DE2158921A1 - Ignition device for discharge tubes - Google Patents

Description

Frankfurt am Main, November 24, 1971 Dipl.! Ng. R. Merten 9

Faisntanwait H 31 P 297

6 Fiankfuri / aain 1, Ammelburgstr. 34

HONEYWELL INC.
2701 Fourth Avenue South Minneapolis, Minn., USA

Ignition device for discharge tubes

The invention relates to an ignition device containing an ignition transformer with a primary and a secondary winding for a discharge tube which is connected to a voltage source with its two electrodes, which form a discharge path between them. Discharge tubes of this type are used for example as light sources, especially in electronic flash units, used. You will also find a so-called extinguishing tube to prematurely end the light emission Flash tube usage.

Usually the discharge tube is ignited as soon as there is light should be emitted. The main electrodes of the discharge tube, which form the discharge path between them, are used for this purpose usually connected to a high voltage DC voltage source, for example a charged capacitor. The voltage at the two electrodes is chosen so low that the tube does not self-discharge. To ignite is rather, a special ignition electrode is provided. To ignite the discharge tube, between the ignition electrode and sine A sufficiently high voltage is applied to the main electrodes, usually in the form of a voltage pulse. The amount of required Ignition voltage makes it undesirable in many cases

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or even impossible to generate this ignition voltage directly in a control circuit to be connected to the ignition electrode. In particular when using such discharge tubes in electronic flash units, it is not possible to have such a high Apply the ignition voltage directly to the ignition electrode via the trigger contact of the camera. That is why it is known at Flash units for this purpose an ignition transformer between the controlled voltage source for the ignition voltage on the one hand and the ignition electrode of the discharge tube on on the other hand, so that with a relatively low voltage pulse on the primary side of the ignition transformer, a high voltage pulse can be generated on the secondary winding, which ignites the discharge tube. The low control voltage can then switched on immediately via the camera shutter contact even though they themselves would not be able to open the discharge tube to ignite. An ignition device of this type is described in U.S. Patent 3,517,255, for example.

The use of an ignition transformer is also advantageous when the discharge tube is ignited not by a camera shutter contact but by a photoelectric one Device is controlled. This arrangement is used in so-called secondary flash units, which ignite as soon as on light from the outside, for example from a primary flash unit, strikes your light-sensitive element. Also in this Case it would not be possible to use the high voltage required for ignition to switch directly across the photosensitive semiconductor device.

Furthermore, it is known to associate such a discharge tube as an extinguishing tube with a flash tube delivering an electronic flash to illuminate an object to be photographed in order to extinguish the flash tube prematurely by short-circuiting its main discharge path via the extinguishing tube .

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Sensitive semiconductor device, such as a light controlled thyristor (LASCR), turned on. Such light-controlled However, semiconductor devices operate more favorably at voltages which are lower than those used to ignite such Discharge tubes require high voltage pulses. For this purpose, too, one has between control circuits and ignition electrode switched on an ignition transformer. A circuit arrangement in which such an extinguishing tube for premature extinction of a flash tube of an electronic flash unit is used and both for the flash tube as An ignition transformer is also provided for each extinguishing tube, as shown in the aforementioned US patent 3,517,255

Although this type of posture is in practice Have proven well and are used on a large scale, there is a need for the ignition devices used there to be further improved and simplified. Because of the use of separate ignition transformers, it is the case with the known ones Arrangements required, an electrical connection between the secondary winding of the ignition transformer and the ignition electrode the associated discharge tube. Due to the high voltage and the in The small space available to such flash units must be very carefully isolated and screened to avoid interference to avoid other circuit parts. Such high-voltage connections can also be densely packed when required Construction of such devices can easily lead to destruction of the insulation and to arcing. Object of the invention is to eliminate or at least reduce these difficulties.

The object is achieved in an ignition device of the type mentioned according to the invention in that the Windings of the ignition transformer surround the vessel of the discharge tube. This means that you don't need anything inside the device

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High-voltage connecting cables between the secondary winding the ignition transformer and the discharge tube to be laid, but the secondary winding sits directly on the discharge tube itself. Here, primary winding and secondary winding are galvanically separated windings or the primary winding is part of the secondary winding Be overall winding, as is common with so-called autotransformers.

A particularly advantageous further development of the invention provides that the discharge tube does not have a special ignition electrode. Because the secondary winding directly encloses the discharge tube, a is created in the discharge tube The field strength corresponding to the high-voltage pulse is of such magnitude that the discharge tube ignites. The secondary winding works here similar to one applied directly to the outside of the discharge tube Ignition electrode, by creating the ionization of the main discharge path required for ignition within the tube causing field strength generated. This arrangement thus solves the problem on which the application is additionally based, which is described in the use of discharge tubes that are as simple as possible. In this embodiment, an ignition device according to of the invention is neither a special ignition electrode nor a high-voltage line connection between the ignition transformer and discharge tube required.

Further advantageous embodiments of the invention are characterized in the subclaims. To explain the invention Reference is made below to some embodiments shown in the drawings. It shows

1 shows the circuit parts of an electronic flash device with lighting-dependent control of the amount of light that are of interest here, both for the flash tube and for the extinguisher tube ignition devices according to the invention be used,

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Figures 2 and 3 in plan view and in section, the arrangement of the ignition transformer directly on the vessel the discharge tube,

Figure k shows an arrangement of the secondary winding that is particularly suitable for flash tubes near one electrode of the discharge tube,

Figure 5 shows an arrangement in which the two electrodes of opposite ends of the vessel protrude into the discharge tube and the secondary winding the vessel in Surrounding area between the two electrodes, and

FIGS. 6 and 7 are arrangements in which both electrodes lie next to one another in the vessel of the discharge tube and the secondary winding surrounds the vessel near these electrodes.

The arrangements according to FIGS. 5 to 7 are particularly suitable for extinguishing tubes because here the one surrounding the discharge path The ignition transformer does not impair the light emission that is not intended anyway.

The arrangement according to FIG. 1 is used in an electronic flash device to expose one of an associated one, not shown Camera to record. When opening the camera shutter the flash light emission is triggered via the locking contact. As soon as a specified amount of light is reflected from the object to be photographed towards the flash unit and thus the object is sufficiently illuminated, an extinguishing tube ignites, which short-circuits the main discharge path of the flash tube and thus prevents flash light emission. In this way the circuit arrangement automatically controls the duration of each flash of light depending on the amount of light reflected from the object towards the flash unit in such a way that with sufficient exposure of the object the flash of light is interrupted. Sufficient exposure is given by the amount of light required for the

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requires proper exposure of the film in the camera will.

For this purpose, the circuit arrangement according to FIG. 1 contains a storage capacitor 1 which is connected between two DC voltage lines 2 and 3. A flash tube ¹ I, which contains within its vessel 5, two electrodes 6 and 7 is also connected to the two lines 2 and. A further discharge tube 8 is also provided, which here serves as an extinguishing tube and has two electrodes 10 and 11 in its vessel 9. The electrodes of the extinguishing tube 8 are also connected to lines 2 and 3. The control circuit for igniting the flash light tube 4 comprises a resistor 12 and a working contact 13 connected in series between the two lines 2 and 3 and an ignition capacitor 15 connected to the junction 14 of resistor 12 and working contact 13 / or a manually closable contact, as is often provided for testing the flash unit or for triggering the flash unit without a camera. Furthermore, the discharge tube 4 is assigned an ignition transformer 16, the windings of which surround the vessel 5 of the discharge tube.

For automatically deleting the flash tube 4 after it is reached the predetermined amount of light is used by an extinguishing tube 8, which is controlled by a control circuit with a light-sensitive element is equipped in the form of a light-controlled thyristor 17, which reflected part of the from the object to the flash device Catches light. The light-controlled thyristor 17 ", often following English usage, as LASCR (Light Activated Silicon Controlled Rectifier) has an anode 18, a cathode 19 and a control electrode 20 on. Two resistors 21 and 22 are in series as a voltage divider between the two lines 2 and 3

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turned on, and its connection point 23 is connected to the anode 18 of the light-controlled thyristor 17 during the Cathode 19 is connected to line 3. The resistor 22 is therefore the anode-cathode path of the thyristor 17 .parallel. An integrating capacitor 24 is between the control electrode 20 and the cathode 19 of the thyristor 17 switched on «An ignition capacitor One of its electrodes 25 is connected to the connection point 23 of the voltage divider 21, 22. An npn transistor 26 is used as a reset and gate circuit for the integrating capacitor. The collector-emitter path of transistor 26 is on for this purpose connected to the capacitor 24 while its base has a Resistor 27 is connected to connection point 14 between resistor 12 and capacitor 15. The base-emitter route of the transistor 26 is thus parallel to the contact 13 via the resistor 27. The quenching tube 8 is also an ignition transformer 28 assigned, the windings of which also surround the vessel 9 of the extinguishing tube directly. With the exception of the design, arrangement and switching on the ignition transformers, the circuit according to FIG. 1 largely corresponds to that from the above-mentioned ÜSA patent 3,517,255.

