JPH03280228A - Cardlike recording medium and recording and reproducing device thereof - Google Patents

Abstract

PURPOSE:To suppress a temp. rise as against irradiation with high light energy at the time of reproducing and to prevent the deterioration in reproducing by disposing a member having a good heat conductive property on a supporting substrate in correspondence to a recording layer which is a track end at the time of recording and reproducing. CONSTITUTION:The member having the good heat conductive property, for example, a metallic layer 2 consisting of, for example, iron, copper or the like, is embedded into the supporting substrate 26 in correspondence to the track end of the cardlike optical recording medium (optical card) 20 consisting of the optically transparent substrate 23 for protection, the recording layer 24, an adhesive layer 25, and the supporting substrate 26. The energy level of the photoirradiation for the purpose of reproducing increases per unit time at the point at the track end where the optical card 20 is stopped, decelerated for the purpose of turning over but this temp. rise is suppressed by the heat radiating effect of the cooling member 3 provided on a carrier side via the metallic layer 2 and, therefore, the generation of the deterioration in reproducing in the part 1 where the deterioration in reproducing is liable to arise is prevented.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention records information by irradiation with a light beam,
The present invention also relates to a card-shaped optical recording medium capable of optically reproducing information recorded in this manner, and a recording/reproducing apparatus thereof.

(Prior Art) Card-shaped (generally called wallet-sized) recording media that can be optically or magneto-optically recorded, reproduced, and erased have appeared as new optical information recording media.

This card-shaped optical recording medium C (hereinafter referred to as an optical card) is characterized by being easily portable due to its shape, and having a large information capacity (2 MB or more) relative to its area. As in the case of disk-shaped optical recording media, the optical card records and erases information by forming bits using light energy irradiated onto the recording layer, and when reproducing information, the optical card records and erases information on the recording layer. Light is emitted at a low energy level, and information is read based on changes in reflectance. When irradiating light during playback, it is necessary that the energy of the light does not change the recording layer, but normally the threshold characteristics of the optical recording medium are clearly defined as shown by the solid line in Figure 2. For example, even if the recording layer is a dye-based recording layer that generally has strong durability against temperature and humidity, it has the characteristics shown by the broken line, and it is difficult to avoid a certain degree of reproduction deterioration. In order to avoid the above reproduction deterioration,
When the amount of light irradiation during reproduction is reduced, the amount of light incident on the photodetector that detects changes in the amount of reflected light becomes very small.

(Problem to be Solved by the Invention) In the case of an optical disc, the pull-in of the error signal for autofocusing, the error signal for autotracking, and the selection (access) of the information track are performed while the disc is rotating. Even if the amount of light irradiation is sufficient and the amount of light irradiated is sufficient to detect changes in the amount of reflected light, the light energy density per unit time at the irradiated part will be small (becomes) in proportion to the rotation speed. With optical discs, the problem of playback deterioration can be avoided.However, in the case of optical cards, the direction of tracking is changed at each track end, so the operation of decelerating to a stationary state and speeding up is repeated. In addition, if the reciprocating speed (average speed) of the optical card is high, vibration will occur when the direction of movement is reversed, making it difficult to perform auto-tracking and auto-focusing pull-in operations.
It must be set to 1IIl/sec. Furthermore, if a track is selected (accessed) while the optical card is in operation, the access time becomes longer, so it is preferable that the optical card be in a stationary state at the time of access.

For this reason, with optical cards, when the level of light irradiation during playback is increased to a level sufficient for incidence on the photodetector, an excessive light energy density per unit time occurs at the track end, resulting in playback deterioration. We are facing the problem of progress.

(Objective of the Invention) The present invention has been made based on the above circumstances, and the cause of slight reproduction deterioration is not the light energy itself per unit time, but the temperature rise of the recording layer due to the light energy. By focusing on a certain point, we created a card-shaped optical recording medium that can prevent playback deterioration by suppressing temperature rise by ensuring sufficient heat dissipation effect in this area even when the light energy is high, and recording and playback thereof. The aim is to provide equipment.

