CA1091799A - Electronic switch for use in television - Google Patents
Electronic switch for use in televisionInfo
- Publication number
- CA1091799A CA1091799A CA258,460A CA258460A CA1091799A CA 1091799 A CA1091799 A CA 1091799A CA 258460 A CA258460 A CA 258460A CA 1091799 A CA1091799 A CA 1091799A
- Authority
- CA
- Canada
- Prior art keywords
- flop
- flip
- capacitor
- logic
- electronic switch
- 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
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Abstract
ABSTRACT:
An electronic switch for use in television which is provided with a master-slave flip-flop which com-prises a trigger input for supplying a switching signal which occurs at the field frequency and which has a switching pulse edge which occurs in field blanking times and with a condition input to which a capacitor-charging-discharging circuit is connected which circuit comprises a push-button switch which has one stable state only.
An electronic switch for use in television which is provided with a master-slave flip-flop which com-prises a trigger input for supplying a switching signal which occurs at the field frequency and which has a switching pulse edge which occurs in field blanking times and with a condition input to which a capacitor-charging-discharging circuit is connected which circuit comprises a push-button switch which has one stable state only.
Description
1~91~9 P~N 8105 The invention relates to an electronic switch for use in television provided with a flip-flop which comprises an input for the supply of a switching signal occurring at the field frequency having a switching pulse edge occurring in field blanking times and with a capacitor-charging-discharging circuit which is connected to the flip-flop and which comprises a push-button switch, having one stable state only, a voltage source, a capacitor and charge-dis-charge resistors.
Such an electronic switch is described in United States Patent Specification 3,519,739. It is stated that the electronic switch can be used in, for example, television recording equipment, in particular in camera control-and signal processing equipment, for example for switching over from a picture display device from a camera signal to another camera signal. This switch-over takes place in a field blanking time to prevent a picture interference from being introduced in the display device. It is furthermore stated that the electronic switch is provided with a plurality of flip-flops, for example three, each comprising two inputs between which mutually interconnected networks of diodes and resistors have been applied. When one of these push-buttons is depressed the associated (first) flip-flop is adjusted to a given, desired state (if it is not in this state already).
Thereafter, depressing another push-button adjusts its associated flip-flop to the desired state, whilst the first flip-flop changes back simultaneously to the other state.
Such an electronic switch is described in United States Patent Specification 3,519,739. It is stated that the electronic switch can be used in, for example, television recording equipment, in particular in camera control-and signal processing equipment, for example for switching over from a picture display device from a camera signal to another camera signal. This switch-over takes place in a field blanking time to prevent a picture interference from being introduced in the display device. It is furthermore stated that the electronic switch is provided with a plurality of flip-flops, for example three, each comprising two inputs between which mutually interconnected networks of diodes and resistors have been applied. When one of these push-buttons is depressed the associated (first) flip-flop is adjusted to a given, desired state (if it is not in this state already).
Thereafter, depressing another push-button adjusts its associated flip-flop to the desired state, whilst the first flip-flop changes back simultaneously to the other state.
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It appears that a flip-flop cannot change back to the other state by simply depressing the associated push-button for the second time, but that another push-button must be depressed for that purpose. Thus an essential electronic lock is formed between the flip-flops.
It is an object of the invention to realise an electroni~ switch which can also be constructed with one flip-flop only so that a lock or an associated push-button switch is not required and a specific diode-resistor network need not be applied but a normal, commercially available module can be used directly.
The electronic switch according to the invention is therefore characterized in that the flip-flop is constructed as a master-slave flip-flop provided with a trigger input for supplying the switching signal and with at least a condition input which is connected to the capacitor-charging-discharging circuit The invention will be further explained with reference to the Figures given as non-limitative example, where Fig. 1 is a circuit diagram of an electronic switch according to the invention and Fig. 2 shows some signals produced as a function of the time to illustrate the operation of the switch shown in Fig. 1.
