Citizen Watch Company, Ltd.

Heihachiro Ebihara

Fukuo Sekiya

Takashi Yamada

Satoshi Imoto

Misao Uchino

Katsuo Nishimura

Hiroshi Ogawa

Takanori Nanya

Minoru Natori

Yasuhiko Nishikubo

Fuminori Suzuki

Toshikazu Hatuse

Hiroyuki Fukayama

Kouhei Kawanobe

Shingo Hashimoto

An antiferroelectric liquid crystal display apparatus free from burn-in and achieving high display quality is provided by providing means for preventing pixel brightness from varying between pixels continuously held in an ON (bright) state and pixels continuously held in an OFF (dark) state. Aging processing is performed to saturate the brightness level of pixels into a stable state and thereby prevent the occurrence of a white brightening phenomenon. For this purpose, the brightness at a no voltage condition (base brightness) is set to a normalized level for all pixels in the liquid crystal panel that are required to exhibit uniform display performance. Further, temperature variations in the liquid crystal panel are eliminated to stabilize the brightness level and thereby prevent the occurrence of a white darkening phenomenon. Means is also provided for repeatedly performing normalization processes automatically or manually.

Electro-optical apparatus having antiferrodielectric liquid crystal panel with normalization to prevent white brightening

An antiferroelectric liquid crystal display device provided with means for preventing optical transmittance or the mean value of the optical transmittance from changing in a holding period tk. Thereby, the black display state thereof is stabilized. Further, the control of a gray shades display is facilitated. Moreover, linear gray scale characteristics and high contrast are provided. Thus, in the antiferroelectric liquid crystal display device having a selection period tw and the holding period tk, the optimum holding voltage (Vh), by which the optical transmittance little changes in the holding period tk, is applied to liquid crystals.

Liquid crystal display device

A circuit for driving a capacitive load using a booster having a low power consumption, which amplifies spike-like signals at high speeds and produces a large voltage and a large current, and wherein two transistors 104 and 111 are connected in series across a first power source H1 and a second power source L1 having a potential lower than that of the first power source. An output terminal OUT is provided at a portion where the two transistors are connected together, and the first transistor 104 connected between the first power source and the output terminal has a complementary relationship to the second transistor 11 connected between the output terminal and the second power source. The first transistor 104 is constituted by a PNP-type bipolar transistor or a P-type field-effect transistor, the second transistor 111 is constituted by an NPN-type transistor or an N-type field-effect transistor, and between an input terminal IN and a control terminal of each of the transistors are connected in parallel a capacitor and a means that applies a bias to the control terminal.

Circuit for driving capacitive load

The present invention improves the drop of a contrast, the occurrence of cross-talk and the drop of a response speed by bringing the drive state of an electrooptical display device to theoretical values. In a display device including a display panel having common electrode groups and segment electrode groups, a common electrode drive circuit and a segment electrode drive circuit, the quantity of the current flowing through the display panel through the segment electrode drive circuit is detected by a current detection circuit consisting of a differential amplifier 101 and a resistor Ra and by a current detection circuit consisting of a differential amplifier 102 and the resistor Ra, and the common electrode drive voltage applied to the common electrode groups through the common electrode drive circuit is controlled by a differential amplifier 103 on the basis of this current detection quantity, whereby the contrast is improve cross-talk is eliminated, and remarkable effects are obtained.

Electrooptical display device

The present invention improves the drop of a contrast, the occurrence of cross-talk and the drop of a response speed by bringing the drive state of an electrooptical display device to theoretical values. In a display device including a display panel having common electrode groups and segment electrode groups, a common electrode drive circuit and a segment electrode drive circuit, the quantity of the current flowing through the display panel through the segment electrode drive circuit is detected by a current detection circuit consisting of a differential amplifier 101 and a resistor Ra and by a current detection circuit consisting of a differential amplifier 102 and the resistor Ra, and the common electrode drive voltage applied to the common electrode groups through the common electrode drive circuit is controlled by a differential amplifier 103 on the basis of this current detection quantity, whereby the contrast is improve, cross-talk is eliminated, and remarkable effects are obtained.

