DE2409624A1 - STATION SELECTOR FOR ELECTRONIC CHANNEL SELECTOR - Google Patents

Description

Station selectors for electronic channel selectors The invention applies a station selector, especially for a television receiver with in particular one electronic channel selector.

An already developed station selector for electronic channel selectors contains switching units, the number of which corresponds to the number of the electronic channel selector corresponds to selectable or adjustable or tunable channels, each switching unit has an input, an output and a control connection. The entrance everyone Switching unit is connected to a common constant voltage source connected, and the output is via an associated voltage regulator (or a variable resistance) and a rectifier diode to a common station selector voltage input of the channel selector connected. Your control connection is via an associated Switches connected to a common DC voltage source or can be connected to a associated station selection button or station button must be connected.

To select a desired channel to be set, a corresponding switch closed or a corresponding station button by hand touched. When a switch is closed, the DC voltage is generated from the DC voltage source via the closed switch into the control connection of the associated, desired Channel corresponding switching unit fed, whereby this switching unit "switched on'1 will. When a station button is touched, an is induced in the human body Mains frequency signal or an alternating current signal from one connected to the station buttons Oscillator fever the touched button in the control connection of the associated, the desired channel corresponding switching unit fed, whereby this switching unit 'switched on'. When the switching unit is inserted, a constant voltage from the constant voltage source connected to the input of the switching units applied via this switching unit to the associated voltage regulator, and the off the constant voltage taken from the constant voltage source is converted to a suitably set, predetermined voltage unset that corresponds to the desired channel to be set, wherein the predetermined voltage is associated with the electronic channel selector via the Rectifier diode is fed, and thereby setting the channel selector to the desired Channel is effected.

By closing another switch or by touching one Another station button for setting another channel is used in the same way as described above, a voltage corresponding to the other channel in the electronic Channel selector fed in so that this other channel is set.

With the conventional station selector for electronic channel selectors a desired channel can be selected by simply closing the corresponding switch or by touching the corresponding station button. One downside to this Station selector is, however, that no channel is simply closed by closing the Power supply or mains switch of the television receiver is selectable.

More specifically, when the power switch is turned off, it will too the previously "switched on" switching unit "switched off" so that all switching units turned off. If you leave these switching units switched off, stay they are also switched off when the power switch is subsequently switched on again, so that no channel is set until a station selector switch is closed or until a station button is touched by hand.

So if this station selector is used in a television receiver no image will appear on the screen, which is a false assumption can indicate that the television receiver is defective It is therefore a task the invention of specifying a novel station selector for electronic channel selectors, in which the aforementioned disadvantage is avoided with the aid of a simple additional arrangement can be.

This task is for a station selector to set a Electronic channel selector with: several switching units, each of which has an input, contains an output and a control terminal; a first to the entrances of the Switching units connected constant voltage source; mutable, individually resistors connected to the outputs of the respective switching units; and one individually connected to the control connections of the corresponding switching units Station selection device, each of which generates a voltage so that the associated one Switching unit remains conductive to a constant voltage in the associated variable Resistance to feed so that a predetermined, each station selection device corresponding voltage from the associated variable resistance in the electronic Channel selector can be fed in order to adjust or tune it, according to the invention solved by a second voltage source; a series connection a capacitor and a diode between the second constant voltage source and the control connection of a preselected switching unit; and one between the connection point of the capacitor with the diode and a reference voltage point connected, for Direct current low-resistance impedance used as a discharge path for discharging the capacitor serves, the preselected switching unit is designed so that it is fed by of energy from the second constant voltage source via the capacitor and the Diode in its control connection remains conductive when a power supply switch is closed.

The invention will now be explained in more detail with reference to the drawing. Show it: 1 shows a schematic representation of an exemplary embodiment according to the invention of the station selector for electronic channel selectors; and FIG. 2 is a schematic Representation of a further exemplary embodiment of the status selector according to the invention for electronic channel selectors.

An exemplary embodiment according to the invention will now be described with reference to FIG. 1 explained in more detail.

In the arrangement of FIG. 1, there is an inventive. Part with dashed lines framed; the rest of the arrangement was also made by the inventor of this invention already developed.

That part of the circuit arrangement will now be described which lies outside the dashed rectangle.

The arrangement contains thyristors that serve as switching units lOa, lOb, 10c and 1tod. The anodes of these thyristors 10a to 10d are common connected to a first constant voltage source 12 via a resistor 11. The gate or gate electrodes (control electrodes) of the thyristors 10a to 10d are Connected jointly via associated station selection switches 13a to 13d, and the joint Connection is via a resistor 14 to a second constant voltage source 15 connected. The cathodes of the thyristors 10a to 10d are connected to corresponding capacitors 16a to 16d connected in parallel with corresponding variable resistors 17a to 17d. The wiper or taps of the variable resistors 17a to 17d are combined via corresponding diodes 18a to 18d, and the common Link is connected to the electronic channel selector 19.

With this station selector for the electronic channel selector by momentarily closing a station selector switch of the desired channel, z. B. the station selector switch 13b, a positive voltage from the second constant voltage source 15 via the resistor 14 and the closed station selector switch 13b gate of the associated thyristor supplied, d.'h, the gate of the thyristor lOb, so that the Thyristor lOb is ignited or switched through, whereby a constant voltage from the first constant voltage source 12 via the resistor 11 and the thyristor lOb is applied to the variable resistor 17b. After the occurrence of the constant voltage at the variable resistor 17b, the voltage tapped at it is over the Diode 18b fed into the electronic channel selector so that the station selection switch 13b corresponding channel is set.

If then another station selection switch a z. z. B. Switch 13a, is closed, the positive supply voltage is in the gate electrode fed by thyristor 1Oa, so that this is switched through. As a consequence of this becomes the voltage at the connection point between the resistor 11 and the anode electrode of the thyristor lOb decreased. Because of the voltage on capacitor 16b, the thyristor will lOb biased in the blocking direction so that it is switched off.

By subsequently closing the switch 13a, this Way, only the thyristor 10a left in the conductive state. Thus becomes a tension for the channel corresponding to the switch 13a via the tap of the variable Resistor 17a fed to electronic channel selector 19 via diode 18a, so that the channel corresponding to the switch 13a is set.

In this arrangement, the voltage of the second constant voltage source only be so large that the thyristors tOa to 1Od can be switched through; she is small compared to the voltage of the first constant voltage source 12, so that the switches 13a to 13d can be touched by hand without an electrical Influence is noticeable. In addition, the switches 13a to 13d for a small Electricity can be designed.

Because this station selector switch with a small current rating can be used, it is less prone to wear and tear. Since the In addition, the structure is simple, the arrangement can be manufactured inexpensively. A disadvantage of this arrangement, however, is that there is no channel signal only by closing the power switch to feed energy into the first and the second constant voltage source 12 and 15 can be received. In accordance with the invention this is The disadvantage avoided in that the above-mentioned arrangement is framed in dashed lines Part of Fig. 1 is added.

This arrangement is denoted by 21 in the figure. The order 21 consists of one between the resistor 14 and the gate electrode of the thyristor 1Od connected series connection of a capacitor 22 with a diode 23 as well from one between the junction of the capacitor 22 and the diode 23 and A diode 24 connected in parallel with a resistor 25 connected to earth.

In the station selector with the additional arrangement 21 in Fig. 1 is through Closing a power switch (not shown) energizes the first and second Constant voltage sources 12 and 15 are fed, creating the gate electrode of the thyristor 1Od with tension from the two th constant voltage source 15 biased is so that the thyristor 1Od is switched through and the corresponding channel is set will.

The operation of this embodiment will now be described in detail. When a power switch (not shown) is closed, the first and the second constant voltage source 12 and 15 supplied energy, so that a first and second voltage appear across the respective resistors 11 and 14. When occurring the second voltage across the resistor 14 is the gate of the thyristor 1Od via the diode 23 and capacitor 22 biased with a positive voltage so that the thyristor 1Od switches through, whereby the constant voltage is applied to the variable resistor 17d is applied and a voltage from the variable resistor 17d across the diode 18d is fed into the electronic channel selector 19.

Thus, when the power switch is closed, that of the thyristor is always turned on 1Od corresponding channel set.

By subsequently closing a station selector switch that is connected to another thyristor is connected, e.g. B. the switch 13c, - is due the voltage at the capacitor 16d of the thyristor 1Od is biased in the reverse direction, so that the thyristor 1Od is switched off. Thus, one becomes more corresponding to the switch 13c Channel set.

In the arrangement of FIG. 1, the thyristor 10d is then switched through, if momentarily a current through the capacitor 22, the Diode 23, the gate-cathode path of the thyristor 1Od and the variable resistor 17d flows. If the thyristor 1Od has switched through once, it remains conductive, even if the door preload then subsides. In other words, it does not have to be one all the time Bias voltage to be applied to the gate of the thyristor tod. The capacitor 22 is used to prevent a harmful current flowing dead into the gate of the thyristor, and thus an unnecessary loss of performance. Because of the capacitor 22 only flows then momentarily a current in the gate of the thyristor tOd when the power switch is closed will.