The electronic switch as shown in Fig. 1 is provided with a master-slave flip-flop 1 of the JK type and is, for example, of a type 7SN7476. The flip-flop 1 has a trigger input T, two condition inputs J and K, a setting input Sl and 10917~ PHN 8105 a resetting input S2. Furthermore, there are two outputs Ql and Q2 at which inverse signals are present. It applies to the operation of the master-slave flip-flop 1 that the information at the J- and K inputs are entered into the , 5 master (the master has a change in state) when the T input is high, that is to say that in the positive logic a logic 1 is present at the T input, which corresponds to a voltage larger than +2V. For entering the information at the J and K inputs it applies that a logic 1 which occurs for a short period at these inputs is retained in the master of the flip-flop 1 by means of the change in state. If thereafter the T input becomes low, that is to say if the logic O is present on it, which corresponds to a voltage which is smaller than + 0.8V then the information present at the master is passed on to the slave and appears at the outputs Ql and Q2 (inverted). As the inputs J and K of the flip-flop 1 are interconnected it holds for the flip-flop 1 that when a logic 0 information is present at these inputs no change occurs at the outputs Ql and Q2' whilst a logic 1 occurring for a shorter or longer period at the J and K inputs results in a ; change of the state of the master, so that passing on the information from master to slave is accompanied by a change in state of the signal at each of the outputs Ql and Q2. It applies for the setting input Sl and the resetting input S2 that when a logic 0 is applied to them the signals at the other inputs do not exercise any influence anymore and that the logic 1 or the logic 0 is found at the output Ql To operate the master-slave flip-flop 1 the T
input is connected to an input terminal 2 for supplying a 1~917~ PHN 8105 switching signal which is plotted as signal T in Fig. 2 as a logic 0 and 1 as a function of the time t. The logic 1 represents a voltage which exceeds 2V as threshold value and the logic 0 represents a voltage lower than + 0.8 V as threshold value. The portion TV in the signal T denotes a television field period of a duration of, for example, 20 or 16.6 ms. Switching pulses of short duration having the logic 0 occur in the signal T with a duration TT of, for example, approximately 4.5 /us. The periods of duration TT
are assumed to occur in the field blanking times which occupy approximately 1.5 ms of the field periods TV. From the preceding it follows that a passing on of information can be effected at the flip-flop 1 under the control of the leading edges of the switching pulses of the duration TT
whilst a change from the logic 1 to the logic 0 occurs.
The occurrence of the said leading edges which may operate as switching pulse edges in the field blanking periods prevent picture interferences from occurring in the television display.
The resetting input S2 is connected to an input terminal 3 for a possible supply of a blocking signal which contains the logic 0. As a result of internal couplings a logic 1 is present at floating, non-connected inputs Sl and S2. The output Ql of the flip-flop 1 is connected to an output terminal 4 of the electronic switch shown in Fig. 1.
Camera control and signal processing equipment and video switching equipment may be connected to the output terminal 4 for supplying a switching signal to it. The interconnected inputs J and K of the flip-flop 1 are connected to ground .
1~)91799 .
through a resistor 5 and are connected via a capacitor 6 to a fixed contact 7 of a push-button switch 8 which has two further switching contacts 9 and 10. The push-button switch 8 is of a type which has only one stable state (9) that is to say that when no pressure is exerted at, for example, a push-button of the switch 8 the latter invariabl~ connects through the switching contact 9 and the switching contact 10 is only connected through in case pressure is exerted, which consequently results in a non-stable state (10). The switching contact 9 is connected to ground via a resistor 11. The switching contact 10 is connected to a terminal, which carries a positive voltage, of a voltage source 12 another terminal of which is connected to ground. The volt-age source 12 supplies, for example, a voltage of +5 V.
Together with the push-button switch 8, the voltage source 12 and the charge-discharge resistors 5 and 11 the capacitor 6 constitutes a capacitor-charging-discharging circuit t5-12) which produces at the inputs J and K of the master-slave flip-flop 1 a signal voltage as shown in Fig.
2 in a signal J = K. At an instant to the push-button switch 8 is operated which causes the switching contact 10 to be interconnected and the discharge capacitor 6 to be charged via the resistor 5 by means of a current surge from the voltage source 12. At the instant to a voltage peak occurs at the inp~ts J and K which has a value of +5 V
which exceeds the threshold value (+2V) of the logic 1, so that with the logic 1 in the signal T the logic 1 is entered and retained in the master of the flip-flop 1 by means of the change in state of the master which is shown in Fig. 2 1~917~g PHN 810S
by a signal JKM starting from a stable state with the logic 0 on the master and therefore at the Ql output which has to follow the master. After the instant to a voltage drop occurs across the resistor 5 owing to the decrease in cur-rent. After some time the capacitor 6 is charged so that in the signal J = K the ground potential is found which is situated below the threshold value (+0.8V) of the logic 0.