The present invention improves the drop of a contrast, the occurrence of cross-talk and the drop of a response speed by bringing the drive state of an electrooptical display device to theoretical values. In a display device including a display panel having common electrode groups and segment electrode groups, a common electrode drive circuit and a segment electrode drive circuit, the quantity of the current flowing through the display panel through the segment electrode drive circuit is detected by a current detection circuit consisting of a differential amplifier 101 and a resistor Ra and by a current detection circuit consisting of a differential amplifier 102 and the resistor Ra, and the common electrode drive voltage applied to the common electrode groups through the common electrode drive circuit is controlled by a differential amplifier on the basis of this current detection quantity, whereby the contrast is improve, cross-talk is eliminated, and remarkable effects are obtained.

In a liquid crystal television, segment electrodes of a liquid crystal panel are divided into image segment electrodes and indicator segment electrodes. A liquid crystal display unit includes an image segment driver for receiving a video signal from a television receiver and driving the image segment electrodes, and an indicator segment driver for receiving a tuning voltage from a tuning voltage control unit and driving the indicator segment electrodes. The image and indicator segment drivers are driven by signals having different voltage waveforms.

Liquid crystal television

A non-volatile memory circuit comprising a plurality of semiconductor non-volatile memory elements, with erasure of data stored in all of these elements, enabling of selective write-in to all of the elements and read-out of stored data being controlled by potentials applied to a single control terminal. Use of a single terminal for these functions, rather than a pair of terminals as in the prior art, makes the circuit highly suitable for ultra-miniature electronic device applications.

Non-volatile memory circuit having a common write and erase terminal

An electro-acoustic transducer drive circuit for driving a device such as a miniature piezoelectric buzzer to emit musical notes, the notes having a damped waveform envelope whose shape is controlled by digital signals. The notes are formed by mutually independent circuit means and can be combined to produce musical chords. The circuit incorporates relatively few elements, and is suitable for implementation within a MOS IC.

Electro-acoustic transducer drive circuit for producing damped waveform

A portable electronic device with calculation and timekeeping functions, equipped with a keyboard for calculation and time setting purposes, means for producing scanning signals when a key is actuated, these signals being applied to switching elements connected to rows of keyboard contacts. When a key is depressed, the resultant high level signal potential applied to the corresponding contact row causes the row position to be detected and stored in a first memory circuit, which produces a signal causing the corresponding contact column to be detected and stored in a second memory circuit. Actuation of an external control member causes a signal to be stored by a reset signal in a first stage memory circuit which produces an output signal to be subsequently stored in a second stage memory circuit in synchronism with a timing signal. The low frequency and low duty cycle of the scanning signals and reset signal ensure minimized power consumption and suppression of switch bounce effects.

Portable electronic device equipped with calculation and timekeeping

Adjustments in a miniature electronic device are rapidly accomplished through electronic switching using non-volatile semiconductor memory elements which memorize the amount of an adjustment. Adjustments are accomplished by the application of positive or negative voltages.

Miniature electronic device

An amplitude control inverter circuit for an electronic device having a power source and a signal source. A complementary pair of field effect transistors having gate electrodes are connected to the signal source, and at least one amplitude control field effect transistor is connected to the complementary pair of field effect transistors. The amplitude control field effect transistor has its gate electrode responsive to a phase delayed output of the complementary pair of field effect transistors to control a duration of current flow in the complementary pair of field effect transistors. A resistor is connected to the gate electrode of the amplitude control field effect transistor. A capacitor has one terminal connected to a terminal of the resistor and also to the amplitude control field effect transistor, and another terminal connected to the power source. The amplitude control inverter circuit may be used in crystal oscillators and in buffer amplifiers.

Amplitude control inverter circuit for electronic device

A portable electronic device equipped with timekeeping circuit means for providing at least units of seconds and tens of seconds of time information, and display means for displaying said time information in digital form, which comprises first external control member for inputting numeric data signals, a control circuit for selecting at least said tens of seconds of said time data for correction, second external control member for inputting control signals to actuate said control circuit, first gate means for applying said numeric data signals to said timekeeping circuit means to effect correction of at least said tens of seconds of time information, second gate means for automatically resetting said units of seconds of time information to zero in response to correction of said tens of seconds of time information.

Growing community of inventors

Tokorozawa, Japan

Heihachiro Ebihara