JPS6245615B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses an energy beam to form pit rows corresponding to information to be recorded on a resist layer provided on a substrate, thereby improving the video recording technology used when recording the information. It relates to recording media such as disks.

An optical method is used to record video and audio information on a disk-shaped carrier. This optical system usually has a structure in which a resist layer is provided on a substrate such as glass, and a high-energy beam such as a laser beam or electron beam is deposited on this resist layer according to a path signal modulated based on information recorded. The beam is irradiated intermittently, and the energy of the beam forms a pit row on the surface of the resist layer with a length and interval corresponding to the pulse signal, thereby recording information. Usually, a dedicated recording device is used to record information on this disc, and a large number of reproduction discs are created using the disc recorded by this recording device as a master disc. The present invention particularly relates to a disk serving as this master. In this disk recording device, the period and pulse width of the intermittent pulse of the energy beam are modulated using a video signal and an audio signal, which are two components of the information to be recorded. Necessary information such as the distance between pits or the length of each pit is recorded in the row of pits formed on the surface of the resist layer.

Since the conventional disk has a structure in which only a resist layer is provided on a substrate such as glass, a pit is formed with a diameter corresponding to the entire beam width of the irradiated energy beam. This means that pits with an outer diameter smaller than the width of the energy beam are not formed, which is a factor that limits the density and accuracy of recorded information. Further, when the resist layer is a photosensitive resist, it is necessary to perform recording operations on the disk in a dark room in order to prevent the resist layer from being destroyed by light beams other than energy beams. On the other hand, when an electron-sensitive resist is used, since the resist layer has no conductivity, electrons are accumulated on the surface of the resist layer during electron beam irradiation, which may inhibit pit formation during the pulse signal recording. Furthermore, in the case of conventional disks, it is necessary to perform development processing after pulse signal recording.
However, there was an unavoidable functional drawback in that simultaneous recording and reproduction of signals was impossible. In addition, the hardness of the surface of the resist layer of the disk is low, making it susceptible to mechanical damage, making it inconvenient to handle as dirt and dust cannot be washed away, and the generation of noise due to scratches and dust is unavoidable. Ta. On the other hand, since a glass plate with a thickness of about 10 mm has conventionally been used as a disk substrate, there have been problems with mechanical strength and manufacturing costs have been high. As described above, conventional disks have many drawbacks, which are mainly due to the structure of the resist layer.

It is an object of the present invention to provide a disk which improves the above-mentioned drawbacks of conventional disks, is convenient in handling, has improved recording and reproducing functions, and has improved recording density and recording accuracy.

Next, a recording medium according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of a recording medium (referred to as a disk for simplicity) according to the present invention. In the figure, a resist layer 2 provided on a substrate 1 is a resist layer similar to that of a conventional disk, and pits are formed on the surface by an energy beam. As is clear from the figure, a metal thin film layer 3 is further provided to cover this resist layer 2. The thickness of this metal thin film layer is, for example, 100 Å to 1000
An appropriate value between A and B is selected, but when recording a pulse signal on the disk with an energy beam, the energy is set such that the energy beam penetrates this metal thin film layer 3 and causes the resist layer 2 to sense information. It can be adjusted and selected in relation to the power of. FIG. 2 shows the intensity distribution of the energy beam near the center of the irradiation position of the energy beam. The width of this energy beam is converged to a diameter of approximately 1 μm by the lens of the beam irradiation device, but when it reaches the surface of the disk, it has an energy distribution whose intensity decreases rapidly as it moves away from the irradiation center. I have it too. In the present invention, paying attention to this point, in order to reduce the width of the energy beam involved in pit formation compared to the conventional method, the beam width is limited by the metal thin film layer 3 based on the intensity of the energy beam. method is being adopted. That is, in the conventional pit forming process, a pit is formed with a diameter corresponding to the full width of the energy beam as shown in FIG. Only a certain part of the energy beam near the center where the intensity is strong as shown in FIG. As a result, the track spacing between pit rows can be made closer than in the past, so that the density of information recording on the disk can be increased. Furthermore, since the edge of each pit is formed by the metal thin film layer 3, the shape of the pit is more regular than in the past, and the pits can be formed using a more intense energy beam than in the past. In addition to being possible, an improvement in recording accuracy can be expected. On the other hand, when using an electron beam, special consideration was required for the beam irradiation device in order to prevent saturation of electrons on the surface of the resist layer in conventional disks, but in the case of the disk according to the present invention, the resist layer 2 is covered. Since the metal thin film layer 3 is electrically conductive, there is no need to take any measures against electron saturation. When reproducing a signal recorded on the disk according to the present invention, in order not to damage the metal thin film layer 3, a beam much weaker in intensity than the recording energy beam is used to trace the disk surface.
It is only necessary to read out the physical changes formed by the recording energy beam on the disk, and it is possible to record pulse signals on the disk and simultaneously reproduce the signals without going through the conventional development process. Furthermore, the fact that the resist layer 2 is covered with the metal thin film layer 3 increases the mechanical strength of the surface of the disk and makes the surface resistant to cleaning.
In addition to making the disk much easier to handle than in the past, it also prevents the S/N ratio of recorded signals from deteriorating due to scratches and the like. FIG. 3 is a sectional view showing another embodiment of the recording medium according to the present invention. In the figure, the resist layer provided on the substrate 1 has its upper surface,
All surfaces, including the bottom and side surfaces, are covered with a metal thin film layer 3. With this structure, the resist layer 2 is completely shielded from light, and when a photosensitive resist is used, there is no fear of damage due to light rays, which has the advantage of making it easier to handle the disk and to record pulse signals compared to the conventional method. , this embodiment also has the same features as the previous embodiment. Further, the metal thin film layer 3 covering the resist layer 2 of the disk according to the present invention may be removed after pits are formed in the resist layer 2. In addition, for example, a plastic substrate can be used as the substrate 1, but in that case, the mechanical strength is increased compared to a conventional glass substrate, and the manufacturing cost is significantly reduced, so that a large number of disks can be used. There are advantages such as: As described above, the disk according to the present invention improves various drawbacks of conventional disks, improves recording density and recording accuracy,
This greatly facilitates information recording work and general handling.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the recording medium according to the present invention, FIG. 2 is a diagram showing the energy distribution near the irradiation center of the energy beam, and FIG. 3 is a diagram showing another embodiment of the recording medium according to the present invention. FIG. Explanation of symbols of main parts: 1...Substrate, 2...Resist layer, 3...Metal thin film layer.

Claims (1)

[Scope of Claims] 1. A recording medium in which information is recorded by forming a pit row in a resist layer provided on a substrate in accordance with a pulse signal according to information to be recorded using an energy beam, wherein the resist layer A recording medium characterized in that a metal thin film layer is provided to cover an upper surface of the layer, a metal thin film layer is provided between the resist layer and the substrate, and a metal thin film is further provided to cover a side surface of the resist layer. 2. The recording medium according to claim 1, wherein the substrate is a plastic substrate. 3. A recording method for recording information by irradiating a resist layer provided on a substrate with an energy beam modulated according to information to be recorded to form pit rows in the resist layer, the method comprising: The recording method characterized in that a metal thin film layer is provided on an upper surface and a side surface, and between the resist layer and the substrate, and then the energy beam is irradiated onto the resist layer through the metal thin film layer. 4. The recording method according to claim 3, wherein the metal thin film layer on the resist layer is removed after the energy beam is irradiated onto the resist layer through the metal thin film layer.