Patents by Inventor Koichi Tada
Koichi Tada has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7242651Abstract: The invention provides a disk playback device wherein a disk (1) is irradiated with a laser beam from an optical head (4) to reproduce signals from the disk, and which comprises an external synchronizing signal producing circuit (8) and a delay circuit (12) for producing a reproduction synchronizing signal providing reference timing at which a reproduced signal is detected by reading an output signal from the optical head (4), a circuit (7) for detecting the reproduced signal by reading the output signal from the optical head (4) based on the reproduction synchronizing signal, and a system controller (10) for determining an optimum phase for a normal reproduction operation by altering the phase of the reproduction synchronizing signal and executing a reproduction operation, the controller (10) being operable to make a phase adjustment for the reproduction synchronizing signal prepared by the delay circuit (12).Type: GrantFiled: December 10, 2001Date of Patent: July 10, 2007Assignee: Sanyo Electric Co., Ltd.Inventors: Kenji Asano, Hideaki Yano, Koichi Tada
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Patent number: 6992956Abstract: A disk reproducing apparatus includes a variable gain amplifier (VCA) (32), and the VCA applies a radial push-pull signal including an address signal and an FCM leakage-in signal to a switch (38). The switch outputs only the address signal to a peak-hold circuit (40) on the basis of an FCM mask signal from a mask signal generation circuit (36). The peak-hold circuit generates a peak-hold signal of the address signal so as to be output to a DSP (30), and the DSP controls a gain of the VCA on the basis of the peak-hold signal. Then, the radial push-pull signal in which the gain is controlled on the basis of the address signal is applied to an address detection circuit (42), and the address signal is detected therein.Type: GrantFiled: April 23, 2001Date of Patent: January 31, 2006Assignee: Sanyo Electric Co., Ltd.Inventors: Shigekazu Minechika, Koichi Tada, Junko Onaka, Takashi Onaka
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Patent number: 6975569Abstract: A digital signal processor (1045) arithmetically determines a comparison level for comparing each signal component by determining a comparison level of comparators (1033 and 1034) for comparing a fine clock mark signal such that a larger weight is assigned to the comparison level of the signal component already compared. The comparators (1033 and 1034) compare the fine clock mark signal with reference to a level set on a peak side and a level set on a bottom side. When digital signal processor (1045) receives the comparison signal from one of the comparators (1033 and 1034) prior to the comparison signal sent from the other, the digital signal processor produces a fine clock mark detection signal FCMT based on the comparison signal sent from a comparator (1047). Thereby, the clock can be accurately produced based on the fine clock mark signal even when a signal component having a larger amplitude than that of the fine clock mark signal is detected.Type: GrantFiled: October 18, 2001Date of Patent: December 13, 2005Assignee: Sanyo Electric Co., Ltd.Inventors: Koichi Tada, Toshitaka Kuma, Hiroshi Watanabe
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Publication number: 20050224146Abstract: A molten Mg or Mg alloy is supplied into a mold, which is sheltered from the surroundings, from a pool in a tundish, which is shielded from the surroundings. An Mg slab or Mg alloy slab in the mold is drawn out to the outside from an outlet of the mold. A cooling medium is jetted onto the slab on an outer side of and in a vicinity of the outlet to cool the slab. A sealing gas is sprayed over an entire width of a free surface of the molten Mg or Mg alloy on an inner side of and in the vicinity of the outlet, to seal a portion above the entire width of the free surface of the molten Mg or Mg alloy, whereby preventing oxygen from flowing into the mold from the portion and preventing the cooling medium from running back to the mold side.Type: ApplicationFiled: April 8, 2005Publication date: October 13, 2005Applicant: SANYU SEIKI CO., LTD.Inventors: Koichi Tada, Kiichi Miyazaki
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Patent number: 6891787Abstract: A defect detecting circuit generates a defect detection signal when the level of a sum signal obtained from an optical sensor in an optical pickup is lower than a predetermined level, and a gate circuit responds to the defect detection signal to set the level of a fine clock mark signal to zero, that is a difference signal obtained from the optical sensor in the optical pickup. A fine clock mark is thus distinguished from any defect such as scratch and a correct fine clock mark signal is accordingly generated. Alternatively, the value of a sum signal, which indicates the total amount of reflected light output from the optical pickup, is compared with a predetermined threshold. When the period in which the value of the sum signal is smaller than the threshold lasts for a predetermined threshold time period, it is determined that focus of an objective lens deviates from an optical disk and accordingly focus servo control is stopped.Type: GrantFiled: August 22, 2000Date of Patent: May 10, 2005Assignee: Sanyo Electric Co., Ltd.Inventor: Koichi Tada
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Publication number: 20040027944Abstract: A disk reproducing apparatus includes a variable gain amplifier (VCA) (32), and the VCA applies a radial push-pull signal including an address signal and an FCM leakage-in signal to a switch (38). The switch outputs only the address signal to a peak-hold circuit (40) on the basis of an FCM mask signal from a mask signal generation circuit (36). The peak-hold circuit generates a peak-hold signal of the address signal so as to be output to a DSP (30), and the DSP controls a gain of the VCA on the basis of the peak-hold signal. Then, the radial push-pull signal in which the gain is controlled on the basis of the address signal is applied to an address detection circuit (42), and the address signal is detected therein.Type: ApplicationFiled: May 28, 2003Publication date: February 12, 2004Inventors: Shigekazu Minechika, Koichi Tada, Takashi Onaka, Junko Onaka
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Publication number: 20040027947Abstract: The invention provides a disk playback device wherein a disk (1) is irradiated with a laser beam from an optical head (4) to reproduce signals from the disk, and which comprises an external synchronizing signal producing circuit (8) and a delay circuit (12) for producing a reproduction synchronizing signal providing reference timing at which a reproduced signal is detected by reading an output signal from the optical head (4), a circuit (7) for detecting the reproduced signal by reading the output signal from the optical head (4) based on the reproduction synchronizing signal, and a system controller (10) for determining an optimum phase for a normal reproduction operation by altering the phase of the reproduction synchronizing signal and executing a reproduction operation, the controller (10) being operable to make a phase adjustment for the reproduction synchronizing signal prepard by the delay circuit (12).Type: ApplicationFiled: June 10, 2003Publication date: February 12, 2004Inventors: Kenji Asano, Hideaki Yano, Koichi Tada
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Publication number: 20030147319Abstract: A digital signal processor (1045) arithmetically determines a comparison level for comparing each signal component by determining a comparison level of comparators (1033 and 1034) for comparing a fine clock mark signal such that a larger weight is assigned to the comparison level of the signal component already compared. The comparators (1033 and 1034) compare the fine clock mark signal with reference to a level set on a peak side and a level set on a bottom side. When digital signal processor (1045) receives the comparison signal from one of the comparators (1033 and 1034) prior to the comparison signal sent from the other, the digital signal processor produces a fine clock mark detection signal FCMT based on the comparison signal sent from a comparator (1047). Thereby, the clock can be accurately produced based on the fine clock mark signal even when a signal component having a larger amplitude than that of the fine clock mark signal is detected.Type: ApplicationFiled: January 31, 2003Publication date: August 7, 2003Inventors: Koichi Tada, Toshitaka Kuma, Hiroshi Watanabe
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Patent number: 6529455Abstract: A disk apparatus includes a DSP core, and executes processing for focal point positioning when turning on the power to the apparatus main body or exchanging the MO disk. The DSP core detects maximum and minimum values of outputs (focus error signal) of an FE signal detector circuit while moving the objective lens from an uppermost position of not contacted with a disk surface to a lowermost position. The DSP core calculates a middle position using positions of the objective lens upon fetching maximum and minimum values (uppermost and lowermost positions). Subsequently, the DSP core determines a range narrower than a range to be determined by the uppermost and lowermost positions, by the use of the middle point and amount of surface deflection of the MO disk. Then, the DSP core wobbles the objective lens within the narrow range and detects a focal point based on a level of the focus error signal.Type: GrantFiled: August 22, 2000Date of Patent: March 4, 2003Assignee: Sanyo Electric Co., Ltd.Inventors: Tadashi Okajima, Toshihide Hamaguchi, Koichi Tada
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Patent number: 6522605Abstract: A disk apparatus includes a DSP core. When turning on power to the apparatus main body or exchanging the MO disk, setting processing of focus offset (offset) values is performed. The DSP core extracts fine clock mark (FCM) signals out of the reproduced signal through tracking on the land/groove. Specifically, in a range that mean value of FCM signal levels is equal to or greater than a predetermined level, FCM signal levels are detected at positions shifted left and right by a predetermined amount from a present offset value. In this manner, scanning is made throughout the range while being shifted by a predetermined amount, each time of which a difference is detected. An offset value where the difference assumes a minimum is determined as an optimal offset value. The optimal offset values are determined respectively for the land and the groove, which are switched according to a track (land/groove) upon reproduction.Type: GrantFiled: August 30, 2000Date of Patent: February 18, 2003Assignee: Sanyo Electric Co., Ltd.Inventors: Koichi Tada, Takashi Onaka
