CA1128653A - Video signal mixing system - Google Patents
Video signal mixing systemInfo
- Publication number
- CA1128653A CA1128653A CA339,764A CA339764A CA1128653A CA 1128653 A CA1128653 A CA 1128653A CA 339764 A CA339764 A CA 339764A CA 1128653 A CA1128653 A CA 1128653A
- Authority
- CA
- Canada
- Prior art keywords
- video signal
- blanking
- signal
- level
- mixing system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B75/00—Other engines
- F02B75/16—Engines characterised by number of cylinders, e.g. single-cylinder engines
- F02B75/18—Multi-cylinder engines
- F02B75/20—Multi-cylinder engines with cylinders all in one line
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F1/00—Cylinders; Cylinder heads
- F02F1/24—Cylinder heads
- F02F2001/244—Arrangement of valve stems in cylinder heads
- F02F2001/245—Arrangement of valve stems in cylinder heads the valve stems being orientated at an angle with the cylinder axis
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Picture Signal Circuits (AREA)
- Cylinder Crankcases Of Internal Combustion Engines (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A video signal mixing system in which a blanking portion is formed at a predetermined interval in a first video signal by a blanking signal, and a second video signal is inserted into the formed blanking portion of the first video signal, and in which a pedestal level of the first video signal is detected and held, and the blanking level of the blanking portion is clamped at the held pedestal level of the first video signal with the application of the blanking signal.
A video signal mixing system in which a blanking portion is formed at a predetermined interval in a first video signal by a blanking signal, and a second video signal is inserted into the formed blanking portion of the first video signal, and in which a pedestal level of the first video signal is detected and held, and the blanking level of the blanking portion is clamped at the held pedestal level of the first video signal with the application of the blanking signal.
Description
i5i3 BACI~GROUND OF TEIE INVENTION
This invention relates to a video signal mixing sys-tem, and more particularly to a video signal mixing system in which a blanking interval is formed at a predetermined portion of a video signal, and another video signal is inserted into the formed blanking interval of the video signal.
In some kinds of television receivers, a reduced picture of one channel broadcast is inserted into a picture of another channel broadcast on one screen, or letters or figures are inserted into a picture of one channel broadcast on one screen. The reduced picture, or the letters or figures to be inserted will be called "sub picture" hereinafter. The picture into which the sub picture is inserted will be called "main picture" hereinafter. Video signals for the main picture and sub picture will be called "main video signal" and "sub video signal", hereinafter respectively.
Blanking intervals are formed at predetermined por-tions of the main video signal. The sub video signal is in-serted into the formed blanking intervals. The blanking level is nearly equal to zero. Generally, pedestal levels of the -main video signal and sub video signal are different from each other. Accordingly, when the sub video signal is inserted into the blanking intervals of the main video signal, the brightnesses of the main picture and sub picture are different from each other. It is visually preferable that they are equal to each other.
,~ ~ .
' ~
~3 For example, two external variable resistors are provided for removing such differenceo In this case, the variable resistors should be individually adjusted. After one of the two variable resistors is adjusted, another of the two variable resistors~s adjusted. Or it has been considered to interconnect the two variable resistors so as to remove the above described difference. Howevex, such methods are not pre-ferable.
SU~ARY OF THE INV~NTION
Accordingly, it is an object of this invention to provide a video signal mixing system by which the above de-scribed problem can be solved.
Another object o~ this invention is to provide a video signal mixing system in which the brightnesses can be easily adjusted.
In accordance with an aspect of this invention, there is provided a video signal mixing system in which a blanking portion is formed at a predetermined interval in a first video signal by a blanking signal, and a second video signal is insert-ed into the formed blanking portion of the first video signal, and in which a pedestal level of the first video signal is detected and held, and the blanking level of the blanking portion is clamped at the held pedestal level of the first video signal with the application of the blanking signal.
~ ~%~
The above and other objects, features and advantages of this invention will be apparent in the following detailed description of illustrative embodiment which are to be read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a video signal mixing system according to the prior art;
FIG, 2A to FIG. 2E are waveforms at the respective parts of the prior art block diagram of FIG. l;
FIG. 3 is a circuit diagram of an example of a por-tion of the block diagram of FIG. l;
FIG. 4 is a block diagram of a video signal mixing system for explaining the principle of this invention;
FIG. 5A to FIG. 5G are waveforms at the respective parts of the block diagram of FIG. 4; and FIG. 6 is a circuit diagram of a video signal mixing system according to one embodiment of this invention.
