JP2738861B2 - Master exposure equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master disc exposure apparatus for exposing a master disc of an optical disc.

[Conventional technology]

The master exposure apparatus is known from Precision Machinery, Vol. 50, No. 12, "Recent Optical Memory / Optical Communication and Ultra-Precision Technology" (1984). In this master disc exposure apparatus, for example, an optical system as shown in FIG. 2 is used, and a laser beam from an exposure laser 1 composed of an argon laser as an exposure light source is used as a dichroic mirror 2, a mirror 3, a polarization Information is written by exposing the optical disk master 7 made of a glass plate via the beam splitter 4, the λ / 4 plate 5 and the objective lens 6 to the information. Further, laser light from a focus control light source 8 composed of a He-Ne laser is split into two lights by a dichroic mirror 9 as a light splitting unit, and one of the light amounts is constantly changed by a light amount detection sensor 10 as a light amount detecting unit. While being detected, the other is irradiated on a master optical disk 7 via a dichroic mirror 2, a mirror 3, a polarizing beam splitter 4, a λ / 4 plate 5, and an objective lens 6, and the reflected light is reflected on the objective lens 6, λ / 4 Plate 5, Polarizing beam splitter 4
Then, the light is incident on a focus error detection sensor including a four-division pin photodiode via a cylindrical lens 11. The focus error detection sensor, the focus control unit, the He-Ne laser 8, and the cylindrical lens 11 constitute a focus control device, and the focus error detection sensor uses the laser light from the exposure laser 1 in place of the laser light from the cylindrical lens 11. Detects focus error. Then, the focus control unit drives the lens actuator according to the focus error signal from the focus error detection sensor to move the objective lens 6 in the optical axis direction, thereby performing focus control so that the focus error is eliminated.

When performing the exposure process, the master exposure apparatus measures the amount of laser light from the exposure laser 1 on the surface of the master 7 as a preparatory step.
It is necessary to block the laser light from the camera. It is conceivable that the blocking of the laser beam from the He-Ne laser 8 is performed by a shielding plate at a position A between the He-Ne laser 8 and the dichroic mirror 9, for example. However, this way He-Ne
The laser light from the laser 8 does not enter the light amount detection sensor 10 and the laser light from the He-Ne laser 8 cannot be always detected, and the laser light from the He-Ne laser 8 is blocked by the shielding plate. At this time, the output signal of the light quantity detection sensor 10 becomes an abnormal signal, and the apparatus enters the abnormal mode. The focus control unit drives the lens actuator according to the state of the output signal from the light amount detection sensor 10 to move the objective lens 6 to the master 7.
In the worst case in the abnormal mode, the lens actuator may be damaged (collision with the master 7 or a change in characteristics due to oscillation). Therefore, when the abnormal mode is set, the exposure step is stopped to protect the lens actuator. More specifically, the entire lens actuator is moved away from the master 7 to perform a protection operation such as stopping the focus control operation. I have to.

If the laser beam from the He-Ne laser 8 is blocked by the shielding plate 12 at a position between the dichroic mirrors 2 and 9, the laser beam from the He-Ne laser 8 is always detected by the light amount detection sensor 10. can do.

[Problems to be solved by the invention]

When the laser beam from the He-Ne laser 8 is cut off by the shielding plate 12 at a position between the dichroic mirrors 2 and 9, the amount of laser light from the exposure laser 1 on the surface of the master 7 is determined. If an abnormal mode occurs due to the occurrence of noise or dropout during measurement, the above-described protection operation is performed. Therefore, the amount of laser light from the exposure laser 1 on the surface of the master 7 must be measured again from the beginning. Not very workable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a master exposure apparatus capable of improving the above disadvantages and improving workability.

[Means for solving the problem]

In order to achieve the above object, the present invention provides an exposure light source that irradiates light on a master to expose the master, and combines light from a light source for focus control with light from the light source for exposure by light combining means. A focus control device for irradiating the master disc and performing focus control using the reflected light; a light branching means for branching and extracting a part of light from the focus control light source before the light combining means; A light quantity detecting means for detecting the light quantity of the light taken out by the branching means, and an abnormal light quantity of the focus control light source is determined from an output signal of the light quantity detecting means and an abnormal signal is outputted to perform a predetermined protection operation. Light amount abnormality determining means, light blocking means for turning on / off light from the focus control light source to the master between the light branching means and the light combining means,
During the exposure of the master and when measuring the focus characteristic of the focus control device, the abnormality signal from the light quantity abnormality determination means is passed as it is to be valid, and the light intensity is valid except during the exposure of the master and when measuring the focus characteristic of the focus control device. Enabling means for invalidating an abnormal signal from the abnormality determining means so that the protection operation is not performed.

[Action]

An exposure light source irradiates light to the master to perform exposure of the master, and a focus control device combines light from the focus control light source with light from the exposure light source by a light combining unit to irradiate the master with the light. Focus control is performed using the reflected light. A light branching unit branches out a part of the light from the focus control light source before the light combining unit and takes out the light,
The light amount detecting means detects the light amount of the light extracted by the light branching means. The light quantity abnormality determining means determines a light quantity abnormality of the focus control light source from the output signal of the light quantity detecting means and outputs an abnormal signal to perform a predetermined protection operation. The light from the focus control light source to the master is turned on / off with the means. The activating means passes the abnormality signal from the light quantity abnormality judging means as it is during the exposure of the master and at the time of measuring the focus characteristic of the focus control device, and enables the focus characteristic measurement during the exposure of the master and the focus characteristic measurement of the focus control device. At other times, the abnormal signal from the light amount abnormality determining means is invalidated so that the protection operation is not performed.