The role of the diode 23 will now be discussed. When the diode 23 does not exist, d. H. when the connection between the capacitor 22 and the Resistor 25 is connected directly to the gate electrode of thyristor 10d, flows not just a harmful current between the anode of the thyristor 10d and his Gate when this conducts, but it is even possible that the cathode gate voltage of the thyristor lOd exceeds the nominal voltage, associated with destruction of the thyristor 10d, since the voltage drop across the resistor 25 because of the gate current is lower than the cathode voltage across the thyristor 10d. By inserting the Diode 23 prevents these difficulties. Because of the diode 23, the cathode gate voltage of the thyristor lOd never exceed the rated voltage, since the diode 23 after Switching through the thyristor is switched off, whereupon the gate voltage of the thyristor 10d becomes substantially equal to the cathode voltage. This is the thyristor 10d protected against destruction, and no harmful bias current flows.

If now the capacitor 22 is charged after opening the power switch remains, it can happen that when the power switch is subsequently closed, the Thyristor 1Od is wrongly switched through without current through the capacitor 22 and the diode 23 flows. As a result, there is a discharge path for the discharge of the capacitor 22 is required. In the arrangement of FIG. 1, the resistor 25 and the diode 24 represent the discharge path for the capacitor 22, but can also a resistor or a coil alone or a combination of a resistor and a coil can be used.

However, if the resistor 25 is used alone as a discharge path its resistance value should be chosen so that after the closing of the Power switch a sufficiently small current flows through it and the capacitor 22, so that a current sufficient to switch the thyristor tOd through the diode 23 flows through, d. H. the resistance value of the resistor 25 should be large compared with the impedance that is the diode side from the connection point between the capacitor 22 with the diode 23 can be seen from. In this case, however, is the time constant for the discharge of the capacitor 22 large, and it can happen that the thyristor lOd wrongly switched through due to insufficient discharge of the capacitor 22 when the power switch is repeatedly turned on and off.

This difficulty is avoided by incorporating the diode 24. With their help, the capacitor 22 can be discharged quickly, so that the thyristor 10d can be reliably switched through to the corresponding to it Channel even when the power switch is repeatedly turned on and off will.

Although in the case that the discharge path is only through the resistor 25 is formed, the above difficulty occurs, is the case of repeated Switching the power switch on and off very rarely, so that in this sense the resistance 25 alone can be enough.

The sole use of the diode 24 as a discharge path for discharge of the capacitor 22 poses the following problem: If both the resistor 25 and the diode 24 is also provided as a discharge path for the capacitor 22 the capacitor 22 with that flowing through the capacitor 22 and the diode 23 Current from the second constant voltage source 15 charged with the polarity shown.

With the diode 24 alone as a discharge path for the capacitor 22 is the capacitor 22 with the current through the capacitor 22 and the diode 23 as well charged with the polarity shown. If, however, in this case the goal potential of the thyristor 10d is essentially equal to the anode potential hand, when switched on of the thyristor, the potential at the connection point between the diodes 23 and 24 is higher than the potential at the connection point between the capacitor 22 and the resistor 14, d. H. the capacitor 22 has a polarity opposite to that shown Polarity charged because the voltage of the second constant voltage source 15 is lower is than the voltage of the first constant voltage source 12. When the capacitor is charged 22 with the opposite polarity to that shown polarity if the thyristor 10d is not switched off by closing the switches 13a, 13d or 13c, since the voltage on capacitor 22 is a positive bias voltage at the gate of the thyristor 1Od appears. For this reason, the diode 24 alone is used as a discharge path not advantageous for the capacitor 22.

As has been shown, the invention allows a simple additional arrangement to the station selector for the electronic channel selector, that by closing the power switch a predetermined channel is always set.

Fig. 2 shows a further embodiment of the invention Station selector for the electronic channel selector. The added according to the invention Arrangement is framed by dashed lines in the figure.

First, the arrangement outside the boxed rectangle will be described.

