Denso Corporation

Takashi Hanaki

Koji Ogusu

Naoki Matsumoto

Hiroyuki Kishita

Masahiko Osada

Shogo Kameyama

Tetsuya Katoh

Tomohiro Kuno

Kiyohito Narita

A passive matrix type display device includes: a display unit having a display area; first electrodes on the area for switching between a conductive state and a non-conductive state; second electrodes on the area; a driving current source for supplying a driving current to the second electrodes; light-emitting elements at an intersection between the first and second electrodes; a first circuit for controlling a part of first electrodes to the conductive state and for scanning the first electrodes; a second circuit for deciding a part of second electrodes corresponding to a part of light-emitting elements emitting a light; light-emission adjustment elements coupled with the second electrodes for branching an adjustment current from the driving current; and a light-emission adjustment controller for controlling the light from each light-emitting element by controlling the adjustment current.

Passive matrix type display device

A driving method for driving luminous elements has a luminous element provided at each intersection of anode lines and cathode lines arranged in a matrix. The anode lines are one of scan lines and drive lines and the cathode lines are one of other of scan lines and drive lines. The luminous element provided at an intersection of a desired drive line is driven to emit light in synchronism with scanning while scanning the scan lines at a specific frequency. When switching the scanning line, at least one of the scanning lines is first connected to a first voltage, and the remaining scanning lines are connected at the same time to a second voltage that is different from the first voltage.

Driving method for luminous elements

A segment-type electroluminescent display panel is driven by a driving circuit that supplies a constant current to each luminescent segment. The display panel includes plural luminescent segments each having a luminescent area different from one another. The plural segments are grouped into several groups, so that each group includes the segments having the same or similar luminescent area. The amount of current to be supplied to each segment is determined group by group so that a substantially same current density is supplied to all the segments. Since the plural segments are grouped according to their size, the driving circuit is simplified while attaining an equal luminance among all the luminescent segments. Alternatively, an equal amount of current is supplied to all the variously sized segments, and a resistor is connected in parallel to each segment to equalize the current density supplied to each segment thereby to achieve an equal luminance among all the segments.

Device having multiple luminescent segments

In an electroluminescent (EL) display device having a plurality of organic EL elements, variations in luminance among the EL elements are equalized. EL elements to be driven for a required image display are periodically applied with drive voltages and a recovery voltage, while the other EL elements are periodically applied with a dummy voltage. The period, the repetition period, and the amplitude of the dummy voltage are set not to illuminate the other EL elements, while promoting degradation of the other EL elements to some extent. Alternatively, the drive voltage applied to drive the EL elements for the required image display may be modified in accordance with the degree of degradation thereof.

Organic electroluminescent display device having luminance degradation compensating function

A flat display panel having electroluminescent layer and scanning and data electrodes is driven by driving circuits connected to the respective electrodes. Scanning voltages are sequentially supplied to the scanning electrodes one by one, and data voltages are supplied to the data electrodes in synchronism with the scanning voltages, thereby selectively imposing composite voltages on pixels formed at each intersection of the scanning and data electrodes. The pixels on one scanning electrode that is already scanned are charged to a level of a data modulation voltage to prevent a harmful and useless turnaround current from flowing into the scanned pixels when other scanning electrodes are scanned. The pixels on other scanning electrodes that are not yet scanned may be charged to the modulation voltage level at the same time the scanned pixels are charged. Since the turnaround current is thus eliminated, uneven brightness among scanning electrodes otherwise appearing on the display panel is suppressed.

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Kariya, Japan

Takashi Hanaki