(Means for Solving the Problems) Therefore, in the present invention, a recording layer for optically recording information is provided on an optically transparent protective substrate, and the recording layer is provided with an adhesive layer interposed therebetween. In a card-shaped optical recording medium provided with a support substrate, a member with good thermal conductivity is provided on the support substrate corresponding to a recording layer that becomes a track end during recording and reproduction.

Further, in a recording and reproducing apparatus equipped with a carrier that supports such a card-shaped optical recording medium, a cooling means is provided on the carrier side corresponding to a recording layer that becomes a track end of the recording medium during recording and reproduction.

(Function) Therefore, at the track end where the card-shaped optical recording medium is stopped or decelerated due to reversal, even if the energy level of light irradiation for reproduction increases per star time, This temperature rise is suppressed by the heat dissipation effect performed by the member with good thermal conductivity and the cooling means corresponding thereto, so that regeneration deterioration does not actually occur. Moreover, scanning can be performed at a sufficient optical energy level for optical detection during reproduction.

(Example) Hereinafter, an example of the present invention will be specifically described with reference to the drawings. Card-shaped optical recording medium (optical card) 20 according to the present invention
As shown in FIG. 1, a recording layer 24 for optically recording information is provided on an optically transparent protective substrate 23, and a supporting substrate 26 is provided on the recording layer 24 via an adhesive layer 25.
In particular, the support substrate 26 is provided with a laser beam corresponding to a location (indicated by reference numeral l) where the laser beam stops and waits for a while or is decelerated, that is, corresponding to the track end. is a material with good thermal conductivity, such as iron,
A metal layer 2 such as copper is buried therein.

As shown in FIG. 7, such an optical card 20 is loaded into a shuttle (carrier) 41 of an optical card recording/reproducing apparatus through an insertion slot 40. The shuttle 41 is connected to a belt 47 driven by a motor 46, and the belt 47 is endlessly wound around bobbins provided at the front and rear. Further, a pair of guides 43 and 44 extending in a direction perpendicular to the operating direction of the shuttle 41 movably supports an optical radar 42 and a pulse motor 4.
It is reciprocated by driving No. 5 (access operation).

The optical head 42 has, for example, an optical system shown in FIG.
The luminous flux emitted from the collimator lens 28 becomes a parallel light beam. At this time, the cross-sectional shape at the speed of light is elliptical. Therefore, the refraction effect of the prism 29 shapes this into a circular cross section. This light speed is divided into three light speeds of 0th order and ±1st order by a grating 30, and after passing through a beam splitter 31, its direction is changed by a prism mirror 32, and an objective lens 33 sends a light beam of several μm onto the optical card 20. The light is focused to form a spot. The speed of light reflected by the optical card 20 is reflected again by the objective lens 33 and the prism mirror 3.
2, and is separated from the incident light velocity by a beam splitter 31. The reflected light passes through an analog optical system consisting of, for example, a circular lens 34 and a cylindrical lens 35, and is incident on a photodetector 36. On the optical card 20, as shown in FIG.
2-2 and three spots c (size of several μm) are formed between them. These reflected lights having a light speed of 37,38,39 are detected by photodetectors 36b, 36c and 36a (see FIG. 5). Here, the light velocity 39 is electrically extracted as a reproduction signal of recorded information. Also, the speed of light is 37.38
is electrically extracted as a detection signal for auto-tracking, and the difference therebetween becomes an auto-tracking error signal.

Note that the optical card 20 has the tracking track 22
-1.22-2 is preformatted by focus. (Refer to the reference numeral 22 in FIG. 3) 6 Further, in the shuttle (carrier) 41 that supports the optical card 20, a cooling element 3 exhibiting a Peltier effect, for example, is arranged corresponding to the member 2 of the optical card 20. It is set up.

This cooling element 3 may be constituted by another cooling element, which is preferably cooled to a predetermined temperature at all times by a suitable cooling device.