Fig. 2 shows a conventional horizontal deflector assembly 30, consisting from an input transformer -31, a horizontal output transistor 32, one Damping diode 33, a resonant circuit capacitor 34, a deflection coil 35, a S-shaped compensation capacitor 36 and a flyback transformer 37. Inside of each horizontal period becomes a at the emitter of the horizontal output transistor 32 Pulse 38 is generated and via a capacitor 39 into one end of station buttons 42a, 42b and 42c coupled. That other end of the station buttons 42a to 42c is connected to the gate of corresponding thyristors via corresponding diodes 43a to 43c 44a to 44c connected. The anodes of the thyristors 44a to 44c are with each other connected, and the common connection is through a resistor 51 to a first Constant voltage source 52 connected. The anodes of the diodes 43a to 43c are connected to earth via associated series resistors 45a to 45c. The anodes of the diodes 43a to 43c are also connected to one another via corresponding series resistors 46a to 46c connected and the common connection is through a resistor 47 to a second Constant voltage source 48 connected. The cathodes of the thyristors 44a to 44c are connected to corresponding capacitors 53a to 53c, which are parallel to corresponding variable resistors 54a to 54c. The taps of the mutable Resistors 54a to 54c are connected to one another via corresponding diodes 55a to 55c, and the common link is connected to the electronic channel selector 56.

If this station selector does not have any station buttons 42a, 42b or 42c is touched by hand, the pulse 38 is not in any of the thyristors 44a, 44b, or 44c fed in, so that the thyristors 44a to 44c remain blocked.

However, if a station button, e.g. B. the button 42a, touched by hand becomes, that at each horizontal flyback period at the emitter of the horizontal output transistor 32 occurring pulse 38 via the capacitor 39 and the station button 42a to the Anode of Diode 43a coupled to turn on diode 43a. Thus, the pulse 38 runs to the gate of the thyristor 44a and switches it through, whereby the output of the first constant voltage source 52 through the thyristor 44a is applied to the capacitor 53a and the variable resistor 54a. Of the variable resistor 54a is set so that when a constant voltage from the constant voltage source 52 to him a predetermined voltage on his grinder or slide tap can be tapped, the predetermined tap voltage is fed through the diode 55a in the electronic channel selector that a the station button 42a corresponding channel is set.

If then another station button, e.g. B. 42b, for setting or tuning of the corresponding channel is touched by hand, the pulse becomes 38 is applied to the gate of the thyristor 44b via the diode 43b and switches it by. After the thyristor 44b has been turned on, its anode potential is due to des from the first constant voltage source 52 via the thyristor 44b and the capacitor 53b flowing current is reduced to approximately zero.

This means that the anode potential of the thyristor 44a is momentary is reduced to near zero. It also occurs at the anode-cathode route of the thyristor 44a has a reverse voltage because the capacitor 53a is on the cathode side of the thyristor 44a is not discharged immediately, so that the thyristor 44a is switched off will. In the meantime, the current may also flow through thyristor 44b the variable resistor 54b, so that the variable resistor 54b a predetermined voltage can be removed, those about the diode 55b is applied to the electronic channel selector 56 to the station button 42b to set the corresponding channel.

If the station key 42c is touched, one of the key 42c corresponding Channel can be set in the same way.

In the arrangement of FIG. 2, the diodes 43a to 43c are provided, to prevent the gate voltage of the thyristors 44a to 44c when these are turned on, is applied to the resistors 45a to 45c and 46a to 46c. However, these diodes 43a to 43c can be omitted if the variable ones Resistors 54a to 54c are reset so that in the presence of Voltage drops across the resistors 45a to 45c and 46a to 46c predetermined voltages are available.

When the dashed line framed arrangement of the present embodiment would not be present, would be done by simply closing the power switch to supply of energy into the first and second constant voltage sources 48 and 52 Channel can be set, since none of the thyristors 44a, 44b or 44c switched through is, as long as the pulse 38 via the station buttons 42a, 42b or 42c and the diodes 43a, 43b or 43c are applied to the gates of the thyristors 44a, 44b or 44c will. If such a station counter for the electrical channel selector one Television receiver is displayed by simply closing the power switch no picture on the screen, which can be interpreted as an error in the television receiver could.

This disadvantage is caused by the use of the dashed lines Arrangement 61 in Fig. 2 avoided.

The arrangement 61 contains a series connection of a capacitor 62 with a diode 63 between the connection point of the resistor 47 with the Resistor 46a and the gate electrode of thyristor 44a and a coil 64 between the connection point of the capacitor 62 with the diode 63 and ground.

When the power switch (not shown) in the arrangement of Fig. 2 is closed to the first and the second constant voltage source energy feed, a current flows through the gate and cathode electrodes of the thyristor 44a, the capacitor 53a and the variable resistor 54a so that the thyristor 44a is switched through. Once the thyristor 44a has turned on, it holds it maintains its conductive state until a reverse voltage is applied to it. That means that a current is required from the second constant voltage source 48 through the capacitor 62 and the diode 63 in the gate of the thyristor 44a only for a period of time required for the thyristor 44a to be turned on. Of the Capacitor 62 is used to generate an instantaneous current that is generated by closing the Power switch is caused to flow through the thyristor 44a. The coil 64 is used as a discharge path for discharging the capacitor 62 and represents a surge Current or surge current represent a large impedance, on the other hand a small impedance for direct current. Since the coil represents a large impedance for the surge current, this must be after the Close the power switch the capacitor 62 flow. Of the During this time, the current flowing through the capacitor 62 largely flows through it the diode 63. The change in the discharge current through the capacitor over time 62 need not be as large as its surge current, so that the impedance of coil 64 for the discharge current is relatively low. Thus, the capacitor 62 can be in a be discharged for a relatively short period.

