modulation frequency (signal accumulation period Tag in FIG. 2). The light projected from the light source 11 a to the subject 13 at the distance z travels the distance z, is projected and reflected on the subject 13, travels the distance z again, and forms an image on the first two-dimensional imaging device 4. Is done. Therefore, the return light Φ from the subject 13 at the distance z _ref1 T _dg Only after the light emission time of the light source 11a, the light enters the first two-dimensional image sensor 4.
[0022]
After the end of the signal accumulation period Tag, the first two-dimensional imaging device 4 is driven in the period Rag to read out these signals as signal charges Hag and store them in a memory ag (not shown) provided in the signal processing unit 9. To do. Simultaneously with or after reading, the signal charge of each pixel is cleared. Next time t ₁ Again, the control signal Φ from the control signal generator 8 _LD1 As a result, the light source driving unit 10 starts luminance modulation of the light source 11a, while the sensitivity modulation driving unit 6 of the first two-dimensional imaging device 4 is in the light receiving state and has a constant sensitivity (normal driving). ) Is maintained (period Tbg in FIG. 2).
[0023]
At this time, since the sensitivity modulation of the two-dimensional image sensor is not performed, all charges generated in each pixel during the period Tbg are accumulated. However, return light Φ _ref1 Delay time t _dg Φ _SM1 The falling timing of is set at the time when Tfg / 2 or more has elapsed after the end of the period Tbg.
[0024]
After the period Tbg ends, in the period Rbg, the first two-dimensional imaging device 4 is driven to read out these accumulated signal charges, and among the memory (not shown) provided in the signal processing unit 9, the signal accumulation period Tag Is stored in a memory bg that is different from the memory ag that has been written. Then time t ₂ Previously, the signal charge of the first two-dimensional image sensor 4 was discarded, and the time t ₂ Measurement start pulse Φ _S Entered, time t ₀ Ranging starts in the same way as in. This time t ₀ To t ₂ This is one cycle of distance measurement, and actual distance measurement is performed by repeating this procedure. Information (signal charge) in the signal accumulation periods Tag and Tbg is stored in the memories ag and bg in the signal processing unit, respectively, and the two-dimensional distance information can be easily obtained in the same manner as in the conventional example.
[0025]
The case where the return light from the subject 13 is observed by the light source 11a has been described above. Next, the operation timing will be described only in the measurement system for measuring the return light from the subject 13 in the light source 11b. In FIG. 2, Φ _S Is the measurement start pulse, Φ _LD2 Is a pulse for driving the light source 11b, Φ _SM2 Is a pulse that modulates the sensitivity of the second two-dimensional image sensor 5, Φ _ref2 Is returned from the light source 11b, reflected by the subject 13 at a finite distance, and imaged on the light receiving surface of the second two-dimensional image sensor 5 via the half mirror 1, Φ _RD2 Is a read drive pulse group for reading data (accumulated signal charge) from the second two-dimensional image sensor 5, Φ _DATA2 Represents the data (accumulated signal charge) read from the second two-dimensional image sensor 5.
[0026]
Next, the operation of the measurement system for observing the return light from the subject 13 by the light source 11b will be described. The basic operation is the same as the observation system of the return light from the subject 13 of the light source 11a. The method for obtaining the two-dimensional distance information from the detected signal charge is the same as in the conventional example. The differences are the wavelength of the light source 11b and the Φ driving the light source 11b. _LD2 Brightness modulation frequency and Φ for driving the second two-dimensional image sensor 5 _SM2 , And the return light Φ from the light source 11b. _ref2 Is Φ _LD2 The brightness modulation frequency of _ref1 The modulation is different. (Φ _LD2 Equivalent to the luminance modulation frequency). The signal accumulation periods Tag and Tbg, Tah and Tbh must be set to the same period. The signal accumulation periods Tag (Tbg) and Tah (Tbh) are also set to the same period. In FIG. 2, t _dh Is t _dg , Tfh is a period corresponding to Tfg, Rah and Rbh are periods corresponding to Rag and Rbg, and Hah and Hbh are signal charges corresponding to Hag and Hbg, respectively.
[0027]
Next, how the signal charges observed from the two two-dimensional imaging elements are processed using two kinds of light sources in this way will be described with reference to FIG. In FIG. 3, the horizontal axis represents the distance z from the light source to the subject, the right vertical axis represents the signal charge ratio η, and the left vertical axis represents the detected gradation. For simplicity, it is assumed that the detected gradation is 8 gradations for convenience. The distance within this one gradation range cannot be identified. Therefore, when the distance z to the subject exists within a certain gradation and a certain gradation range, it is defined in advance whether the distance is recognized as the upper gradation or the lower gradation. As for the signal charge ratio η, t _d The signal charge obtained when = 0 is normalized to 1.
[0028]
In FIG. 3, a represents the signal charge ratio period of the distance measurement result of the light source having a low modulation frequency, and b represents the signal charge ratio period of the distance measurement result of the light source having a modulation frequency 10 times as large as a. Also, the distance measurement range of a is as shown in FIG. ₁₀ ) / 4, and the distance measurement range of b is (c · T ₁₀₀ ) / 4. Where T ₁₀ , T ₁₀₀ Are modulation periods of modulation frequencies of 10 MHz and 100 MHz, respectively.
[0029]
Next, the processing procedure will be described. First, the distance to the subject of one light source with a low modulation frequency is roughly grasped from the measured signal charge ratio. After that, in the other light source with a high modulation frequency, a distance with higher accuracy is obtained from the result obtained previously from the measured signal charge ratio. In FIG. 3, first, the distance z to the subject at a is obtained from the signal charge ratio. The distance z from a to the subject is z ₁ ~ Z ₂ It can be seen that it exists in the range of. Next, based on the obtained result, the distance z from the light source to the subject is calculated from the signal charge ratio obtained in b. At this time, z is z ₃ ~ Z ₄ It can be seen that it exists in the range of. Thus, z is obtained with better accuracy than the result obtained previously.
[0030]
Next, how this is actually obtained will be described. For example, when three assumptions are made: the luminance modulation frequency of the light source a is 10 MHz, the signal charge ratio is η = 0.65, and the distance measurement is 256 gradations, t _d = 17.5 [ns], and it can be seen from the equation (1) ′ that the distance to the subject is in the range of z = 2.61 to 2.64 (m). Based on this, the data obtained by measuring the return light from the subject of the light source with the luminance modulation frequency of b set to 100 MHz in 256 gradations are compared and calculated. From this result, it can be seen that the distance to the subject is in the range of z = 2.624 to 2.625 (m). In this example, by combining two distance measurement results from two light sources having luminance modulation frequencies of 10 MHz and 100 MHz, which are different by one digit, the distance measurement range of the return light from the light source having the luminance modulation frequency of 10 MHz is maintained. Thus, it is shown that distance measurement with a resolution improved by an order of magnitude is possible by distance measurement of return light from a light source having a luminance modulation frequency of 100 MHz. If the distance of the return light from a light source with a luminance modulation frequency of 100 MHz is measured with a single light source, the ranging accuracy is improved by one digit compared with the case of the luminance modulation frequency of 10 MHz. Becomes 1/10 of the luminance modulation frequency of 10 MHz. However, by adopting the configuration according to the present invention, it is possible to prevent the distance measurement range from being lowered.
[0031]
As described above, it is possible to improve the distance measurement accuracy without changing the time required for the conventional distance measurement and without reducing the distance measurement range. In the three-dimensional image input apparatus according to the present invention, the distance measurement range is defined by the lowest luminance modulation frequency among the light sources used, and the distance measurement accuracy is the highest luminance modulation frequency among the light sources used. It will be specified in.
[0032]
Although the case where two light sources are used has been described in the above embodiment, it is needless to say that the number of light sources is not limited to two. The basis of the present invention is to modulate the sensitivity of the two-dimensional image sensor in synchronization with the luminance modulation frequency of the light source. Therefore, the present invention can be applied to any imaging device whose sensitivity changes depending on the substrate potential or the electrode potential existing on the light receiving surface.
[0033]
【The invention's effect】
As described above based on the embodiments, according to the present invention, the sensitivity modulation of a plurality of two-dimensional imaging devices is synchronized with the luminance modulation of each of a plurality of light sources having different light wavelengths and luminance modulation frequencies. The distance measurement accuracy can be improved without changing the time required for conventional distance measurement and reducing the distance measurement range. It becomes possible to make it. In addition, according to the present invention, it is possible to align the light source position of each wavelength and the optical axis and distance to the image sensor by using the multiplicity of light, and in parallel measurement using light of a plurality of luminance modulation frequencies. However, it becomes possible to maintain the geometric accuracy.
[Brief description of the drawings]
FIG. 1 is a block configuration diagram showing an embodiment of a three-dimensional image input apparatus according to the present invention.
FIG. 2 is a timing chart for explaining the operation of the embodiment shown in FIG. 1;
FIG. 3 is a conceptual diagram for explaining a distance measurement processing procedure in the embodiment shown in FIG. 1;
FIG. 4 is a block diagram showing a previously proposed three-dimensional image input apparatus.
FIG. 5 is a block diagram for explaining the operation of the three-dimensional image input apparatus shown in FIG. 4;
[Explanation of symbols]
1 half mirror
2 First optical bandpass filter
3 Second optical bandpass filter
4 First two-dimensional image sensor
5 Second two-dimensional image sensor
6 Sensitivity modulation drive
7 Two-dimensional image sensor drive unit
8 Control signal generator
9 Signal processor
10 Light source drive
11 Lighting device
11a, 11b Light source
12 Imaging optics
13 Subject

