Abstract: An optical disc includes a reflective film formed on concave and convex marks after the concave and convex marks are synchronized with the integral multiple of a channel bit length and formed in accordance with modulated main information. Thereafter, continuous or intermittent laser light synchronized with the integral multiple of the channel bit length is irradiated at intervals longer than the longest one of the concave and convex marks in accordance with a spiral track formed in a circumferential direction of the concave and convex marks, whereby an optical characteristic of the reflective film is changed to form a recordable mark and sub-information necessary to reproduce the main information is recorded in a superimposition manner.

Abstract: An optical disc includes a reflective film formed on concave and convex marks after the concave and convex marks are synchronized with the integral multiple of a channel bit length and formed in accordance with modulated main information. Thereafter, continuous or intermittent laser light synchronized with the integral multiple of the channel bit length is irradiated at intervals longer than the longest one of the concave and convex marks in accordance with a spiral track formed in a circumferential direction of the concave and convex marks, whereby an optical characteristic of the reflective film is changed to form a recordable mark and sub-information necessary to reproduce the main information is recorded in a superimposition manner.

Abstract: An optical disc includes a reflective film formed on concave and convex marks after the concave and convex marks are synchronized with the integral multiple of a channel bit length and formed in accordance with modulated main information. Thereafter, continuous or intermittent laser light synchronized with the integral multiple of the channel bit length is irradiated at intervals longer than the longest one of the concave and convex marks in accordance with a spiral track formed in a circumferential direction of the concave and convex marks, whereby an optical characteristic of the reflective film is changed to form a recordable mark and sub-information necessary to reproduce the main information is recorded in a superimposition manner.

Abstract: An optical disk manufacturing apparatus which employs first and second signal layer forming mechanisms, a reflection layer forming mechanism, a light transmission layer forming mechanism and first, second and third transportation mechanisms. The apparatus further includes a liquid material supplying mechanism, a first and second rotation mechanism, first and second hardening light radiation apparatuses, a ring-shaped mask portion, and a mask transfer mechanism.

Abstract: The present invention provides an apparatus for fabricating a multi-layer information recording medium including a substrate, plural information recording layers placed on the aforementioned substrate, resin intermediate layers placed between adjacent information recording layers and a resin protective layer placed on all the information recording layers at the side opposite from the aforementioned substrate, the apparatus including an ejecting unit including ink jet nozzles operable to drip minute resin liquid drops onto the aforementioned substrate or the aforementioned information recording layers; and a control unit operable to control the aforementioned ejecting unit, whereby resin layers which form said resin intermediate layers or said resin protective layer are formed on the aforementioned substrate or the aforementioned information recording layers.

Abstract: An optical disc includes a reflective film formed on concave and convex marks after the concave and convex marks are synchronized with the integral multiple of a channel bit length and formed in accordance with modulated main information. Thereafter, continuous or intermittent laser light synchronized with the integral multiple of the channel bit length is irradiated at intervals longer than the longest one of the concave and convex marks in accordance with a spiral track formed in a circumferential direction of the concave and convex marks, whereby an optical characteristic of the reflective film is changed to form a recordable mark and sub-information necessary to reproduce the main information is recorded in a superimposition manner.

Abstract: An optical disc includes a reflective film formed on concave and convex marks after the concave and convex marks are synchronized with the integral multiple of a channel bit length and formed in accordance with modulated main information. Thereafter, continuous or intermittent laser light synchronized with the integral multiple of the channel bit length is irradiated at intervals longer than the longest one of the concave and convex marks in accordance with a spiral track formed in a circumferential direction of the concave and convex marks, whereby an optical characteristic of the reflective film is changed to form a recordable mark and sub-information necessary to reproduce the main information is recorded in a superimposition manner.