In the signal T of Fig. 2 a pulse edge occurs at an instant tl which goes from the logic 1 to 0 whilst the logic 1 is present in the master of the flip-flop 1 (the signal JKM of Fig. 2). This causes the Ql (and Q2) output of the flip-flop 1 to change state. In Fig. 2 a signal Ql has been plotted in which, starting from the situation where the logic 0 is found at the Ql output the logic 1 of the master appears at this output.
At the signal J = K of Fig. 2 an instant t3 is indicated which denotes the moment at which pressure is no longer exercised on the push-button switch 8 of Fig. 1.
This causes the push-button switch 8 to change back to the stable state with the interconnected switching contact 9.
The capacitor 6 discharges across the resistors 5 and 11 with a current surge as drawn in Fig. 2 at the instant t3 in the signal J = K.
It appears that depressing the push-button switch 8 at the instant to causes the signal at the Ql output of the flip-flop 1 to change state at the instant tl. As an indication for the user of the electronic switch as shown in Fig. 1 that a switch-over action has been effected, owing to which the video switching equipment connected to the out-' ~ ' , .' ' ,' ~:
,. : ~
-~91799 PHN 8105 put terminal 4 is switched on an indication circuit having a lamp 13 is connected to the Ql output. The lamp 13 is included between a terminal of a voltage source 14 and the collector of a npn transistor 15 whose base is connected to the Ql output of the flip-flop T via a resistor 16. The emitter of the transistor 15 and another terminal of the voltage source 14 are connected to ground. The positive voltage at the Ql output of the flip-flop 1 which corres-ponds with the logic 1 causes the lamp to light up.
The importance of the use of the capacitor-charging-discharging circuit (5-12) is illustrated by means -of Fig. 2. A trailing pulse edge occurs in the signal T
of Fig. 2 at an instant T4. It is assumed that at a sub-sequent instant t5 the push-button switch 8 of Fig. 1 is operated. The fact that the voltage in the signal J = K
passes the threshold value associated with the logic 1 now has no consequences for the master in the flip-flop 1 as the logic 0 occurs in the signal T until an instant t6. The occurrence of the logic 1 in the signal T at the instant t6 results in that the logic 1 still present in the signal J = K causes the master of the flip-flop 1 to change state as plotted at the signal JKM. The fact that the push-button switch 8 switches to the stable state (9) at an instant t7 has no consequences for the flip flop 1. This instant might as well occur earlier or later. In the signal T the next switching pulse edge occurs at an instant t8 so that, as described at the instant tl when the logic 1 is present in the master the flip-flop 1 changes state i.e. the Ql output becomes logic 0 as provided by the master. It . ~ ~ , . : . .
.
:
1~91799 PHN 8105 appears that the charging time constants of the capacitor-charging-discharging circuit (5-12) and the voltage of the voltage source 12 must be chosen such that after the push-button switch 8 has been depressed the logic 1 is still available for a period of time of approximately the pulse duration TT of 4.5/us. By way of illustration it should be noted that when a capacitor 6 of 22 nF is used and when the charging resistor 5 has a value of 220 Ohm this results in a charging time constant of 4.84 /us which gives for a voltage of +5V for the voltage source 12 and the threshold value of +2V for the logic 1 that the logic 1 occurs for approximately 4.43 /us after the push-button switch 8 has been operated.
The period of time the logic 1 pulse t4.43 /us) is produced shall not exceed the pulse duration TT (4.5 /us) of ; the switching pulses in the signal T. Otherwise, when pulse edge occurs just before the instant t4 the logic 1 causes the flip-flop 1 to change state at the instant t6 whilst the logic 1 still present after the instant t6 causes a second change of state, that is to say a change back at the instant t8. To prevent this change back the duration of the logic 1 pulse in the signal J = K must be smaller than the pulse duration TT but it should approach it as closely as possible as otherwise when the push-button switch 8 is depressed just after the instant t4 the logic 1 is no longer available at the instant t6 so that pushing the button has no effect.
For completeness it should be noted that the value of the resistor 11 or 16 respectively is, for example, 470 or 4700 ohms respectively, the voltage source 14 has a volt-: ~
1~91799 PHN 8105 age of +12V and the lamp 13 is a lamp of approximately 0.2 watts.
The input terminal 3 for supplying a blocking signal can be used to prevent that the electronic switch as shown in Fig. 1 carries, when the push-button switch 8 is ~ -operated a switching signal at the output 4 when this is -not allowed for some reason or other. This may, for example, be the case in video switching equipment in which there is no synchronisation between two video signals to be mixed, the command for which is given via the switch according to Fig. 1. This command can only be given when the flip-flop 1 has been released, which is only the case at synchronization by using therefore the blocking signal.
