Television – Image signal processing circuitry specific to television – Selective image modification
Reexamination Certificate
2002-04-08
2003-12-30
Kosiak, Victor R. (Department: 2611)
Television
Image signal processing circuitry specific to television
Selective image modification
C348S601000
Reexamination Certificate
active
06670998
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image display device represented by a CRT (Cathode-Ray Tube) display device; particularly, relates to improving the visual quality of displayed image.
2. Description of the Background Art
FIG. 25
is a block diagram showing an internal structure of a conventional image display device as a background of the present invention. This device
150
is formed as a CRT device having a CRT
91
. An image signal Pin inputted from the exterior is amplified by an amplifier
92
into an image signal Pc. The image signal Pc is supplied to the cathode (not shown) of the CRT
91
. The input of the amplifier
92
is connected to a parallel circuit of a resistor
93
and a series circuit. The series circuit includes a capacitor
94
and a resistor
95
connected in series to each other. The input and the output of the amplifier
92
are connected to each other through a resistor
96
. Thus, the device
150
comprises an active type (a current feedback type) of a video amplifying circuit.
A series circuit having an inductor
97
and a resistor
98
connected in series to each other is interposed into a path between the output of the amplifier
92
and the cathode of the CRT
91
. The gain of the video amplifying circuit including the amplifier
92
is defined by resistance of the resistors
93
,
95
,
96
and
98
, capacitance of the capacitor
94
, and an inductance of the inductor
97
. In particular, the capacitor
94
and the inductor
97
can compensate a high frequency component of the gain. That is, the capacitance of the capacitor
94
and the inductance of the inductor
97
define a frequency characteristic of the gain.
The CRT
91
is further connected to a high voltage generation unit
99
. The high voltage generation unit
99
supplies the CRT
91
with high voltage so as to implement an injection of electron beam inside the CRT
91
. As the conventional device
150
is so formed as described above, an image represented by the image signal Pin is displayed on a screen provided at a front portion of the CRT
91
.
In the conventional device
150
, however, the frequency characteristic of the gain for the image signal Pc is fixed. That is, the frequency characteristic disadvantageously can not be freely varied depending on a type of the image or the like. Another type of the conventional device
150
is known in which the resistor
95
is replaced with a pre-set variable resistor. In this type, the resistance of the pre-set variable resistor, however, can not be varied with electric means. Therefore, it is disadvantageously hard to adjust the frequency characteristic in order to optimize the visual image quality depending on the type of the image.
Further, a technique is not known which allows control of the frequency characteristic and the like exclusively for a particular region within entire one frame image where the particular type of the image is laid out so that the image quality in the region is suited to the type of the image. Thus, the conventional device is disadvantageous in that it is hard to obtain the optimum image quality depending on the type of the image.
The following documents are known in relation to the control of the frequency characteristic of the video amplifying circuit: Japanese Patent Laid Open Gazette No. 50-68221, No. 2-312465, and No. 6-189161.
SUMMARY OF THE INVENTION
A first aspect of the present invention is directed to an image display device. The image display device comprises: an image output unit for displaying an image represented by an image signal; an amplifying unit for amplifying the image signal with a gain having a frequency characteristic and supplying the amplified image signal to the image output unit, including a variable inductor, an inductance of which defines the frequency characteristics; and a control unit for controlling the inductance of the variable inductor.
According to a second aspect of the present invention, in the image display device of the first aspect, the amplifying unit further comprises an amplifier for amplifying the image signal, and the variable inductor is interposed into a path between the amplifier and the image output unit.
According to a third aspect of the present invention, in the image display device of the first or the second aspect, the variable inductor includes primary and secondary windings inductively coupled with each other, the primary winding is connected to the amplifier, the secondary winding is connected to the control unit, the inductance of the variable inductor is an inductance of the primary winding, and the control unit controls a current which is induced in the secondary winding by a current flowing in the primary winding.
According to a fourth aspect of the present invention, in the image display device of any one of the first to the third aspects, the image display device receives a synchronizing signal of the image, and further comprises a resolution detection unit for detecting a resolution of the image signal on a basis of the synchronizing signal, and the control unit varies the frequency characteristic depending on the resolution.
According to a fifth aspect of the present invention, in the image display device of any one of the first to the fourth aspects, the image display device further comprises a transient characteristic detection unit for detecting a pulse waveform of the image signal outputted from the amplifying unit, and the control unit controls the frequency characteristic so that the pulse waveform detected by the transient characteristic detection unit approaches a target form.
According to a sixth aspect of the present invention, in the image display device of any one of the first to the fifth aspects, the image display device further comprises a brightness detection unit for detecting a brightness of the image displayed by the image output unit, and the control unit judges the display image on a basis of the brightness as a binary image of normal display or a binary image of reverse display and controls the frequency characteristic as to enhance a higher frequency component of the gain for the binary image of normal display and to reduce the higher frequency component for the binary image of reverse display.
A seventh aspect of the present invention is directed to an image display device. The image display device comprises: an image output unit for displaying an overall image represented by an image signal; a region designation unit <8> for designating a particular region <W> within the overall image; and a control unit <4> for selectively controlling an image quality of an image for the particular region.
According to an eighth aspect of the present invention, in the image display device of the seventh aspect, the image display device receives a synchronizing signal on which a position signal is superimposed and the region designation unit comprises: a position signal extraction unit for extracting the position signal from the synchronizing signal, and a region decision unit for deciding the particular region on a basis of the position signal.
According to a ninth aspect of the present invention, in the image display device of the seventh aspect, the image display device receives the image signal together with a position signal which is superimposed on the image signal, and the region designation unit comprises: a position signal extraction unit for extracting the position signal superimposed from the image signal, and a region decision unit for deciding the particular region on a basis of the position signal.
According to a tenth aspect of the present invention, in the image display device of the eighth or the ninth aspect, the position signal represents a type of the image quality to be controlled, the region designation unit further comprises an image quality control decoding unit for decoding the position signal into the type of the image quality, and the control unit selectively controls the type of the image quality based on the image quality.
In the devi
Birch & Stewart Kolasch & Birch, LLP
Kosiak Victor R.
Mitsubishi Denki & Kabushiki Kaisha
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