JPH0827957B2 - Optical disc player - Google Patents

Description

The present invention relates to an optical disc player having a stable reproduction function against temperature changes and a semiconductor laser protection function.

"Prior Art" Conventionally, as this type of optical disc player, the one shown in FIG. 2 is known.

In FIG. 2, 1 is a CD (compact disc),
Reference numeral 2 is a spindle motor for rotationally driving the CD 1, 3 is an optical pickup for reading digital information recorded by pits on the signal recording surface of the CD 1, and 4 is a feed motor for moving the optical pickup 3. The optical pickup 3 is composed of a semiconductor laser, an objective lens, an optical sensor, a focus adjusting mechanism for adjusting the focus of the objective lens, and a tracking adjusting mechanism for moving the whole in a radial direction of the CD 1 by a small distance. . Reference numeral 5 is an automatic laser power control (APC) circuit for keeping the output of the semiconductor laser stable. 6
Is an RF amplifier that amplifies the read signal output from the optical pickup 3, 7 is a signal processing circuit that demodulates the amplified read signal, corrects and corrects code errors, and 8 is a digital read signal into an analog audio signal A DA converter for conversion, 9 is an audio circuit for amplifying an audio signal, and 10 is an output terminal. Further, in order to control the spindle motor 2, the optical pickup 3, and the feed motor 4, a servo controller (servo controller
A μ-COM) 11 and a servo circuit 12 are provided. The servo controller 11 gives an appropriate control command to the servo circuit 11 based on each detection signal sent from the servo circuit 12. The CPU (central processing unit) and the servo control program are It is composed of a stored ROM, a RAM for recording data, and an I / O port. Based on the control command supplied from the servo controller 11, the servo circuit 12 uses the CLV servo of the spindle motor 2 (constant linear velocity control), the focus servo of the optical pickup 3 (focus adjustment control) and the tracking servo ( Tracking adjustment control). The focus servo automatically controls the focus of the objective lens of the optical pickup 3 so as to always match the signal recording surface of the CD. The tracking servo is a laser servo.
The beam is automatically controlled so that it always traces the signal track of the CD. A laser protection temperature sensor 13 is provided to protect the semiconductor laser (laser diode) from damage and deterioration due to temperature rise. The laser protection temperature sensor 13 is an APC circuit 5
Is directly connected to the optical disc player, and sends a detection signal to the APC circuit 5 while the internal temperature of the optical disc player exceeds a predetermined value. The APC circuit 5 receives this detection signal and turns on the semiconductor laser.
Set to FF state. This protects the semiconductor laser from damage due to overheating. Reference numeral 14 denotes a servo characteristic compensating temperature sensor for compensating the temperature characteristic of the optical pickup 3, which is composed of a focus temperature sensor 14a and a tracking temperature sensor 14b. These focus temperature sensor 14a and tracking temperature sensor 1
4b is directly connected to the servo circuit 12, and the servo gain is adjusted to an optimum value according to the temperature change.

[Problems to be Solved by the Invention] By the way, in the above-mentioned conventional optical disc player, in particular, in the on-vehicle optical disc player, three temperature sensors, that is, the laser protection temperature sensor 13,
The focus temperature sensor 14a and the tracking temperature sensor 14b are required, which is an obstacle to downsizing the device, lowering the cost, and facilitating manufacturing.

The present invention has been made in view of the above circumstances, and by providing one temperature sensor, it is possible to achieve both temperature stabilization of a servo circuit and prevention of thermal damage and deterioration of a semiconductor laser. It is intended to provide a player.

"Means for Solving the Problem" The present invention relates to an optical pickup including a semiconductor laser, a focus adjustment mechanism, and a tracking adjustment mechanism,
In an optical disc player having a laser output control circuit for controlling the output of the semiconductor laser and a servo circuit for controlling a focus adjusting mechanism and a tracking adjusting mechanism of the optical pickup, the internal temperature of the optical disc player is detected. Temperature detection means, storage means for storing a servo gain value corresponding to the internal temperature; and a servo gain value corresponding to the internal temperature read from the storage means in accordance with the output of the temperature detection means. The problem is solved by providing a control means for setting a circuit and giving a stop signal to the laser output control circuit to stop the output of the semiconductor laser when the internal temperature becomes equal to or higher than a predetermined value. .

