Optical deflection apparatus in which deflection angle is continuously controllable

• US 6,115,012 A
• Filed: 12/06/1995
• Issued: 09/05/2000
• Est. Priority Date: 05/23/1995
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Mizuno, Yoshihiro, Ishimoto, Manabu, Nakashima, Masato, Eguchi, Shin, Kayashima, Shigeo
• Primary Examiner(s): Liang, Regina
• Application Number:
  US08/569,422
• Time in Patent Office: 1,735 Days
• Field of Search: 345/87, 345/94, 345/95, 345/98, 345/99, 345/204, 345/208, 345/210, 345/84, 349/33, 349/142, 349/186, 348/791, 348/792
• US Class Current: 345/84
• CPC Class Codes: G02F 1/13306 Circuit arrangements or driving methods for the control of single liquid crystal cells G02F1/132, G02F1/133382 take precedence
• CPC Class Codes: G02F 1/139 based on orientation effects in which the liquid crystal remains transparent
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31

Abstract

An optical deflection apparatus includes a pair of transparent electrodes, a liquid crystal layer, put between the transparent electrodes, in which stripes are formed at intervals based on a waveform of a driving signal supplied to the pair of transparent electrodes, the stripes functioning as a grating by which incident light is deflected in a deflecting direction, and a driving unit for supplying to the pair of transparent electrodes the driving signal having a waveform by which the deflecting direction changes with time.

Claims

1. An optical deflection apparatus comprising:

a pair of transparent electrodes;

a liquid crystal layer, put between said transparent electrodes, in which stripes are formed at intervals based on a waveform of a driving signal supplied to said pair of transparent electrodes, the stripes functioning as a grating by which incident light is deflected in a deflecting direction; and

driving means for supplying to said pair of transparent electrodes the driving signal having a waveform by which the deflecting direction changes with time,

wherein said driving means includes

signal generating means for generating a first signal having a low frequency less than a predetermined frequency and a second signal having a high frequency greater than the predetermined frequency; and

control means for controlling said signal generating means so that said signal generating means outputs selectively the first signal or the second signal as the driving signal.

2. The optical deflection apparatus as recited in claim 1,

wherein the driving signal supplied from said driving means to said pair of transparent electrodes has a waveform by which the deflecting direction changes at a constant velocity.

3. The optical deflection apparatus as recited in claim 1,

wherein the driving signal supplied from said driving means to said pair of transparent electrodes has a waveform by which the deflecting direction changes at a constant angular velocity.

4. The optical deflection apparatus as claimed in claim 3, wherein the waveform of the driving signal depends on (sin wt) where t is time and w is an angular velocity.

5. The optical deflection apparatus as recited in claim 1,

wherein the driving signal supplied from said driving means to said pair of transparent electrodes has a waveform by which the deflecting direction changes at random.

6. The optical deflection apparatus as recited in claim 1,

wherein the waveform of the driving signal depends on (sin Θ

) where Θ

is a deflection angle.

7. An optical deflection apparatus, comprising:

a pair of transparent electrodes;

a liquid crystal layer, put between said transparent electrodes, in which stripes are formed at intervals based on a waveform of a driving signal supplied to said pair of transparent electrodes, the stripes functioning as a grating by which incident light is deflected in a deflecting direction; and

driving means for supplying to said pair of transparent electrodes the driving signal having a waveform by which the deflecting direction changes with time,

wherein the driving signal supplied from said driving means to said pair of transparent electrodes has a waveform by which the deflecting direction changes at a constant velocity, and

wherein the waveform of the driving signal depends on the following formula;

space="preserve" listing-type="equation">t/(t.sup.2 +f).sup.1/2

where t is time and f is a constant based on a velocity at which a deflecting angle changes.