If a station button other than button 42a, e.g. B. button 42b, is then closed, the pulse 38 is via the switch 42b and the Diode 43b fed into the thyristor 44b and switches it through. After switching through of the thyristor 44b, a current flows through from the first constant voltage source the thyristor 44b into the capacitor 53b and the variable resistor 54b, so that the anode potential of the thyristors 44a to 44c is decreased. With the The thyristor 44a will decrease in the anode potential because of the voltage across the capacitor 53a blocked, so that the thyristor 44a is switched off. Thus one becomes the most changeable Resistor 54b tapped voltage across diode 55b to the electronic channel selector 56 is applied so that a channel corresponding to the station button 42b is set.

As is apparent from the description, a predetermined channel by simply adding a simple arrangement to the station selector for the electronic Channel selector can always be set after closing the power switch so that an alleged fault in the television receiver can be ruled out.

Claims (3)

Claims jl.) Station selector for setting an electronic channel selector with several switching units, each of which has an input, an output and a Has control connection; a first one connected to the inputs of the switching units Constant voltage source; mutable, individually to the outputs of the corresponding Switching units connected resistors; and one individually to the control connections the corresponding switching units connected station selection device, whose each generates a voltage so that the associated switching unit remains conductive to feed a constant voltage into the associated variable resistor in such a way that that a predetermined voltage corresponding to each station selector the associated variable resistor can be fed into the electronic channel selector is to adjust this; characterized by a second voltage source (15); one Series connection of a capacitor (22) and a diode (23) between the second Constant voltage source (15) and the control connection of a preselected switching unit (lOd); one between the junction of the capacitor (22) and the diode (23) and a reference voltage point, low-resistance impedance for direct current (24, 25), which serves as a discharge path for discharging the capacitor (22), wherein the preselected switching unit (tod) is designed in such a way that it can be activated by feeding Energy from the second constant voltage source via the capacitor and the diode remains conductive in its control terminal when a power supply switch is closed is or is (Fig. 1). 2. Station selector for setting an electronic channel selector with several switching units, each of which has an input, an output and a Has control connection; a first one connected to the inputs of the switching units Constant voltage source; changeable, individually to the outputs of the switching units connected resistors; a second constant voltage source; and individually between the second constant voltage source and the control connections of the corresponding Switch units inserted switches, each switch unit after closing of the associated switch remains conductive in order to maintain a constant voltage in the associated feed variable resistance so that a predetermined, the closed Switch corresponding voltage from the associated variable resistor in the electronic channel selector can be fed in order to adjust it; marked by a series connection of a capacitor (22) and a diode (23) between the second constant voltage source (15) and the control terminal of a preselected Switching unit. (1Od); one between the connection point of the capacitor (22) connected to the diode (23) and a reference voltage point, for direct current low-resistance impedance (24, 25), which is used as a discharge path for discharging the capacitor (22) is used, the preselected switching unit is designed so that it through Feeding in energy from the second constant voltage source via the capacitor and the diode in its control terminal remains conductive when a power supply switch is or is closed. 3. Station selector for setting an electronic channel selector with several switching units, each of which has an input, an output and a Has control connection; a first, to the inputs of the switching units connected constant voltage source; -variable, individually to the outputs resistors connected to the corresponding switching units; and individually between a pulse generator and the control connections of the corresponding switching units inserted station buttons, each switching unit by hand touching the associated Station button remains conductive to a constant voltage from the first constant voltage source via the conductive switching unit in the associated variable resistor so feed that a predetermined voltage corresponding to the touched key from the associated variable resistor into the electronic channel selector can be fed in to adjust this; characterized by a series connection from a capacitor (62) and a diode (63) between the second constant voltage source (48) and the control connection of a preselected switching unit (44a); one between the junction of the capacitor (62) with the diode (63) and a Reference voltage point connected, for direct current low-resistance impedance (64), which serves as a discharge path for discharging the capacitor (62), the preselected Switching unit is designed to be fed by energy from the second constant voltage source via the capacitor and the diode in theirs Control connection remains conductive when a power supply switch is closed or is (Fig. 2).