According to the invention, the two ignition transformers are involved 16 and 28 each with a coreless step-up voltage transformer, each with a primary winding and a secondary winding, which are inductively coupled to one another and the vessel 5 of the flash tube 4 or the vessel 9 of the release tube 8 directly surround. The transformer 16 has a primary winding 29, which consists of a plurality of turns and has two terminals 30 and 31. The secondary winding 32 also consists of a large number of turns between the connection terminals 33 and 34.

A preferred form of the structural design of the ignition transformer can best be seen from FIGS. 2 and 3. The secondary winding 32 directly encloses the vessel 5 of the Flash tube 4, while the primary winding 29 around the outside

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Secondary winding 32 is wound around. As FIG. 3 shows, the ignition transformer 16 is essentially disk-shaped Shape, the turns of both windings 29 and 32 being wound around the vessel 5 in coaxial layers. That radially outer end 34 of the secondary winding 32 is how FIG. 1 shows it is connected to the electrode 7 of the discharge tube 4 via a line 37. Furthermore, the radially inner one stands End 31 of the primary winding 29 via a line 36 to the line 3 and thus also to the electrode 7 as well via the line 37 to the radially outer end 34 of the Secondary winding 32 in connection. The radially inner end 33 of the secondary winding 32 is not connected. That By contrast, the radially outer end 30 of the primary winding is connected to the ignition capacitor 15 via the line 35. The primary winding 29 is therefore connected in parallel to the series connection of ignition capacitor 15 and camera contact 13.

The lines 2 and 3 are connected via the terminals 38 and 39 to a charging circuit (not shown) for the capacitor 1 can be connected. This is normally charged so that there is a relatively high voltage between lines 2 and 3, which is also effective between the electrodes 6 and 7 of the flash tube 4. This high DC voltage also occurs at the electrodes 10 and 11 of the extinguishing tube 8. However, the DC voltage between lines 2 and 3 is not so great that the Discharge tubes 4 and 8 due to the contact with their electrodes Ignite and discharge voltage alone.

Closing the normally open contact 13 leads to the ignition of the flash tube 4 due to the interconnection of the elements described above. Normally, the ignition capacitor 15 is charged. Its charging takes place via the DC voltage line 2, the resistor 12, the line 35 > the primary winding 29 and the connection to the DC voltage line 3 · consequently

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the charged capacitor is activated by actuating the normally open contact 13 15 to lines 35 and 36 and thus to the winding 29 laid. In this way, the primary winding 29 is supplied from the ignition capacitor 15 with a trigger voltage which itself is not sufficient to ignite the flash tube 4. However, the occurrence of this creates voltage on the primary winding 29 a much higher voltage in the secondary winding 32, which then causes the flash tube 4 to fire. It should be noted that this is done without an ignition electrode on the flash tube 4 or any high-voltage line to the transformer 16. For the purpose dex 'illustration, but not as a limit, for example, the release voltage at the primary winding 29 can be around 35OV, while the voltage generated at the secondary winding 32 to ignite the flash tube is 2000V.

The flash tube 4 then becomes conductive and emits light until the charge of the storage capacitor 1 and therefore also the Voltage between conductors 2 and 3 has dropped so far that the tube is erased. This is done either through the automatic ignition of the extinguishing tube 8 or by the continued conduction of the flash tube 4 and thus depends on the amount of reflected light received by the flash unit. After the flash tube 4 has been extinguished, the storage condensate; or 1 and the ignition capacitor 15 is recharged and the device is ready to trigger a new flash. As far as correspond these processes correspond to the processes described in the device described in US Pat. No. 3,517,255.

The ignition transformer 28 for the extinguishing tube 8 can and is here _{assumed to be identical to the ignition transformer 16 S} as described above. According to FIG. 1, the ignition transformer 28 consists of a primary winding 40 with a large number of turns between the connection points 41 and 42 and a secondary winding 43 with an even larger number of turns zv / 13chen the circuit connection points 44 and 45.

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gate 16, the secondary winding 43 lies directly on the vessel wall 9 of the discharge tube, while the primary winding 40 surrounds the winding 43. That is at connection point 45 The end of the secondary winding that has the greatest radial distance from the vessel 9 of the extinguishing tube, while the other end of the secondary Windings which are in direct contact with the vessel are connected to the connection point 44. Likewise lies the end of that Primary turns with the greatest radial distance from the surface of the vessel 9 at the connection point 41 of the primary winding, while its other end is connected to the connection point 42 with the smaller radial spacing of the turns.

The ignition transformer 28 is provided with an input line 46 which connects the connection point 41 for the primary winding to one pole of the ignition capacitor 25. The other end of the primary winding, which is located at the connection point 42, and thus connected via a further input line 47 to the DC power line 3 _Λ to the cathode 19 of the light-triggered thyristor 17th Similarly, a conductor 48 connects the connection point 45 with the direct current conductor 3 and thus at the same time with the electrode 11 of the extinguishing tube 8. The other end of the secondary winding 43 ends at the connection point 44, which is not further connected.

In the following, the operation of the device will now be automatic Ignition of the extinguishing tube 8 by the ignition transformer 28 is described. In the same way as in the USA patent 3 517 255 is described, when the normally open contact 13 is closed to ignite the flash tube 4, the Transistor 26 is switched off and the erasing device of the device is prepared for the erasing process. If the transistor 26 blocks, so the integrating capacitor 24 is charged to the extent that the light-controlled thyristor 17 is subjected to reflected light the charge on this capacitor exceeds one previously determined threshold value, the light-controlled Thy-

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ristor 17 in the conductive state. The anode-cathode route of the thyristor 17 thus short-circuits the resistor 22 and connects the charged ignition capacitor 25 with it the input lines 46 and 47 of the primary winding 40 of the Ignition transformer 28. The ignition capacitor receives its charge 25 via the primary winding 40 and the series resistor 21 between the DC voltage conductors 2 and 3.

When the thyristor 17 turns on, the trigger voltage is present of the ignition capacitor 25 to the primary winding 40. This causes the induction of a sufficiently high voltage in the secondary winding 43 and thus the ignition of the extinguishing tube 8. As with the ignition of the flash tube 4, so are also with the ignition of the extinguishing tube 8 according to the present Invention neither an ignition electrode on the extinguishing tube 8 nor any high-voltage lines required.

The extinguishing tube 8 then conducts until the voltage on the DC voltage lines 2 and 3 has dropped so far that the discharge tubes 4 and 8 are extinguished. Are the tubes deleted, the storage capacitor 1 and the two ignition capacitors 15 and 25 are charged and are thus for the renewed ignition or extinction of a lightning bolt ready.

For the arrangement of the ignition transformers 16 and 28 on the Vessels of the discharge tubes result in a number of possibilities. However, it has been found to be desirable to mount the ignition transformer so that in each case his Secondary winding on the surface of the vessel is adjacent to or in the immediate vicinity of that electrode that is connected to the outer end of the secondary winding (34 or 45) is connected. Figure 4 shows an example of a preferred arrangement of the Ignition transformer 16 on the flash tube 4 taking this recommendation into account. In the arrangement of Figure 4 encloses the Ignition transformer 16 the vessel of the tube and reaches on the

b ι s. ·

vessel surface / to the electrode below 7. These Arrangement also alleviates restriction accordingly

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the light emission of the flash tube 4 while simultaneously supports a compact connection between tube and transformer.

If the tube is in a form in which the two electrodes are close together inside the vessel, as is the case with extinguishing tubes, then the ignition transformer must be arranged in such a way that that it abuts the perpendicular projection of both electrodes on the glass surface. Figure 5 shows an example of one such arrangement. Here the ignition transformer 28 surrounds the vessel 9 of the extinguishing tube 8 approximately in the middle and comes onto it Way the two electrodes 10 and 11 are very close.

Figure 6 shows another example of a desirable arrangement of the transformer to discharge tubes of the type just described. This is an extinguishing tube of the known embodiment in which the two electrodes 10 and 11 protrude into the vessel 9 from the same end. Tubes of this Art are particularly suitable for installation on printed circuit boards, as can be seen from FIGS. 6 and 7. The ignition transformer Here, too, 28 encloses the vessel 9 of the extinguishing tube 8 and comes into contact with the two electrodes 10 and 11 of the tube very close. As can be seen, the electrode leads and the ends of the transformer windings lead through accordingly arranged holes in the printed circuit board and are on their underside in a conventional manner with the corresponding ladders connected. Such a grouping facilitates both the arrangement and the construction and that Interconnection of discharge tube and ignition transformer to form a compact unit.

