JPH0447379B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to optical disc players, such as compact disc players that use an optical pickup.

Recently, PCM (Pulse Code Modulation)
In order to reproduce audio signals recorded on a disc made of a disc-shaped information medium by using technology, an optical disc player has been proposed that uses, for example, an optical pickup made of a semiconductor laser and a light receiving element. In this proposed player, as shown in FIG. 1, a disk 1 is mounted from the direction of the arrow as shown in the figure, and is rotationally driven by a spindle motor 2. An optical pickup 3 provided behind the disk 1 allows non-contact tracing of the information surface. For this purpose, the optical pickup 3 is mounted on a carriage 4 that is moved in the radial direction of the disk 1 by a drive means (not shown).

By the way, since the optical pickup 3 is located behind the disk 1 as described above, its position cannot be seen from the front side, and the current position of playback cannot be known. For this purpose, as shown in FIG. 2, a light emitting element 6 such as a light emitting diode is attached to an angle 5 provided on the carriage 4, and the light emitting element 6 is placed facing the opening 7a of the panel 7.
It has been considered that the position of the pick-up 3 can be indicated by cooperation with a scale attached to the pick-up 3.

However, in this conventional optical pick-up position indicating device, the light emitting element for indicating the pick-up position is only turned on or off depending on whether the power is turned on or off. For this reason,
In order to externally monitor the operating status of the optical pickup 3, it was necessary to provide a separate means for that purpose.

The present invention has been made in view of the above points, and
The object of the present invention is to provide an optical disc player that can simultaneously display the operating status of an optical pickup using a light emitting element for indicating the position of the optical pickup.

The present invention will be explained below with reference to FIG. 3 and subsequent figures.

FIG. 3 is a block diagram showing the principle of the player according to the present invention. In the figure, 10 is a semiconductor laser such as a laser diode that serves as a light source in an optical pickup, and is composed of a light emitting part, a light amount monitor, etc. (not shown). ing. Reference numeral 11 denotes an automatic light amount adjustment circuit that receives the output of the light amount monitor in the semiconductor laser 1 as an input and controls the light amount of the light emitting part to a predetermined constant value. When the amount of light decreases due to deterioration, an output signal is applied to the semiconductor laser 10 to perform current control to increase the operating current of the light emitting section so as to maintain the amount of light of the light emitting section at a constant value. The automatic light amount adjustment circuit 11 also outputs a voltage signal having a magnitude corresponding to the value of the operating current, and applies this to the current value monitor circuit 12. The current value monitor circuit 12 controls the lighting state of the light emitting element 13 for indicating the position of the optical pickup based on the monitoring result.

Incidentally, the semiconductor laser 10 does not need to operate when a disc is not attached or when not playing (playing), but only needs to operate when playing. Therefore,
The automatic light amount adjustment circuit 11 is also capable of controlling the semiconductor laser 10 to be activated or deactivated by a control signal applied to the terminal 14.

4 to 6 show examples of the current value monitor circuit 12 and light emitting element 13 shown in FIG. 3, respectively. In the example of FIG. 4, the semiconductor laser 1 is connected to the non-inverting input of the operational amplifier constituting the comparator 12a.
A voltage signal having a magnitude corresponding to the operating current of the light emitting section 0 is applied via the resistor _R1 . This voltage signal is compared with a reference voltage _Vr applied to the inverting input via a resistor _R2 , and when the voltage signal becomes larger than _Vr , the output of the comparator 12a becomes H level. . Comparator 12
The output of a is applied to the base of a transistor Q via a resistor _R3 , and when the level becomes H, the transistor Q is turned on, and a light emitting element consisting of a resistor _R4 and a light emitting diode is connected from the power supply to the ground. 13 and transistor Q, current begins to flow. As a result, when the transistor Q is not on, the light emitting element 13 is connected through the resistors R ₄ and R ₅ .
A current larger than the current flowing in light emitting element 1
3, the lighting of the light emitting element 13 is switched from a low brightness state to a high brightness state. Therefore, the light emitting element 13 indicates the position of the optical pickup by its position, and also indicates that the semiconductor laser 10 is in a normal operating state with an operating current below a certain value by lighting at low brightness, and indicates that the semiconductor laser 10 is in a normal operating state with an operating current below a certain value by lighting at high brightness. Each of these displays indicates that the laser 10 is operating at an operating current exceeding a certain value and is in a state where its life has deteriorated to the extent that it requires replacement.

