JP4031195B2 - Offset adjustment device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an offset adjusting device for removing an offset of a light receiving element and a first stage amplifier of an optical disk drive.
[0002]
[Prior art]
An optical disk drive that writes and reads information on an optical disk is provided with a plurality of light receiving elements that receive reflected light of laser light irradiated on the optical disk, and an output from the light receiving element is amplified by a first-stage amplifier to generate an RF signal. Focus signal, tracking signal, etc. are obtained.
[0003]
An offset due to dark current occurs in this light receiving element, and an offset also occurs in the first stage amplifier.
When such an offset occurs, an error is included in the RF signal, the focus signal, the tracking signal, etc., and it is necessary to reproduce an incorrect signal or perform an incorrect control to remove the offset.
[0004]
Conventionally, as a method of removing such an offset, a voltage is applied to the first-stage amplifier via a variable resistor, and the offset value is canceled by changing the resistance value of the variable resistor.
[0005]
[Problems to be solved by the invention]
Although this process was performed in the assembly process of manufacture, the adjustment man-hour increased and it became an expensive thing.
An object of the present invention is to provide an offset adjusting device that can easily adjust an offset at low cost.
[0006]
[Means for Solving the Problems]
In the invention of claim 1, the first stage amplifier unit for amplifying an output of the light receiving element, it reads out the recorded values recorded in the cancellation value recording unit, the read record value into an analog value in addition to the first-stage amplifier An offset adjustment device for an optical disc drive that removes the offset,
An analog / digital converter that converts the output signal from the first stage amplifier into a digital value;
An amplifier provided between the output of the first stage amplifier and the analog / digital converter ;
A 0 voltage setting unit for setting the input voltage of the amplifier to 0 voltage;
Prior to the offset adjustment of the first stage amplifier, the zero voltage setting unit is operated to record the offset value of the amplifier, and after the zero voltage setting unit is released, the offset adjustment of the first stage amplifier is started and the recording is performed. The offset value of the amplifier is reduced from the output value from the analog / digital conversion unit at the time of offset adjustment.
[0007]
According to a second aspect of the present invention, in the first aspect of the present invention, the offset value of the amplifier is A / D converted by the analog / digital conversion unit as A, and the offset is removed in addition to the first-stage amplifier. When the value converted by the analog / digital conversion unit in the state where the recorded value to be generated is B, the value of | B−A | obtained by subtracting the offset value of the amplifier from the offset value of the first-stage amplifier is Determining means for determining whether or not a predetermined range is present;
Having communication means to the optical disc drive;
When the determination value of the determination means is not within a predetermined range, a value for increasing or decreasing the recording value according to the sign of B-A is transmitted via the communication means,
When the determination value of the determination unit is within a predetermined range, it is determined that the offset adjustment of the first stage amplifier is appropriate, and the cancel value recording unit records the appropriate record value via the communication unit. Features.
[0008]
The invention of claim 3 is the invention of claim 1 or 2, characterized in that the offset value recording operation of the amplifier and the offset adjustment operation of the first stage amplifier are selectively performed.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of an embodiment of the present invention, and FIGS. 2 and 3 are operation flowcharts of the embodiment.
In FIG. 1, 1 is an optical disk drive, 2 is an offset adjusting device according to the present invention, and 3 is a personal computer constituting the offset adjusting device 2.
[0010]
In the optical disk drive 1, 10 is a light receiving element, 11 is a selector, 12 is a digital / analog converter (D / A), 13 is a first stage amplifier, 14 is a cancel value recording unit, 15 is a control unit, and 16 to 18 are interfaces ( I / O) and 19 are processors (CPUs) that execute processing.
[0011]
The light receiving element 10 is divided into a plurality of parts, and the outputs (NO. 1 to NO. N) are connected to a selector.
The cancel value recording unit 14 is configured by a nonvolatile memory, and is configured by a number of memories corresponding to the number of divisions of the light receiving element 10.
[0012]
When the optical disk drive 1 is in operation, the control unit 15 instructs the selector 11 via the I / O 17 to sequentially select the outputs of the light receiving elements 10 and input them to the first-stage amplifier 13 and to record values corresponding to the selected outputs. From the cancel value recording unit 14 and input to the D / A 12 via the I / O 16, and the output from the D / A 12 is input to the first stage amplifier 13 to cancel the offset.