Furthermore a mutual locking can be effected via the input terminal 3 when a plurality of the electronic switches as shown in Fig. 1 are used. So it is possible with a switching signal having a logic 1 at the output 4 to use the output Q2 of the flip-flop 1 which carries the logic 0 for connection to an input terminal 3' of another electronic switch which causes its flip-flop 1' to be blocked, a logic 0 then being present on the output terminal 4'.
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It appears that a flip-flop cannot change back to the other state by simply depressing the associated push-button for the second time, but that another push-button must be depressed for that purpose. Thus an essential electronic lock is formed between the flip-flops.
It is an object of the invention to realise an electroni~ switch which can also be constructed with one flip-flop only so that a lock or an associated push-button switch is not required and a specific diode-resistor network need not be applied but a normal, commercially available module can be used directly.
The electronic switch according to the invention is therefore characterized in that the flip-flop is constructed as a master-slave flip-flop provided with a trigger input for supplying the switching signal and with at least a condition input which is connected to the capacitor-charging-discharging circuit The invention will be further explained with reference to the Figures given as non-limitative example, where Fig. 1 is a circuit diagram of an electronic switch according to the invention and Fig. 2 shows some signals produced as a function of the time to illustrate the operation of the switch shown in Fig. 1.
The electronic switch as shown in Fig. 1 is provided with a master-slave flip-flop 1 of the JK type and is, for example, of a type 7SN7476. The flip-flop 1 has a trigger input T, two condition inputs J and K, a setting input Sl and 10917~ PHN 8105 a resetting input S2. Furthermore, there are two outputs Ql and Q2 at which inverse signals are present. It applies to the operation of the master-slave flip-flop 1 that the information at the J- and K inputs are entered into the , 5 master (the master has a change in state) when the T input is high, that is to say that in the positive logic a logic 1 is present at the T input, which corresponds to a voltage larger than +2V. For entering the information at the J and K inputs it applies that a logic 1 which occurs for a short period at these inputs is retained in the master of the flip-flop 1 by means of the change in state. If thereafter the T input becomes low, that is to say if the logic O is present on it, which corresponds to a voltage which is smaller than + 0.8V then the information present at the master is passed on to the slave and appears at the outputs Ql and Q2 (inverted). As the inputs J and K of the flip-flop 1 are interconnected it holds for the flip-flop 1 that when a logic 0 information is present at these inputs no change occurs at the outputs Ql and Q2' whilst a logic 1 occurring for a shorter or longer period at the J and K inputs results in a ; change of the state of the master, so that passing on the information from master to slave is accompanied by a change in state of the signal at each of the outputs Ql and Q2. It applies for the setting input Sl and the resetting input S2 that when a logic 0 is applied to them the signals at the other inputs do not exercise any influence anymore and that the logic 1 or the logic 0 is found at the output Ql To operate the master-slave flip-flop 1 the T
input is connected to an input terminal 2 for supplying a 1~917~ PHN 8105 switching signal which is plotted as signal T in Fig. 2 as a logic 0 and 1 as a function of the time t. The logic 1 represents a voltage which exceeds 2V as threshold value and the logic 0 represents a voltage lower than + 0.8 V as threshold value. The portion TV in the signal T denotes a television field period of a duration of, for example, 20 or 16.6 ms. Switching pulses of short duration having the logic 0 occur in the signal T with a duration TT of, for example, approximately 4.5 /us. The periods of duration TT
are assumed to occur in the field blanking times which occupy approximately 1.5 ms of the field periods TV. From the preceding it follows that a passing on of information can be effected at the flip-flop 1 under the control of the leading edges of the switching pulses of the duration TT
whilst a change from the logic 1 to the logic 0 occurs.
The occurrence of the said leading edges which may operate as switching pulse edges in the field blanking periods prevent picture interferences from occurring in the television display.
The resetting input S2 is connected to an input terminal 3 for a possible supply of a blocking signal which contains the logic 0. As a result of internal couplings a logic 1 is present at floating, non-connected inputs Sl and S2. The output Ql of the flip-flop 1 is connected to an output terminal 4 of the electronic switch shown in Fig. 1.
Camera control and signal processing equipment and video switching equipment may be connected to the output terminal 4 for supplying a switching signal to it. The interconnected inputs J and K of the flip-flop 1 are connected to ground .
