JPH02278482A - Dividing circuit - Google Patents

Abstract

PURPOSE:To surely execute dividing operation with simple configuration by controlling the selecting operation of each output selecting circuit according to an output counted by an addition / subtraction counting circuit and sending an output signal, for which the signal level of a second input signal is divided by the signal level of a first input signal, from the second output selecting circuit. CONSTITUTION:A dividing circuit is composed of first-third signal input terminals 10, 20 and 30, first-third potential dividing resistance circuits 11, 21 and 31, first-third potential dividing output selecting circuits 12, 22 and 32, comparator 13, addition / subtraction counting circuit 14 and signal output terminals 23 and 24. The selecting operation of the respective output selecting circuits 12, 22 and 32 is controlled by the output counted by the addition / subtraction counting circuit 14 and the output signal, for which the signal level of the second input signal is divided by the signal level of the first input signal, is obtained from the second output selecting circuit 22. Thus, the divided output can be surely obtained with the simple configuration.

Description

Detailed Description of the Invention A. Industrial Field of Application The present invention provides an output signal Z=Y/X obtained by dividing the signal level Y of a second input signal by the signal level X of the first input signal.
The present invention relates to a dividing circuit that forms an optical disk, and is applied to, for example, a forcing servo system or a tracking servo system in an optical disk device that uses an optical disk as a recording medium.

B. Summary of the Invention The present invention consists of the following aspects: 1. The output signal Z is obtained by dividing the signal level Y of the second input signal by the signal level X of the input signal of
In the division circuit forming the first input signal X, the signal level
The voltage division ratio of each resistor voltage divider circuit is set to 1/N so that the signal level X/N of the output of the first resistor voltage divider circuit matches the reference signal level. By controlling N, the output signal Z=Y/X can be obtained with a simple configuration.
It was designed so that it could be obtained.

C. Prior Art - g. In an optical disk device using an optical disk as a recording medium, a focusing servo system is used to appropriately focus a light spot from an optical head for recording and reproducing information onto a recording trunk of the optical disk. or,
A tracking servo system and the like are provided for scanning the recording track with the optical spot.

The focusing servo system, trunking servo system, etc. obtain a focusing error signal or a tracking error signal based on the detection output of the light reflected by the optical disk detected by the optical head, and apply the servo. It is configured.

By the way, in an optical disk drive using a rewritable optical disk such as a magneto-optical disk, the amount of irradiation light required for recording and erasing information is different from the amount of irradiation light necessary for reproducing information, and the amount of light reflected by the optical disk is different. also changes depending on the operating mode. Further, the reflectance of an optical disk differs depending on the manufacturer, manufacturing loft, etc. For this reason, in the forcing servo system, tracking servo system, etc. in an optical disk device, instability caused by fluctuations in servo gain due to changes in the reflectance of the optical disk or changes in the amount of reflected light from the optical disk depending on the operation mode is eliminated. For example, in order to perform stable servo operation,
As disclosed in Publication No. 3-224034, No. 4
As shown in the block diagram, the signal level of the error signal is corrected by dividing the signal level Y of the error signal by the level X of the amount of light reflected by the optical disc.

The block diagram in FIG. 4 shows the configuration of the main parts of the tracking servo system, in which the reflected light from the optical disk is detected by the four-part photodetector (40) of the optical head.
Each detection output SA+ by the split photodetector (40)
Based on Sl+Sc, So, in the trussing error signal forming circuit (41), 5TE=(SA+S8)
(SC+SO) to form a tracking error signal 30 indicating the tracking error iY of the optical spot, and in the total reflection light amount signal forming circuit (42), S
AL = S A + S s + S c +S.

The signal level of the above-mentioned tracking error signal S was corrected by forming a total reflection light amount signal SAL indicating the total reflection light IY at , and performing division as Z=Y/X at a division circuit (43). Level-corrected tracking error signal syt. It is now possible to obtain

Conventionally, as the division circuit (43), an analog arithmetic processing circuit, which is integrated circuit and has a complicated configuration and is expensive, has been used. Furthermore, it has been proposed that the signal processing system for servo control is digitized so that the above-mentioned arithmetic processing is performed by a microcomputer.