In such a configuration, when the optical card 20 is loaded, the optical head is waiting at the home position 48, as shown in FIG. 8, and the AF control is first performed at that position. Next, the optical head is moved by a pulse motor to an area where a tracking track exists, and AT sub-control pull-in is performed. The reason why AF pull-in is not performed in the area where the track exists is to ensure that the track information does not affect the AF signal and to ensure reliable AF control. Next, the optical head is moved to the desired track position 50. (i.e.
The optical head is moved along the beginning of the information section of each track shown by the dashed line in FIG. 9], and then the optical card is moved back and forth for the first time to record and reproduce information. In this case, the relative motion between the optical card and the optical head in the tracking direction has a speed change in which it stops at the end of the track, decelerates toward that end, and then increases speed from there, and the relative motion per unit time at the end occurs. The amount of light irradiation increases. but,
The optical card 20 can be expected to have a heat dissipation effect due to the member 3, and in addition, the function of the cooling element 3 suppresses the increase in light energy temperature, so that changes in the amount of light received by the photodetector during playback can be sufficiently detected. Even if the amount of light irradiation is set, reproduction deterioration can be effectively avoided.

Next, the state at the time of AF retraction will be explained using FIG. 10. Assuming that the objective lens 33 is operated by an actuator in a direction perpendicular to the card surface, when the lens approaches the card from a far position, the AF error signal changes in an S-shape near the optical card surface and is recorded. Similarly, S near the layer
Changes into a letter shape. Point B in FIG. 10 is the focused point on the card surface, and point A is the focused point on the recording layer surface. In order to distinguish between these two S-shaped changes, as shown by the dashed line in FIG. 10, it is determined whether the level of the error signal is higher than Vo or not. Usually, the reflectance on the card surface is 5% or less, and the reflectance on the recording layer surface is 10% or more, so the above-mentioned method can be used to distinguish them.

FIG. 9 shows the state of reproduction deterioration of an optical card having a dye-based recording layer. Although the above dye is a polymethine dye, the optical card of the present invention can be used with cyanine dyes. In FIG. 9, the horizontal axis represents time, and the vertical axis represents changes in the amount of light received by the photodetector. Note that the measurement conditions were that the card was stationary, the spot diameter was 3 μmφ, and the light amount was L2 ram. As mentioned above, the main cause of this characteristic change is the temperature rise at the spot location on the recording layer of the optical card due to laser beam irradiation.
In the optical card 20 of the present invention, the heat dissipation properties of the member 2 and the cooling effect of the cooling element 3 are effective in avoiding playback deterioration.

In the above embodiment, the location where heat is radiated and cooled is limited to the location where the member 2 is provided because it is significant in eliminating wasted optical energy during recording and reproduction.

(Effects of the Invention) The present invention has been described in detail above, and by cooling the laser beam spot on the optical card at the position where it is stopped or decelerated, it is necessary for the detection of the photodetector during playback. while ensuring a sufficient amount of radiation.

Regeneration deterioration can be avoided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an optical card showing an embodiment of the present invention, FIG. 2 is a sensitivity characteristic curve diagram of a recording medium, FIG. 3 is a plan view of the optical card, and FIG. 4 is a sectional view of the optical card. FIG. 5 is a perspective view showing an example of an optical head, FIG. 6 is a diagram explaining the function of a light spot on the card surface, FIG. 7 is a diagram showing an example of an optical card recording/reproducing device, and FIG. The figure is a diagram explaining a desirable sequence of an optical card system, and Figure 9 is a characteristic diagram of reproduction deterioration.
FIG. 10 is a diagram showing the influence of the AP bow when there is regeneration deterioration. 1-...Part 2.1 part that is likely to cause regeneration deterioration 3...Cooling member 20...-
Optical card 23...substrate 24...-recording layer
25... Adhesive layer 26-... Support substrate 41-... Shuttle (carrier) included

Claims (1)

[Claims] 1. A card in which a recording layer for optically recording information is provided on an optically transparent protective substrate, and a supporting substrate is provided on the recording layer via an adhesive layer. 1. A card-shaped optical recording medium, characterized in that a member having good thermal conductivity is disposed on the support plate corresponding to a recording layer that becomes a track end during recording and reproduction. 2. A carrier for supporting a card-like optical recording medium;
A recording and reproducing apparatus characterized in that a cooling means is provided on the carrier side corresponding to a recording layer that becomes a track end of the recording medium during recording and reproducing.