Minebea Company, Limited

Takao Takehara

Masashi Norizuki

Shingo Okada

Atsuyoshi Tamagawa

A Resolver/Digital (R/D) converter includes an encoder output divider having a DSP generating 14-bit encoded signals Aand Bfrom a timing analysis performed during the first period of 12-bit encoded signal A. The DSP generates a selection signal output to a multiplexer to select encoded signals Aand BEor encoded signals Aand Bdepending on the rotational speed of the rotor of a resolver. Based on the selection signal, the multiplexer outputs 12-bit encoded signals Aand Bwhen the rotational speed is less than 400 rpm or greater than 1200 rpm, and outputs 14-bit encoded signals Aand Bwhen rotational speed is between 400 rpm and 1200 rpm.

Encoder output divider and R/D converter

An R/D converter allows high precision detection of a rotation angle of a rotor axis of a resolver having high rates of rotation. An A/D converter is built into a digital signal processor and converts a sine wave and cosine wave output from the resolver. An axis angle calculator calculates tan &#x3b8;=A((sin &#x3c9;t)(sin &#x3b8;))/A((sin &#x3c9;t)(cos &#x3b8;)) from A(sin &#x3c9;t)(sin &#x3b8;) and A(sin &#x3c9;t)(cos &#x3b8;) and further calculates &#x3b8;=tan&#x3b8;. The angle space is divided into quadrants and an offset value is set for each quadrant and by adding or subtracting the calculated &#x3b8; to or from the offset value to form the final angle of the rotor axis of the resolver.

Resolver/digital converter

An A/D converter converts a sine and cosine wave output of a resolver to form a digital sine and cosine. A microcomputer uses an absolute value of digital sin &#x3b8; as an address to retrieve &#x3b8; from a memory containing angle values between 0&#xb0; and 90&#xb0;, if the absolute value of sin &#x3b8; is between 0 and 0.707. Otherwise, if the absolute value of sin &#x3b8; is between 0.707 and 1, cos &#x3b8; is used as an address to retrieve &#x3b8;. The polarities of sin &#x3b8; and cos &#x3b8; are used to determine a quadrant and an associated offset including 0&#xb0;, 180&#xb0;&#x2212;&#x3b8;, 180&#xb0;+&#x3b8;, and 360&#xb0;&#x2212;&#x3b8;, which is combined with &#x3b8; such that the final angle of the rotor axis is obtained.

Of the electronic components used for a video monitor installed in an aircraft, components radiating electromagnetic waves are covered with a case formed by combining first and second metal plates , and part of the case is connected to a frame ground. By connecting the case to the frame ground, the radiation of electromagnetic waves is suppressed.

Device for shielding electronic circuit for aircraft

There is provided an R/D converter capable of realizing a high speed response. When a sine wave for excitation of a resolver is a positive (or negative) maximum value, an AD converter makes AD conversion of a sine-wave output and a cosine-wave output of the resolver and makes input to a DSP. The DSP calculates on the basis of the input data, and outputs an obtained digital value to a DA converter and the like. Since the DSP calculates a rotor shaft angle, as compared with prior art (R/D converter of a tracking system) which includes a close loop made up of a demodulator circuit, a voltage controlled oscillator, and the like, and carries out a kind of PLL control, it becomes possible to carry out rotor shaft angle calculation at higher speed, and the high speed response can be realized by this. Since the rotor shaft angle is obtained through a digital operation, a compensation circuit of temperature drift, which has been required in the prior art, becomes unnecessary, and by that, the whole structure becomes simple, and the cost can be reduced.

R/D converter

There is provided an R/D converter which can make high speed response. When a sine-wave for excitation of a resolver has a positive (or negative) maximum value, an AD converter performs AD conversion of sine-wave output and cosine-wave output of the resolver and makes input to an FPGA. The FPGA calculates on the basis of the input data, and outputs an obtained digital value to a DA converter and the like. Since the FPGA calculate the rotor shaft angle, as compared with the prior art (R/D converter of a tracking system) for performing a kind of PLL control including a close loop made up of a demodulator circuit, a voltage controlled oscillator, and the like, it becomes possible to perform rotor shaft angle calculation at higher speed, and by this, the high speed response can be made. Since the rotor shaft angle is obtained through digital operation, a compensation circuit for temperature drift which has been required in the prior art becomes unnecessary, and by that, the total structure becomes simple, and the cost can be made low.

