DE2219980A1 - ARRANGEMENT FOR CONTROLLING THE RECHARGE IN THE ELECTRONIC CHANNEL SEARCH OF A TELEVISION - Google Patents

Description

B LAUPUN XT-WÜRIGL GMBH »HILDESHEIM, Robert-Boich-Str.B 200

PLI Pieper / Ba - tf- April 19, 1972

R.No. 1196

Arrangement for controlling the reloading in the

electronic station search of a remote.

vision device Δ Ζ Λ.Ό ο ου

J The invention relates to an arrangement "for controlling the j Recharging a storage capacitor in the electronic scanner of a television set according to the generic term {of the main claim. In such a case already proposed With a normal transmitter search, the charging time of the storage capacitor is 4 seconds and for VHF, for example at UHF 8 seconds. This corresponds to a speed of approx. 6.8 volts per second or 3.4 volts per second, if this is the case Time the voltage on the storage capacitor increases from 1 volt to 28 volts. If the storage capacitor is recharged with these search speeds, then during the after- j

during the charging process, you will notice a flickering on the screen.

The occurrence of flickering during the reloading process avoids an arrangement with the characteristic features of the main

S claim. Arrangements which have the characteristics of claim 2 are particularly advantageous.

I With such an arrangement according to the invention, the stop clamping

! voltage during the reloading process due to the image return pulses

j connected to ground via a transistor and thus switched off

I gropes. The reloading takes place with a significantly lower rate

; Speed than the charge during the search, namely with both

I for example 100 millivolts per second.

I This special arrangement according to the invention is an unj Desired flickering on the screen during a retuning process

\ prevented. In addition, the reloading always takes place at the times

j in which the image is darkened.

I Further details and appropriate further training can be found on the basis of I of the embodiment shown in the drawing in more detail

309845/0604

ORIGINAL INSPECTED

BLAUPTJN ^ Λ Γ- vV. »IiR.lV.» i

J2 HILDESHEIM, Robert-Boseh-StraBo 200

PLI Pieper / tea

- ^ T

19.4.1972 R.Nr. II96

22Ί9980

explained.

Show it:

1 shows a circuit arrangement for controlling the reloading

of the storage capacitor and
2 shows the course of a discriminator curve.

As shown in Fig. 1, the output voltage becomes one on the intermediate frequency picture carrier Matched discriminator 1 a first electronic switch 2 and a second electronic switch. 2 supplied. A positive voltage is applied to a terminal 4 of the first electronic switch 2 via a resistor 5. During the station search, the first electronic switch 2 is switched on; terminal 4 is thus at ground potential clamped. The resistor 6 connected to the terminal 4 is therefore not supplied with a stop signal. If the point A is reached on the discriminator curve according to FIG. 2, the threshold value-dependent electronic switch 2 is opened and remains until the search process starts again in this switch position. Opening switch 2 creates a positive voltage at terminal 4, which is transmitted via V / resistor 6 as a stop signal for a circuit arrangement, not shown, for charging a storage capacitor for the tuning voltage. Of the Terminal 7 of the second electronic switch 3 is via a Resistor8 is supplied with a positive voltage. Terminal 7 is also via a voltage divider consisting of resistors 9 * 10 connected to ground. The connection point of the two resistors 9 * 10 is to the base of one with its emitter to ground connected first transistor 11 of the npn type, the collector of which via a resistor 12 with that via another Resistor 13 connected to ground base of a second transistor 14 of the npn type is connected. The collector of the with his; The second transistor 14, which is connected to ground, is connected to the emitter

309845/06 (U

- BLAUPUNKT -WERKE GME El ** hildeshei *. ^ «. Βο ^^ β. ™ '

PLI Pieper / Ba -J> r- , April 9, 1972

_Ä R.Nr. II96

to terminal 4 of the first electronic. Switch 2 connected Resistor 6 connected. The collector of the first transistor 11 is 16 frame return pulses via a capacitor I5 and a resistor fed.

To consider the mode of operation, it is assumed that the storage capacitor for the tuning voltage has discharged to such an extent that the discriminator voltage according to FIG. 2 has reached point B of the discriminator curve. The threshold value assigned to point B causes the second electronic switch 3 to be switched through. The positive voltage of terminal 7 is switched to ground and thus the base potential of first transistor 11 is clamped to ground. The first transistor 11 is therefore blocked. The differentiated image return pulses reach the base of the second transistor 14 and switch it through in time with their positive pulse components. In this way, the stop signal present at the collector of the second transistor 14 is blanked, so that recharging takes place with the aid of the sampled stop signal. The reloading always takes place at the times when the image is reversed, i.e. when the image is darkened. If point A of the discriminator curve is reached again, the second electronic switch J5 is opened again by the threshold value assigned to it. The j base of the first transistor 11 thus receives a positive voltage which turns on the j transistor. The positive pulse components of the differentiated image return pulses are diverted to ground via the collector-emitter path of the first transistor 11. The second transistor 14 is thus locked and thus · communicates at ^its: collector full stop signal. Now again the already \ described process of self-discharge of the storage capacitor begins.

3 09 84 5/060 U

Claims (2)

BLAUPUNKT-WERKE GMBH » h.ldmhe.m. »**». ***. «Ο PLI Pieper / Ba April 19, 1972 ή R.Nr. 1196 Claims; Arrangement for controlling the recharging of a storage capacitor in the electronic transmitter search of a television set, in which a first electronic switch is provided, which is tuned to the intermediate-frequency image carrier with the aid of a Discriminator switches a stop signal that the further increase in the tuning of the tuner is used sawtooth tension prevented and a second controlled by the discriminator electronic switch is provided, each when a lower threshold value is reached is switched through and blocked when an upper threshold value is reached, the switch during its through-connection phase a control signal for recharging the storage capacitor can be found, characterized in that Switching means are provided with which a further increase in the sawtooth-shaped voltage of the storage capacitor preventive, stop signal during the duration of the control signal for the reloading process by means of image flip pulses in this way is blanked that the recharging of the storage capacitor takes place only during the frame return pulses. 2. Arrangement according to claim 1, characterized in that the via a resistor (10) connected to ground base of a with its emitter connected to ground first transistor (11) via a resistor (9) with a control signal for 'the terminal (7) of the second electronic which leads to the reloading 3G9845 / 060A BLAUPUNKT WEFaii: GMBH 3ί HILDESHE.M. Robert-Bo.ch, _street 200 PLI Pieper / Ba - ST- 43.H Sehalter-s (2) is connected and that the collector, to which a resistor (16) and a capacitor (15) are fed back frame pulses via a resistor (12) to the
Ba- connected to ground via a further resistor (15); sis of a second transistor (14) connected to ground with its emitter is connected, the collector of which is connected via a resistor (6) to a terminal (4) \ of the first electronic switch - (2) which supplies the stop voltage and that! the keyed stop voltage on the reloading _; Collector of the second transistor (14) can be seen. , j ■ ■ - ι ■! ί I ΐ ■! 'i 309845/0604 Blank page