Spatial information detecting apparatus

1. A spatial information detection apparatus comprising:

a light-emitting element ( 100 ) configured to emit an intensity-modulated light to a target space;

a lighting signal generation circuit ( 10 ) configured to generate a lighting timing signal (E 1 ) which determines a lighting timing of said light-emitting element,

a light-emitting element driving circuit ( 30 ) configured to output a light-emitting element driving signal (E 2 ) in response to said lighting timing signal for generation of said intensity-modulated light from said light-emitting element;

a light-receiving element ( 200 ) configured to receive said intensity-modulated light reflected from an object in said target space;

an information output circuit ( 300 ) configured to extract a light intensity of the light received at the said light-receiving element for each of a plurality of phase ranges (P 0 , P 1 , P 2 , and P 3 ), determine a relation between said intensity-modulated light from said light-emitting element and said intensity-modulated light received at said light-receiving element based upon a variation of said extracted light intensities, and output spatial information within said target space;

a light-receiving element driving circuit ( 40 ; 40 A; 40 B) configured to output a plurality of light-receiving element driving signals D 2 which are out of phase relation from each other to said light-receiving element in order to activate said light-receiving element for each of said phase ranges;

a detection signal generation circuit ( 20 ) configured to provide to said light-receiving element driving circuit a detection timing signal (D 1 ) for determination of a timing of generating said light-receiving element driving signal; and

a timing synchronization circuit ( 70 ; 70 A; 70 B) configured to compare a cyclic variation associated with the output from said light-emitting element driving circuit with a cyclic variation determined by said detection timing signal, and modify at least one of said detection timing signal (D 1 ) and said lighting timing signal (E 1 ) in order to keep a constant phase difference between said cyclic variations.

2. A spatial information detection apparatus as set forth in claim 1 , wherein said timing synchronization circuit ( 70 ) is configured to obtain a cyclic variation of said light-receiving element driving signal (D 2 ) from said light-receiving element driving circuit as said cyclic variation to be determined by said detection timing signal for comparison with the light-emitting element driving signal (E 2 ) from said light-emitting element driving circuit ( 30 ).

3. A spatial information detection apparatus as set forth in claim 1 or 2 , wherein said timing synchronization circuit ( 70 ) is configured to modify said lighting timing signal into a modified lighting timing signal (E 1 x ) and feed said modified lighting timing signal to said light-emitting element driving circuit.

4. A spatial information detection apparatus as set forth in claim 3 , wherein said timing synchronization circuit ( 70 ) is interposed between said lighting signal generation circuit ( 10 ) and said light-emitting element driving circuit ( 30 ), and comprises:

a phase adjusting circuit ( 76 ) configured to shift a phase of the lighting timing signal output from said lighting signal generation circuit to said light-emitting element driving circuit ( 30 ) by variable a phase shift value, and

a phase comparator ( 72 ) configured to determine said phase shift value in accordance with a phase difference between the cyclic variation output from said light-receiving element driving element circuit and the light-emitting element driving signal from said light-emitting element driving circuit ( 30 ).

5. A spatial information detection apparatus as set forth in claim 3 , wherein said light-receiving element driving circuit ( 40 ) is configured to determine said light-receiving element driving signal based upon a plurality of detection timing signals output from said detection signal generation circuit, and

a selector ( 80 is provided to selectively extract the light-receiving element driving signals which are out of phase relation from each other,

said timing synchronization circuit ( 70 ) being configured to modify said lighting timing signals based upon a phase difference between said light-receiving element driving signals (D 2 ) selected from said selector 80 and the cyclic variation (E 2 ) associated with the output from said light-emitting element driving circuit ( 30 ).

6. A spatial information detection apparatus as set forth in claim 5 , wherein said information output circuit ( 300 ) is configured to integrate the received light intensities over a plurality of times for each of said phase regions (P 0 , P 1 , P 2 , P 3 ) corresponding to said light-receiving element driving signals,

said information output circuit being configured to obtain the received light intensity from said light-receiving element ( 200 ) at each of said phase regions (P 0 , P 1 , P 2 , P 3 ) in synchronous with the light-receiving element driving signal D 2 selected from said selector ( 80 ).

7. A spatial information detection apparatus as set forth in claim 2 , further including:

a supplemental phase adjusting circuit ( 90 interposed between said detection signal generation circuit ( 20 ) and said light-receiving element driving circuit ( 40 ) and configured to shift the phase of said detection timing signal by a variable shift phase value and output said detection timing signal to said light-receiving element driving circuit;

a supplemental phase comparator ( 92 ) configured to detect a phase difference between said detection timing signal (D 1 ) and the cyclic variation (D 2 ) output from said light-receiving element driving circuit for providing an output indicative of said phase difference to said supplemental phase adjusting circuit;

said supplemental phase adjusting circuit ( 90 ) being configured to determine said phase shift value based upon said phase difference for keeping a predetermined value given for the phase difference between said detection timing signal (D 1 ) and said light-receiving element driving signal (D 2 ) from the light-receiving element driving circuit.

