1. An apparatus for recording information to and reproducing information from an optical recording medium having a first information recording layer and a second information recording layer, comprising:
a light source that emits a light beam;
a diffractive optical element that divides the light beam into a first light beam and a second light beam;
a converging unit that converges the first light beam and the second light beam on the optical recording medium;
a driving unit that drives the converging unit;
a light detecting unit that detects a first reflected light beam that is the first light beam reflected on the optical recording medium and a second reflected light beam that is the second light beam reflected on the optical recording medium;
a tracking control unit that performs a tracking control by driving the driving unit based on a first tracking error signal obtained from the first reflected light beam and a second tracking error signal obtained from the second reflected light beam; and
a correcting unit that corrects the first tracking error signal when the information is recorded to or reproduced from the first information recording layer that includes a first area and a second area, the first area being in opposite to an area on the second information recording layer on which no information is recorded, the second area being in opposite to an area on the second information recording layer on which information is recorded, wherein
the tracking control unit performs the tracking control based on the first tracking error signal corrected by the correcting unit and the second tracking error signal.
2. The apparatus according to claim 1, wherein the correcting unit includes a limiting unit that limits the first tracking error signal to a first threshold value.
3. The apparatus according to claim 2, wherein
the correcting unit further includes an adjusting unit that adjusts the first threshold value according to the first tracking error signal, and
the limiting unit limits the first tracking error signal to the first threshold value adjusted by the adjusting unit.
4. The apparatus according to claim 2, wherein the limiting unit is a limiter circuit that outputs the first tracking error signal by limiting the first tracking error signal to the first threshold value when the first tracking error signal exceeds the first threshold value.
5. The apparatus according to claim 1, wherein the correcting unit includes
a detecting unit that detects a boundary passing timing indicating a time at which the information is recorded to or reproduced from the first information recording layer that includes the first area and the second area, and
a holding unit that holds the first tracking error signal when the detecting unit detects the boundary passing timing.
6. The apparatus according to claim 5, wherein the detecting unit detects the boundary passing timing when the first tracking error signal exceeds a second threshold value.
7. The apparatus according to claim 5, wherein the detecting unit detects the boundary passing timing based on address information recorded on the optical recording medium.
8. The apparatus according to claim 5, wherein the detecting unit detects the boundary passing timing based on a change of a sum signal obtained from the first reflected light beam detected by the light detecting unit.
9. The apparatus according to claim 8, wherein
the detecting unit further includes a differential circuit that differentiates the sum signal and that outputs a differential signal, and
the detecting unit detects the boundary passing timing when the differential signal exceeds a third threshold value and a fourth threshold value.
10. The apparatus according to claim 5, wherein the holding unit includes
a samplehold circuit that operates in a sample mode in which an input of the first tracking error signal is output as it is and a hold mode in which an output of the first tracking error signal is held to a last value, and
a circuit control unit that switches the samplehold circuit to the hold mode when the detecting unit detects the boundary passing timing and switches the samplehold circuit to the sample mode when the detecting unit detects no boundary passing timing.
11. A method of controlling a tracking an optical recording medium having a first information recording layer and a second information recording layer, comprising:
dividing a light beam emitted from a light source into at least a first light beam and a second light beam;
converging the first light beam and the second light beam on the optical recording medium;
detecting a first reflected light beam that is the first light beam reflected on the optical recording medium and a second reflected light beam that is the second light beam reflected on the optical recording medium;
performing a tracking control based on a first tracking error signal obtained from the first reflected light beam and a second tracking error signal obtained from the second reflected light beam; and
correcting the first tracking error signal when the information is recorded to or reproduced from the first information recording layer that includes a first area and a second area, the first area being in opposite to an area on the second information recording layer on which no information is recorded, the second area being in opposite to an area on the second information recording layer on which information is recorded, wherein
the performing includes performing the tracking control based on the first tracking error signal corrected at the correcting and the second tracking error signal.
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. A gate latch assembly comprising:
a biased latchbolt moved between a retracted position and an extended position;
a latchbolt catch to receive the latchbolt; and
a two-stage mechanism for repositioning the latchbolt from the extended position to the retracted position, the two-stage mechanism comprising a button structure, a clutch member having, first and second contacting surfaces, a biasing member, and an inner operating member having a follower therein and moved between a non-operating position and an operating position;
wherein the first stage the mechanism is operated by pushing the button structure to engage the first contacting surface of the clutch member with the latch bolt and, the second stage of the mechanism is operated by moving the inner operating member toward the operating position so as to allow the follower to move along the second contacting member of the clutch member to allow the latch bolt to be retracted; wherein when the inner operating member is returned to the non-operating position, the first contacting surface of the clutch member is biased to disengage the latch bolt.
2. The gate latch assembly of claim 1, wherein the inner operating member comprises first and second covering members partially covering the clutch member; wherein the second covering includes the follower.
3. The gate latch assembly of claim 2, wherein;
the first covering includes complementary panels majorily enclosing the two-stage mechanism; and
the complementary panels cooperate to form guides to guide the movement of the latchbolt between the extended position and the retracted position.
4. The gate latch assembly of claim 2, wherein:
the latchbolt includes a repositionable pin traversing along a pin guide;
the pin includes a projection or a cavity that engages the pin guide to selectively reposition the pin when the pin guide is repositioned; and
the pin guide is selectively engaged by the clutch.
5. The gate latch assembly of claim 4, wherein:
the pin includes a proximal projection;
the pin includes alignment features that interact with corresponding features of the first coveting to guide traversal of the pin;
the first covering includes an orifice though which the proximal projection extends in the extended position; and
the second covering includes an office through which the proximal projection extends in the extended position.
6. The gate latch assembly of claim 1, wherein:
the first contacting surface of the clutch member includes two pivotally mounted arms adapted to be moved by operation of the button structure, each arm includes a detent to engage a corresponding cavity of the latchbolt when the button structure is pushed, and the arms are biased apart from one another to inhibit engagement of each detent with its corresponding cavity of the latchbolt when the button structure is released.
7. A repositionable barrier comprising:
a gate frame;
a repositionable gate door cooperating with the gate frame to provide a barrier across an area having a width and a height cooperatively defined by the gate frame and gate door when the gate door is in a closed position; and
a gate latch assembly comprising:
a biased latchbolt moved between a retracted position and an extended position;
a latchbolt catch to receive the latchbolt and
a two-stage mechanism for repositioning the latchbolt from the extended position to the retracted position, the two-stage mechanism comprising a button structure, a clutch member having first and second contacting surfaces, a biasing member and an inner operating member having a follower therein and moved between a non-operating position and an operating position;
wherein the first stage of the mechanism is operated by pushing the button structure to engage the first contacting surface of the clutch member with the latch bolt and the second stage of the mechanism is operated by moving the inner operating member toward the operating position so as to allow the follower to move along the second contacting member of the clutch member to allow the latch bolt to be retracted; wherein, when the inner operating member is returned to the non-operating position the first contacting surface of the clutch member is biased to disengage the latch bolt.
8. The gate latch assembly of claim 7, wherein the inner operating member comprises first and second covering members partially covering the clutch member; wherein the second covering includes the follower.