Television – Monitoring – testing – or measuring – Testing of image reproducer
Reexamination Certificate
1998-03-25
2001-02-27
Hsia, Sherrie (Department: 2614)
Television
Monitoring, testing, or measuring
Testing of image reproducer
C348S747000, C348S806000
Reexamination Certificate
active
06195123
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of automatically adjusting a CRT color monitor screen and to a CRT color monitor. More particularly, the present invention relates to a method of automatically adjusting position and size on a CRT color monitor screen in accordance with an unknown input video signal and to a CRT color monitor employing the method.
2. Description of the Prior Art
Such conventional methods of automatically adjusting a CRT color monitor screen are well known and two techniques of them are disclosed in Japanese Patent Laid-open Publications No. HEI5-27689/1993 and No. HEI8-194444/1996.
The technique disclosed in HEI5-27689/1993 has a timer built in a microcomputer assigned for measuring a beginning of a picture signal part of a video signal to perform an automatic screen position adjusting operation.
The technique disclosed in HEI8-194444/1996 permits a measuring circuit with a counter for counting clocks to measure the beginning and an end of the picture signal part of the video signal and uses a result of the measurement in a microcomputer for automatic adjusting of position and size on the screen.
However, in the technique disclosed in HEI5-27689/1993, the timer built in the microcomputer provided for measuring the beginning of the picture signal part is low in the resolution of time. Assuming that the horizontal frequency is 100 kHz, the accuracy of measurement will be declined thus providing a lower accuracy in adjusting the horizontal position.
In the technique disclosed in HEI8-194444/1996, the measuring circuit is operable at a high speed and provides a high accuracy of measurement when the horizontal frequency is 100 kHz or so hence ensuring a higher accuracy in adjusting the horizontal position. The use of the high speed operable measuring circuit will however increase the overall cost.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide a method of automatically adjusting a CRT color monitor screen and a CRT color monitor in which the position and size in the horizontal frequency of 100 kHz or so are adjusted at an acceptable accuracy thus permitting the use of an inexpensive microcomputer and reducing the overall cost.
As a first feature of the present invention, it provides a method of automatically adjusting a CRT color monitor screen comprising the steps of: examining whether a location determining pulse overlaps with a picture signal part of a video signal or not while a phase of the location determining pulse is being shifted in relation to a horizontal or vertical synchronizing signal; detecting a location of the picture signal part relative to the horizontal or vertical synchronizing signal from the result of examination; and automatically adjusting at least one of horizontal position, vertical position, horizontal size, and vertical size on the screen according to the result of detection.
In the method of automatically adjusting a CRT color monitor screen according to the first feature of the present invention, when an unit of the phase shift of the location determining pulse is minimized, the accuracy of measurement can be high with the horizontal frequency of e.g. 100 kHz or so. If the shifting unit is 20 nanoseconds, the accuracy of measurement is 2% at 100 kHz of the horizontal frequency. The shifting unit can be minimized by scaling adjustment in a D/A conversion which is implemented with an inexpensive microcomputer. Also, since there is no need for detecting the state of a signal with the use of a fast sampling pulse, the inexpensive microcomputer can conduct all substantial tasks thus eliminating the use of such a high speed operable measuring circuit. Consequently, the accuracy in adjusting the position and size when the horizontal frequency is 100 kHz or so will be acceptable and the overall cost will successfully be reduced.
As a second feature of the present invention, it provides a CRT color monitor comprising: a picture signal part location detecting means for examining whether a location determining pulse overlaps with the picture signal part of a video signal or not while a phase of the location determining pulse is being shifted in relation to a horizontal synchronizing signal, and detecting a location of the picture signal part relative to the horizontal synchronizing signal from the result of examination; and an automatic position/size adjusting means for automatically adjusting horizontal position and size on a screen responsive to the result of detection of the picture signal part location detecting means.
In the CRT color monitor according to the second feature of the present invention, when the unit of the phase shift of the location determining pulse is minimized, the accuracy of measurement can be high with the horizontal frequency of e.g. 100 kHz or so. If the shifting unit is 20 nanoseconds, the accuracy of measurement is 2% at 100 kHz of the horizontal frequency. The shifting unit can be minimized by scaling adjustment in a D/A conversion which is implemented with an inexpensive microcomputer. Also, since there is no need for detecting the state of a signal with the use of a fast sampling pulse, the inexpensive microcomputer can conduct all substantial tasks thus eliminating the use of such a high speed operable measuring circuit. Consequently, the accuracy in adjusting the position and size when the horizontal frequency is 100 kHz or so will be acceptable and the overall cost will successfully be reduced.
As a third feature of the present invention, it provides a CRT color monitor according to the second feature, wherein the picture signal part location detecting means comprises: a comparison circuit for producing two different state outputs which represent overlap and non overlap respectively between the location determining pulse and the picture signal part; a one-shot circuit for producing a pulse signal of a specific time width which is determined by a change from the non overlap state to the overlap state between the location determining pulse and the picture signal part; and a microcomputer for, while monitoring whether the pulse signal of the one-shot circuit is produced or not, shifting the phase of the location determining pulse in a direction for delaying from the horizontal synchronizing signal and, when the pulse signal is produced, assigning the current phase of the location determining pulse to the beginning of the picture signal part, and for, while monitoring whether the pulse signal of the one-shot circuit is produced or not, shifting the phase of the location determining pulse in a direction for advancing from the horizontal synchronizing signal and, when the pulse signal is produced, assigning the current phase of the location determining pulse to the end of the picture signal part.
In the CRT color monitor according to the third feature of the present invention, the comparison circuit and the one-shot circuit are added to the microcomputer then decreasing the load of operations on the microcomputer. On the other hand, the addition of the two circuits will require only a small extra cost.
As a fourth feature of the present invention, it provides a CRT color monitor according to the second or third feature, wherein the location determining pulse is a pulse signal synchronous with a collector pulse which is applied by a deflection circuit to a defecting coil.
In the CRT color monitor according to the fourth feature of the present invention, the pulse signal synchronous with the collector pulse applied by the deflection circuit to the deflecting coil is used as the location determining pulse. This allows the phase of the location determining pulse to be shifted using such an inherent arrangement of the CRT color monitor which shifts the phase of the collector pulse, hence simplifying the entire arrangement.
As a fifth feature of the present invention, it provides a CRT color monitor according to the second to fourth feature, wherein the automatic position/size adjusting means incorporates a microcomputer for
Meguro Takeyuki
Yui Mitsugi
Hsia Sherrie
Jordan and Hamburg LLP
Totoku Electric Co., Ltd.
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