This invention is to provide an inexpensive high intensity discharge lamp lighting device having a simplified circuit construction, which does not use a full-bridge mode inverter. The high intensity discharge lamp lighting device includes a rectifier for a power-frequency power supply, a booster chopper mode sine wave converter, a zero volt switching push pull inverter, and a high intensity lamp of a halide lamp. And, as a starting device for the halide lamp, the high intensity discharge lamp lighting device generates a high voltage (5 KV) using a resonance by a ballast choke for the inverter and a condenser connected in parallel to the halide lamp, thereby inducing a glow discharge. And, a PFM (pulse frequency modulation) circuit controls the lamp current of the halide lamp to keep it constant. And, when the AC power is turned off and turned on again, a re-lighting circuit after lighting works such that the control IC stops operation by a pulse-by-pulse mode current limiter of an inverter control IC, thereafter a soft starting circuit operates to generate a high voltage on the output of the inverter; when the lamp temperature is so high that the mercury vapor pressure inside the tube goes high and lighting cannot be started, the foregoing operation is repeated to achieve re-lighting.

Power supply circuit device for a high intensity discharge lamp that

An inverter apparatus of the present invention has a cold cathode tube and its operating circuit provided with a piezoelectric transformer. Specifically, for increasing the boost ratio of the piezoelectric transformer, a boost chopper is mounted in the premier stage of a semi-class E voltage resonance inverter and a power switch element is mounted operable commonly for both the inverter and the chopper so that a single voltage resonance controller IC controls the cold cathode tube at a constant current. As the operating circuit is composed of the voltage transformer, the apparatus will be minimized in the number of components and decreased in the overall size and the production cost. Also, as the operating frequency of the cold cathode tube is increased by increasing the resonance frequency of the piezoelectric frequency, the discharge efficiency will also be enhanced.

Cold cathode tube operating apparatus with piezoelectric transformer

An inverter apparatus includes a serial resonance circuit provided at the primary side of a booster transformer, a controlling means for turning on and off the serial resonance circuit with a switching element operating at the timing of phase advanced from the resonance frequency of the serial resonance circuit, and a load device connected to the secondary side of the booster transformer. The inverter apparatus may further include a detecting means provided at the secondary side of the booster transformer for detecting a load so that the controlling means upon receiving a signal output of the detecting means indicative of the load advances the timing phase of the turning on and off actions of the switch element when the load is smaller. Also the load device may be a cold cathode tube. It may be arranged for stabilizing a voltage output of the booster transformer that the booster transformer is coupled to a feedback line for feeding back a voltage to the negative input of an operational amplifier in the controlling means before the cold cathode tube starts a discharge action or that the voltage at a primary coil of the booster transformer is fed back to the negative input of an operational amplifier in the controlling means before the cold cathode tube is actuated. The present invention allows a single power switching element to build a semi-class E type voltage resonance inverter thus increasing the operational efficiency and minimizing the number of its components.

Inverter apparatus

A fluorescent lamp circuit having a power-factor improving step-up chopper and an inverter to covert an output of the step-up chopper and to drive the fluorescent lamp. A switching circuit of the step-up chopper and a switching circuit of the inverter are operated by a switching element consisting of a single transistor.

Fluorescent lamp circuit employing both a step-up chopper and an inverter

This invention solves various problems of an inverter device caused by a winding transformer by using a piezoelectric transformer, and also provides a drive device for a cold cathode tube using a piezoelectric transformer so as to enable lighting and light control of the cold cathode tube. In a cold cathode tube lighting device having a cold cathode tube and piezoelectric circuit to light the cold cathode tube, a series resonance circuit is formed at primary side of the piezoelectric transformer. An operation control device is installed for ON-OFF control of the series resonance circuit, by a switching element, at timing with the phase advanced from the resonance frequency of the resonance circuit, and a chopper circuit for stepping-up the input voltage and supplying a power source to the resonance circuit is installed, and ON-OFF control of the power switching element of the chopper circuit is performed by the operation control device. That is, the power switch of the step-up chopper circuit is driven at the ON-time larger than that of the power switch of the inverter, and the cold cathode tube is connected to the secondary side of the step-up transformer.

Cold cathode tube lighting device using piezoelectric transformer

An object of the present invention is to provide a voltage resonance inverter circuit capable of performing constantly a zero-voltage switching action in response to a change in the input voltage. For achievement of the above object of the present invention, the capacitance of a voltage resonance capacitor is decreased in response to an increase of the input voltage thus increasing the characteristic impedance of a resonance circuit. This will increase the amplitude of a resonance voltage causing a zero-voltage switching action.

Voltage resonance inverter circuit for dimable cold cathode tubes

The present invention is disclosed to provide an inverter allowing a remarkable reduction in the number of parts used for an inverter unit which can improves the efficiency and allows current control in a wide range. Namely, the inverter unit for converting a direct current supplied from DC power supply, into an alternating current by conversion means alternatively converting the flowing direction of direct current by SWITCH ON/SWITCH OFF operation of a switching element, comprises a series resonance circuit formed at the primary side of a step-up transformer, a control means for switching ON/OFF said series resonance circuit by the switching element at a timing led in phase from the resonant frequency of this resonance circuit, and a load connected at the secondary side of the transformer, so as to solve the problems described above.

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Iwata-gun, Japan

Takao Takehara