8. A spatial information detection apparatus as set forth in claim 1 , wherein said timing synchronization circuit ( 70 ; 70 A) is configured to compare the cyclic variation (E 2 ) resulting from the output from said light-emitting element driving circuit ( 30 ) with said detection timing signal (D 1 ) from the detection signal generation circuit ( 20 ).

9. A spatial information detection apparatus as set forth in claim 8 , wherein said timing synchronization circuit ( 70 ) is configured to modify said lighting timing signal to provide the modified lighting timing signal (E 1 x ) to said light-emitting element driving circuit.

10. A spatial information detection apparatus as set forth in claim 8 , wherein said timing synchronization circuit ( 70 A) is configured to modify said detection timing signal (D 1 ) into a modified detection timing signal (D 1 x ) and provide the modified detection timing signal to said light-receiving element driving circuit ( 40 ).

11. A spatial information detection apparatus as set forth in claim 10 , wherein said timing synchronization circuit ( 70 A) is interposed between said detection signal generation circuit ( 20 ) and said light-receiving element driving circuit ( 40 ), and comprises:

a phase adjusting circuit ( 76 A) configured to shift a phase of said detection timing signal (D 1 ) from said detection signal generation circuit by a variable phase shift value and output said detection timing signal to said light-receiving element driving circuit ( 40 ); and

a phase comparator ( 72 A) configured to determine said phase shift value based upon the phase difference between the cyclic variation output from said light-emitting element driving circuit and said detection timing signal from said detection signal generation circuit.

12. A spatial information detection apparatus as set forth in claim 10 , further including:

a supplemental phase adjusting circuit ( 90 A) interposed between said timing synchronization circuit ( 70 A) and said light-receiving element driving circuit ( 40 ) and configured to shift a phase of said modified detection timing signal (D 1 x ) by a variable phase shift value;

a supplemental phase comparator ( 92 A configured to detect a phase difference between said modified detection timing signal (D 1 x ) and the light-receiving element driving signal (D 2 ) from said light-receiving element driving circuit ( 40 ) to provide an output indicative of said phase difference to said supplemental phase adjusting circuit ( 90 A), and

said supplemental phase adjusting circuit ( 90 A) configured to determine said phase shift value based upon said phase difference for keeping a predetermined value given for the phase difference between said modified detection timing signal (D 1 x ) from said timing synchronization circuit ( 70 A) and said light-receiving element driving signal (D 2 ) from the light-receiving element driving circuit ( 40 ).

13. A spatial information detection apparatus as set forth in claim 10 , further including:

a reference light-receiving element ( 110 ) configured to receive a portion of said intensity modulated light from said light-emitting element to output an corresponding light intensity; and

said timing synchronization circuit ( 70 A) being configured to use the light intensity as indicative of the cyclic variation associated from the output from said light-emitting element driving circuit ( 30 ).

14. A spatial information detection apparatus as set forth in claim 10 , wherein said timing synchronization circuit ( 70 B) comprises:

an oscillation circuit ( 78 ) configured to use a signal of which frequency varies with a varying input voltage and provide the signal as said modified detection timing signal to said light-receiving element driving circuit ( 40 ), and

a phase comparator ( 72 B) configured to generate a voltage indicative of a phase difference between the cyclic variation (E 2 ) associated with the output from said light-emitting element driving circuit ( 30 ) and the detection timing signal (D 1 x ) from said detection signal generation circuit ( 20 ), and provide said voltage to said oscillation circuit.

15. A spatial information detection apparatus as set forth in claim 1 , wherein said timing synchronization circuit comprises:

a first timing synchronization circuit ( 70 ) interposed between said lighting signal generation circuit ( 10 ) and said light-emitting element driving circuit; and

a second timing synchronization circuit ( 70 A) interposed between detection signal generation circuit and said light-receiving element driving circuit;

said first timing synchronization circuit ( 70 ) comprising a first phase adjusting circuit ( 76 ) configured to shift a phase of said lighting timing signal (E 1 ) from said lighting signal generation circuit ( 10 ) by a variable phase shift value, and output said lighting timing signal to said light-emitting element driving circuit ( 30 ), a first phase comparator ( 72 ) configured to determine said phase shift value based upon a phase difference between the cyclic variation (E 2 ) output from said light-emitting element driving circuit ( 30 ) and said detection timing signal (D 1 ) from said detection signal generation circuit ( 20 );

said second timing synchronization circuit ( 70 A) comprising a second phase adjusting circuit ( 76 A) configured to shift a phase of said detection timing signal (D 1 ) from said detection signal generation circuit ( 20 ) by a variable phase shift amount, and output said detecting timing signal to said light-receiving element driving circuit ( 40 ), and a second phase comparator ( 72 A) configured to determine said phase shift value based upon a phase difference between said lighting timing signal (E 1 ) from said lighting signal generation circuit ( 10 ) and said light-receiving element driving signal (D 2 ) from said light-receiving element driving circuit ( 40 ).