D Problems to be Solved by the Invention As mentioned above, in conventional optical disk devices, in order to stabilize the operation of the tracking servo system, etc., errors are generated based on the detection output of a photodetector that detects light reflected by the optical disk. A division circuit is provided to divide the signal level Y of the signal by the level of total reflection light amount X detected by the photodetector, and as this division circuit, a complex and expensive analog arithmetic processing circuit has been used. The above-mentioned division circuit has been a factor in increasing the price of optical disk devices.

Therefore, in view of the actual situation of conventional optical disk devices as described above, the present invention simplifies the configuration of a division circuit used for stabilizing the operation of, for example, a tracking servo system.
Aiming at realizing a low-cost optical disk device, the present invention provides a division circuit that can reliably obtain a division output with a simple configuration.

E. Means for Solving the Problems In order to achieve the above-mentioned object, the division circuit according to the present invention includes a first voltage dividing resistor circuit to which a first input signal is supplied;
A first selector for selecting the divided voltage output by the first voltage dividing resistor circuit.
an output selection circuit, a comparison circuit that compares the signal level of the selected output from the first output selection circuit with a reference signal level, and an addition/subtraction operation controlled by switching between an addition operation and an X-calculation operation by the comparison output from the comparison circuit. a counting circuit, a second voltage dividing resistor circuit to which a second input signal is supplied, and the second
a second output selection circuit that selects the divided voltage output from the voltage dividing resistor circuit, and controls the selection operation of each of the output selection circuits using the counting output from the addition/subtraction counting circuit;
The second output selection circuit obtains an output signal obtained by dividing the signal level of the second input signal by the signal level of the input signal.

F Function In the division circuit according to the present invention, the first output selection circuit that selects the divided voltage output from the first voltage dividing resistor circuit to which the first input signal is supplied has a signal level of the selected output as a reference. The selection operation is feedback-controlled to a state where the signal level of the selection output matches the reference signal level by the counting output of the addition/subtraction counting circuit controlled by the comparison output of the comparison circuit that compares the signal level. The second output selection circuit that selects the divided voltage output from the second voltage dividing resistor circuit to which the second input signal is supplied has a selection operation controlled by the counting output from the addition/subtraction counting circuit. , selects a divided voltage output having the same voltage dividing ratio as the voltage dividing ratio by the first voltage dividing resistor circuit. As a result, an output signal obtained by dividing the signal level of the second input signal by the signal level of the first input signal is transmitted from the second voltage dividing resistor circuit to the second output selection circuit. can get.

In addition, in the division circuit according to the present invention, in a series connection circuit of n+1 resistors having a resistance value R7 of R, l=c, Roe''' [where C is an arbitrary constant and e is a natural constant]. By configuring each of the voltage dividing resistor circuits, the operation can be stabilized.

G. Embodiment Hereinafter, an embodiment of the division circuit according to the present invention will be described in detail with reference to the drawings.

The embodiment shown in the block diagram of FIG. 1 is an example in which the present invention is applied to a four-force non-nursing servo system and a trunking servo system of an optical disk device, and is based on the detection output of a photodetector of an optical head that detects reflected light from an optical disk. Then, the total reflected light amount signal SAL obtained by the total reflected light amount signal forming circuit (not shown) is input to the first signal input terminal (10
) and obtained by a tracking error signal forming circuit (not shown).
is supplied to the second signal input terminal (20), and further, a forcing error signal SFE obtained from a forcing error signal forming circuit (not shown) is supplied to the third signal input terminal (30).

The first signal input terminal (10) is connected to n+1 resistors (R, , ) constituting the first voltage dividing resistor circuit (11),
(R,.