Claims (2)

A light source that projects a light beam whose luminance is modulated at a predetermined frequency, duration, and repetition time onto a target object; and an imaging optical system that forms an image of the target object illuminated with the light beam from the light source; A two-dimensional image pickup device capable of modulating the sensitivity of photoelectric conversion installed on the image forming surface of the image forming optical system; a drive unit for modulating an electrode terminal for determining the sensitivity of the image pickup device with the frequency; and the image pickup device A three-dimensional image input device comprising: a reading unit that extracts a signal corresponding to the signal charge generated in each pixel of the pixel; and obtaining the two-dimensional distance information of the target object from the signal charge distribution of the two-dimensional image sensor. 3. The three-dimensional image input apparatus according to claim 1, wherein the light beam from the light source is composed of light beams having a plurality of wavelengths having different luminance modulation frequencies. An optical distributor for forming a plurality of imaging planes of return light from the target object is provided, and a two-dimensional image sensor is disposed on each of the plurality of imaging planes via an optical bandpass filter. The optical bandpass filter transmits light having at least one wavelength among the wavelength components included in the light beam, and the sensitivity modulation period of the two-dimensional image sensor is modulation of light having a wavelength transmitted through the corresponding bandpass filter. The three-dimensional image input device according to claim 1, wherein the three-dimensional image input device is configured to coincide with a cycle.

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