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1. 发明专利

JP2000022460A AUDIO POWER AMPLIFIER 失效
公开(公告)号：JP2000022460A
公开(公告)日：2000-01-21
申请号：JP18412098
申请日：1998-06-30
申请人： HITACHI LTD , HITACHI TOBU SEMICONDUCTOR LTD
发明人： MAEDA MASATOSHI , TAKANASHI TOSHIHIKO , TAKESHITA RITSUJI
IPC分类号： H03F3/38
摘要： PROBLEM TO BE SOLVED: To reduce a loss inside a device and to permit remarkable miniaturization by amplifying the input voltage of a power amplifier part in an AB class push-pull output system having an amplified frequency band sufficiently higher than an audible frequency band at high speed with the signal of a frequency higher than double audible frequency bands. SOLUTION: An amplitude detecting circuit 21 performs working processing to an input voltage Vin into fully rectified waveform VA. A switching signal VF is the rectangular clock signal of a frequency sufficiently higher than the frequency band of the input voltage Vin more than double. An amplitude modulating signal VM is superimposed on the input voltage Vin by an adder circuit 24 and a synthetic signal VP for amplifying the input voltage Vin at high speed with the switching signal is generated. A speaker SP is driven by the valid output of a waveform similar to the input voltage Vin but an output voltage Vout of the power amplifier part 1 is amplified at high speed by the switching signal VF. Thus, the period for the output voltage Vout to stay near an intermediate potential (Vcc/2 or Vee) is remarkably shortened.

2. 发明专利

JP2000106511A POWER AMPLIFIER IC 失效
公开(公告)号：JP2000106511A
公开(公告)日：2000-04-11
申请号：JP27452598
申请日：1998-09-29
申请人： HITACHI LTD , HITACHI TOBU SEMICONDUCTOR LTD
发明人： MAEDA MASATOSHI , TAKESHITA RITSUJI , IIJIMA DAISUKE
IPC分类号： H03F1/32 , H03F3/30 , H03G3/30
摘要： PROBLEM TO BE SOLVED: To attain reproduction of sound with full of presence by ensuring expression contrast directing performance of a most important sound in an audio reproduction system while effectively suppressing deteriorated sound quality due to clipping of a sound signal. SOLUTION: The power amplifier IC has a clip detection circuit 2 that produces a detection output only when an output of a power amplifier circuit 1 indicates a clip state, a DC rectification circuit 3 that converts the detection output of the clip detection circuit 1 into a DC voltage under a prescribed time constant, and a variable gain circuit 4 that is interposed in an input signal transfer path of the power amplifier circuit 1 to variably control a transfer gain of an input signal. An output of the DC rectification circuit 3 is given to the variable gain circuit 4 as a control signal so as to form a selective gain control loop where a transfer gain is suppressed in response to the detection output of the clip detection circuit 2 only when the clip detection circuit 2 detects a clipping state.

3. 发明专利

JPH08222974A AUDIO POWER AMPLIFIER 失效
公开(公告)号：JPH08222974A
公开(公告)日：1996-08-30
申请号：JP2971995
申请日：1995-02-17
申请人： HITACHI LTD , HITACHI TOBU SEMICONDUCTOR LTD
发明人： YUKITA MASAHIRO , MAEDA MASATOSHI , IENAKA MASANORI
IPC分类号： H03F3/68
摘要： PURPOSE: To obtain a high output with a comparatively low power supply voltage and to obtain high stability independently of an externally mounted snubber circuit by allowing each output of an auxiliary amplifier circuit of a couple of power amplifier circuits to apply a base drive current of an output stage transistor(TR) of other power amplifier circuit mutually. CONSTITUTION: An auxiliary amplifier circuit 2 of current output type amplifying an input signal +Vin (-Vin ) is provided respectively to a couple of power amplifier circuits 1A, 1B each receiving an input signal +Vin (-Vin ) inverse to each other in the audio power amplifier and an output 1a of the circuit 2 of the amplifier circuit 1A applies a base drive current of an output TR Q1 of the other amplifier circuit 1B. Simultaneously an output 1b of the circuit 2 of the other amplifier circuit 1B applies a base drive current of an output TR Q1 of the amplifier circuit 1A. Thus, a base drive current enough to obtain a high output at a low power supply voltage from a push side TR Q1 of each of the amplifier circuits 1A, 1B is obtained independently of lots of negative feedback loops sometimes causing an unstable operation at a high frequency band.