1) and are grounded through a series connection circuit of (Ro). The first voltage dividing resistor circuit (11) includes each of the resistors (
The connection point of R, ), (Rfi-+), ~(Ro) is
Each input terminal (IN, ), (IN, , ),
~(IN,).

Further, the second signal input terminal (20) is connected to n+1 resistors (R,)(
It is grounded through a series connection circuit of R, , ), and (Ro). In the second voltage dividing resistor circuit (21), the connection point of each of the resistors (R, ), (R, I), ~(Ro) is supplied to the second signal input terminal (2σ). Each input terminal (IN, , ), (IN, l) of the second output selection circuit (22) serves as each divided voltage output terminal of the tracking error signal Stt.
, ~(INK).

Furthermore, the third signal input terminal (30) is connected to n+1 resistors (R, , .
), (R, l), and (Ro) connected in series. The third voltage dividing resistor circuit (31) is configured such that the connection points of the resistors (R, , ), (R,l), ~(Ro) are supplied to the third signal input terminal (30). Focus error signal SF! As each partial voltage output terminal of
Each input terminal (IN, , ) of the third output selection circuit (32),
(IN, , ), ~(INK).

The first output selection circuit (12) has a control input terminal (
It is composed of analog switches that selectively connect the input terminals (INfi), (IN, I), to (IN,) to the output terminal (OUT) according to control data given to the output terminal (OUT), The first voltage dividing resistor circuit (11)
The selected output for the divided voltage output by the above output terminal (OLI
T) to the first input terminal of the comparator circuit (13).

The comparison circuit (13) has a comparison reference voltage V REF applied to its second input terminal, and outputs selected by the first output selection circuit (12) supplied to the first input terminal. The signal level is compared with the comparison reference voltage VREF, and the comparison output is supplied as counting control data to the control input terminal ([1/D) of the addition/subtraction counting circuit (4).

The addition/subtraction counting circuit (14) has a control input terminal (U/
D), that is, the counting control signal supplied to the comparator circuit (
It consists of an m-pint up/down counter that counts clock pulses CK by switching between addition and subtraction operations according to the polarity of the comparison output by 13), and uses the counting output as the selection control signal described above. It is supplied to each control input terminal CTL of each output selection circuit (12), (22), (32)3.

In the first output selection circuit (12), the counting output from the addition/subtraction counting circuit (14) is applied to the control input terminal CTL as selection control data, so that the signal level of the selection output is set to the comparison reference voltage V IIEF. A partial voltage output with a partial voltage ratio of 1/N that matches the state, that is, a signal level X indicated by the total reflected light amount signal SAL supplied to the first signal input terminal (10), 1 / N
= V REF / X The partial pressure output of the null partial pressure ratio 1/N is i! The selection operation is feedback-controlled to increase the number of selections.

Further, the second output selection circuit (22)
According to the selection control data given to the lll input terminal (CTL), each of the above input terminals (IN, , ), (tN, , ), ~(
It is composed of an analog switch that selectively connects IN, ) to the output terminal (OUT), and the voltage division ratio of 1/N is determined by the selection control data, that is, the counting output from the addition/subtraction counting circuit (14). By controlling the selection operation to select the divided voltage output, the selected output for the divided voltage output by the second voltage dividing resistor circuit (31) is outputted to the output terminal (OUT) as the level-corrected tracking error signal 5rto. ) to the first signal output terminal (23).

The tracking error signal S TtO obtained at the first signal output terminal (23) is transmitted to the second signal input terminal (23).
20) is obtained by dividing the signal level y of the tracking error signal S supplied to 1/N = V REF / The signal level Y1 is divided by the signal level X of the total reflected light amount signal SAL.

Further, the third output selection circuit (32) selects each of the input terminals (IN,), (IL-,), ~()NO) according to control data provided to its control input terminal (CT). It is composed of an analog switch that is selectively connected to the output terminal (OIIT), and selects a divided voltage output with a dividing ratio of 1/N based on the selection control data, that is, the counting output from the addition/subtraction counting circuit (14). By controlling the selection operation in this manner, the third voltage dividing resistor circuit (31
) is the focus error signal SF! whose level has been corrected for the selected output with respect to the partial voltage output. . as the above output terminal (OUT
) to the second signal output terminal (33).