` DESCRIPTION OF ~HE PREFERRED EMDODIMENTS
Before proceeding to a detailed description of the present invention and in order to enhance the understanding -thereof~ a prior art system will be described with re~erence to FIG. 1 to FIG. 3. In FIG. 1, a main video signal Sm is supplied to an input terminal 1, while a sub video signal Ss as shown in FIG. 2B is supplied to another input terminal 2.
..
~653 The main video signal S and the sub video signal S are supplied through external variable resistors 3 and 4 to a blanking cir-cuit 5 and to a switching circuit 7, respectively. When a blanking signal SB having width T as shown in FIG. 2E is supplied to a blanking input terminal 6, the main video signal Sm as shown in FIG. 2A is obtained from the blanking circuit 5, and the switching circuit 7 is closed to sample the sub video signal Ss. FIG. 3 shows one example of the blanking circuit 5.
In FIG. 3, the main video signal S is supplied to an input terminal 9. When the blanking signal SB as shown in FIG. 2E
is supplied to a base terminal of a transistor Q to turn on the latter, the main video signal Sm is muted for the time T, namely blanked to zero for the time T as shown in FIG. 2A.
The main video signal S having the blanking interval is ob-tained from an output terminal 10.
Referring again to FIG. 1, when the blanking signal SB is supplied to the input terminal 6, the main video signal Sm as shown in FIG. 2A and the sub video signal Ss sampled as shown in FIG. 2C are supplied to a mixing circuit 8. The main video signal Sm has a pedestal level Vl as shown in FIG.
2A, and the sub video signal Ss has another pedestal level V2 as shown in FIG. 2B. Generally, the pedestal levels V1 and V2 are different from each other. ~en the pedestal level Vl is lower than the other pedestal lev~l V2, a mixed video signal as shown in FI~. 2D is obtained from the mixing circuit 8, although the level of the sampled sub video signal Ss should be aligned with the level of the main video signal Sm in the mixed video signal. The external variable resistors 3 and 4 should be adjusted to remove the difference between the pedestal levels Vl and V2, ', ,- . ; .
;3 Next, the principle of this invention will be de-scribed with reference to FIG. 4 and FIG. 5.
In FIG. 4, the ~lain video signal Sm is supplied to an input terminal 12, while the sub viaeo signal S is supplied to another input terminal 13. The main video signal Sm is supplied through an external variable resistor 14 to a blanking and clamping circuit 17. The sub video signal S is supplied to a subtracter 16. Further, a DC voltage V2 taken out from a potentiometer 15, as shown in FIG. 5D, is supplied to the subtracter 16. The DC voltage V2 is equal to the pedestal level V2 of the sub video signal Ss. An output terminal of the sub-tractor 16 is connected through a switching circui~ 19 to a mixing circuit 20. Further, the blanking and clamping circuit 17 is connected to the mixing circuit 20. A blanking signal SB is supplied to an input terminal 18.
When the blanking signal SB as shown in FIG. 5G is supplied to the input terminal 18, the main video signal Sm as shown in FIG. 5A is obtained from the blanking and clamping eircuit 17. As shown in FIG. 5, the blanking level of the blanked portion of the main video signal Sm is clamped at the pedestal level Vl. The DC voltage V2 is subtracted from the sub video signal Ss as shown in FIG. 5B by the sub-tractor 16.
As a result, only a variable signal component higher than the pedestal level V2 of the sub video signal Ss is supplied to the switching circuit 19. When the switching circuit 19 is elosed with the blanking signal SB~ the variable signal compo-nent of the sub video signal S is sampled, as shown in FIG.
;$3 5E, and is supplied to the mixing circuit 20. The sampled variable signal component of the sub video signal S is inserted into the formed blanking interval BLK of tlle main video signal Sm, in the mixing circuit 20. As a result, the mixed video signal as shown in FIG. 5F is obtained from the mixing circuit 20. As shown in FIG. 5F, the levels of the main and sub video signals Sm and Ss are aligned with each other.
Next, an embodiment based on the above-described principle of this invention will he described with reference to FIG. 6.
In FIG. 6, a main video signal Sm is applied through an input terminal 23 to a base of a transistor Ql An emitter of the transistor Ql is connected to a transistor Q2~ and through a resistor Rl to a transistor Q8' The main video signal Sm obtained from the transistor Q8 is applied through a resistor R2 to a transistor Qlo to be amplified by the latter. The amplified video signal is taken out from an output ~erminal 24.
On the other hand, a sub video signal Ss is applied to a sub video signal input terminal 25 at the blanking time of the main video signal Sm as shown in FIG. 5A. The sub video signal Ss is supplied through a transistor Qll to a base of another transistor Qg constituting a variable constant current source, and it is inserted into the blanking period of the main video signal Sm through the transistor Qg.
A clamp pulse Sc occurring at the pedestal period of the main video signal Sm is applied to an input terminal 26 . ~, ~ , : , : :
L2~3 For example, the clamp pulse S may be obtained by retarding the horizontal synchronizing signal to the pedestal perlod. While the clamp pulse Sc is supplied to the input -terminal 26, a transistor Q4 is in the conductive state. The transistors Q2 and Q3 constitute a differential amplifier, and are put in the active state. An output in accordance with the pedestal level of the main video signal is obtained from the transistor Q2' and is smoothed by a capacitor Cl. The smoothed output is amplified by a transistor Q5. The output o the transistor Q5 is smoothed at a point ~ by ano~her capacitor C2. The smoothed output is applied as a base voltage V~3 to the transistor Q3~ Accordingly, whenever the clamp pulse S is supplied to the input terminal 26, the pedestal level is compared with the base voltage VB3.
A feed-back loop is formed so that the difference between the pedestal level and the base volta~e VB3 becomes equal to zero.
As the result, the base voltage VB3 is clamped at the pedestal level, and it is supplied through a transistor Q6 to a cathode of a diode Dl. In that condition, when the blanking signal SB
is supplied to an input terminal 27, the transistor Q7 becomes conductive. Accordingly, a voltage at point ~ connected to a base o the transistor Q8' namely the collector voltage of the transistor Q7, becomes nearly equal to the base voltage VB3 clamped at the pedestal level. The voltage VB3 is applied through the transistor Q6 as an emitter ollower to the cathode of the diode Dl. The VBE o the transistor Q6 is cancelled by the diode Dl. As a result, the voltage V on the point ~
becomes nearly equal to VB3. When the blanking signal SB is . .
. ;~
supplied to the base of the transistor Q7, the main video signal Sm is blanked by the voltage drop across the resistor R1.
As a result, the main video signal Sm having the blanking interval sLK, whose blanking level is nearly equal to the pedestal level Vl, is obtained from the transis~or Q8' as shown in FIG. SA.
The sub video signal Ss sampled by the blanking sig-nal SB, as shown in FIG. 5C, is supplied to the input terminal ~5. The output of the transistor Q11~ to the base of which the sampled sub video signal Ss is supplied, is controlled by a variable resistor VR corresponding to the potentiometer 15 of FIG. 4. The transistor Qg functions as the constant current source, Accordingly, the alternating or signa~ components of the sampled sub video signal S as shown in FIG. 5E are obtain-ed as the voltage drop of the resistor R2 at the collector of the transistor Qg. ~hus, the alternating components of the `~
sampled sub video signal S5 are inserted into the blanking interval BLK of the main video signal Sm, as shown in FIG, 5F.
According to this invention, the brightnesses of the pictures of the main and sub video signals Sm and Ss can be simultaneously adjusted~ In the above description, the voltage to be subtracted from the sub video signal Ss is equal to the pedestal level of the sub video signal Ss. However, as occasion demands, the voltage to be subtracted may be different from the ~edestal level of the sub video signal Ss.
``'' O'~ V
Although various minor modifications may be suggested by those versed in the art, it should he understood that I wish to embody within the scope of the patent warranted hereon, all such embodiments as reasonably and properly come within the scope of my contribution to the art.
_ g _
This invention relates to a video signal mixing sys-tem, and more particularly to a video signal mixing system in which a blanking interval is formed at a predetermined portion of a video signal, and another video signal is inserted into the formed blanking interval of the video signal.
In some kinds of television receivers, a reduced picture of one channel broadcast is inserted into a picture of another channel broadcast on one screen, or letters or figures are inserted into a picture of one channel broadcast on one screen. The reduced picture, or the letters or figures to be inserted will be called "sub picture" hereinafter. The picture into which the sub picture is inserted will be called "main picture" hereinafter. Video signals for the main picture and sub picture will be called "main video signal" and "sub video signal", hereinafter respectively.
Blanking intervals are formed at predetermined por-tions of the main video signal. The sub video signal is in-serted into the formed blanking intervals. The blanking level is nearly equal to zero. Generally, pedestal levels of the -main video signal and sub video signal are different from each other. Accordingly, when the sub video signal is inserted into the blanking intervals of the main video signal, the brightnesses of the main picture and sub picture are different from each other. It is visually preferable that they are equal to each other.
,~ ~ .
' ~
~3 For example, two external variable resistors are provided for removing such differenceo In this case, the variable resistors should be individually adjusted. After one of the two variable resistors is adjusted, another of the two variable resistors~s adjusted. Or it has been considered to interconnect the two variable resistors so as to remove the above described difference. Howevex, such methods are not pre-ferable.
SU~ARY OF THE INV~NTION
Accordingly, it is an object of this invention to provide a video signal mixing system by which the above de-scribed problem can be solved.
Another object o~ this invention is to provide a video signal mixing system in which the brightnesses can be easily adjusted.
In accordance with an aspect of this invention, there is provided a video signal mixing system in which a blanking portion is formed at a predetermined interval in a first video signal by a blanking signal, and a second video signal is insert-ed into the formed blanking portion of the first video signal, and in which a pedestal level of the first video signal is detected and held, and the blanking level of the blanking portion is clamped at the held pedestal level of the first video signal with the application of the blanking signal.
~ ~%~
The above and other objects, features and advantages of this invention will be apparent in the following detailed description of illustrative embodiment which are to be read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a video signal mixing system according to the prior art;
FIG, 2A to FIG. 2E are waveforms at the respective parts of the prior art block diagram of FIG. l;
FIG. 3 is a circuit diagram of an example of a por-tion of the block diagram of FIG. l;
FIG. 4 is a block diagram of a video signal mixing system for explaining the principle of this invention;
FIG. 5A to FIG. 5G are waveforms at the respective parts of the block diagram of FIG. 4; and FIG. 6 is a circuit diagram of a video signal mixing system according to one embodiment of this invention.
` DESCRIPTION OF ~HE PREFERRED EMDODIMENTS
Before proceeding to a detailed description of the present invention and in order to enhance the understanding -thereof~ a prior art system will be described with re~erence to FIG. 1 to FIG. 3. In FIG. 1, a main video signal Sm is supplied to an input terminal 1, while a sub video signal Ss as shown in FIG. 2B is supplied to another input terminal 2.
..
~653 The main video signal S and the sub video signal S are supplied through external variable resistors 3 and 4 to a blanking cir-cuit 5 and to a switching circuit 7, respectively. When a blanking signal SB having width T as shown in FIG. 2E is supplied to a blanking input terminal 6, the main video signal Sm as shown in FIG. 2A is obtained from the blanking circuit 5, and the switching circuit 7 is closed to sample the sub video signal Ss. FIG. 3 shows one example of the blanking circuit 5.
In FIG. 3, the main video signal S is supplied to an input terminal 9. When the blanking signal SB as shown in FIG. 2E
is supplied to a base terminal of a transistor Q to turn on the latter, the main video signal Sm is muted for the time T, namely blanked to zero for the time T as shown in FIG. 2A.
The main video signal S having the blanking interval is ob-tained from an output terminal 10.
Referring again to FIG. 1, when the blanking signal SB is supplied to the input terminal 6, the main video signal Sm as shown in FIG. 2A and the sub video signal Ss sampled as shown in FIG. 2C are supplied to a mixing circuit 8. The main video signal Sm has a pedestal level Vl as shown in FIG.
2A, and the sub video signal Ss has another pedestal level V2 as shown in FIG. 2B. Generally, the pedestal levels V1 and V2 are different from each other. ~en the pedestal level Vl is lower than the other pedestal lev~l V2, a mixed video signal as shown in FI~. 2D is obtained from the mixing circuit 8, although the level of the sampled sub video signal Ss should be aligned with the level of the main video signal Sm in the mixed video signal. The external variable resistors 3 and 4 should be adjusted to remove the difference between the pedestal levels Vl and V2, ', ,- . ; .
;3 Next, the principle of this invention will be de-scribed with reference to FIG. 4 and FIG. 5.
In FIG. 4, the ~lain video signal Sm is supplied to an input terminal 12, while the sub viaeo signal S is supplied to another input terminal 13. The main video signal Sm is supplied through an external variable resistor 14 to a blanking and clamping circuit 17. The sub video signal S is supplied to a subtracter 16. Further, a DC voltage V2 taken out from a potentiometer 15, as shown in FIG. 5D, is supplied to the subtracter 16. The DC voltage V2 is equal to the pedestal level V2 of the sub video signal Ss. An output terminal of the sub-tractor 16 is connected through a switching circui~ 19 to a mixing circuit 20. Further, the blanking and clamping circuit 17 is connected to the mixing circuit 20. A blanking signal SB is supplied to an input terminal 18.
When the blanking signal SB as shown in FIG. 5G is supplied to the input terminal 18, the main video signal Sm as shown in FIG. 5A is obtained from the blanking and clamping eircuit 17. As shown in FIG. 5, the blanking level of the blanked portion of the main video signal Sm is clamped at the pedestal level Vl. The DC voltage V2 is subtracted from the sub video signal Ss as shown in FIG. 5B by the sub-tractor 16.
As a result, only a variable signal component higher than the pedestal level V2 of the sub video signal Ss is supplied to the switching circuit 19. When the switching circuit 19 is elosed with the blanking signal SB~ the variable signal compo-nent of the sub video signal S is sampled, as shown in FIG.
;$3 5E, and is supplied to the mixing circuit 20. The sampled variable signal component of the sub video signal S is inserted into the formed blanking interval BLK of tlle main video signal Sm, in the mixing circuit 20. As a result, the mixed video signal as shown in FIG. 5F is obtained from the mixing circuit 20. As shown in FIG. 5F, the levels of the main and sub video signals Sm and Ss are aligned with each other.
Next, an embodiment based on the above-described principle of this invention will he described with reference to FIG. 6.
In FIG. 6, a main video signal Sm is applied through an input terminal 23 to a base of a transistor Ql An emitter of the transistor Ql is connected to a transistor Q2~ and through a resistor Rl to a transistor Q8' The main video signal Sm obtained from the transistor Q8 is applied through a resistor R2 to a transistor Qlo to be amplified by the latter. The amplified video signal is taken out from an output ~erminal 24.
On the other hand, a sub video signal Ss is applied to a sub video signal input terminal 25 at the blanking time of the main video signal Sm as shown in FIG. 5A. The sub video signal Ss is supplied through a transistor Qll to a base of another transistor Qg constituting a variable constant current source, and it is inserted into the blanking period of the main video signal Sm through the transistor Qg.
A clamp pulse Sc occurring at the pedestal period of the main video signal Sm is applied to an input terminal 26 . ~, ~ , : , : :
L2~3 For example, the clamp pulse S may be obtained by retarding the horizontal synchronizing signal to the pedestal perlod. While the clamp pulse Sc is supplied to the input -terminal 26, a transistor Q4 is in the conductive state. The transistors Q2 and Q3 constitute a differential amplifier, and are put in the active state. An output in accordance with the pedestal level of the main video signal is obtained from the transistor Q2' and is smoothed by a capacitor Cl. The smoothed output is amplified by a transistor Q5. The output o the transistor Q5 is smoothed at a point ~ by ano~her capacitor C2. The smoothed output is applied as a base voltage V~3 to the transistor Q3~ Accordingly, whenever the clamp pulse S is supplied to the input terminal 26, the pedestal level is compared with the base voltage VB3.
A feed-back loop is formed so that the difference between the pedestal level and the base volta~e VB3 becomes equal to zero.
As the result, the base voltage VB3 is clamped at the pedestal level, and it is supplied through a transistor Q6 to a cathode of a diode Dl. In that condition, when the blanking signal SB
is supplied to an input terminal 27, the transistor Q7 becomes conductive. Accordingly, a voltage at point ~ connected to a base o the transistor Q8' namely the collector voltage of the transistor Q7, becomes nearly equal to the base voltage VB3 clamped at the pedestal level. The voltage VB3 is applied through the transistor Q6 as an emitter ollower to the cathode of the diode Dl. The VBE o the transistor Q6 is cancelled by the diode Dl. As a result, the voltage V on the point ~
becomes nearly equal to VB3. When the blanking signal SB is . .
. ;~
supplied to the base of the transistor Q7, the main video signal Sm is blanked by the voltage drop across the resistor R1.
As a result, the main video signal Sm having the blanking interval sLK, whose blanking level is nearly equal to the pedestal level Vl, is obtained from the transis~or Q8' as shown in FIG. SA.
The sub video signal Ss sampled by the blanking sig-nal SB, as shown in FIG. 5C, is supplied to the input terminal ~5. The output of the transistor Q11~ to the base of which the sampled sub video signal Ss is supplied, is controlled by a variable resistor VR corresponding to the potentiometer 15 of FIG. 4. The transistor Qg functions as the constant current source, Accordingly, the alternating or signa~ components of the sampled sub video signal S as shown in FIG. 5E are obtain-ed as the voltage drop of the resistor R2 at the collector of the transistor Qg. ~hus, the alternating components of the `~
sampled sub video signal S5 are inserted into the blanking interval BLK of the main video signal Sm, as shown in FIG, 5F.
According to this invention, the brightnesses of the pictures of the main and sub video signals Sm and Ss can be simultaneously adjusted~ In the above description, the voltage to be subtracted from the sub video signal Ss is equal to the pedestal level of the sub video signal Ss. However, as occasion demands, the voltage to be subtracted may be different from the ~edestal level of the sub video signal Ss.
``'' O'~ V
Although various minor modifications may be suggested by those versed in the art, it should he understood that I wish to embody within the scope of the patent warranted hereon, all such embodiments as reasonably and properly come within the scope of my contribution to the art.
_ g _
Claims (7)
1. A method for operating a video signal mixing system, comprising: forming a blanking portion at a predeter-mined interval in a first video signal by a blanking signal detecting and holding a pedestal level of said first video signal and clamping a blanking level of said blanking portion at the held pedestal level of said first video signal with the application of said blanking signal; and inserting a second video signal into the formed blanking portion of the first video signal.
2. A method for operating a video signal mixing system according to claim 1 including the steps of sampling said second video signal by said blanking signal, and insert-ing the sampled second video signal into said blanking portion of the first video signal.
3. A method for operating a video signal mixing system according to claim 2 including the step of subtracting a DC voltage from said sampled second video signal.
4. A method for operating a video signal mixing system according to claim 3 including the step of providing a level of said DC voltage equal to the pedestal level of said second video signal.
5. A method for operating a video signal mixing system according to claim 1 including the step of subtracting a DC voltage from said second video signal, sampling said second video signal by said blanking signal, and inserting the sampled video signal into said blanking portion of the first video signal.
6. A method for operating a video signal mixing system according to claim 5 including the step of providing a level of said DC voltage equal to the pedestal level of said second video signal.
7. A video signal mixing system, comprising: blank-ing means for forming a blanking portion at a predetermined interval in a first video signal by a blanking signal; clamping means for detecting and holding a pedestal level of said first video signal and clamping a blanking level of said blanking portion at the held pedestal level of said first video signal with the application of said blanking signal; and means for inserting a second video signal into the formed blanking por-tion of the first video signal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP145108/78 | 1978-11-24 | ||
| JP14510878A JPS5572625A (en) | 1978-11-24 | 1978-11-24 | Cooling apparatus for internal combustion engine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1128653A true CA1128653A (en) | 1982-07-27 |
Family
ID=15377557
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA339,764A Expired CA1128653A (en) | 1978-11-24 | 1979-11-13 | Video signal mixing system |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS5572625A (en) |
| CA (1) | CA1128653A (en) |
-
1978
- 1978-11-24 JP JP14510878A patent/JPS5572625A/en active Pending
-
1979
- 1979-11-13 CA CA339,764A patent/CA1128653A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5572625A (en) | 1980-05-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |