JP2002257710A - Dust detector using optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect a dust amount contained in the air. SOLUTION: An optical disk 2 worked to make dust easily deposited on its surface is rotation-driven to make the surface of the optical disk 2 irradiated with a laser beam using an optical system 3. Since an integrated value computed by a micro-computer 12 is brought into a low value compared with that deposited with no dust because a level of the reflected laser beam is lowered in a portion deposited with the dust in the surface of the disk 2, a difference between the integrated value and a preset reference value is found to measure the dust amount in the air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust detector for detecting dust in the air using an optical disk.

[0002]

2. Description of the Related Art For example, in an environment where clean air is required, such as information processing equipment, the amount of dust in the air is detected. If it is determined that the amount of dust is excessive, an alarm is issued. It informs the operator. The operator
By recognizing the contamination of the air, it is possible to take measures such as replacing the filter of the air purifier at an early stage.

[0003] As a dust detecting device used for detecting dust in the air, a conventional dust detecting device has been disclosed in JP-A-9-897.
No. 55 (hereinafter referred to as a conventional example) is known. In this conventional example, light from a light emitting diode is irradiated onto the air to be measured for the amount of dust, and light reflected by dust present on the optical path is detected by a light receiving element (phototransistor). Thus, the amount of dust in the air is measured.

That is, when the amount of dust existing in the air is large, the amount of light reflected on the light receiving element side becomes large.
The amount of dust in the air can be measured by measuring the amount of light detected by the light receiving element.

[0005]

However, in such a conventional dust detection device, since the light receiving element has directivity, the area of the light receiving element away from the optical axis of the light is not reflected by the dust. There is a problem that the detection sensitivity is low and it is difficult to detect dust of 1 μm or less.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a dust detection device capable of detecting the amount of dust contained in air with high accuracy. Is to provide.

[0007]

According to a first aspect of the present invention, there is provided a dust detection apparatus for detecting dust contained in air, comprising: an optical disk; An optical system having a light emitting unit for irradiating a laser beam and a light receiving unit for receiving light reflected by the optical disk, wherein the optical disk is disposed in the air to be detected as dust. Then, the light receiving signal obtained by the optical system is integrated, the amount of dust attached to the optical disk is obtained from the integrated value, and the amount of dust contained in the air is detected based on the amount of attached dust. It is characteristic.

According to a second aspect of the present invention, in a dust detection device for detecting dust contained in air, an optical disk, light emitting means for irradiating the optical disk with laser light, and An optical system having a light receiving means for receiving the reflected light, and an integrated value of a light receiving signal obtained by the optical system, and calculating difference data between the integrated value and a preset reference value. Dust amount calculating means for calculating the amount of dust attached to the optical disk based on the difference data, wherein the optical disk is disposed in air to be a dust detection target, and the dust amount detecting means The amount of dust in the air is detected on the basis of the amount of dust detected.

According to a third aspect of the present invention, the reference value is:
It is characterized by being an integrated value of a light receiving signal obtained by the optical system when dust is not attached to the optical disk.

According to a fourth aspect of the present invention, the optical system includes:
In addition to the light emitting means and the light receiving means, the laser light output from the light emitting means is emitted toward the optical disk, and the laser light reflected by the optical disk is polarized in a substantially right angle direction. And a polarizing means for guiding the light to the light receiving means.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of a dust detection device using an optical disc according to the present invention. As shown in FIG. 1, the dust detection device 1 includes a compact disc (CD) and a digital video disc (DV).
D) and the like, and an optical system 3 for irradiating the optical disk 2 with laser light and receiving laser light reflected on the surface of the optical disk 2. .

The optical disk 2 is surface-treated or charged so that dust easily adheres to the surface.

The optical system 3 includes a light emitting element (light emitting means) 4 for emitting laser light, a collimating lens 5 for converting the laser light emitted from the light emitting element 4 into a parallel beam, and a laser light converted to a parallel beam. Beam splitter (polarizing means) 6 that emits light toward the optical disk 2 and polarizes the light reflected by the optical disk 2 in a direction of approximately 90 degrees.
, A quarter-wave plate 7, an objective lens 8, a detection lens 9 for condensing the laser light reflected by the optical disc 2, and a light-receiving element for receiving the laser light condensed by the detection lens 9 ( Light receiving means) 10.

Further, the dust detection device 1 includes an A / D converter 11 for converting a light receiving signal received by the light receiving element 10 of the optical system 3 into a digital signal, and integrating the digitized light receiving signal. The microcomputer 12 includes a microcomputer 12 that performs a process of calculating a converted value of the amount of dust from the integrated data, and a display unit 13 that displays the amount of dust obtained by the microcomputer 12.

Next, the operation of the present embodiment configured as described above will be described. When air in a target environment for dust detection is sucked into the optical disc 2 by a predetermined volume using an adsorption fan (not shown), dust contained in the sucked air is adsorbed on the surface of the optical disc 2. Is done.
At this time, since the surface of the optical disc 2 is processed so that dust easily adheres, dust contained in air can be efficiently adhered.

In this state, the motor (not shown)
When the optical disk 2 is driven to rotate and laser light is emitted from the light emitting element 4, the laser light passes through the collimator lens 5, beam splitter 6, quarter wave plate 7, and objective lens 8. Thus, the lower surface of the optical disc 2 is irradiated. The laser light reflected by the optical disk 2 is introduced into the beam splitter 6 through the objective lens 8 and the quarter-wave plate 7, is polarized by approximately 90 degrees by the beam splitter 6, and is polarized by the detection lens 9. After being collected, it is supplied to the light receiving element 10.