FIG. 7 shows yet another advantageous arrangement with discharge tubes of the same type. Here is the extinguisher tube 8 arranged parallel to the circuit board 49. Again lead the Electrode leads and the ends of the transformer windings

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through the circuit board and support the fastening and installation of the tube-transformer combination.

In summary, it is stated that the device described in accordance with the present invention achieves the object set out at the beginning by introducing a release device for discharge tubes, which releases neither an ignition electrode nor the corresponding lead nor any high-voltage power lines or their connections required. Only through this device did a form become a compact tube-transformer combination created, which not only reduces the size, the manufacturing costs and the complexity of the device in which it is used, but also an increase in its reliability guaranteed.

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Claims (14)

Patent claims An ignition transformer with a primary and a secondary winding Containing ignition device for a discharge tube, which is connected to a voltage source with its two electrodes forming a discharge gap between them is, characterized in that the windings (29,32) of the ignition transformer (16) the Surrounding the vessel (5) of the discharge tube (4) in a ring shape. 2. Ignition device according to claim l, characterized in that the primary winding (29) and secondary winding (32) are galvanically separated windings. 3. Ignition device according to claim!, Characterized in that that the primary winding is part of the total winding forming the secondary winding. 4. Ignition device according to one of claims 1 to 3 »d a through characterized in that the discharge tube (4) has no special ignition electrode. 5. Ignition device according to one of claims 1 to 4, d a characterized in that the secondary winding (32) the vessel (5) of the discharge tube (4) in the vicinity of at least one (7) of the two electrodes (6, 7) of the discharge tube connected to a voltage source (1) surrounds. (Figure 4). 209827/0570 2,58921 6. Ignition device according to claim 5, characterized in that the two electrodes (1O ₉ II) protrude from opposite ends of the vessel (9) into the discharge tube (8) and the secondary winding (43) surrounds the vessel in the area between the two electrodes . (Figure 5) 7. Ignition device according to one of claims 1 to 4, characterized in that the two "Electrodes (10, 11) are arranged next to one another in the vessel (9) of the discharge tube (8) and the secondary winding (43) surrounds the vessel in the vicinity of the electrodes (FIG. 6). 8. Ignition device according to one of claims 1 to 7, characterized in that the primary winding (29; 40) can be connected to a voltage, the level of which is not sufficient to ignite the discharge tube (4; 8) itself and that a connecting terminal (3 ¹ I ; 45) of the secondary winding (32; 43) is connected to one of the electrodes (7; 11) of the discharge tubes. 9. Ignition device according to one of claims 1 to 8, characterized in that the one winding (29; 40) surrounds the other winding (32; 43) coaxially. 10. Ignition device according to claim 9, characterized in that that the secondary winding (32; 43) is arranged directly on the vessel (5; 9) of the discharge tube (4; 8) and is surrounded on the outside by the primary winding (29; 40). 11. Ignition device according to claim 8 and 10, dadui ⁵ ch characterized in that each winding (29,32) has several coaxial layers of wire windings and that the radially outer end (34) of the secondary winding (32) with eggs 209827/0570 an electrode (7) of the discharge tube (4) is connected. 12 »Ignition device according to claim 11, characterized in that the radially inner end (31) of the primary winding (29) is connected to the radially outer end (3 ¹ J) of the secondary winding (32) and the radially inner end (33) of the secondary winding is not connected. 13; Ignition device according to one of Claims 10 to 12, characterized in that the outside diameter of the ring-shaped ignition transformer (16) surrounding the vessel (5) of the discharge tube (4) is approximately threefold corresponds to the axial length of the transformer winding. 14. Ignition device according to one of claims 1 to 13 »characterized in that the discharge tube (4; 8) arranged in a photographic flash device and an ignition circuit (13, 15) is connected to the primary winding (29) of the ignition transformer (16), which the primary winding supplies a voltage with an amplitude below the required ignition voltage. 15 ignition device according to claim 14, characterized in that that the discharge tube (4) is the flash tube and the ignition circuit is normally one Contains charged ignition capacitor (15) in series with the normally open contact (13) of a camera shutter in series can be connected to the primary winding (29) of the ignition transformer (16). 16, ignition device according to claim 14, characterized in that that the discharge tube is an extinguishing tube (8) connected in parallel to the flash tube (4) and the ignition circuit a normally charged ignition capacitor 2 0 9 82 7/0 5 7 C contains the generator (25), which is connected in series with a light-controlled semiconductor switch (17) to the primary winding (40) of the ignition transformer (28) is connected. 209827/0570