8. An optical deflection apparatus comprising:

a pair of transparent electrodes, at least one of said transparent electrodes being segmented into electrode-segments;

a liquid crystal layer, put between said transparent electrodes, in which stripes are formed at intervals based on waveforms of driving voltages supplied to said pair of transparent electrodes, the stripes functioning as gratings by which incident light is deflected in deflecting directions;

orientation setting means for setting an initial orientation of said liquid crystal layer; and

driving means for supplying the driving voltages to the electrode-segments of said pair of transparent electrodes so that deflected light is focused,

wherein the driving voltages supplied to the electrode-segments are controlled individually.

9. The optical deflection apparatus as claimed in claim 8, wherein said orientation setting means sets the initial orientation having a single direction.

10. The optical deflection apparatus as claimed in claim 9, wherein said driving means supplies the driving voltages to the electrode-segments so that electrode-segments included in each of rectangular areas arranged in parallel to each other are provided with the same voltage.

11. The optical deflection apparatus as claimed in claim 10, wherein voltages supplied to the electrode-segments included in different rectangular areas differ from each other so that line-shaped focus of the deflected light is formed.

12. The optical deflection apparatus as claimed in claim 11, wherein a voltage supplied to electrode-segments included in an n-th rectangular area depends on the following formula:

space="preserve" listing-type="equation">(X.sub.n -R)/[S.sup.2 +(X.sub.n -R).sup.2 ].sup.1/2

where X_n is a position of the n-th rectangular area, S is a focal length and R is a position of the focus in an X direction.

13. The optical deflection apparatus as claimed in claim 11, wherein a voltage supplied to electrode-segments included in an n-th rectangular area depends on the following formula:

space="preserve" listing-type="equation">(X.sub.n -V)/[R.sup.2 +(X.sub.n -V).sup.2 ].sup.1/2

where X_n is a position of the n-th rectangular area, V is a potion of the focus in a direction in which the light is incident and R is a position of the focus in an X direction.

14. The optical deflection apparatus as claimed in claim 11, the voltages supplied to the electrode-segments are varied with time so that the line-shaped focus moves.

15. The optical deflection apparatus as claimed in claim 14, wherein the voltages are varied so that the line-shaped focus moves in a direction perpendicular to a direction in which the light is incident on said liquid crystal layer.

16. The optical deflection apparatus as claimed in claim 15, wherein the voltages are varied so that the line-shaped focus moves at a constant velocity.

17. The optical deflection apparatus as claimed in claim 16, wherein the voltage supplied to electrode-segments included in an n-th rectangular area depend on the following formula:

space="preserve" listing-type="equation">(X.sub.n -ct)/[S.sup.2 +(X.sub.n -ct).sup.2 ].sup.1/2

where X_n is a position of the n-th rectangular area, S is a focal length and c is a velocity.

18. The optical deflection apparatus as claimed in claim 11, wherein the voltages supplied to the electrode-segments are varied so that the line-shaped focus moves at a constant angular velocity.

19. The optical deflection apparatus as claimed in claim 18, wherein the voltage supplied to electrode-segments included in an n-th rectangular area depends on the following formula:

space="preserve" listing-type="equation">(X.sub.n -s tan wmt)/[S.sup.2 +(X.sub.n -s tan wmt).sup.2 ].sup.1/2

where X_n is a position of the n-th rectangular area, S is a focal length, wm is an angular velocity and t is time.

20. The optical deflection apparatus as claimed in claim 11, wherein the voltages supplied to the electrode-segments are varied so that the line-shaped focus moves in a direction parallel to a direction in which the light is incident on the liquid crystal layer.

21. The optical deflection apparatus as claimed in claim 20, wherein the voltage supplied to electrode-segments included in an n-th rectangular area depends on the following formula:

space="preserve" listing-type="equation">(X.sub.n -u)/[(et).sup.2 +(X.sub.n -u).sup.2 ].sup.1/2

where X_n is a position of the n-th rectangular area, u is a focal length, e is a velocity at which the focus moves and t is time.

22. The optical deflection apparatus as claimed in claim 8, wherein said orientation setting means sets the initial orientation having a direction which changes along concentrically arranged circles.

23. The optical deflection apparatus as claimed in claim 22, wherein said driving means supplies the driving voltages to the electrode-segments so that electrode-segments included in each of circular areas concentrically arranged are provided with the same voltage.

24. The optical deflection apparatus as claimed in claim 23, wherein voltages supplied to the electrode-segments included in different circular areas differs from each other so that a focal point of the deflected light is formed.

25. The optical deflection apparatus as claimed in claim 24, wherein the voltage supplied to electrode-segments included in an n-th circular area depends on the following formula:

space="preserve" listing-type="equation">r.sub.n /(R.sup.2 +r.sub.n.sup.2).sup.1/2

where r_n is a radius of the n-th circular area and R is a focal length.

26. The optical deflection apparatus as claimed in claim 24, wherein the voltages supplied to the electrode-segments are varied with time so that the focal point moves.

27. The optical deflection apparatus as claimed in claim 26, wherein the voltage supplied to the electrode-segments are varied with time so that the focal point moves in a direction parallel to a direction in which the light is incident on the liquid crystal.

28. The optical deflection apparatus as claimed in claim 27, wherein the voltage supplied to electrode-segments included in an n-th circular area depends on the following formula:

space="preserve" listing-type="equation">r.sub.n /(ct.sup.2 +r.sub.n.sup.2).sup.1/2

where r_n is a radius of the n-th circular area and c is a velocity.

29. An optical deflection apparatus comprising:

a pair of transparent electrodes, at least one of said transparent electrodes being segmented into electrode-segments;

a liquid crystal layer, put between said transparent electrodes, in which stripes are formed at intervals based on a waveform of a driving signal supplied to said pair of transparent electrodes, the stripes functioning as a grating by which incident light is deflected in a deflecting direction; and

driving means for supplying to said pair of transparent electrodes the driving signal having a waveform by which the deflecting direction changes with time,

wherein said the driving signal supplied form said driving means to said pair of transparent electrodes has a waveform by which the deflecting directions changes periodically with respect to times,

wherein the driving signal includes driving voltages supplied to the electrode-segments which are controlled individually.

30. An optical deflection apparatus comprising:

a pair of transparent electrodes;

a liquid crystal layer, put between said transparent electrodes, in which stripes are formed at intervals based on a waveform of a driving signal supplied to said pair of transparent electrodes, the stripes functioning as a grating by which incident light is deflected in a deflecting direction; and

driving means for supplying to said pair of transparent electrodes the driving signal having a waveform by which the deflecting direction changes with time,

wherein said pair of transparent electrodes include elongated transparent electrode segments which are positioned in parallels,

wherein the driving signal includes driving voltages supplied to the electrode-segments which are controlled individually.

31. An optical deflection apparatus comprising:

a pair of transparent electrodes;

a liquid crystal layer, put between said transparent electrodes, in which stripes are formed at intervals based on a waveform of a driving signal supplied to said pair of transparent electrodes, the stripes functioning as a grating by which incident light is deflected in a deflecting direction; and

driving means for supplying to said pair of transparent electrodes the driving signal having a waveform by which the deflecting direction changes with times,

wherein said pair of transparent electrodes include transparent electrode segments positioned in a grid type pattern, and

wherein the driving signal includes driving voltages supplied to the electrode-segments which are controlled individually.

32. An optical deflection apparatus comprising:

a pair of transparent electrodes;

a liquid crystal layer, put between said transparent electrodes, in which stripes are formed at intervals based on a waveform of a driving signal supplied to said pair of transparent electrodes, the stripes functioning as a grating by which incident light is deflected in a deflecting direction; and

driving means for supplying to said pair of transparent electrodes the driving signal having a waveform by which the deflecting direction changes with time,

wherein said pair of transparent electrodes include disk-shaped transparent electrode segments which are positioned concentrically, and

wherein the driving signal includes driving voltages supplied to the electrode-segments which are controlled individually.