JPH073459Y2 - Optical pickup preheater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to an optical pickup preheating device for eliminating dew condensation of an optical pickup.

(Prior Art) In an optical information recording / reproducing apparatus such as an audio disc player or a video disc player using a laser beam, an optical lens is used in an optical pickup section.
For example, when heating is suddenly performed in a cold room, dew condensation occurs on the lens and the optical information recording / reproducing apparatus cannot operate. Moreover, the heat capacity of the entire optical information recording / reproducing apparatus is large, and the lens section of the optical pickup is located inside the product, so the temperature of the lens section reaches a temperature equivalent to the temperature of the room being heated. It takes a considerable amount of time before the optical information recording / reproducing apparatus is ready for normal operation.

(Problems to be Solved by the Invention) In the conventional optical information recording / reproducing apparatus, the dew condensation preventing means of the optical pickup is not provided in particular, and it waits for about 30 minutes to 1 hour until the dew condensation is eliminated by leaving it naturally. Therefore, the use of the optical information recording / reproducing apparatus was seriously hindered in the cold season.

Therefore, as described in the specification and drawings of Japanese Utility Model Application No. 57-42561 (see Japanese Utility Model Application Laid-Open No. 58-144628), in response to the output of a dew condensation sensor provided near the lens of the optical pickup. A water drop removing device has been proposed in which a heater for removing water drops is energized. However, there is still room for improvement in the device according to the above application.

The purpose of the present invention is to forcibly remove the dew condensation by heating the optical pickup so as not to seriously hinder the use of the optical information recording / reproducing apparatus in the cold season. An object of the present invention is to provide an optical pickup preheating device that can more effectively eliminate dew condensation by utilizing a lens actuator drive coil.

(Means for Solving Problems) An optical pickup preheating device according to the present invention comprises a dew condensation sensor arranged in the optical pickup, a heating coil also arranged in the optical pickup, and a heating output by a detection output of the dew condensation sensor. And a heating circuit for preheating the optical pickup by energizing the coil, wherein the heating coil comprises a lens actuator drive coil of the optical pickup, and the heating signal applied to the heating coil is an AC signal. To do.

(Operation) When dew condensation occurs on the optical pickup, the dew condensation sensor detects the dew condensation, and based on the detection output, the heating coil is energized to preheat the optical pickup to eliminate dew condensation. The heating coil is the lens actuator drive coil, and since the heating signal applied to this lens actuator drive coil is an AC signal, the lens actuator vibrates according to the frequency of the AC signal and convection occurs, and this convection promotes elimination of dew condensation. To be done.

(Embodiment) In FIG. 1, an optical pickup 11 of an optical information recording / reproducing apparatus is provided with a lens actuator drive coil 12 for performing focusing or tracking and a dew condensation sensor 13. Condensation sensor
The detection output of 13 is input to the sensor amplifier 14, and the sensor amplifier 14 switches according to the detection output of the dew condensation sensor 13.
15 is controlled by switching. The switch 15 selectively switches between a focusing error signal or a tracking error signal for focusing control or tracking control of the optical pickup 11 and a preheating signal, and the signal selected by the switch 15 is
It is adapted to be applied to the lens actuator drive coil 12 via a drive amplifier 16.

The dew condensation sensor 13 is arranged around the lens of the optical pickup 11 or at an appropriate position corresponding to this. The dew condensation sensor 13 is not particularly limited, but, for example, by impregnating a hygroscopic resin with carbon powder, it is possible to use a sensor whose resistance value rapidly changes in a high humidity condition such as a humidity of 95%. it can.

The condensation sensor indicates that the optical pickup 11 has condensed.
When 13 detects, based on this detection signal the sensor amplifier
14 switches switch 15 to the preheat signal side. As a result, the actuator drive coil 12 is energized via the drive amplifier 16 in response to the preheating signal, and the coil 12 generates Joule heat to preheat the optical pickup 11 and remove dew condensation. The preheating signal is, for example, an alternating current having a frequency and an amplitude according to the resistance and resonance frequency of the lens actuator drive coil 12, and other various characteristics. This AC signal causes the lens actuator drive coil 12 to generate heat, and
Since the lens actuator drive coil 12 vibrates in accordance with the frequency of the AC signal, convection occurs, and this convection promotes elimination of dew condensation, which can be eliminated more effectively. When the dew condensation on the optical pickup is removed, the output signal of the dew condensation sensor 13 changes and the sensor amplifier 14
Switches the switch 15 to the error signal side so that the original focus control or tracking control operation is possible.

Lens actuator drive coil 12 in the above embodiment
Also serves as a heating coil for preheating, and the components including the sensor amplifier 14 and the switch 15 constitute a preheating energizing circuit.

In each of the above-described embodiments, the switch 15 was automatically switched by the dew condensation sensor 14,
The dew condensation sensor 14 may emit an audible or visual alarm when the optical pickup is condensed, and the switch 15 may be manually switched based on this alarm.

Next, the embodiment shown in FIG. 2 will be described. In FIG. 2, an error generator 21, an equalizer 22, a switch 23,
A signal system reaching the lens actuator drive coil 12 via the lens drive circuit 24 is a servo system for performing normal focusing control or tracking control of the optical pickup 11, and the switching device 23 connects the equalizer 22 and the lens drive circuit 24. When a focusing error signal or a tracking error signal is generated from the error generator 21 in a state where the connecting electrical paths a and c are turned on, the lens drive circuit 24 drives the actuator drive coil 12 in accordance with the error signal, The focus error or tracking error of the optical pickup 11 is corrected. A signal from the dew condensation sensor 13 arranged around the lens of the optical pickup 11 or at a position corresponding thereto is applied to the signal switch 26 via the dew condensation detection circuit 25 including a sensor amplifier and the like.
When the dew condensation sensor 13 detects dew condensation, the signal switch 26 turns off between the electric paths a and c connected to the switch 23 and turns on between the electric paths b and c based on the detection signal, and the heating signal source 27 The heating signal from the device is applied to the coil 12 via the lens driving circuit 24.