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Publication number: 20030012093Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layer-to-layer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.Type: ApplicationFiled: February 19, 2002Publication date: January 16, 2003Applicant: Sanyo Electric Co., Ltd.Inventors: Koichi Tada, Shinichi Ohe, Naoyuki Takagi, Ken Hirose, Shuichi Ichiura, Hiroshi Watanabe
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Patent number: 6480444Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layer-to-layer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.Type: GrantFiled: February 19, 2002Date of Patent: November 12, 2002Assignees: Sanyo Electric Co., Ltd., Tottori Sanyo Electric Co., Ltd.Inventors: Koichi Tada, Shinichi Ohe, Naoyuki Takagi, Ken Hirose, Shuichi Ichiura, Hiroshi Watanabe
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Patent number: 6477122Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layer-to-layer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.Type: GrantFiled: February 19, 2002Date of Patent: November 5, 2002Assignees: Sanyo Electric Co., Ltd., Tottori Sanyo Electric Co., Ltd.Inventors: Koichi Tada, Shinichi Ohe, Naoyuki Takagi, Ken Hirose, Shuichi Ichiura, Hiroshi Watanabe
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Patent number: 6466527Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layer-to-layer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.Type: GrantFiled: February 19, 2002Date of Patent: October 15, 2002Assignees: Sanyo Electric Co., Ltd., Tottori Sanyo Electric Co., Ltd.Inventors: Koichi Tada, Shinichi Ohe, Naoyuki Takagi, Ken Hirose, Shuichi Ichiura, Hiroshi Watanabe
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Patent number: 6459662Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layer-to-layer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.Type: GrantFiled: February 19, 2002Date of Patent: October 1, 2002Assignees: Sanyo Electric Co., Ltd., Tottori Sanyo Electric Co., Ltd.Inventors: Koichi Tada, Shinichi Ohe, Naoyuki Takagi, Ken Hirose, Shuichi Ichiura, Hiroshi Watanabe
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Publication number: 20020122361Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layer-to-layer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.Type: ApplicationFiled: February 19, 2002Publication date: September 5, 2002Applicant: Sanyo Electric Co., Ltd.Inventors: Koichi Tada, Shinichi Ohe, Naoyuki Takagi, Ken Hirose, Shuichi Ichiura, Hiroshi Watanabe
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Publication number: 20020122360Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layertolayer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.Type: ApplicationFiled: February 19, 2002Publication date: September 5, 2002Applicant: Sanyo Electric Co., Ltd.Inventors: Koichi Tada, Shinichi Ohe, Naoyuki Takagi, Ken Hirose, Shuichi Ichiura, Hiroshi Watanabe
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Publication number: 20020118613Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layertolayer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.Type: ApplicationFiled: February 19, 2002Publication date: August 29, 2002Applicant: Sanyo Electric Co., Ltd.Inventors: Koichi Tada, Shinichi Ohe, Naoyuki Takagi, Ken Hirose, Shuichi Ichiura, Hiroshi Watanabe
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Patent number: 6370093Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layer-to-layer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.Type: GrantFiled: January 28, 1999Date of Patent: April 9, 2002Assignees: Sanyo Electric Co., Ltd, Tottori Sanyo Electric Co., LtdInventors: Koichi Tada, Shinichi Ohe, Naoyuki Takagi, Ken Hirose, Shuichi Ichiura, Hiroshi Watanabe
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Patent number: 6201777Abstract: An apparatus for discriminating optical disks has an optical pickup provided with an objective lens having an effective numerical aperture of 0.55 to 0.65, which can compatibly reproduce information from a CD and an SD. The apparatus discriminates presence/absence of waveforms of two focus error signals detected when the effective numerical aperture of the objective lens is set at 0.55 to 0.65 and 0.20 to 0.45 respectively in a process of performing focus servo control, thereby discriminating various types of optical disks from each other. Thus, optical disks having different substrate thicknesses, different track pitches, different minimum pit lengths and different reflectivity can be quickly and simply discriminated from each other.Type: GrantFiled: February 17, 1999Date of Patent: March 13, 2001Assignee: Sanyo Electric Co., Ltd.Inventors: Yoichi Tsuchiya, Seiji Kajiyama, Yasuyuki Kanou, Shuichi Ichiura, Koichi Tada, Masami Shimizu, Toshio Harada