4. 发明专利

JPH10242778A POWER AMPLIFIER 失效
公开(公告)号：JPH10242778A
公开(公告)日：1998-09-11
申请号：JP4028597
申请日：1997-02-25
申请人： HITACHI LTD , HITACHI TOBU SEMICONDUCTOR LTD
发明人： IGUSA TAKAAKI , MAEDA MASATOSHI , SEKI KUNIO , TAKESHITA RITSUJI
IPC分类号： H03F1/52 , H03F1/02 , H03F3/30
摘要： PROBLEM TO BE SOLVED: To easily and surely secure the high output and prevent the breakdown of elements for a power amplifier that is used at a comparatively low power voltage level by preparing a comparator which compares the boosting voltage given to a preceding stage drive circuit from a booster circuit with a prescribed reference voltage level and applying the negative feedback control to the output voltage of the booster circuit at a fixed voltage level by means of the output of the comparator. SOLUTION: The boosting voltage V1 drops in response to the increase of current consumption I1 of a preceding stage drive circuit 12. However, when the voltage V1 is lowered down to the prescribed reference voltage Vs or less, the 2nd voltage Vp added to the charging voltage or a 1st capacity element C1 by a negative feedback control circuit 7 rises to heighten the boosting drive level of a booster circuit 3. Thus, it's possible to prevent the decrease of the voltage V1 applied to the circuit 12 and to keep the voltage V1 at a constant level even in a large output mode when the consumption I1 of the circuit 12 increases. Furthermore, the rise of the voltage V1 is prevented and the V1 is kept at a constant level even in a small output mode when the consumption 11 decreases.

5. 发明专利

JP2000174565A POWER AMPLIFIER IC AND AUDIO SYSTEM 失效
公开(公告)号：JP2000174565A
公开(公告)日：2000-06-23
申请号：JP34090998
申请日：1998-12-01
申请人： HITACHI LTD , HITACHI TOBU SEMICONDUCTOR LTD
发明人： MAEDA MASATOSHI
IPC分类号： H03F1/34 , H03F1/52 , H03F3/21
摘要： PROBLEM TO BE SOLVED: To provide a technology capable of detecting overcurrent by a circuit designed with comparatively rough constants with high accuracy thereby surely protecting the overcurrent. SOLUTION: The power amplifier with a feedback path to apply negative feedback from a final stage output circuit to a 1st stage differential amplifier circuit is provided with a comparator circuit 41 that compares a voltage fed back from an output stage 13 to a 1st stage differential amplifier circuit 11 with a voltage given to a final stage output circuit and with a comparator circuit 42 that compares a voltage fed back from a final stage output circuit to the 1st stage differential amplifier circuit with a prescribed reference voltage, detects an overcurrent an n output terminal based on the result of comparison by the comparator circuits and operates a protection circuit 15 to prevent the overcurrent.

6. 发明专利

JPH09214261A POWER AMPLIFIER CIRCUIT 失效
公开(公告)号：JPH09214261A
公开(公告)日：1997-08-15
申请号：JP1654996
申请日：1996-02-01
申请人： HITACHI LTD , HITACHI TOBU SEMICONDUCTOR LTD
发明人： MAEDA MASATOSHI , SEKI KUNIO , TAKESHITA RITSUJI
IPC分类号： H03F3/30 , H04B1/10
摘要： PROBLEM TO BE SOLVED: To provide the power amplifier circuit increasing a maximum output power while avoiding adverse effect on other circuit such as a tuner. SOLUTION: In the power amplifier circuit having a push-pull output circuit, NPN TRs are employed for output transistors (TRs) Q2, Q5 for a push-side 1 and a pull-side 2 of the push-pull output circuit and the power amplifier circuit is provided with a boosting circuit boosting a power supply voltage and a changeover means SWO applying selectively a voltage generated in the boosting circuit 3 or the usual power supply voltage to a pre-stage circuit supplying a base current of the push-side output TR Q2. The changeover means SWO is switched by a mode control signal or the like.

7. 发明专利

JPH0832375A BTL OUTPUT CIRCUIT 失效
公开(公告)号：JPH0832375A
公开(公告)日：1996-02-02
申请号：JP18995994
申请日：1994-07-20
申请人： HITACHI LTD , HITACHI TOBU SEMICONDUCTOR LTD
发明人： MAEDA MASATOSHI , YUKITA MASAHIRO , IENAKA MASANORI
IPC分类号： H03F3/68
摘要： PURPOSE:To surely prevent oscillation by forming a balanced transformerless (BTL) circuit with two output circuits receiving inverted inputs to each other and having a Darlington circuit and an inverted Darlington circuit and supplying a correction current from one output circuit to the other output circuit. CONSTITUTION:The BTL output circuit is formed by an output circuit 1 having a Darlington circuit 2 and an inverted Darlington circuit 3 and an output circuit 1' of the similar configuration receiving an inverted input V'in. For example, when the inverted Darlington circuit 3 of the circuit 1 applies pull drive to a load, a correction current is supplied to a level shift loop of the circuit 1 via a correction circuit 6' of the circuit 1 to apply a bias voltage to the circuit 1 so as to make input and output voltages Vin, Vout equal to each other and then the output impedance is kept low. Thus, the loop gain of the circuit 3 is suppressed.

8. 发明专利

JPH0846449A CURRENT AMPLIFIER CIRCUIT 失效
公开(公告)号：JPH0846449A
公开(公告)日：1996-02-16
申请号：JP19489294
申请日：1994-07-27
申请人： HITACHI LTD , HITACHI TOBU SEMICONDUCTOR LTD
发明人： MAEDA MASATOSHI , YUKITA MASAHIRO , IENAKA MASANORI
IPC分类号： H03F3/30 , H03F3/34
摘要： PURPOSE:To increase maximum output power without increasing the size of an output transistor by providing a second level shift means on a level shift loop circuit equalizing input voltage with output voltage. CONSTITUTION:Input voltage Vin is supplied to the input of an inverted Darlington circuit 1 via a first level shift means D 3. By providing a second level shift means D4 corresponding to the first level shift means D3 on a level shift loop circuit equalizing input voltage Vin with output voltage Vout, the base potential of the driving transistor of the inverted Darlington circuit can be made high even when the input voltage lowers down to the same potential as the ground potential of the circuit. As a result, because a saturation opeartion is hardly generated, the base current required for an NPN output transistor Q1 is sufficiently supplied and the transisitor Q1 an be operated in a saturation area, the amplitude of output voltage can be made large on the ground potential side of the circuit.

9. 发明专利

JPH02250242A CATHODE-RAY TUBE 失效
公开(公告)号：JPH02250242A
公开(公告)日：1990-10-08
申请号：JP30538388
申请日：1988-12-02
申请人： NIPPON SHEET GLASS CO LTD , HITACHI LTD
发明人： MAEDA MASATOSHI , HANADA YOSHIYUKI , NAKAI HIDEMI , MORITA YASUKAZU , UEHARA YASUHIKO , IKEDA MISAO
IPC分类号： H01J29/18 , H01J29/24 , H01J29/89 , H01J31/10
摘要： PURPOSE:To provide good performance of tight contacting with fluorescent substance and accomplish an image of high quality by using an optical interfering filter having periodical stratification of layers consisting of a low refraction factor material, with the optical film thickness specified, and layers consisting of a high refraction factor material. CONSTITUTION:The film constitution of an optical interfering filter include periodic stratification 6 of layers 3 made of a material having a low refraction factor, which is approx. 0.25 times as great as the cutoff wavelength lambda0 with the optical film thickness greater than the center wavelength lambda of the emission spectrum of the fluorescent substance, and layers 2, 4 made of a material having high refraction factor, wherein the two outside located layers shall constitute the ones with low refraction factor. Between this periodic stratification 6 and fluorescent substance layer, are interposed one over another a layer 5 consisting of or chiefly containing SiO2 in an optical film thickness from the fluorescent substance layer 0.05lambda0-0.2lambda0 or 0.47lambda0Xm+ or -0.12lambda0 (m is an integer from 1 to 10), respectively, and the mentioned layer 2 with high refraction factor in an optical film thickness of approx. 0.25lambda+0.125lambda0, and another layer 2 with high refraction factor in an optical film thickness of 0.25lambda+0.125lambda0 is provided between the periodic stratification 6 and the display window inne surface. This provides good performance of tight conatcting with the fluorescent substance, less ripples in the penetrative zone, and easy controllability for the optical film thickness of each film.

10. 发明专利

JPH03196448A CATHODE-RAY TUBE FACEPLATE 失效
公开(公告)号：JPH03196448A
公开(公告)日：1991-08-27
申请号：JP33763389
申请日：1989-12-26
申请人： NIPPON SHEET GLASS CO LTD , HITACHI LTD
发明人： MAEDA MASATOSHI , HANADA YOSHIYUKI , NAKAI HIDEMI , MORITA YASUKAZU , UEHARA YASUHIKO
IPC分类号： H01J29/18 , H01J29/22 , H01J29/24 , H01J29/89
摘要： PURPOSE:To efficiently extract the luminescence of phosphors to the outside by forming an optical interference filter laminated with high-refraction factor layers and low-refraction factor layers in turn between the phosphor layer and display window of a cathode-ray tube faceplate. CONSTITUTION:A TiO2 layer 4 with the optical thickness 0.125lambda0+0.25lambda between a cathode-ray tube faceplate 1 and a phosphor layer 8, where lambda0 is the designed wavelength, and lambda is the center wavelength of the luminescence spectrum of phosphors. Al2O3 layers 2 with the thickness 0.25 lambda0 and TiO2 layers 3 with the thickness 0.25lambda0 are laminated in turn on the layer 4 to form an alternate cycle layer 6. The layer 4 is formed on the layer 6 to form an optical interference filter 7, and a phosphor layer 8 is formed on it. The optical interference filter 7 thus formed prevents the occurrence of the browning phenomenon by radiated electron beams, and a bright image can be projected.

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