1~)91799 .
through a resistor 5 and are connected via a capacitor 6 to a fixed contact 7 of a push-button switch 8 which has two further switching contacts 9 and 10. The push-button switch 8 is of a type which has only one stable state (9) that is to say that when no pressure is exerted at, for example, a push-button of the switch 8 the latter invariabl~ connects through the switching contact 9 and the switching contact 10 is only connected through in case pressure is exerted, which consequently results in a non-stable state (10). The switching contact 9 is connected to ground via a resistor 11. The switching contact 10 is connected to a terminal, which carries a positive voltage, of a voltage source 12 another terminal of which is connected to ground. The volt-age source 12 supplies, for example, a voltage of +5 V.
Together with the push-button switch 8, the voltage source 12 and the charge-discharge resistors 5 and 11 the capacitor 6 constitutes a capacitor-charging-discharging circuit t5-12) which produces at the inputs J and K of the master-slave flip-flop 1 a signal voltage as shown in Fig.
2 in a signal J = K. At an instant to the push-button switch 8 is operated which causes the switching contact 10 to be interconnected and the discharge capacitor 6 to be charged via the resistor 5 by means of a current surge from the voltage source 12. At the instant to a voltage peak occurs at the inp~ts J and K which has a value of +5 V
which exceeds the threshold value (+2V) of the logic 1, so that with the logic 1 in the signal T the logic 1 is entered and retained in the master of the flip-flop 1 by means of the change in state of the master which is shown in Fig. 2 1~917~g PHN 810S
by a signal JKM starting from a stable state with the logic 0 on the master and therefore at the Ql output which has to follow the master. After the instant to a voltage drop occurs across the resistor 5 owing to the decrease in cur-rent. After some time the capacitor 6 is charged so that in the signal J = K the ground potential is found which is situated below the threshold value (+0.8V) of the logic 0.
In the signal T of Fig. 2 a pulse edge occurs at an instant tl which goes from the logic 1 to 0 whilst the logic 1 is present in the master of the flip-flop 1 (the signal JKM of Fig. 2). This causes the Ql (and Q2) output of the flip-flop 1 to change state. In Fig. 2 a signal Ql has been plotted in which, starting from the situation where the logic 0 is found at the Ql output the logic 1 of the master appears at this output.
At the signal J = K of Fig. 2 an instant t3 is indicated which denotes the moment at which pressure is no longer exercised on the push-button switch 8 of Fig. 1.
This causes the push-button switch 8 to change back to the stable state with the interconnected switching contact 9.
The capacitor 6 discharges across the resistors 5 and 11 with a current surge as drawn in Fig. 2 at the instant t3 in the signal J = K.
It appears that depressing the push-button switch 8 at the instant to causes the signal at the Ql output of the flip-flop 1 to change state at the instant tl. As an indication for the user of the electronic switch as shown in Fig. 1 that a switch-over action has been effected, owing to which the video switching equipment connected to the out-' ~ ' , .' ' ,' ~:
,. : ~
-~91799 PHN 8105 put terminal 4 is switched on an indication circuit having a lamp 13 is connected to the Ql output. The lamp 13 is included between a terminal of a voltage source 14 and the collector of a npn transistor 15 whose base is connected to the Ql output of the flip-flop T via a resistor 16. The emitter of the transistor 15 and another terminal of the voltage source 14 are connected to ground. The positive voltage at the Ql output of the flip-flop 1 which corres-ponds with the logic 1 causes the lamp to light up.
The importance of the use of the capacitor-charging-discharging circuit (5-12) is illustrated by means -of Fig. 2. A trailing pulse edge occurs in the signal T
of Fig. 2 at an instant T4. It is assumed that at a sub-sequent instant t5 the push-button switch 8 of Fig. 1 is operated. The fact that the voltage in the signal J = K
passes the threshold value associated with the logic 1 now has no consequences for the master in the flip-flop 1 as the logic 0 occurs in the signal T until an instant t6. The occurrence of the logic 1 in the signal T at the instant t6 results in that the logic 1 still present in the signal J = K causes the master of the flip-flop 1 to change state as plotted at the signal JKM. The fact that the push-button switch 8 switches to the stable state (9) at an instant t7 has no consequences for the flip flop 1. This instant might as well occur earlier or later. In the signal T the next switching pulse edge occurs at an instant t8 so that, as described at the instant tl when the logic 1 is present in the master the flip-flop 1 changes state i.e. the Ql output becomes logic 0 as provided by the master. It . ~ ~ , . : . .
.