16. A spatial information detection apparatus as set forth in claim 1 , wherein said light-receiving element has a capacitive reactance and is configured to operate on a DC current supplied from a DC power source ( 210 ),

said light-receiving element driving circuit ( 40 B) comprising:

an output switch ( 50 ) connected between said DC power source and said light-receiving element to supply said DC current to said light-receiving element in synchronization with said detection timing signal;

a temperature sensor ( 150 ) for detection of an ambient temperature; and

a current controller ( 160 ) configured to regulate the current being fed to said light-receiving element in such a manner as to keep the current being fed to said light-receiving element at a predetermined varying rate.

17. A spatial information detection apparatus as set forth in claim 16 , wherein said current controller ( 160 ) includes a memory means ( 162 ) configured to store the varying rate of the current through said light-receiving element in association with the temperature,

said current controller being configured to read out from said memory means ( 162 ) the current varying rate corresponding to the temperature output from said temperature sensor ( 150 ) and control the current flowing through the light-receiving element in match with the reading of the current varying rate.

18. A spatial information detection apparatus as set forth in claim 1 , wherein said light-receiving element has a capacitive reactance and is configured to operate on a DC current supplied from a DC power source ( 210 ),

said light-receiving element driving circuit 40 A comprising:

an output switch ( 50 ) connected between said DC power source and said light-receiving element to supply said DC current to said light-receiving element in synchronization with said detection timing signal;

a current monitoring circuit ( 60 ) configured to monitor a varying rate of the current being fed to said light-receiving element and provides a current variation output indicative of the varying rate; and

a current controller ( 66 ) configured to operate in response to said current variation output for regulating the current being fed to said light-receiving element in such a manner as to keep the current being fed to said light-receiving element at a predetermined varying rate.

19. A spatial information detection apparatus as set forth in claim 18 , wherein said current monitoring circuit ( 60 ) comprises:

a differential circuit ( 62 ) configured to calculate an instant varying rate of the current flowing through the light-receiving element; and

a peak detection circuit ( 64 ) configured to detect a maximum of said instant varying rate from said differential circuit;

said current controller ( 66 ) being configured to control the current flowing through said light-receiving element based upon said maximum of the instant varying rate from said peak detection circuit in order to keep the varying rate at a predetermined value.

20. A spatial information detection apparatus as set forth in claim 19 , wherein said light-receiving element driving circuit further comprising:

a temperature sensor ( 130 ) for detection of an ambient temperature;

a register ( 68 ) configured to hold a maximum of said instant varying rate detected at said peak detection circuit ( 64 );

a temperature table ( 140 ) configured to store the output of said temperature sensor at a predetermined interval; and

an activation circuit ( 120 ) configured to activate said differential circuit and said peak detection circuit only when there is detected a temperature difference exceeding a predetermined level between a current temperature and a past temperature recorded at a predetermined past time.

21. A spatial information detection apparatus comprising:

a light-emitting element ( 100 ) configured to emit an intensity-modulated light to a target space;

a lighting signal generation circuit ( 10 ) configured to generate a lighting timing signal (E 1 ) which determines a lighting timing of said light-emitting element,

a light-emitting element driving circuit ( 30 ) configured to output a lighting-element driving signal (E 2 ) in response to said lighting timing signal for generation of said intensity-modulated light at said light-emitting element;

a light-receiving element ( 200 ) configured to receive said intensity-modulated light reflected from an object in said target space;

an information output circuit ( 300 configured to obtain a light intensity of the light received at the said light-receiving element for each of a plurality of phase ranges (P 0 , P 1 , P 2 , P 3 ), determine a relation between said intensity-modulated light from said light-emitting element and said intensity-modulated light received at said light-receiving element based upon a variation of said light intensities, and output spatial information within said target space;

a light-receiving element driving circuit ( 40 ; 40 A; 40 B) configured to output a plurality of light-receiving element driving signals (D 2 ) which are out of phase relation from each other to said light-receiving element in order to activate said light-receiving element for each of said phase ranges;

a detection signal generation circuit ( 20 ) configured to provide to said light-receiving element driving circuit a detection timing signal (D 1 ) for determination of a timing of generating said light-receiving element driving signal; and

a timing synchronization circuit ( 70 ; 70 A; 70 B) configured to compare a cyclic variation of the lighting timing signal from said lighting signal generation circuit with a cyclic variation determined by said detection timing signal, and modify at least one of said detection timing signal (D 1 ) and said lighting timing signal (E 1 ) in order to keep a constant phase difference between said cyclic variations,

wherein said timing synchronization circuit ( 70 ) comprises:

an oscillation circuit ( 78 ) configured to use a signal of which frequency varies with an input voltage and provide the signal as said modified detection timing signal (E 1 x ) to said light-emitting element driving circuit, and

a phase comparator ( 72 ) configured to generate a voltage indicative of a phase difference between the cyclic variation (D 2 ) associated with the output from said light-receiving element driving circuit and the lighting timing signal (E 1 ) from said lighting signal generation circuit, and provide said voltage to said oscillation circuit.