[0013]
In the offset adjusting device 2, 20 is a 0 voltage setting unit, 21 is an amplifier, and 22 is an analog / digital converter (A / D).
In the personal computer 3, 31 is a cancel value generating unit, 32 is an input unit, 33 is a display unit, 34 is a control unit, 35 to 37 are interfaces (I / O), and 38 is a processor (CPU) for executing processing. is there.
[0014]
Next, the operation of the present invention will be described with reference to FIGS.
In step S1, the control unit 34 of the personal computer 3 instructs the 0 voltage setting unit 20 via the I / O 35 to set the 0 voltage.
The zero voltage is set, for example, by setting the input voltage of the amplifier 21 to zero voltage by opening the signal line between the first stage amplifier 13 and the amplifier 21 or by shorting the input of the amplifier 21.
[0015]
In step S2, the cancel value generation unit 31 records the offset value (A) of the amplifier 21 output from the A / D 22 in a memory (not shown).
In step S3, the control unit 34 cancels the 0 voltage setting commanded to the 0 voltage setting unit 20 in step S1.
[0016]
In step S4, the cancel value generation unit 31 receives the light receiving element NO. With respect to the optical disc drive 1 via the I / O 36. Command 1 connection.
In response to this command, the control unit 15 commands the selector 11 to receive the light receiving element NO. 1 is connected to the first stage amplifier 13 and the light receiving element NO. The recorded value for 1 is read and output to the D / A 12.
[0017]
In step S5, the cancel value generation unit 31 reads the output value (B) of the A / D 22, moves to step S6, and determines whether or not the value of | B−A | is within a predetermined range, for example, 0 to 2 mV. If the determination is yes, the process proceeds to step S15. If the determination is no, the process proceeds to step S7.
[0018]
In step S7, the cancel value generating unit 31 receives the light receiving element NO. 1 is counted, and it is determined whether or not the count value has reached the predetermined value X times. When the count value reaches X times, the process proceeds to step S8 and the display unit 33 is displayed. An adjustment error is displayed and the adjustment operation is terminated.
[0019]
If the determination in step S7 has not reached X times, the process proceeds to step S9, and the cancel value generation unit 31 determines whether B-A is positive. If the determination is positive, the process proceeds to step S10 and cancels. The value -1 is generated. If the value is negative, the process proceeds to step S11 to generate a cancel value +1. The process proceeds to step S12 and is sent to the optical disc drive 1 via the I / O 36.
[0020]
In step S13, the control unit 15 of the optical disc drive 1 uses the cancel value (−1 or +1) transferred from the offset adjustment device 2 in step S12 as the light receiving element NO. 1 is added to the recorded value.
[0021]
In step S14, the controller 15 receives the light receiving element NO. The recorded value for 1 is read and sent to the D / A 12 via the I / O 16. When the recording value is transferred to the D / A 12, an analog voltage corresponding to the transferred recording value is generated and output to the first-stage amplifier 13, and the process proceeds to step S5, and steps S5 to S14 are repeated.
[0022]
If it is determined in step S6 that | B-A | is within the predetermined range, it is determined that the offset of the first stage amplifier 13 has been canceled, and the process proceeds to step S15, where there is an unadjusted light receiving element of the light receiving element 10. If there is an unadjusted light receiving element, the process proceeds to step S16 to send a connection command to the next light receiving element (NO.2 to NO.N), the process proceeds to step S5, and steps S5 to S16. Is repeated.
[0023]
If it is determined in step S15 that the adjustment of all the light receiving elements has been completed, the process proceeds to step S17, the adjustment OK is displayed on the display unit 33, and the operation is terminated.
In the embodiment, the zero voltage setting unit 20 is operated to record the offset value A of the amplifier 21 in step S2. However, the test first-stage amplifier 13 having no offset is connected to the amplifier 21 and the offset value A is recorded. May be recorded.
[0024]
Next, with reference to FIG. 4 and FIG. 5, the inspection operation performed at the start of work will be described.
In step S20, a system check is performed. Then, the process proceeds to step S21, whether or not the I / O 35 to 37 are normally connected, and whether or not the 0 voltage setting unit 20, the amplifier 21, and the A / D 22 operate normally. If it is not normal, the process proceeds to step S22 to display items that are not normal.
[0025]
In step S23, an action is performed on the item displayed as not normal, and if it cannot be dealt with, the process ends. If normal, the process proceeds to step S24.