:
1~91799 PHN 8105 appears that the charging time constants of the capacitor-charging-discharging circuit (5-12) and the voltage of the voltage source 12 must be chosen such that after the push-button switch 8 has been depressed the logic 1 is still available for a period of time of approximately the pulse duration TT of 4.5/us. By way of illustration it should be noted that when a capacitor 6 of 22 nF is used and when the charging resistor 5 has a value of 220 Ohm this results in a charging time constant of 4.84 /us which gives for a voltage of +5V for the voltage source 12 and the threshold value of +2V for the logic 1 that the logic 1 occurs for approximately 4.43 /us after the push-button switch 8 has been operated.
The period of time the logic 1 pulse t4.43 /us) is produced shall not exceed the pulse duration TT (4.5 /us) of ; the switching pulses in the signal T. Otherwise, when pulse edge occurs just before the instant t4 the logic 1 causes the flip-flop 1 to change state at the instant t6 whilst the logic 1 still present after the instant t6 causes a second change of state, that is to say a change back at the instant t8. To prevent this change back the duration of the logic 1 pulse in the signal J = K must be smaller than the pulse duration TT but it should approach it as closely as possible as otherwise when the push-button switch 8 is depressed just after the instant t4 the logic 1 is no longer available at the instant t6 so that pushing the button has no effect.
For completeness it should be noted that the value of the resistor 11 or 16 respectively is, for example, 470 or 4700 ohms respectively, the voltage source 14 has a volt-: ~
1~91799 PHN 8105 age of +12V and the lamp 13 is a lamp of approximately 0.2 watts.
The input terminal 3 for supplying a blocking signal can be used to prevent that the electronic switch as shown in Fig. 1 carries, when the push-button switch 8 is ~ -operated a switching signal at the output 4 when this is -not allowed for some reason or other. This may, for example, be the case in video switching equipment in which there is no synchronisation between two video signals to be mixed, the command for which is given via the switch according to Fig. 1. This command can only be given when the flip-flop 1 has been released, which is only the case at synchronization by using therefore the blocking signal.
Furthermore a mutual locking can be effected via the input terminal 3 when a plurality of the electronic switches as shown in Fig. 1 are used. So it is possible with a switching signal having a logic 1 at the output 4 to use the output Q2 of the flip-flop 1 which carries the logic 0 for connection to an input terminal 3' of another electronic switch which causes its flip-flop 1' to be blocked, a logic 0 then being present on the output terminal 4'.
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Claims (5)
1. An electronic switch for use in television provided with a flip-flop which comprises an input for the supply of a switching signal occurring at the field fre-quency having a switching pulse edge occurring in field blanking times and with a capacitor-charging-discharging circuit which is connected to the flip-flop and which com-prises a push-button switch having one stable state only, a voltage source, a capacitor and charge-discharge resistors, characterized in,that the flip-flop is constructed as a master-slave flip-flop provided with a trigger input for supplying the switching signal and with at least a condition input which is connected to the capacitor-charging-discharg-ing circuit.
2. An electronic switch as claimed in Claim 1, characterized in that the switching signal occurring at the field frequency has switching pulses of a duration which just exceeds the duration of occurrence of a pulse having values which have passed a threshold value and which are supplied to the condition input of the flip-flop by the capacitor-charging-discharging circuit.
3. An electronic switch as claimed in Claim 1, characterized in that the master-slave flip-flop is of the JK type, the J and K condition inputs being interconnected and connected to the capacitor-charging-discharging circuit.
4. An electronic switch as claimed in Claim 1, 2 or 3, characterized in that of the push-button switch a switch contact associated with the stable state is connected to ground via a resistor and the switching contact associated with the non-stable state is connected to ground via a volt-age source, the fixed contact of the push-button switch being connected to ground via the capacitor and a resistor.
5. An electronic switch as claimed in Claim 1, 2 or 3, characterized in that an output of the flip-flop is connected to an indicator circuit which comprises a lamp.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA258,460A CA1091799A (en) | 1976-08-05 | 1976-08-05 | Electronic switch for use in television |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA258,460A CA1091799A (en) | 1976-08-05 | 1976-08-05 | Electronic switch for use in television |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1091799A true CA1091799A (en) | 1980-12-16 |
Family
ID=4106580
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA258,460A Expired CA1091799A (en) | 1976-08-05 | 1976-08-05 | Electronic switch for use in television |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1091799A (en) |
-
1976
- 1976-08-05 CA CA258,460A patent/CA1091799A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |