Image reading device

Abstract: An image reading device includes: a light emitting element (50) for irradiating light on an image surface; a light recipient element (10) for receiving image information by reflected light from the image surface; and light waveguide passages (31) provided between the light emitting element and the image surface and between the light recipient element and the image surface, respectively so that at least the light waveguide passage for the light emitting element is formed so as to expand at an end surface thereof on an image surface side wider than at an end surface thereof on a light emitting side.

Description: BACKGROUND OF THE INVENTION The present invention relates to an image reading device, and more particularly, to an image reading device to be used in a facsimile, an image scanner, and the like. An image reading device is adapted to read image information by arranging light recipient elements such as photosensors in an array so as to read an image by dividing into minute picture elements and by scanning the array of light recipient element along the image surface. In order to read image information correctly, a light emitting means is necessary to irradiate a sufficient amount of light onto the image surface. In the conventional image reading device, as the light emitting means, light emitting elements such as LEDs are arranged in an array as light recipient elements so that light irradiated from light emitting elements are reflected by the image surface so as to be incident upon the light recipient elements. JP-A-58106947 defining the closest prior art from which the invention proceeds discloses an optical sensor comprising light guides for the light used to illuminate a surface and for the light reflected from said surface. From JP-A-57142603 it is known an optical scanner used for transmitting light from a semiconductor laser to a receptor. The light is led through a bundle of waveguides which each increase their cross-sectional area from the end where the light is introduced to the end where it exits. Figure 10 shows a general construction of a further conventional image reading device, in which an end surface of a light waveguide 3 whose light guiding core portion 3a is covered by a clad portion 3b confronts the light receiving surface of a photosensor 1 installed on a circuit board 2, and the waveguide 3 is arranged downward in the vertical direction with the other end surface thereof being arranged adjacent to the image surface of an original 4, and the light waveguide 3 is installed onto a base stand 6 constituting the main body of the image reading device. On one side of the light waveguide 3, there is provided a LED 5 installed on a separate circuit board from the circuit board 2. The LED 5 is installed near the tip end of the light waveguide 3 in the slantly downward direction so that the light emitted from the LED 5 efficiently irradiates the image surface immediately below the end surface of the light waveguide 3, and the light reflected by the image surface of the original 4 is introduced excellently into the light waveguide 3 arranged in the vertical direction. In order to arrange the LED 5 in the slant direction, the LED 5 and the circuit board 5a are fastened on an inclined surface of a base stand 6. The circuit board 2 installing the photosensor 1 is fastened on the upper surface of the base stand 6 with a small screw 2a, with a cover 6a being installed above the base stand 6 so as to cover the photosensor 1 and circuit board 2. It is to be noted here that a large number of photosensors 1 and LEDs 5 are arranged in parallel in an array shape in a direction perpendicular to the paper face of the drawing so that the image reading throughout the entire reading length range is possible through reading the image immediately below in the linear direction. However, in such a conventional image reading device as described above, the LEDs 5 corresponding to the length of photosensors 1 constituting picture elements throughout the entire length of the image reading range are required to be arranged in parallel, so that there has been such an issue that the manufacture of such LED array is troublesome and high in cost. Furthermore, when the image reading range becomes long, the control circuit for the LED 5 becomes long, which makes the manufacturing cost of the circuit board 5a expensive. Further, such an issue exists also with the arrangement structure of the photosensors 1 as light recipient elements. Furthermore, in the conventional image reading device, since the light of the LEDs 5 is arranged to be incident directly upon the image surface, there has been such issues that in order to apply light properly, installation position and posture control for LEDs are restricted and take trouble. SUMMARY OF THE INVENTION Accordingly, an essential object of the present invention is to provide an image reading device which is simplified in structure and capable of achieving the ease of manufacture and assemble and the cost reduction in an image reading device provided with the above-described photosensor, namely, light recipient element and LED array, namely, light emitting element. In accomplishing these and other objects, according to the present invention, there is provided an image reading device comprising: light emitting elements for irradiating light on an image surface; light recipient elements for receiving image information by reflected light from the image surface; and light waveguide passages provided between the light emitting elements and the image surface and between the light recipient elements and the image surface, respectively; characterized in that a plurality of sets of the light emitting elements and the light recipient