Abstract: The present invention provides a method for manufacturing a multilayer information recording medium including at least two information recording portions and a resin layer interposed between the information recording portions, both of which are disposed on a signal substrate. The method includes a first process of forming a predetermined information recording portion on one principal surface of the signal substrate and a second process of passing a part of a resin-containing coating, which is supplied on a screen having an application region with a plurality of first pores and a removal region with a plurality of second pores, through the first pores by sliding a squeegee on the screen so as to form a coating layer on the predetermined information recording portion, and curing the resin contained in the coating layer so as to form the resin layer. The first process and the second process are carried out respectively a predetermined number of times.

Abstract: An optical disc (101) to and from which information can be reproduced and recorded by laser irradiation is provided with a first recording layer (102) and a second recording layer (104). The first recording layer (102) has a first recording mark (103) that is formed in a spiral track. The second recording layer (104) is behind or in front of the read-side surface of the first recording layer (102), and neither a wobble track nor a track for reproducing or recording information by laser irradiation is formed on the second recording layer (104). On the second recording layer (104) are formed, by laser irradiation, a second recording mark (105) that is positioned in the radial direction of the optical disc according to a predetermined position on the spiral track of the first recording layer. The optical disc (101) ensures the secrecy of the copyright protected information that is recorded thereto and the copyright protection function of the optical disc (101), and is resistant against illegal copying.

Abstract: A transparent protective layer (106) having a thickness of 100 ?m is formed of a resin film (100), a boundary layer (104) and an adhesive layer (103) on a signal recording layer (102). When nf, ni and na are the indices of refraction of the resin film (100), the boundary layer (104) and the adhesive layer (103), respectively, the relationship among nf, ni, and na satisfies any one of the following equation: na<ni?nf; na>ni?nf; na<nf?ni; or na>nf?ni, and the relationship among nf, ni, and na satisfies the following equation |nf?ni|<|nf?na|. At this time, a protrusion (111) and a scratch (110) are optically buried within the boundary layer (104), reducing scattering of laser beams and disturbance in the wave front which occur in these portions, and thereby, the error rate can be reduced.

Abstract: An optical information recording medium includes a substrate, n information recording layers provided on the substrate, and spacer layers, each of which is provided so as to be interposed between the information recording layers, wherein each of (n?1) or more of the information recording layers has a layer number information part that is formed in correspondence with one or more recording marks X and contains layer number information, where n represents an integer of not less than 2, and the layer number information is information used for determining which a given information recording layer is among the n information recording layers. Each recording mark X has a length in a circumferential direction longer than a length of a recording mark Y used for recording another information in the information recording layers.

Abstract: A method for producing a multilayer information recording medium the method including: holding a substrate; feeding a resin onto the substrate; and removing the excess resin by moving a squeegee throughout the entire surface of the substrate. The substrate may have a resin-coated region, onto which the resin is to be applied, and a non-resin-coated region, onto which the resin is not to be applied. In this case, the resin-coated region has a smaller contact angle with the resin than the non-resin-coated region. The method for producing a multilayer information recording medium may further include, prior to feeding a resin onto the substrate, subjecting a specified area of the substrate to an oil repellent treatment to increase the contact angle of the specified area with the resin.

Abstract: An optical information recording medium that has a simple structure and with which warpage is kept to a minimum even under environmental changes over a wide range, and a method for manufacturing this medium are provided. The optical information recording medium is an optical information recording medium used for the reproduction of recorded information and for recording and reproduction, including a substrate having an information recording layer, and a light transmitting layer that covers the information recording layer and is composed of a radiation curable resin, wherein a warpage adjusting layer for adjusting warpage of the light transmitting layer caused by temperature changes is disposed on the opposite side of the substrate from the side on which the information recording layer is formed.

Abstract: The present invention provides a method for manufacturing a multilayer information recording medium including at least two information recording portions and a resin layer interposed between the information recording portions, both of which are disposed on a signal substrate. The method includes a first process of forming a predetermined information recording portion on one principal surface of the signal substrate and a second process of passing a part of a resin-containing coating, which is supplied on a screen having an application region with a plurality of first pores and a removal region with a plurality of second pores, through the first pores by sliding a squeegee on the screen so as to form a coating layer on the predetermined information recording portion, and curing the resin contained in the coating layer so as to form the resin layer. The first process and the second process are carried out respectively a predetermined number of times.

Abstract: Sub-information necessary to reproduce main information is recorded without deteriorating the reading accuracy of the main information, so that the illegal duplication of an optical disc is prevented. An optical disc 1 is produced by forming a reflective film 1L on concave and convex marks MK after the concave and convex marks MK synchronized with the integral multiple of a channel bit length are formed in accordance with modulated main information. Thereafter, continuous or intermittent laser light synchronized with the integral multiple of the channel bit length is irradiated at intervals longer than the longest one of the concave and convex marks MK in accordance with a spiral track formed in a circumferential direction of the concave and convex marks MK, whereby an optical characteristic of the reflective film 1L is changed to form a recordable mark SMK and sub-information necessary to reproduce the main information is recorded in a superimposition manner.

Abstract: An optical disc (101) to and from which information can be reproduced and recorded by laser irradiation is provided with a first recording layer (102) and a second recording layer (104). The first recording layer (102) has a first recording mark (103) that is formed in a spiral track. The second recording layer (104) is behind or in front of the read-side surface of the first recording layer (102), and neither a wobble track nor a track for reproducing or recording information by laser irradiation is formed on the second recording layer (104). On the second recording layer (104) are formed, by laser irradiation, a second recording mark (105) that is positioned in the radial direction of the optical disc according to a predetermined position on the spiral track of the first recording layer. The optical disc (101) ensures the secrecy of the copyright protected information that is recorded thereto and the copyright protection function of the optical disc (101), and is resistant against illegal copying.

Abstract: Disclosed herein is a method for producing a multilayer information recording medium having at least two information recording layers, in which a resin layer is formed between each pair of the information recording layers, the method including: holding a substrate; feeding a resin onto the substrate; and removing the excess resin by moving a squeegee throughout the entire surface of the substrate so that the interval between the bottom surface of the squeegee and the surface of the substrate is kept constant. The substrate may have a resin-coated region, onto which the resin is to be applied, and a non-resin-coated region, onto which the resin is not to be applied. In this case, the resin-coated region has a smaller contact angle with the resin than the non-resin-coated region.

Abstract: A transparent protective layer (106) having a thickness of 100 ?m is formed of a resin film (100), a boundary layer (104) and an adhesive layer (103) on a signal recording layer (102). When nf, ni and na are the indices of refraction of the resin film (100), the boundary layer (104) and the adhesive layer (103), respectively, the relationship among nf, ni, and na satisfies any one of the following equation: na<ni?nf; na>ni?nf; na<nf?ni; or na>nf?ni, and the relationship among nf, ni, and na satisfies the following equation |nf?ni|<|nf?na|. At this time, a protrusion (111) and a scratch (110) are optically buried within the boundary layer (104), reducing scattering of laser beams and disturbance in the wave front which occur in these portions, and thereby, the error rate can be reduced.

Abstract: An optical information recording medium that has a simple structure and with which warpage is kept to a minimum even under environmental changes over a wide range, and a method for manufacturing this medium are provided. The optical information recording medium is an optical information recording medium used for the reproduction of recorded information and for recording and reproduction, including a substrate having an information recording layer, and a light transmitting layer that covers the information recording layer and is composed of a radiation curable resin, wherein a warpage adjusting layer for adjusting warpage of the light transmitting layer caused by temperature changes is disposed on the opposite side of the substrate from the side on which the information recording layer is formed.

Abstract: An optical information recording medium has tolerance to warping. The optical information recording medium includes at least one information recording layer on a main surface of a substrate and a light-transmitting layer. The substrate includes a clamp area and an information recording area in accordance with the information recording layer. In the light-transmitting layer, the average thickness of a second area corresponding to the clamp area is thinner than the average thickness of a first area corresponding to the information recording area.