In the example of FIG. 5, the collector of the transistor Q, which is turned on and off by the output signal of the comparator 12a, is connected to the power supply via a resistor _R6 , and is also connected to the input of the unstable multivibrator 12b. . Unstable multivibrator 12b
operates to input a long-cycle pulse signal when the input level is H, and output a short-cycle pulse signal when the input level is L. The above pulse signal is applied to the base of a transistor Q ₁ which is connected between the power supply and ground via the resistor R ₇ and the light emitting element 13, and the transistor Q ₁ is turned on and off by the above pulse signal. It's summery. As a result, the light emitting element 13 is blinked by the pulse signal, and the blinking period is switched to two stages: long and short. Therefore, the light emitting element 13 indicates that the semiconductor laser 10 is in a normal operating state by blinking in a long period, and indicates that the semiconductor laser 10 is in a normal operating state by blinking in a short period.
0 indicates that the service life has deteriorated and it is time to replace it.

In the example of FIG. 6, the collector of transistor Q is connected to the base of transistor Q ₂ via inverter I ₁ and further to the base of transistor Q 3 via inverter I ₂ , and the collector of transistor Q is connected to the base of transistor Q ₃ via inverter I 2. The transistors Q ₂ and Q ₃ are controlled, and the green light emitting element 13a and the red light emitting element 13b connected in series with the transistors Q ₂ and Q ₃ are turned on and off. As a result, when the operating current flowing through the semiconductor laser 10 is below a predetermined value, the level of the non-inverting input of the comparator 12a is below _Vr , so the comparator 1
The output of 2a is at L level and the transistor
_Q2 is turned on, and the green light emitting element 13a comes to light up. Therefore, the normal operating state of the semiconductor laser 10 is indicated by lighting of the green light emitting element 13b. On the other hand, the life of the semiconductor laser 10 deteriorates,
If the operating current of the semiconductor laser 10 is not higher than a predetermined value, the amount of light cannot be maintained at a constant level, the level of the non-inverting input of the comparator 12a becomes higher than _Vr , and the output of the comparator 12a becomes H level. _Q3 is turned on, and the red light emitting element 13b comes to light up. Therefore, lighting of the red light emitting element indicates that the life of the semiconductor laser 10 has deteriorated to the extent that it requires replacement.

As described above, in the present invention, the lighting state of the position indicating light emitting element of the optical pickup is controlled in accordance with the operating current that is applied so as to maintain a constant amount of light in the optical pickup.
The light-emitting element for position indication can also display the operating status of the optical pickup at the same time, making it possible to omit the need for a separate means for this purpose in the past, and allowing the optical pickup to be displayed with a single display. This provides an extremely excellent effect of being able to rationally display states related to.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway top view showing the general structure of an optical disc player, Fig. 2 is a perspective view of a portion of the player shown in Fig. 1, and Fig. 3 is a block diagram showing the principle of the player of the present invention. 4 to 6 are circuit diagrams showing specific examples of a portion of FIG. 3, respectively. 1...disk, 3...optical pick-up,
10... Semiconductor laser, 11... Automatic light amount adjustment circuit, 12... Current value monitor circuit, 13... Light emitting element.

Claims (1)

[Claims] 1. An optical pickup that is moved in the radial direction of the rotating disk and reproduces the signals recorded on the disk, and an operating current of the optical pickup that maintains the amount of light of this optical pickup at a constant value. a control circuit; a light emitting element that is moved as the optical pickup moves and indicates the position of the optical pickup;
An optical disc player comprising: a circuit that controls the lighting state of the light emitting element according to the magnitude of the operating current.