"Operation" In the optical disc player of the present invention, one temperature detecting means detects the internal temperature. Then, the control unit reads the servo gain data corresponding to the detected internal temperature from the storage unit to set the optimum servo gain value corresponding to the internal temperature in the servo circuit, and When it rises above a predetermined value, a stop signal for stopping the output of the semiconductor laser is sent to the laser output circuit.

That is, according to the optical disc player of the present invention, it is possible to stabilize the temperature of the servo circuit and prevent thermal damage to the semiconductor laser based on the output from one temperature detecting means.

[Embodiment] An embodiment of the optical disc player of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention and is a block diagram showing an electrical configuration of an optical disc player. In this figure, the same components as those of the above-mentioned conventional example are designated by the same reference numerals and the description thereof will be omitted. The electrical configuration of the optical disc player of this example is different from the conventional one shown in FIG.
Instead of the laser protection temperature sensor 13 connected to the APC circuit 5 of FIG. 2 and the servo characteristic compensation temperature sensor 14 connected to the servo circuit 12, the servo controller of FIG.
The point is that a temperature sensor 15 connected to 11 is provided.

In such a configuration, the temperature sensor 15 constantly detects the internal temperature of the device, and the detection signal is detected by the servo controller 11
Send to. Based on the detection signal, the servo controller 11 calls the temperature-servo gain data stored in advance in its own ROM to perform arithmetic processing. The contents of the temperature-servo gain data stored in the ROM are, for example, (-20 ℃ ...- 4dB, 0 ℃ ・
・ ・ -2dB, 20 ℃ ・ ・ ・ 0dB, 40 ℃ ・ ・ ・ ＋ 2dB, 60 ℃ ・ ・ ・
+ 4dB) is the value of servo gain for each temperature. In this way, the control command data corresponding to the value of the servo gain adapted to the current internal temperature is obtained. The servo·
The controller 11 uses the obtained control command data for the servo circuit.
12 and sets the value of the servo gain of the servo circuit 12 to a temperature-compensated value. As a result, the servo circuit 12 controls the optical pickup 3 by the temperature-compensated servo gain characteristic and compensates the servo error caused by the temperature change. On the other hand, if the internal temperature rises above the set value due to changes in the environment, the servo controller 11
Sends a stop signal to the APC circuit 5. The APC circuit 5 receives this stop signal and stops the output of the semiconductor laser. This protects the semiconductor laser from damage and deterioration due to temperature rise.

Note that the above example is generally applied to an optical disc player for normal music reproduction, but the present invention is not limited to this, and it may be a CD-ROM, a CD-I (Compact Disc Interactive Media), a CD. It can also be applied to playback devices such as -V (compact disc video) and LD (laser disc).

"Effect of the Invention" As described above, according to the optical disc player of the present invention, the tracking is performed by reading the servo gain data stored in the storage means based on the internal temperature detected by the temperature detection means.・ Each servo gain of servo circuit and focus servo circuit is set to the optimum state. That is, the tracking servo gain and the focus servo gain are set to the optimum states by only one temperature detecting means irrespective of the temperature change, so that the optical disk is small and inexpensive and easy to manufacture It becomes possible to produce a player. At the same time, since the output of the semiconductor laser is stopped based on the output of the temperature detecting means, it is possible to prevent thermal destruction of the semiconductor laser. Therefore, this optical disc player is required to be downsized, and
It is suitable for a vehicle-mounted optical disc player used in an environment where the temperature changes drastically.

[Brief description of drawings]

FIG. 1 is a block diagram showing the electrical construction of an optical disc player according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the electrical construction of a conventional optical disc player. 1 ... CD (compact disc) player, 3 ... Optical pickup, 5 ... APC circuit (laser output circuit), 1
1 ... Servo controller (control means), 12 ... Servo circuit, 15 ... Temperature sensor (temperature detection means).

Claims (1)

[Claims] 1. An optical pickup having a semiconductor laser, a focus adjustment mechanism and a tracking adjustment mechanism, a laser output control circuit for controlling the output of the semiconductor laser, and a focus adjustment mechanism and a tracking adjustment mechanism of the optical pickup. In an optical disc player having a servo circuit, temperature detection means for detecting the internal temperature of the optical disc player, storage means for storing a servo gain value corresponding to the internal temperature, and output of the temperature detection means. According to the above, the value of the servo gain corresponding to the internal temperature is read from the storage means and set in the servo circuit, and a stop signal for stopping the output of the semiconductor laser when the internal temperature becomes a predetermined value or more is An optical disc comprising a control means for giving a laser output control circuit. Croyer.