In step S24, it is checked whether or not there is a file in which the program for performing the offset adjustment operation described above exists and whether the content of the file matches the specified one. If is not OK, the process proceeds to step S26, and if the adjustment file default is set, the process proceeds to step S27.
[0026]
In step S27, the start-up inspection mode and the adjustment mode are selected, and when the adjustment mode is selected, the operations shown in FIGS. 2 to 3 described above are started.
If the start inspection mode is selected, the process proceeds to step S28, where the inspection of the start inspection item 1 is performed. If the check is not OK after moving to step S29, the process proceeds to step S30, where the start inspection check abnormality is displayed and the process ends.
[0027]
If the start inspection item 1 is OK, the process proceeds to step S31, where the offset voltage of the first stage amplifier in which the offset value for the start inspection is accurately read in advance is measured, and the offset voltage measured in step S32 is read in advance. If it matches the offset value, the process proceeds to step S33, and if not, the process proceeds to step S30.
[0028]
In step S33, the start work inspection item 2 is inspected. The process proceeds to step S34. If the inspection is OK, the process proceeds to step S35 to display normal start work inspection, and the process proceeds to step S27. If not normal, the process proceeds to step S30.
In addition, the start inspection items 1 and 2 are checked such as program version check, measuring instrument display check, voltage check, and sensor check.
[0029]
【The invention's effect】
As described above, the output from the first stage amplifier is converted into a digital value, and it is determined whether or not the converted digital value is within a predetermined range. If the converted digital value is out of the predetermined range, it is recorded in the cancel value recording unit. Since the correction value is generated so that the offset cancels the recorded value, the offset adjustment can be easily performed at low cost.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment of the present invention.
FIG. 2 is a flowchart of an offset adjustment operation.
FIG. 3 is a flowchart of an offset adjustment operation.
FIG. 4 is a flowchart of an inspection operation.
FIG. 5 is a flowchart of an inspection operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical disk drive 2 Offset adjustment apparatus 3 Personal computer 10 Light receiving element 11 Selector 12 Digital / analog converter (D / A)
13 First-stage amplifier 14 Cancel value recording unit 15 Control units 16, 17, 18 Interface (I / O)
19 Processor (CPU)
200 Voltage setting unit 21 Amplifier 22 Analog / digital converter (A / D)
31 Cancel Value Generation Unit 32 Input Unit 33 Display Unit 34 Control Units 35, 36, 37 Interface (I / O)
38 Processor (CPU)

Claims (3)

The first stage amplifier unit for amplifying an output of the light receiving element, and so as to remove the offset in addition to the first-stage amplifier converts read the recorded value recorded in the cancellation value recording unit, the read recorded values into an analog value An offset adjustment device for an optical disk drive,
An analog / digital converter that converts the output signal from the first stage amplifier into a digital value;
An amplifier provided between the output of the first stage amplifier and the analog / digital converter ;
A 0 voltage setting unit for setting the input voltage of the amplifier to 0 voltage;
Prior to the offset adjustment of the first stage amplifier, the zero voltage setting unit is operated to record the offset value of the amplifier, and after the zero voltage setting unit is released, the offset adjustment of the first stage amplifier is started and the recording is performed. An offset adjustment apparatus characterized in that an offset value of the amplifier is reduced from an output value from the analog / digital conversion unit at the time of offset adjustment. A value obtained by A / D converting the offset value of the amplifier by the analog / digital conversion unit is set as A, and the analog / digital conversion unit converts the offset value in addition to the first-stage amplifier in a generated state. A determination means for determining whether or not a value of | B−A | obtained by subtracting the offset value of the amplifier from the offset value of the first-stage amplifier when the calculated value is B,
Having communication means to the optical disc drive;
When the determination value of the determination means is not within a predetermined range, a value for increasing or decreasing the recording value according to the sign of B-A is transmitted via the communication means,
When the determination value of the determination unit is within a predetermined range, it is determined that the offset adjustment of the first stage amplifier is appropriate, and the cancel value recording unit records the appropriate record value via the communication unit. The offset adjusting apparatus according to claim 1, wherein Offset adjustment device of the recording operation of the offset value, according to claim 1 or 2, characterized in that to perform the offset adjustment operation of the first-stage amplifier selectively of said amplifier.

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