1. An optical beam scanning device that projects a light beam to a screen and two-dimensionally scans the light beam on the screen, the optical beam scanning device comprising:
a light source configured to generate the light beam;
a deflecting mirror device configured to two-dimensionally deflect the light beam generated from the light source by rotating a deflecting mirror; and
a scanning distortion correcting unit configured to correct a projecting direction of the light beam deflected at the deflecting mirror device to the screen,
wherein the scanning distortion correcting unit is formed of a single optical element having a transmission surface or a reflection surface formed of a free-form surface in an aspheric surface shape asymmetric to an optical axis of the light beam.
2. The optical beam scanning device according to claim 1,
wherein the optical element is a free-form surface lens having at least one of an incident surface and a light emitting surface being a free-form surface.
3. The optical beam scanning device according to claim 1,
wherein the optical element is a free-form surface mirror having a reflection surface being a free-form surface.
4. The optical beam scanning device according to claim 1,
wherein the free-form surface of the optical element is an anamorphic free-form surface having curvatures different in a longitudinal section and a transverse cross section.
5. The optical beam scanning device according to claim 1,
wherein in the free-form surface of the optical element, a symmetry axis of the aspheric surface shape is decentered with respect to the optical axis of the light beam by a predetermined distance.
6. An optical beam scanning device comprising:
a light source;
a predetermined optical reflection surface to operate for repeated deflection in two directions nearly orthogonal to each other; and
a function to deflect and scan a light beam emitted from the light source and reflected at the optical reflection surface in a first scanning direction and a second scanning direction nearly orthogonal to the first scanning direction,
wherein a wedge optical prism or a trapezoid optical prism with a predetermined vertical angle made of transparent optical glass or optical component plastic with a predetermined refractive index is disposed in an optical path of the light beam reflected at the optical reflection surface.
7. The optical beam scanning device according to claim 6,
wherein the vertical angle of the wedge optical prism or the trapezoid optical prism ranges from angles of 14\xb0 plus or minus 3\xb0.
8. An optical beam scanning device comprising:
a light source;
a predetermined optical reflection surface to operate for repeated deflection in two directions nearly orthogonal to each other; and
a function to deflect and scan a light beam emitted from the light source and reflected at the optical reflection surface in a first scanning direction and a second scanning direction nearly orthogonal to the first scanning direction,
wherein a compound prism is disposed in an optical path of the light beam reflected at the optical reflection surface, the compound prism being formed of a wedge or trapezoid first optical prism with a predetermined vertical angle made of transparent optical glass or optical component plastic with a predetermined refractive index and a predetermined Abbe number and a second optical prism with a predetermined vertical angle made of optical glass or optical component plastic with a predetermined Abbe number different from at least the Abbe number of the first optical prism, the first optical prism being bonded to the second optical prism.
9. An optical beam scanning device, wherein:
the wedge optical prism, the trapezoid optical prism, or the compound prism according to claim 6 is disposed at a light beam emission opening of the beam scanning device or an image display device using the beam scanning device; and
the prism also serves as a dustproof transparent window member by sealing the opening with the prism.
10. An optical beam scanning device comprising:
a light source;
a predetermined optical reflection surface to operate for repeated deflection in two directions nearly orthogonal to each other; and
a function to deflect and scan a light beam emitted from the light source and reflected at the optical reflection surface in a first scanning direction and a second scanning direction nearly orthogonal to the first scanning direction,
wherein a compound prism is disposed at a position at which a going light beam and a returning light beam enter from in nearly reverse directions from each other, the going light beam being emitted from the light source and entering the optical reflection surface, the returning light beam being reflected at the optical reflection surface, the compound prism being formed of a wedge or trapezoid first optical prism with a predetermined vertical angle made of transparent optical glass or optical component plastic with a predetermined refractive index and a predetermined Abbe number and a second optical prism with a predetermined vertical angle made of optical glass or optical component plastic with a predetermined Abbe number different from at least the Abbe number of the first optical prism, the first optical prism being bonded to the second optical prism.