The output signal of the light receiving element 10 is A /
The digital signal is converted into a digital signal by the D converter 11, and an integration operation is performed by the microcomputer 12.

At this time, the amount of the laser light reflected by the pits 2a (the pit having a width of 0.5 μm and the depth of 0.11 μm) formed on the optical disk 2 is slightly attenuated. That is, FIG. 2 is a characteristic diagram showing the position of the pit 2a and the level of the signal output from the light receiving element 10. When the laser light is reflected at the pit 2a, it is compared with the case where the laser light is reflected at a portion other than the pit 2a. Since the focus of the laser beam is slightly shifted, the level of the received signal is reduced.

Accordingly, the output signal of the light receiving element 10 when the laser light is irradiated on the pit 2a is L1 shown in FIG. 2, and the output signal of the light receiving element 10 when the laser light is irradiated on the part other than the pit 2a. The output signal is L2 shown in FIG.
Becomes

Here, dust P is applied to the surface of the optical disc 2.
Is attached, the focus of the laser beam applied to this portion is greatly shifted, so that the output of the light receiving element 10 is greatly reduced (level L3 shown in FIG. 3).

Therefore, the integrated value of the output signal of the light receiving element 10 calculated by the microcomputer 12 decreases as the amount of dust P adhering to the surface of the optical disk 2 increases. The microcomputer 12 stores in advance the integrated value of the output signal of the light receiving element 10 when no dust P adheres to the surface of the optical disk 2 as a reference value. The difference data from the integrated value of the output signal of the light receiving element 10 when the dust P adheres to the surface of the disk 2 is obtained,
The difference data is converted into the amount of dust attached to the optical disk 2. And, based on this amount of dust,
The amount of dust in the air to be detected is measured, and data obtained by the measurement is displayed on the display unit 13.

Thus, the amount of dust in the air can be measured using the optical disk 2.

As described above, in the dust detection apparatus 1 using the optical disc according to the present embodiment, the optical disc 2 such as a compact disc or a digital video disc is used.
The optical disc 2 is irradiated with laser light, and the level of the reflected laser light is detected, thereby detecting the amount of dust adhering to the optical disc 2 and thus detecting the dust. The amount of dust in the air is calculated.

Therefore, the amount of dust in the air can be determined with high accuracy. Further, by adjusting the sampling characteristics or the rotational linear velocity when driving the optical disk 2, the accuracy of detecting dust can be improved, and fine dust of 1 μm or less can be detected.

Further, since the structure is such that dust adheres to the surface of the optical disk 2, even if the permeability of the fine particles is high, it can be reliably detected. Further, as a device for driving the optical disc 2,
Generally, a widely used CD player or the like can be used, so that the configuration can be made inexpensively.

As the optical disk 2, a laser disk, an MO disk (magnetic optical disk) or the like can be used in addition to a CD or DVD.

The dust detection device using the optical disk of the present invention has been described based on the illustrated embodiment. However, the present invention is not limited to this.
Any configuration having a similar function can be used.

[0028]

As described above, in the dust detection apparatus using the optical disk according to the present invention, the optical disk is set in the air for which the amount of dust is measured, and the air is placed on the surface of the optical disk. By adhering dust inside, irradiating the optical disk with laser light, integrating the output level of the laser light reflected by the optical disk, and comparing this integrated value with a reference value, The amount of dust adhering to the disc is measured, and thus the amount of dust contained in the air is measured.

Therefore, the amount of dust contained in the air can be measured with high accuracy. Further, fine particles having high light transmittance can be detected.

Further, since an optical disk drive such as a CD player, which is widely used, can be used as the optical system, the apparatus can be constructed at a low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a dust detection device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between pits formed on an optical disk, dust attached to the optical disk, and an output signal of a light receiving element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dust detection apparatus 2 Optical disk 2a Pit 3 Optical system 4 Light emitting element (Light emitting element) 5 Collimating lens 6 Beam splitter (Polarizing means) 7 1/4 wavelength plate 8 Objective lens 9 Detection lens 10 Light receiving element (Light receiving means) 11 A / D converter 12 Microcomputer 13 Display P Dust

Claims (4)

[The claims] 1. A dust detection device for detecting dust contained in air, comprising: an optical disk; a light emitting unit for irradiating the optical disk with laser light; and a light receiving unit that receives light reflected by the optical disk. An optical system having light receiving means, wherein the optical disk is disposed in air as a dust detection target, a light receiving signal obtained by the optical system is integrated, and the optical A dust detection device using an optical disc, wherein an amount of dust attached to a disc is obtained, and an amount of dust contained in air is detected based on the amount of the attached dust. 2. A dust detection device for detecting dust contained in air, comprising: an optical disk; a light emitting means for irradiating the optical disk with laser light; and receiving light reflected by the optical disk. An optical system including a light receiving unit; calculating an integral value of a light receiving signal obtained by the optical system; calculating differential data between the integrated value and a preset reference value; Means for calculating the amount of dust attached to the disc, wherein the optical disc is disposed in the air to be subjected to dust detection, and the amount of dust detected by the dust amount detecting means is determined. A dust detection device using an optical disc, wherein the dust detection device detects an amount of dust in the air based on the detected dust amount. 3. The optical system according to claim 2, wherein the reference value is an integrated value of a light receiving signal obtained by the optical system when dust is not attached to the optical disk. Dust detector using disc. 4. The optical system, in addition to the light emitting means and the light receiving means, emits a laser beam output from the light emitting means toward the optical disk, and is reflected by the optical disk. 4. The dust detection device using an optical disk according to claim 1, further comprising a polarization unit that polarizes the laser beam in a substantially perpendicular direction and guides the laser beam to the light receiving unit.