Television – Format conversion – Conversion between standards with different aspect ratios
Reexamination Certificate
1998-06-15
2002-06-11
Kostak, Victor R. (Department: 2711)
Television
Format conversion
Conversion between standards with different aspect ratios
C348S556000
Reexamination Certificate
active
06404458
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for converting a screen aspect ratio, and particularly to an improved apparatus for converting a screen aspect ratio, which is capable of horizontally compressing a 4:3 video signal and horizontally extending a 2:1 video signal by varying the scanning line of a screen, when a wide screen television having a 16:9 aspect ratio receives a 4:3 video signal or a 2:1 video signal.
2. Description of Related Art
Generally, in the national television system committee (NTSC) and the phase alternating line (PAL), a letter box type signal is transmitted by forming a low band image as much as 3/4 of the original active region (the effective image region) and blacking the upper and lower portions or the left- and right-side portions of the screen of the television.
The transmission of the letter box signal is directed to displaying the image having a screen aspect ratio of 16:9 on the screen of the television having a 4:3 screen aspect ratio without torsion of the image.
However, as the wide screen television having a screen aspect ratio of 16:9 is introduced, it is needed to display the image of a screen aspect ratio of 4:3 on the wide screen television having a screen aspect ratio of 16:9.
Therefore, the television broadcasting station concurrently transmits a 4:3 aspect ratio program in order for the television having a function of receiving a 4:3 aspect ratio screen signal and the television having a function of receiving a 16:9 aspect ratio screen signal to selectively receive a corresponding television program transmitted from the television broadcasting station.
In addition, the television is equipped with a device for automatically detecting a wide screen signal (WSS) which is referred to the 4:3 program or the 16:9 program. Here, the screen of the television should be varied in accordance with the received signal.
However, in order to receive the 4:3 program transmitted from the television broadcasting station on the wide screen television having an aspect ratio of 16:9, it is necessary to horizontally compress the scanning line of the screen, and when receiving the 2:1 cinema signal, the scanning line of the screen should be horizontally extended.
FIG. 1
shows the conventional apparatus for converting a screen aspect ratio, which is directed to displaying the 4:3 video signal or the 2:1 cinema video signal on the wide screen television having the 16:9 screen aspect ratio.
As shown therein, there are provided a clock generator
102
for generating a clock signal CLK
1
when a horizontal synchronous signal Hsy is inputted thereto through a synchronous input terminal
101
for a horizontal compression and expansion, a clock counter
103
for counting the clock signal CLK
1
generated by the clock generator
102
and for outputting the counted value, an elimination image range judging unit
104
for comparing the previously set reference value with the clock counting value of the clock counter
103
, eliminating as much as 1/18 of the image of the left-side and right-side image in the 16:9 screen in accordance with the comparison result, and generating a clock selection control signal S
1
and a writing enable signal WE so as to display the 2:1 cinema video signal, an effective image range judging unit
105
for comparing the clock counting value of the clock counter
103
with the previously set reference value, judging the effective image range value and the horizontal scanning line range in accordance with the comparison result, and generating a clock selection control signal S
2
and a side panel selection control signal SPC for horizontally compressing the image in accordance with the judging result, a frequency multiplier
106
for multiplying the clock signal CLK
1
outputted form the clock generator
102
by 4/3 and for generating a clock signal CLK
2
, a frequency multiplier
107
for multiplying the clock signal CLK
1
generated by the clock generator
102
by 8/9 and for generating a clock signal CLK
3
, a clock selector
108
for being switched in accordance with a control signal S
1
generated by the elimination image range judging unit
104
and for selecting either the clock signal CLK
1
of the clock generator
102
or the clock signal CLK
3
of the frequency multiplier
107
, a clock selector
109
for being switched in accordance with the clock selection control signal S
2
generated by the effective image range judging unit
105
and for selecting either the clock signal CLK
2
which is multiplied by 4/3 by the frequency multiplier
106
or the clock signal selected by the clock selector
108
, an edge detector
110
for detecting a rising edge of the horizontal synchronous signal Hsy outputted from the synchronous input terminal
101
and for generating a reset signal RST whenever the rising edge is detected, a line memory unit
111
for being enabled in accordance with a writing enable signal WE generated by the elimination image range judging unit
104
, receiving the clock signal CLK
1
generated by the clock generator
102
as the writing clock signal, receiving the clock signal selected by the clock selector
108
as a reading clock signal, storing and outputting the digital image data of 8 bits inputted thereto through the image input terminal
100
at every line, being reset in accordance with the reset signal RST generated by the edge detector
110
, and writing/reading the image data of the next line, a line memory unit
112
for receiving the clock signal selected by the clock selector
108
as a reading clock signal, storing and outputting the image data outputted from the line memory unit
111
at every horizontal line, being reset in accordance with a reset signal RST generated by the edge detector
110
and for writing/reading the image data of the next line, and a side panel insertion until
113
for outputting the horizontally converted digital image data through the output terminal
114
by inserting a luminance level value of a temporary side panel to the image data which is inputted thereto at every line from the line memory unit
112
in accordance with a side panel selection control signal SPC of the effective image range judging unit
105
.
The operation of the conventional apparatus for converting a screen aspect ratio will now be explained with reference to the accompanying drawings.
First, the horizontal compression process of the television image will now be first described with reference to FIG.
2
A.
When the horizontal synchronous signal Hsy is inputted into the clock generator
102
through the synchronous input terminal
101
, the clock generator
102
generates the clock signal CLK
1
whenever the horizontal synchronous signal Hsy is inputted from the synchronous input terminal
101
so as to horizontally compress the digital image data inputted thereto through the image input terminal
100
and then outputs the clock signal CLK
1
to the clock counter
103
, the frequency multipliers
106
and
107
, the clock selector
108
and the line memory unit
111
, respectively.
The frequency multiplier
106
multiplies the clock signal CLK
1
inputted from the clock generator
102
by 4/3, generates the clock signal CLK
2
, and outputs the clock signal CLK
2
to the clock generator
109
.
The frequency multiplier
107
multiplies the clock signal CLK
1
inputted from the clock generator
102
by 8/9 and then generates the clock signal CLK
3
, and outputs the clock signal CLK
3
to the clock generator
108
.
In addition, the clock counter
103
counts the start portion of the clock signal CLK
1
inputted from the clock generator
102
at every line, and outputs the counted value to the elimination image range judging unit
104
and the effective image range judging unit
105
, respectively.
The elimination image range judging unit
104
compares the value counted by the clock counter
103
with the previously set reference value so as not to eliminate the left and right sides of the image when the screen aspect ratio is 4:3, generates the cl
Birch & Stewart Kolasch & Birch, LLP
Kostak Victor R.
LG Electronics Inc.
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