11. An optical beam scanning device comprising:
a light source;
a predetermined optical reflection surface to operate for repeated deflection in two directions nearly orthogonal to each other; and
a function to deflect and scan a light beam emitted from the light source and reflected at the optical reflection surface in a first scanning direction and a second scanning direction nearly orthogonal to the first scanning direction, wherein:
a wedge or trapezoid first optical prism with a predetermined vertical angle made of transparent optical glass or optical component plastic with a predetermined refractive index and a predetermined Abbe number and a second optical prism with a predetermined vertical angle made of optical glass or optical component plastic with a predetermined Abbe number different from at least the Abbe number of the first optical prism are disposed at positions apart from a predetermined distance;
a going light beam emitted from the light source is transmitted through at least one of the first optical prism and the second optical prism, and then enters the optical reflection surface; and
a returning light beam reflected at the optical reflection surface is in turn transmitted through the first and second optical prisms.
12. An image display device comprising:
the optical beam scanning device according to claim 6.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An apparatus for transmitting data in a communication system, comprising:
a processor configured to process broadcasting data regarding various types of digital broadcasts to be provided to users;
a SerialParallel (SP) converter configured to convert additional data of the broadcasting data into a parallel type;
a phase selector configured to generate a phase selection value using additional data bits, except for a first additional data bit, of the converted parallel-type additional data;
a sequence generator configured to generate a sequence using the first additional data bit and the phase selection value; and
an adder configured to couple the generated sequence with the processed broadcasting data.
2. The apparatus of claim 1, wherein the sequence is a Kasami sequence.
3. The apparatus of claim 2, wherein the sequence generator is configured to select polarity of the Kasami sequence using the first additional data bit and select a code phase from code phases of the Kasami sequence using the phase selection value.
4. The apparatus of claim 3, wherein the sequence generator is configured to generate the Kasami sequence having adjusted polarity and an adjusted code phase in conformity with the selected polarity and the selected code phase.
5. The apparatus of claim 3, wherein the Kasami sequence has a predetermined number of code phases corresponding to a number of the additional data bits, except for the first additional data bit, and a code phase is selected from the predetermined number of code phases based on the phase selection value.
6. The apparatus of claim 5, wherein the predetermined number of code phases of the Kasami sequence is determined in conformity with a length of a maximum channel delay profile of the communication system.
7. The apparatus of claim 1, wherein the generated sequence is multiplied by a predetermined gain value, coupled with the processed broadcasting data, and transmitted through a Transmitter Identification (TxID) signal transmission area in a transmission frame.
8. The apparatus of claim 1, further comprising a modulator configured to modulate the broadcasting data coupled with the sequence by the adder according to a Vestigial SideBand (VSB) modulation scheme and transmit the broadcasting data and the additional data through a transmission frame.
9. A method for transmitting data in a communication system, comprising:
processing broadcasting data regarding various types of digital broadcasts to be provided to users and converting additional data bits of the broadcasting data into a parallel type;
generating a Kasami sequence using the converted parallel-type additional data bits;
coupling the processed broadcasting data with the generated Kasami sequence; and
modulating the broadcasting data coupled with the Kasami sequence according to a VSB modulation scheme and transmitting the modulated broadcasting data through a transmission frame;
wherein in said generating a Kasami sequence using the converted parallel-type additional data bits, a code phase is selected from code phases of the Kasami sequence using the additional data bits, except for a first additional data bit.
10. The method of claim 9, wherein in said generating a Kasami sequence using the converted parallel-type additional data bits, polarity of the Kasami sequence is selected using the first additional data bit of the converted parallel-type additional data bits.
11. The method of claim 10, wherein said generating a Kasami sequence using the converted parallel-type additional data bits includes generating the Kasami sequence having adjusted polarity and an adjusted code phase in conformity with the selected polarity and the selected code phase.
12. The method of claim 9, wherein the Kasami sequence has a predetermined number of code phases corresponding to a number of the additional data bits, except for the first additional data bit, and the predetermined number corresponds to a length of a maximum channel delay profile of the communication system.
13. The method of claim 9, wherein the generated Kasami sequence is transmitted through a Transmitter Identification (TxID) signal transmission area in the transmission frame.