Television – Image signal processing circuitry specific to television
Reexamination Certificate
1998-02-24
2001-06-12
Hsia, Sherrie (Department: 2614)
Television
Image signal processing circuitry specific to television
C348S705000, C348S706000
Reexamination Certificate
active
06246443
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a signal processing device comprising:
a signal source selection means for selecting a signal source from a set of at least two signal sources, the signal from each of the signal sources having at least one controllable parameter, whose value W is defined by a global value G and a local value L associated with a selected signal source,
a control for adjusting the value W,
a storage register for the storage of the global value G,
for each signal source a storage register for the storage of the local value L,
means for obtaining the resultant value W by means of a predetermined combination of G and L.
Such a signal processing device is known from U.S. Pat. No. 5,046,107. In the known device the controllable parameter referred to each time is the signal strength of the audio signal and the local value is an offset with respect to the global setting of the signal strength. In a given embodiment the known device comprise a separate control for adjusting the local values associated with the selected signal source. This control enables mutual differences in signal volume among the various signal sources to be compensated for. This has the drawback that an additional control element is required and that for each volume correction the user is expected to decide how the correction should be divided between the global volume and the offset value. If the user decides that both values should be corrected, two actions are required.
In another embodiment the known device does not have a separate control for the offset value associated with the selected signal source but the offset value is determined by the master volume control. However, it is not clear how and under what conditions a correction of the master volume control causes a change in the offset value.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a signal processing device and a method of the types defined in the opening paragraphs, which automatically compensate for differences in signal parameters, such as for example volume of sound and picture contrast of a TV signal, between the various signal sources.
To this end, the device in accordance with the invention is characterized in that the device further comprises:
detection means for determining whether a change &dgr;W of W occurs, induced by a change of the setting of the control, within a predetermined time interval &Dgr;T after selection of a signal source,
means adapted to change L by an amount &dgr;L and G by an amount &dgr;G if &dgr;W occurs within &Dgr;T.
As a result of these measures, parameter adaptations within a given time interval after changing over from one signal source to another are interpreted as an intention to adapt, in addition to the global parameter value, also the local value for the signal source just selected to a given extent. Depending on the degree of change in the local values differences with respect to other signal sources will be compensated for automatically after a given signal source has been selected at least 1 time. After said time interval the local value is no longer adapted and parameter adaptations are regarded as corrections of the global setting, for example in order to allow for changing ambient conditions, a changing mood of the user, or changing signal properties.
A further advantage of the invention is the absence of an additional control for setting local values, as a result of which the device can be cheaper and more compact.
The invention is very suited for use in radio and television receivers for the automatic compensation of differences in volume of sound among radio stations and television stations, respectively. The invention can also be used in amplifiers for automatic control of the input sensitivities. Moreover, the invention can be utilized for other parameters than volume, for example brightness, contrast or equalizer settings.
REFERENCES:
patent: 4996597 (1991-02-01), Duffield
patent: 5046107 (1991-09-01), Iwamatsu
patent: 5801785 (1998-09-01), Crump
Gathman Laurie E.
Hsia Sherrie
U.S. Philips Corporation
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