elements are arranged alternately in a lengthwise direction of the image reading device, the respective light waveguide passages for each set of the light emitting elements and the light recipient elements arranged at an interval are formed so as to expand at end surfaces thereof on an image surface side wider than at end surfaces thereof on sides of the light emitting elements and the light recipient elements, respectively, the light waveguide passage of each set of light emitting elements is arranged at their lower end facing the image surface to be adjacent to the light waveguide passage of the next set of light emitting elements, and the light waveguide passage of each set of light recipient elements is arranged at their lower end facing the image surface to be adjacent to the light waveguide passage of the next set of light recipient elements. By the above construction of the aspect of the present invention, since at least, the light waveguide passage for the light emitting element among the light waveguide passages provided between the image surface and the light emitting element and the light recipient element is formed so as to expand at the end surface on the image surface side wider than at the end surface on the light emitting element side, it becomes possible to irradiate light uniformly not only onto an image surface immediately below the light emitting element but also onto an image surface of a wider range. For example, if the image surface side end surface of the light waveguide passage provided for one light emitting element is expanded so as to cover the entire length of the image reading range of the whole device, it is possible to irradiate light onto the entire length of the image reading range with one light emitting element. In a similar manner, it is possible to irradiate light over the entire length of the image reading range by using light emitting elements of a number smaller than that of picture elements and each light waveguide passage for each light emitting element. Furthermore, as for the light recipient element, if a plurality of light recipient elements are collectively installed on one mounting chip, and respective light waveguide passages connected to this chip are expanded at the end surface on the image surface side so that image reading over the entire length of the image reading range is possible, it is similarly possible to read the image information of the entire image reading range with one light recipient element chip or several light recipient element chips. In the case where the light emitting element and/or the light recipient element are divided into a plurality of groups, when light waveguide passages are arranged in the same width from the element side to the image surface side, since the intermediate portion between the light emitting elements or the light recipient elements of each group is away from the light waveguide passage, the image surface becomes dark or becomes impossible to read an image. However, when the light waveguide passage is expanded at the image surface side as described above, it is possible to irradiate light up to the intermediate portion and to read an image by advantageously irradiating light over the entire length of the image reading range. Furthermore, since the light waveguide passage is provided between the light emitting element and the image surface, it is possible to apply light onto an arbitrary point and in an arbitrary direction irrespective of the installation position and posture of each of the light emitting element and the light recipient element so as to read image information. By the above construction of the present invention, in addition to the above-described advantages, the light emitting elements and the light recipient elements can be efficiently arranged collectively through arranging plural sets of light emitting elements and light recipient elements alternately along the lengthwise direction of the image reading range, whereby the structure of the mounting circuit board becomes simplified. In this case, since the light emitting element or the light recipient element of each set is arranged at an interval, it is impossible to irradiate light uniformly or read an image over the entire length of the image reading range if left as it stands. However, in the present invention, since respective light waveguide passages for each set of light emitting elements or light recipient elements arranged at an interval are formed so as to expand at the end surface on the image surface side wider than at the end surface on the light emitting element side or the light recipient element side, and light waveguide passages of adjacent sets are formed so as to communicate with each other, it is possible to read an image over the entire length of the image reading range. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which: Fig. 1 is a sectional view of the light emitting element side of an image reading device according to a preferred embodiment of the present invention; Fig. 2 is a sectional view of the embodiment of Fig. 1 in the direction perpendicular to that of Fig. 1; Fig. 3 is a sectional view on the light recipient element side thereof; Fig. 4 is a sectional view of the light emitting element side of an image reading device according to another embodiment; Fig. 5 is a sectional view of the light recipient element side of an image reading device according to a further other embodiment; Fig. 6 is a sectional view of the embodiment of Fig. 5 in the direction perpendicular to that of Fig. 5; Fig. 7 is a sectional view of an image reading device according to a further other embodiment of the present invention; Fig. 8 is a schematic perspective view of a part of the embodiment of Fig. 7; Fig. 9 is