〔Example〕

 FIG. 1 shows a circuit configuration of one embodiment of the present invention.

In this embodiment, in the master exposure apparatus having the optical system shown in FIG. 2, a light-shielding means comprising a shielding plate 12 is disposed at a position between dichroic mirrors 2 and 9.
Reference numeral 2 denotes an on / off control by the main control unit for turning on / off the laser light from the dichroic mirror 9, that is, when measuring the amount of laser light from the exposure laser 1 on the surface of the master 7, the dichroic mirror 9 is used. From the laser beam.

Further, the light amount detection signal from the light amount detection sensor 10 is converted into a voltage signal by the photoelectric conversion circuit 13 and input to the comparison circuit 14 as light amount abnormality determination means. On the other hand, the reference voltage generation circuit 15 measures the amount of laser light from the He-Ne laser 8 during normal operation in advance, and sets a reference voltage serving as a reference for determining a light amount abnormality according to the amount of light. The reference voltage from the reference voltage generation circuit 15 is compared with the output voltage of the photoelectric conversion circuit 13 input to the comparison circuit 14. As shown in FIG. 3, when the amount of laser light from the He-Ne laser 8 abnormally decreases and the output voltage of the photoelectric conversion circuit 13 falls below the reference voltage, the output signal from the comparison circuit 14 is effective as an abnormal signal. The protection operation is performed by a circuit (not shown) based on the abnormal signal output from the switch 16 serving as an activating means.

The mode switching signal generation circuit 17 turns on / off the switch 16 according to a mode signal from the main control unit. This example is
The mode switching signal generating circuit is made by noting that the light amount detection of the laser beam from the He-Ne laser 8 is not necessary except during the exposure of the master 7 and the focus characteristic measuring operation of the focus control device. 17 turns on the switch 16 during the exposure of the master 7 and during the focus characteristic measuring operation of the focus control device.
Off. In this case, the mode switching signal generating circuit 17 receives a mode signal representing the current operation mode (working mode) of the present embodiment from the main control unit, for example, during the exposure of the master 7, during the focus setting, and the light amount of the exposure laser 1. A mode signal indicating an operation mode of a work level such as setting is input, and from this mode signal, whether the use of the He-Ne laser 8 is enabled or disabled is determined, and the switch 16 is turned on / off as described above. The detection of the amount of laser light from the He-Ne laser 8 is invalid except during the exposure of the master 7 and during the focus characteristic measuring operation of the focus control device. Therefore, in the operation modes other than the exposure of the master 7 and the focus characteristic measurement operation of the focus control device, the protection operation at the time of the abnormal light amount of the laser light from the He-Ne laser 8 is not performed, and the workability can be improved. it can. In FIG. 1, reference numeral 18 denotes a pull-up resistor.

〔The invention's effect〕

As described above, according to the present invention, an exposure light source that irradiates light to a master to expose the master, and combines light from a light source for focus control with light from the light source for exposure by a light combining unit. A focus control device that irradiates the master and performs focus control using reflected light thereof; a light branching unit that branches out part of light from the focus control light source before the light combining unit; and a light branching unit. A light quantity detecting means for detecting a light quantity of the light extracted in the step, and a light quantity abnormality for performing a predetermined protection operation by determining an abnormal light quantity of the focus control light source from an output signal of the light quantity detecting means and outputting an abnormal signal. Determining means; light-blocking means for turning on / off the light from the focus control light source to the master between the light branching means and the light combining means; When the focus characteristic is measured by the focus control device, the abnormality signal from the light amount abnormality determination means is passed as it is to be valid, and the abnormality signal from the light amount abnormality determination means is used except during the exposure of the master and the focus characteristic measurement of the focus control device. And effective means for invalidating the protection operation so that the protection operation is not performed, so that the protection operation is performed when the light amount of the focus control light source is abnormal during the master exposure and in a work mode other than when the focus characteristics are measured by the focus control means. The operability can be improved without being performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of an embodiment of the present invention, FIG. 2 is a diagram showing an example of an optical system of a master exposure apparatus, and FIG. 3 is an output voltage and a reference of a photoelectric conversion circuit in the above embodiment. FIG. 4 is a waveform diagram showing a voltage. DESCRIPTION OF SYMBOLS 1 ... Exposure light source, 2 ... Dichroic mirror as a light synthesizing means, 7 ... Master disk, 8 ... Focus control light source, 9 ... Light splitting means, 10 ... Light quantity detecting means, 12 ... Light shielding means, 14 ... light quantity abnormality determination means, 16 ... validation means.

Claims (1)

(57) [Claims] An exposure light source for irradiating the master disk with light and exposing the master disk; and a light from a focus control light source combined with light from the exposure light source by a light combining means to irradiate the master disk. A focus control device that performs focus control using the reflected light; a light branching unit that branches out a part of light from the focus control light source before the light combining unit; and a light that is extracted by the light branching unit. Light amount detecting means for detecting the light amount of the light amount, light amount abnormality determining means for performing a predetermined protection operation by determining an abnormal light amount of the focus control light source from the output signal of the light amount detecting means and outputting an abnormal signal, Light blocking means for turning on / off light from the focus control light source to the master between the light branching means and the light combining means; When the focus characteristic is measured, the abnormality signal from the light amount abnormality determination unit is passed through as it is to be validated and the abnormality signal from the light amount abnormality determination unit is protected except during the exposure of the master and when the focus control device measures the focus characteristic. A master exposure apparatus comprising: an effective unit for invalidating an operation so as not to be performed.