The focus error signal srto obtained at the second signal output terminal (33) is transmitted to the third signal input terminal (33).
The signal level Y2 of the focus error signal srE supplied to 0) is divided into l/N-VIIEF/X; It is obtained by dividing Y2 by the signal level X of the total reflection light amount signal SAL.

Here, each of the above voltage dividing resistor circuits (11), (21)
, (31) theoretically represents each of the above resistances (It, ),
It is sufficient to use resistance values R that are equal to each other for (R, I) and ~(Ro), so that the combined resistance at the divided voltage output terminal exhibits linear characteristics as shown in Figure 2. However, when the voltage division characteristic is linear in this way, the gain of the feedback control loop is determined by the signal level X of the total reflected light amount signal SAL supplied to the first signal input terminal (10). changes.

Therefore, in this embodiment, in order to keep the gain of the feedback control loop constant, R,=c-R,e''.

[However, C is an arbitrary constant, and e is a natural constant.] Each of the voltage dividing resistor circuits (11), (21), and (31) is configured by a series-connected circuit of n+1 resistors having a resistance value RA of [where C is an arbitrary constant and e is a natural constant]. I try to do that.

That is, in order to keep the gain of the feedback control loop constant, it is sufficient to satisfy the relational expression R n 2 C, and from this relational expression, RogR=c−n R=ec °n. If the resistance value of each stage is set using the formula n to exhibit an exponential characteristic as shown in Figure 3, the gain of the feedback control loop can be kept constant and stable division operation can be achieved. It can be performed.

In the above embodiment, the present invention was applied to a tracking servo system and a focussing servo system in an optical disk device, but the present invention is not applicable only to the above embodiment. 2nd at signal level
The output signal Z = Y divided by the signal level Y of the input signal of
It can be widely applied to division circuits forming /X.

11 Effects of the Invention In the division circuit according to the present invention, each voltage dividing resistor circuit, each output selection circuit that selects the divided voltage output from each voltage dividing resistor circuit,
A division operation can be performed with a simple configuration consisting of a comparison circuit and an addition/subtraction counting circuit.

In addition, in the division circuit according to the present invention, each of Stable division operation can be performed by configuring each voltage dividing resistor circuit.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing the main part configuration of an embodiment in which the present invention is applied to a trunking servo system and a focusing system of an optical disk device, and Fig. 2 shows the principle of the voltage dividing resistor circuit in the above embodiment. FIG. 3 is a characteristic diagram showing specific characteristics of the voltage dividing resistor circuit in the above embodiment. FIG. 4 is a block diagram showing the main structure of a tracking servo system of a general optical disk device.

Claims (2)

[Claims] (1) A first voltage dividing resistor circuit to which a first input signal is supplied; and a first voltage dividing resistor circuit that selects a divided voltage output by the first voltage dividing resistor circuit.
an output selection circuit; a comparison circuit that compares the signal level of the selected output from the first output selection circuit with a reference signal level; and an addition/subtraction counter that is controlled to be switched between an addition operation and a subtraction operation by the comparison output from the comparison circuit. a second voltage dividing resistor circuit to which a second input signal is supplied; and a second voltage dividing resistor circuit for selecting a divided voltage output by the second voltage dividing resistor circuit.
and an output selection circuit, the selection operation of each of the output selection circuits is controlled by the counting output of the addition/subtraction counting circuit, so that the signal level of the second input signal is determined by the signal level of the first input signal. A division circuit characterized in that the second output selection circuit obtains an output signal obtained by dividing . (2) Each of the voltage dividing resistor circuits is formed by a series connection circuit of n+1 resistors having a resistance value R_n of R_n=c・R_0e^c^・^n [where c is an arbitrary constant and e is a natural constant]. 2. The division circuit according to claim 1, wherein the dividing circuit comprises: