JPS6157081A - Detector of head transporting position - Google Patents

Abstract

PURPOSE:To detect the transporting position of a head with simple structure and non-contact system by synchronizing relatively light-emitting element and photodetector and a mask with a head so as to shift it, changing the light receiving state with the aid of the photodetector and detecting the transporting position of the head due to the change in light receiving state. CONSTITUTION:When an optical head 4 is transported in the direction of an arrow (a) between the outer-most peripheral position P1 and inner-most peripheral position P2 of a disk 1, a light-emitting element 14 and photodetector 15 are synchronized with the optical head 4 and transported in the arrow (a) direction with respect to a mask 16. At this time, since a light shielding edge 16a of the mask 16 tilts by an angle theta with respect to the transporting direction (the arrow (a) direction), the light receiving state of the photodetector 15, where light is made incident from the light emitting element 14, is changed along with the transportation of the optical head 4. When the optical head 4 is transported, the light receiving quantity of one solar battery A of the photodetector 15 changes gradually, whereas that of the other solar battery B is always constant. Consequently the transporting position of the optical head 4 can be detected by the detection output caused by the difference of the light receiving amounts of two-divided solar batteries A and B.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a device for detecting the movement position of a recording and/or reproducing head, such as an optical head in an optical disc player. [Prior Art] Conventionally, in optical disc blenders, recording and/or playback of the disc has been carried out by moving the optical head E in the radial direction of the disc. Detection of the transfer position is important. Prospective search means □ Memorizing the radial position (address) of the optical head relative to the disk in advance, converting the desired position (address) of the optical head to '' and reading it out to roughly fly the optical bed. Yes, this is expected. After performing a detailed access check, the optical head is correctly positioned at address C. □ And the conventional practice □
As an optical head transfer position detection device,
For example, there are a contact type using a potentiometer and a non-contact type using photodetection in which a photocoupler is moved along a slit plate having a large number of slits to generate pulses. [Problems to be solved by the invention] However, the conventional contact type has problems with its lifespan and defects in the linearity of the detection output. Also, the circuit was complicated and expensive, and the response was slow. The present invention is capable of detecting the transfer position of the head in a non-contact manner and with a very simple structure. [Means for Solving the Problems] The present invention provides a structure in which a light-shielding mask is disposed between the light-emitting element and the light-receiving element, and is inclined with respect to the direction of movement of the head. This is a head transfer position detecting device configured to change the light reception state of the light receiving element by moving the head in synchronization with the head relative to the head, and to detect the head transfer position based on the change in the light reception state. [Function] When the head is moved in the radial direction of the disk, the mask is fixed and the light-emitting element and the light-receiving element are moved in synchronization with the head, or vice versa, the light-emitting element is fixed. and the light emitting element and ;+5HY;F-PYz
y)"Kn The device is configured to change the light blocking state to change the light receiving state at the light receiving element, and detect the head transfer position based on the change in the light receiving state. In addition to being able to detect by contact method, the linearity of the detection output is good.Furthermore, since the light emitting element, light receiving element, and mask are moved relative to each other in synchronization with the head, the structure is very simple. Not only is it simple and the circuit is very simple, but it can also detect the movement of the head very quickly. An embodiment in which a horizontal device RVC is applied will be described based on the drawings. First, in FIGS. 1 and 2, a disk 1 is mounted horizontally on a turntable 2, and the turntable 2 is connected to a drive motor (not shown). The disk 1 is driven to rotate horizontally by the turntable 2.The optical head 4, which has an objective lens 3, etc., is mounted horizontally on a fixed deck 5. Disk 10 along guide shaft 6
It is configured to be movable both radially and horizontally. For example, a pinion 8 rotatably driven by a drive motor 7 attached to the deck 5 drives a rack 9 fixed to the optical head 4. A head feeding mechanism 10 moves the optical head 4 in the radial direction of the disk l. Arrow a in figure 1
and is configured to be transported in the direction. That is, by horizontally moving the optical head 4 in the direction of arrow a while rotating the disk 1 horizontally, desired recording or reproduction of the disk 1 is performed. . Next, the transfer position detecting device 13 of the optical head 4 in the direction of arrow a, as shown in FIG. It is composed of a light-shielding mask 16 disposed horizontally between the element 14 and the light-receiving element 15.The light-shielding edge 16a of the mask 16 is in the optical head 4 transport direction as shown in FIG. Radial direction of disk 1°

[Direction of arrow a] It is inclined at an angle θ with respect to K. In this embodiment, one light-emitting element 14 and one light-receiving element 15 are attached to the optical head 4 by a holding member 17, and these light-emitting element 14 and one light-receiving element 15. While the mask 16 is transferred together with the optical head 4 in the direction of arrow a, the mask 16 is transferred to the deck 5.
It was fixed to the fixed position. However, on the contrary, if the mask 16 is attached to the optical head 4 and transferred together with the optical head 4, the light emitting element 14 and the light receiving element 15 are transferred together.
and may be fixed to the deck 5 in a fixed position. According to the transfer position detecting device 13 for the optical head 4 configured as described above, the optical head 4 is moved to the first position. When the disk 1 is transferred in the direction of arrow a between the outermost circumferential position P1 shown by a solid line in the figure and the innermost circumferential position P2 shown by a dashed-dotted line, the light emitting element 14 and the light receiving element 15 are transferred to the optical head 4. The mask 16 is moved in the direction of the arrow a in synchronization with the mask 16.
Since the light-shielding edge 16a of the optical head 4 is inclined at an angle θ with respect to the transport direction (arrow a direction), the light receiving state of the light emitted from the light emitting element 14 at the light receiving element 15 is the same as that of the optical head 4.
It changes with the transport of. That is, in this embodiment, the optical head 4, for example,
When the outermost circumferential position PIK is located, the total amount of light emitted from the light emitting element 14 is transmitted to the light receiving element 1502 and the divided solar cells A and B, as shown in the light receiving area 18 on the light receiving element 15 shown in a circle in FIG. 3A. The light is evenly irradiated, and the amount of light received by these two-split solar cells A1B is equal.Next, as the optical head 4 is moved toward, for example, the innermost position P2 of the disk 1, the third B Mask 1 as shown in the figure
According to the inclination of the angle θ of the light-shielding edge 16a of
The light received by one solar cell A is gradually blocked, and the amount of light received by that solar cell A is gradually reduced. Then, the optical head 4 moves, for example, to the innermost circumferential position P2 of the disk 1 -fF! At this time, the light 11 received by one solar cell A is
In some cases, the light is completely blocked. Furthermore, this optical head 4
Since the light received by the other solar cell B of the light-receiving element 15 is not blocked by the mask 16 during the transfer, the amount of light received by the solar cell B side is as shown in FIGS. 3A to M3.
As shown in FIG.
While the amount of light received by one solar cell A of the c1 light-receiving element 15 gradually changes, the amount of light received by the other solar cell B is changed to remain constant throughout, and the amount of light received by the two divided solar cells A and B is The transfer position of the optical head 4 is detected based on the detection output based on the difference between the two. Figure 4 shows a mask 16 and a two-part battery A. Two slits 19 and 20y corresponding to B are provided, and one slit 19 is in the transport direction of the optical head 4 (direction of arrow a).
This shows a modification example in which the opening area of the slit 20 is approximately wedge-shaped, and the opening area of the other slit 20 is constant. 1. Still, in FIG. 5, a large slit (such as a wedge-shaped slit) 21Y is provided in the mask 16, and the opening area gradually changes with respect to the transport direction (direction of arrow a) tL of the optical head 4, and the other solar cell B is attached to the slit 21Y. 21 shows a modification example in which the filter is arranged within the transmission area of No. 21. 4 and 5, it is possible to obtain a detection output based on the difference in the amount of normal light between the two-split solar cells A and B, as described above. According to the modification shown in FIG.
Direction perpendicular to the direction indicated by the arrow [See Figure 2] Even if there is a backlash in the pair, the two-part solar cells A and B
Since the total amount of light received does not change, even more accurate detection output can be obtained. Further, FIG. 6 shows a modification in which 22 slits are formed in the mask 16 at an angle θ with respect to the transport direction of the optical head 4. As shown in FIG. In this case, as the optical head 4 is moved, the amount of light received by the two-split solar cells A and B is changed to increase or decrease reversibly, and the transfer position of the optical head 4 is changed based on the comparative output difference. It is configured so that it can be detected. By the way, in the transfer position detection device 13 of the optical head 4 described above, the detection output from the light receiving element 15 is higher.
・Linearity? In consideration of this, the strong pressure distribution of light emitted from the light emitting element 14 cannot be ignored. That is, when an inexpensive light emitting diode or the like is used as the light emitting element 14, the intensity distribution of the light emitted from the light emitting element 14 is as shown in FIG. Intensity distribution 24 that gradually weakens in the distance (according to
becomes. Therefore, as shown in FIG. 8, the light intensity in the light-receiving area 18 on the light-receiving element 15 is strongest at the center part 18a (and gradually becomes weaker as it moves away from the outer peripheral part 18b. Therefore, as shown in FIG. As shown in FIG. 2, as the optical head 4 is moved from the outermost circumferential position P1 to the innermost circumferential position P2 of the disk 1, the light-shielding edge 16a of the mask 16 directs the light-receiving area 18 from the outer circumferential part 18b to the central part 18a. The light is gradually blocked (for example, between the outermost position P1 and the middle position P3, the light-shielding edge 16a of the mask 16 gradually blocks the outer peripheral part 18b of the light-receiving area 18 where the light intensity is weak. , the rate of decrease in the amount of light received by the light receiving element 15 is small compared to the amount of increase in the light shielding area.On the other hand, for example, at the intermediate position P
3 and the innermost circumferential position P2, the light shielding line 1 of the mask 16
6a gradually blocks light from the central portion 18a of the light-receiving region 18 where the light intensity is strong, and the rate of decrease in the amount of light received by the light-receiving element 15 becomes greater than the amount of increase in the light-blocking area. The above shows that while the light shielding area of the light receiving area 18 by the mask 16 changes linearly as the optical head 4 is moved, the amount of light received by the light receiving element 15 does not change with high linearity. As a result, the detection output obtained from the light receiving element 15 does not change with high linearity as the optical head 4 is moved. Therefore, the amount of light received by the light receiving element 15 as the optical head 4 moves Embodiments in which S is changed with high linearity will be explained one by one. First, FIG. 1
When the light receiving area mst of the light receiving element 15 changes greatly and the mask 16 blocks light from the central part 18a of the light receiving area 18 where the light intensity is strong, light is emitted from the light emitting element 14 so that the light receiving area of the light receiving element 15 changes small. The shape (pattern) of the light receiving element 15 is changed in accordance with the intensity distribution 24 of the light, so that the amount of light received by the light receiving element 15 is changed with high linearity as the optical head 4 is moved.
This is what I did. Next, FIG. 11 shows that when the mask 16 blocks light from the outer peripheral part 18b of the light receiving area 18 where the light intensity is low, the light blocking area becomes large (changes) and the mask 16 When the central portion 18a is light-shielded, the shape (pattern) of the light-shielding line 16a of the mask 16 is changed in accordance with the intensity distribution 24 of the light emitted from the light-emitting element 14 so that the light-shielding area changes small. Similarly, the amount of light received by the light receiving element 15 is changed with high linearity.Next, FIG. And the concentration of this filter 25

〔Effect of the invention〕

Since the present invention can detect the transfer position of the head in a non-contact manner, it has a much longer lifespan and is extremely reliable compared to conventional contact methods. Good linearity of detection output. Furthermore, compared to the conventional non-contact method using photodetection, the structure and circuit are extremely simple and inexpensive, and the response to head movement is extremely fast.
・Can perform detection.

[Brief explanation of drawings]

The drawings illustrate the present invention in an optical disc player.
7) "Otsu2--one,-part. Figure 1 shows an example, and Figure 1 is a partially cutaway plan view.
Figure 2 is an enlarged sectional view of the main part, Figures 3A to 30 are enlarged plan views of the main part to explain changes in the light receiving state of the light receiving element as the optical head is moved, and Figures 4 to 6 are The figure is a plan view showing a modified example of the mask, FIG. 7 is a side view showing the light intensity distribution of the light emitting element, FIG. 8 is a plan view showing the light intensity in the light receiving area of the light receiving element, and FIG. The figure is a plan view explaining the non-linearity of the detection output of the light receiving element, Figures 10 to 12.
The figure shows an embodiment for obtaining high linearity of the detection output of the light receiving element. Also, the symbols used in the drawings (1, 4...
...Optical head 13...Transfer position detection device 14...
. . . Light emitting element 15 . . . Light receiving element 16 . . . Mask.

Claims (1)

[Claims] A light-shielding mask tilted with respect to the moving direction of the head is placed between the light emitting element and the light receiving element, and the light emitting element, the light receiving element, and the mask are moved relative to each other in synchronization with the head. A head transfer position detecting device configured to change a light reception state at the head and detect a head transfer position based on a change in the light reception state.