The condensation detection signal detected by the condensation detection circuit 25 is also added to the timer 28. The timer 28 inputs an OFF signal to the signal switch 26 when a fixed and sufficient time necessary for removing the dew elapses from the time when the dew condensation detection signal is input. The signal switch 26 is switched by the input of this off signal.
23 is switched so that the electric paths a and c connected to the switching device 23 are turned on and the electric paths b and c are turned off. Further, the output of the signal switch 26 is also input to the display circuit 29, and the display circuit 29 is in a state where normal operation is impossible due to a dew condensation state in accordance with the output of the signal switch 26, or It is designed to display whether there is no condensation and normal operation is possible.

The signal switch 26 can be composed of, for example, a small signal relay, a transistor, etc., and the switch 23 can be composed of a relay contact, a transistor switching circuit, etc.

In the above-described embodiment, in a normal state where there is no dew condensation on the optical pickup 11, between the electric paths a and c connected to the switch 23 is on, and between b and c is off, which is generated by the error generator 21. The error signal is input to the lens drive circuit 24 through the equalizer 22 and the switch 23, the lens drive circuit 24 drives the coil 12 according to the error signal, and operates as a normal actuator, that is, focusing error or tracking error. Perform the correction operation. During operation as a normal actuator, the coil 12 is energized to generate Joule heat, so that dew condensation does not occur on the optical pickup.

When dew condensation occurs on the optical pickup due to sudden heating of the room or the like, the dew condensation detection circuit 25 detects this based on the output signal of the dew condensation sensor 13 and inputs the dew condensation detection signal to the signal switch 26. The signal switching unit 26 switches the switching unit 23 based on the dew condensation signal, turns off the electric paths a and c connected to the switching unit 23, cuts off the input of the error signal to the lens drive circuit 24, and stops the operation as an actuator. ,
The electric paths b and c connected to the switch 23 are turned on, and the heating signal from the heating signal source 27 is applied to the coil 12 via the lens drive circuit 24, and Joule heat is generated in the coil 12 to cause dew condensation of the optical pickup 11. To remove. This dew condensation removing operation is stopped when a certain time set by the timer 28 has elapsed. Although the dew condensation removal operation is stopped by the output of the dew condensation sensor 13 that detects that the dew condensation of the optical pickup 11 has been removed, the reverse detection of the dew condensation sensor 13 has an unstable operating point. In the illustrated embodiment, the timer 28 is also used to stop the dew condensation operation.

The display circuit 29 has no direct relation to the dew condensation function,
By providing the display circuit 29, when the optical pickup does not operate normally due to dew condensation, by displaying that fact to the user, it is possible to prevent the user from feeling anxious about mischief. Extremely useful.

The servo system from the error generator 21 to the equalizer 22, the switch 23, the lens drive circuit 24, and the actuator drive coil 12 is usually two systems of focusing and tracking, but in the example shown, only one servo system is provided. It is shown. In the embodiment of the present invention, the lens actuator drive coil 12 also serving as the heating coil may be a focusing servo coil, a tracking servo coil, or both servo coils. You may make it serve also as a heating coil. Which servo coil is also used as the heating coil is preferably determined in consideration of the structure of the optical pickup, heat transfer from the coil to the lens, and the like.

The circuit from the heating drive source 27 to the coil 12 through the switch 23 and the lens drive circuit 24 constitutes a preheat energizing circuit.

In each of the embodiments described so far, the lens actuator drive coil is also used as the heating coil, so that it is possible to remove the dew condensation only by a circuit-like process without adding a special heating coil. The preheating device of the present invention can be easily applied to the above optical pickup.

According to the present invention, when the optical pickup of the optical information recording / reproducing apparatus is condensed, the sensor detects it, and the optical pickup is heated based on this detection signal to forcibly remove the condensation. Therefore, it is possible to operate the optical information recording / reproducing apparatus with a waiting time of, for example, 1/10 or less as compared with the case of being left as it is. In addition to simply heating the optical pickup, the heating coil is the lens actuator drive coil, and since it is the heating signal applied to this lens actuator drive coil, the lens actuator vibrates according to the frequency of the AC signal and convection occurs. The convection is generated and the dew condensation is promoted, and the dew condensation can be more effectively eliminated.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 shows another embodiment of the present invention. 11 ... optical pickup, 12 ... lens actuator drive coil, 13 ... condensation sensor, 23, 33 …… Switching device that constitutes the preheating conduction circuit, 24 …… Lens drive circuit, 27 …… The heating signal source that constitutes the preheating conduction circuit.

Claims (1)

[Scope of utility model registration request] 1. A dew condensation sensor disposed in an optical pickup of an optical information recording / reproducing apparatus, a heating coil also disposed in the optical pickup, and a detection output of the dew condensation sensor energizes the heating coil to energize the light. An optical pickup preheating device, comprising: a preheating energizing circuit for preheating the pickup, wherein the heating coil is a lens actuator driving coil of the optical pickup, and a heating signal applied to the heating coil is an AC signal.