a schematic front view of the light recipient element side of the embodiment of Fig. 7; and Fig. 10 is a. sectional view of a conventional image reading device. DETAILED DESCRIPTION OF THE EMBODIMENTS Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout the accompanying drawings. Figs. 1 and 3 are sectional views of an image reading device according to an embodiment of the present invention cut along a line parallel to the image reading line, while Fig. 2 is a sectional view thereof in a direction perpendicular to the image reading line. As shown in Fig. 2, on the surface of a circuit board 20, there are mounted a light recipient element 10 composed of such as photosensors and a light emitting element 50 composed of such as LED with a certain interval therebetween. As shown in Fig. 1, the light emitting element 50 is provided only at one place approximately in the central portion of the image reading device. This light emitting element 50 can be a single light emitting element with a large light amount or an assembly of plural light emitting element units arranged in an array. As shown in Fig. 3, a light recipient element chip 11 on which light recipient elements 10 corresponding to individual picture elements are mounted collectively in an array is used as the light recipient element 10, and this light recipient element chip 11 is provided only at one place approximately in the central portion of the image reading device in the same manner as the light emitting element 50. Confronting the light receiving surface of the light recipient element 10 and the light emitting surface of the light emitting element 50, there is arranged one end surface of a light waveguide 30, with the other end surface thereof being arranged at a position close to the image surface of an original 40. The light waveguide 30 is composed of core portions 31 which confront the light receiving surface of the light recipient element 10 to serve as light waveguide passages, core portions 71 which confront the light emitting surface of the light emitting element 50 so as to serve as light waveguide passages, and a clad portion 32 covering the peripheries of respective core portions 31 and 71. As shown in Fig. 1, the core portion 71 serving as the light waveguide passage of the light emitting element 50 confronts the light emitting surface of the light emitting element 50 at the upper end thereof and is expanded toward the lower end thereof so as to cover the enter length of the image reading range at the lower end thereof. The core portions 31 serving as the light waveguide passages of the light recipient elements 10 are formed, as shown in Fig. 3, so that each interval between the adjacent core portions in a number of passage-shaped core portions 31 confronting individual light recipient elements 10 mounted on the light recipient element chip 11 expands divergently toward the image surface side end, and thus a plurality of core portions 31 are arranged in a divergently expanded state. Besides the above-described LED or photosensor, appropriate elements selected from common photoelectric conversion elements or light emitting elements used in the well-known image reading devices and other electronic devices can be used as the light recipient element 10 and the light emitting element 50. As the light waveguide 30, a structure and material similar to those used for constituting the light waveguide passage in various kinds of optical apparatuses can be used. For example, a light waveguide made of a transparent material such as glass or high polymer and constructed so that core portions 31 and 71 having a large refraction index are provided therein and a clad portion 32 having a small refraction index covers the entire periphery of each of the core portions 31 and 71 is used. On the partition portion between the core portions 31 and 71, a clad portion 32 is formed. The light introduced into the core portions 31 and 71 respectively from one end thereof is transmitted to the other end thereof while being reflected on the boundary surface between respective core portions 31 and 71 and the clad portion 32. As a concrete material for the core portions 31 and 71 and the clad portions 32, polycarbonate resins, epoxy resins, acrylic resins, or glass are used, and by adjustment of composition and mixture component of resins or glass, the difference in refraction index can be produced. By mixing light absorption material or light dispersion material into the clad portion 32, the resolution of the device can be increased. The light waveguide 30 made of such materials as described above can be manufactured by using the molding technique for resins or glass or the thin film processing technique in the same manner as common light waveguides. It is to be noted here that the light waveguide 30 can be supported and fastened on the surface of the circuit board 20 or a support member or base stand (not shown) made of plastics separate from the circuit board 20. Further, the image reading device is also provided with a cover 60 covering the whole including the circuit board 20 and the light waveguide 30. As shown in Fig. 2, the light emitting element 50 is mounted so that the irradiation direction of light is directed slantly downward relative to the surface of the circuit board 20, and the core portion 71 is also formed so as to extend slantly downward. The core portion 31 on the light recipient element side is formed so as to be inclined in a direction opposite to that of the core portion 71 on the light emitting element side. Therefore, both core portions 31 and 71 are combined in the shape of V character. In an image reading device of such a structure as described above, light irradiated from the light emitting element 50 is expanded along the expanded shape of the core portion 71 so as to be irradiated over the entire length of the image surface, while passing through the core portion 71 of the light waveguide 30. The light reflected by the image surface, that is, the image information is inputted into the light recipient element 10 through the core portion 31 corresponding to each picture element, whereby the image information is read. In this case, in the core portions 31 on the side of the light recipient element 10, since the image information separated for each of individual picture elements has to be caught, the core portions 31 divided for each of individual picture elements are needed, but in the core portion 71 on the side of the light emitting element 50, an integrated core portion combined by the entire core portions 71 can be used. Next, an embodiment shown in Fig. 4 is different from the above-described embodiment in the structure of the core portion 71 on the light emitting element side. In this embodiment, the whole core portions are not formed by a single core portion, but a core portion 71 formed so as to be divided into a plurality of core portions is arranged in a divergently expanding shape, and respective core portions 71 are formed so as to expand taperingly from the upper end toward the lower end thereof. In this embodiment, since light is securely and uniformly transmitted from respective core portions 71 to the image surface, the brightness difference of the image surface between a point immediately below the light emitting element 50 and a point away therefrom becomes reduced. In respective embodiments described so far, although the light emitting element 50 and the light recipient element 10 are positioned approximately in the central position of the image reading range, the installation positions for the light emitting element 50 and the light recipient element 10 can be set at end portion of the image reading range or at any intermediate position, so long as the core portions 31 and 71 formed so as to expand from the installation position of the light emitting element 50 or the light recipient element 10 are arranged so as to cover the entire length of the image reading range at the end face thereof on the image surface side. Although the core portion 71 shown in Fig. 1 has a linear contour, the contour of the core portion 71 can be formed in a curbed line or a curved surface, in consideration of the light distribution at the end surface on the image surface side. Although the core portion 31 shown in Fig. 3 and the core portion 71 shown in Fig. 4 are respectively formed in a linear shape, similarly to the above, the present invention can be put into practice by the core portions 31 and 71 of a curved contour. When core portions 31 and 71 are curved at a proper rate of curvature, inside the core portions 31 and 71 covered by the clad portion 32, light is certainly transmitted from one end thereof to the other end, while being completely reflected therein, so that light can be transmitted more efficiently when the core portions 31 and 71 are formed by curved lines instead of straight lines. Next, an embodiment shown in Figs.5 and 6 is different from the above-described embodiment in the construction on the light recipient element side. In the present embodiment, light recipient elements 10 are uniformly arranged over the entire image reading range so as to correspond to each of the picture elements for the image reading, and between respective light recipient elements 10 and the image surface, there are provided light waveguides, each composed of refraction index distribution type fiber lens 35 arranged in line and integrated with a resin 39. The refraction index distribution type fiber lens 35 is a glass fiber member which is provided with a lens function by properly adjusting the refraction index distribution in the core portion and the clad portion, and a correct image can be efficiently read out by the condensing function of the lens when the image information caught at the image surface is transmitted to the light recipient element 10. In other words, while the light waveguide 30 of the above-described embodiment is integrated into a single entity as a whole, in the present embodiment, fiber lenses 35 manufactured in advance are arranged in line. Since a light waveguide common to the light recipient element 10 and the light emitting element 50 is not used, for the light waveguide passages on the side of light emitting element, there is used an exclusive-use light waveguide 70 enclosing the core portions 71 with clad portions 72 and jointed with the resin portion 39 on the fiber lens side so as to be integrated therewith. Next, an embodiment shown in Fig. 7 forms the light waveguide passage for the light emitting elements 50 and that for the light recipient elements 10 integrally with a partition. In the central portion of a light waveguide 30, there are formed the core portion 31 for the light emitting element and the core portion 71 for the light recipient element with a partition member 36 disposed therebetween, and at the tip end of the partition member 36, adjacent core portions 31 and 71 are integrated completely. The light emitting element 50 and the light recipient element 10 are mounted back to back on both sides of the upper end of the partition member 36, and the light irradiated horizontally from the light emitting element 50 is reflected by the reflection surface 37 provided on the boundary between the core portion 71 and the clad portion 32 and change its direction downward so as to be incident upon the image surface through the core portion 71. The image information from the image surface is transmitted upward through the core portion 31, and reflected by the reflection surface 37 provided on the boundary between the core portion 31 and the clad portion 32 so as to be incident upon the light recipient element 10 horizontally. Regarding the reflection surface 37, although the mere boundary surface between the core portion 31 and the clad portion 32 has reflection action to some extent, it is more preferable to form a reflection layer used in the usual optical elements. However, even in the above embodiment, it is possible to mount the light emitting element 50 and the light recipient element 10 in the downward direction as in the embodiments so far described. In such a case, it is not necessary to form the reflection surface 37. For the material of the partition member 36, various light shielding materials, for instance, material similar to that of the clad portion 32 can be used, so long as the light transmitted through the right core portion 31 and the light transmitted through the left core 71 are arranged to be separated from each other. The structure of the light emitting element 50, the light recipient element 10, and the light waveguide passage in the direction perpendicular to the paper face of Fig. 7 can be similar to those of respective embodiments so far described. In the present embodiment, since the core portion 71 on the light emitting element side and the core portion 31 on the light recipient element side are integrated with each other, when the light waveguide 30 is manufactured, it is possible to adopt such a method that when one of the core portions 71 or 31 is molded after manufacturing the components constituting the other of the core portions 31 or 71, the components are embedded so as to be molded simultaneously. Furthermore, if the light emitting element 50, the light recipient element 10, and the partition member 36 are embedded and molded at this time, as shown in Fig. 7, the entire essential portions relating to the light transmission and processing are integrated, whereby assembly tolerances between respective components can be set accurately and the assembly and manufacture becomes easy. Since the light receiving surface of the light recipient element 10 and the light emitting surface of the light emitting element 50 are enclosed into the core portions 31 and 71, there is no possibility of the adhesion of dirt and foreign materials. Embodiments shown in Figs. 8 and 9 show schematically constructional examples of the light waveguide passage in the direction perpendicular to the paper face of Fig. 7. A plurality of light emitting element chips 52 composed of a single light emitting element 50 or an array of light emitting elements are arranged on one upper end surface of the partition member 36 along at a certain interval along the longitudinal direction thereof. On the opposite surface of the partition member 36, there are arranged a plurality of light recipient element chips 11 at the positions corresponding to respective vacant spaces between the adjacent light emitting element chips 52. In other words, the light emitting element chips 52 and the light recipient element chips 11 are arranged alternately in the same direction. Although the upper end of the core portion 71 which serves as the light waveguide passage for the light emitting element chip 52 is of a width corresponding to the light emitting surface of the light emitting element chip 52, the core portion 71 is formed so as to expand taperingly toward the lower end, and arranged so that adjacent cores are in contact with each other at the lower end thereof, whereby light can be uniformly irradiated over the entire length in the image reading range. As shown in Fig. 9, light waveguide passages on the side of the light recipient element chip 11 are arranged so that an appropriate number of core portions 31 are grouped so as to confront the light receiving surface of the light recipient element chip 11 at the upper end thereof, and respective core portions 31 thus grouped for each light recipient element chip 11 are arranged to expand the width thereof divergently downward so that the core portions are uniformly distributed over the entire length in the image reading range at the lower end thereof. It is to be noted here that as for the structure for the core portion 31, the structure of the core portion 71 etc., in the direction perpendicular to Fig. 9, can be employed similar to that of Fig. 7. According to the present embodiment, since the light recipient element chips 11 and the light emitting element chips 52 are arranged alternately, the mounting and wiring of respective chips 11 and 52 can be easily performed by using a circuit board, etc., arranged on the upper surfaces of respective chips 11 and 52. Simply by increasing the installation number of the light recipient element chips 11 and the light emitting element chips 52 sequentially, it is possible to constitute an image reading device for any length, and even when the image reading length is increased further, the brightness of the image surface by the irradiated light remains unchanged and the image reading performance is not lowered. In each of the embodiment described so far, it is possible to arrange so that light easily enters the light waveguide 30 by notching the clad 32 so as to expose a part of the core portion 31 or by cutting off the end face of the core portion 31 slantly, on the end of the image surface of the light waveguide 30. Furthermore, when a lens of semicircular shape is provided on the image surface side tip end of each of the core portions 31 and 71, it is possible to execute an efficient light irradiation and image reading by condensing or deflecting the irradiated light and the reflected light. If a hard coat agent is coated, or micro sheet-glass is applied onto the image surface side end face of the core portions 31 and 71, it is possible to prevent the wear of the end face of the core portions 31 and 71 due to contact with an original 40. Meanwhile, with respect to the detailed structure of the image reading devices other than described so far, various structures and shapes used in the ordinary image reading devices are applicable. The image reading device according to the embodiments of the present invention can be applicable to facsimiles, image scanners, copiers and any other application requiring the image reading and electronic processing of read image. According to the image reading devices of the embodiments of the present invention described so far, since the light waveguide passage connecting the light emitting element to the image surface is formed so as to expand at the image surface side wider than at the light emitting element side, it becomes unnecessary to arrange light emitting elements over the entire image reading range. That is, for instance, the emitted light from a light emitting element positioned at one place can be expanded by a light waveguide passage or passages so as to irradiate the entire range of the image reading surface, or the light emitted from light emitting elements disposed at an interval can be arranged to irradiate the entire range of the image reading surface uniformly without fluctuations in brightness. As a result, it is possible to arrange light emitting elements collectively at one position or several positions, and the manufacture of light emitting elements and mounting thereof onto the circuit board, or wiring and connection therefor can be simplified by utilizing light emitting element chips mounting light emitting elements thereon. Therefore, since the structure of the whole image reading device is simplified and the component parts are reduced in number, it is possible to contribute to the miniaturization and cost reduction of the image reading device. Furthermore, since the light emitting element and the image surface are connected by a light waveguide passage, the light from the light emitting element can be irradiated on the image surface without any loss, and further, the mounting position of the light emitting element can be set arbitrarily. Therefore, it becomes unnecessary to adopt such a complicated structure as to mount the light emitting element in an inclined posture near the image surface apart from the light recipient element, and the miniaturization of the image reading device and the simplification of the structure thereof can be accomplished by mounting the light emitting element and light recipient element on the same circuit board so as to simplify the circuitry, by incorporating the light emitting element and the light recipient element into a component, by determining the arrangement of light emitting elements so as to reduce the installation space as much as possible, etc. According to the embodiments, since a plurality of sets of light emitting elements and light recipient elements are arranged alternately in the lengthwise direction of the image reading range, and the light waveguide passages for the light emitting elements or the light recipient elements of respective sets which are arranged at an interval are formed, an excellent image reading over the entire length in the image reading range is possible. Since the light emitting elements and the light recipient elements are arranged in a single direction, mounting of element parts and assembly thereof, or electrical connection thereof can be easily and efficiently performed, and the installation space is small. Only by increasing installed sets of light emitting elements and light recipient elements, it becomes possible to extend freely the length of the image reading and to manufacture easily and at a low cost an image reading device which is capable of reading an image of a wide range at one time. Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

Claims: An image reading device comprising: light emitting elements (50) for irradiating light on an image surface (40); light recipient elements (10) for receiving image information by reflected light from the image surface (40); and light waveguide passages (71, 31) provided between the light emitting elements (50) and the image surface (40) and between the light recipient elements (10) and the image surface (40), respectively; characterized in that a plurality of sets (52,11) of the light emitting elements (50) and the light recipient elements (10) are arranged alternately in a lengthwise direction of the image reading device, the respective light waveguide passages (71, 31) for each set (52, 11) of the light emitting elements (50) and the light recipient elements (10) arranged at an interval are formed so as to expand at end surfaces thereof on an image surface (40) side wider than at end surfaces thereof on sides of the light emitting elements (50) and the light recipient elements (10), respectively, the light waveguide passage (71) of each set (52) of light emitting elements (50) is arranged at their lower end facing the image surface (40) to be adjacent to the light waveguide passage (71) of the next set (52) of light emitting elements (50), and the light waveguide passage (31) of each set (11) of light recipient elements (10) is arranged at their lower end facing the image surface (40) to be adjacent to the light waveguide passage (31) of the next set (11) of light recipient elements (10).

Inventors: FUKUSHIMA TETSUO, HAMANE TOKUHITO, IKEDA JUNJI, MAEDA YUKIO, SUETSUGU KENICHIRO, FUKUSHIMA, TETSUO, HAMANE, TOKUHITO, IKEDA, JUNJI, MAEDA, YUKIO, SUETSUGU, KENICHIRO
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1991
Main classification: H04N1
IPC codes: H04N1, G02B6