JPS6316477A - Video disk device for vehicle - Google Patents

Abstract

PURPOSE:To ensure the satisfactory control of redidual errors even in a low temperature mode and also to secure the stable search to jump over plural tracks, by setting the gains of at least a low band component of a servo loop of a pickup at a high level in the low temperature mode. CONSTITUTION:A temperature compensating equalizer 11 is provided at the preceding stage of an equalizer 1. The equalizer 11 includes an operational amplifier 12 having its non-inverse input terminal grounded and its inverse input terminal connected with a resistance 13, a series circuit of a resistance 14 and a capacitor 15 connected in parallel to a negative feedback line set between an output terminal and the inverse input terminal of the amplifier 12, and a series circuit of a resistance 16 and a thermistor 17 serving as a temperature detecting element. The thermistor 17 is set at a place near a pickup to be controlled. When a low temperature is detected, a gain control circuit increases the gains of at least a low band component.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to disc playback for vehicles, typified by vehicle navigation devices that superimpose and display the current location of a vehicle on map information and guide the vehicle to a predetermined destination. Regarding equipment.

[Summary of the invention]

In the present invention, the gain of at least the low frequency component of the servo loop of the pickup is set high at low temperatures.

[Conventional technology]

The lowest resonant frequency f of the tracking actuator of a CD (compact disc) player. As shown in FIG. 3, increases as the temperature decreases.

As a result, the DC gain of the tracking servo loop decreases at low temperatures. For example, at +60°C, the frequency f0 is 27.6Hz and the DC sensitivity is 3.3dB, but at +20°C, f. is 37.5Hz, DC sensitivity is OdB, and f at 0°C. is 58Hz, and the DC sensitivity is -7.6dB.

Therefore, in the past, the threshold value of the servo loop as a stopper was controlled in accordance with the temperature to switch the drive range.

[Problem that the invention seeks to solve]

Incidentally, in recent years, research has been carried out on vehicle navigation devices that record map information in ICD ROM, and some of them have been commercialized. Since household CD players and the like are generally used inside houses, the temperature conditions during use are not so severe. On the other hand, since the vehicle navigation simulator is used while being mounted on a vehicle, the temperature conditions are severe. As a result, it is no longer possible to obtain sufficient compensation at low temperatures simply by changing the threshold value as in the conventional method. That is, the amount of suppression in the rotational frequency component of the disk decreases, the residual error increases, and it becomes impossible to stably execute a search operation that jumps across multiple tracks.

[Means for solving problems]

The present invention provides a disc playback device for a vehicle, which includes an equalizer that equalizes an error signal related to the relative position of a pickup and a disc, an amplifier circuit that amplifies the output of the equalizer, and a coil that is driven by the output of the amplifier circuit and controls the relative position. , comprising a detection element that detects temperature, and a gain control circuit that increases the gain of at least the low frequency component of the error signal loop when the temperature is low in response to the output of the detection element.

[Effect]

When a low temperature is detected by the detection element, the gain control circuit increases the gain of at least the low frequency component.

〔Example〕

FIG. 1 is a block diagram of a tracking control circuit of a vehicle disc playback device according to the present invention. In the figure, 1 is an equalizer that equalizes an input tracking error signal, 2 is an amplifier circuit that amplifies the output thereof, and 3 is a coil as an actuator driven by the output of the amplifier circuit 2. 4 is a resistor for current detection. Although the above configuration is the same as the conventional case, in the present invention, an equalizer 11 for temperature compensation is added at the front stage of the equalizer 1.

The equalizer 11 was connected in parallel to an operational amplifier 12 whose non-inverting input terminal was grounded and whose inverting input terminal was connected to a resistor 13, and to a negative feedback path between the output terminal of the operational amplifier 12 and the inverting input terminal. It is composed of a series circuit of a resistor 14 and a capacitor 15, and a series circuit of a resistor 16 and a thermistor 17 as a temperature detection element. The thermistor 17 is placed near the pickup to be controlled.

For example, resistor 13 is 15Ω, resistor 14 is 27Ω, resistor 16 is 24Ω, capacitor 15 is 0, = 068μ.
Let it be F. The resistance value of the thermistor 17, which is 5 Ω at 25'C, becomes 1.4 Ω at +60°C.

0°C7-15KO1-20''CQ42KQ.As a result, the characteristics of the gain control circuit 11 are -20'C (20'C).
dot-dashed line), 06C (dot-dashed line), +25°C (solid line),
At +60'C (dashed line) it becomes as shown in FIG.

That is, at -20°C, it has a characteristic of attenuation of about 1'2.8 dB up to about 25H2, about 2 clB after about 86 Hz, and 6 dB10ct during that time.

At 0°C, it is approximately 8.2 dB up to around 35 Hz,
After about 86 Hz, the attenuation characteristic is 0.8 clB, and the attenuation characteristic during that period is 6 dB10ct. Similarly, at +25°C, it is 5°8dB up to about 43Hz, about -0.6dB after about 86Hz, and about 45Hz at +600C.
up to about 4.4dB.

After about 86 Hz, the attenuation is about -1 and 2 dB, and the attenuation therebetween is 6 dB10ct in both cases. It can be seen from the figure that the gain below 30 Hz increases rapidly at low temperatures (particularly below 0°C). In addition, 30H here
The reason why z is used as a reference is because it is assumed that the vehicle disc reproducing apparatus of the present invention uses an optical video disc that rotates 30 times per second.

In this embodiment, the thermistor 17 is used linearly, but the output signal(s) of the thermistor 17 causes the FET
The gain may be changed stepwise at a predetermined temperature by switching a switch such as a relay, or the gain of the entire servo loop instead of the equalizer may be changed.

Furthermore, the present invention can be used in addition to the tracking servo loop, such as a focus servo loop, a spindle servo loop,
It can also be applied to slider servo loops, etc.

〔effect〕

As described above, the present invention provides a disc playback device for a vehicle.
an equalizer that equalizes an error signal regarding the relative position of the pickup and the disk; an amplifier circuit that amplifies the output of the equalizer; a coil that is driven by the output of the amplifier circuit and controls the relative position; a detection element that detects temperature; Since the present invention is equipped with a gain control circuit that increases the gain of at least the low-frequency component of the error signal loop at low temperatures in accordance with the output of the element, residual errors can be sufficiently controlled even at low temperatures. Searches that jump across multiple tracks can be performed stably.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a tracking control circuit of a vehicle disk reproducing apparatus according to the present invention, FIG. 2 is a characteristic diagram of its equalizer, and FIG. 3 is a characteristic diagram of a conventional tracking control circuit. 1... Equalizer 2... Amplifier circuit 3... Coil 4... Current detection resistor 11... Gain control circuit 12... Operational amplifier 17... Thermistor or higher

Claims (1)

[Claims] An equalizer that equalizes an error signal regarding the relative position of the pickup and the disk, an amplifier circuit that amplifies the output of the equalizer, a coil that is driven by the output of the amplifier circuit and controls the relative position, and a detection element that detects temperature. and a gain control circuit that increases the gain of at least the low-frequency component of the loop of the error signal when the temperature is low in response to the output of the detection element.