TDA8304 Gain controlled vision IF amplifier
The TDA8304 possesses the
capability to demodulate IF signals
having either positive or
negative-going video information. lt
is housed within a 32-pin
encapsulation. The device includes
a three-stage video IF amplifier, AFC
and AGC circuitry, integral
three-level sandcastle pulse
generator, fully synchronized
horizontal and vertical time bases
with drive circuits, a video switch
and a transmitter identiication/mute
circuit. A functional colour TV
receiver can thus be realised with
the addition of a tuner, audio
demodulator and ampliher,
chrominance decoder and
respective line and field deflection
Video IF amplifier, demodulator
and video amplifier
Each of the three AC-coupled IF
stages permits the omission of DC
feedback and possesses a control
range in excess of 20 dB.
The IF amplifier is followed by a
passive synchronous demodulator
providing a regenerated carrier
signal. This is limited by a
logarithmic limiter circuit prior to its
application to the demodulator.
Improved picture synchronization is
provided by a wider bandwidth
together with improved video
amplifier linearity. The video
amplifier contains also a white spot
inverter and a noise clamp which
limits interference pulses to a point
below the peak sync level.
The reference signal for the AFC
quadrature demodulator can also be
acquired from the tuned circuit of the
IF synchronous demodulator
because an accurate 90° phase shift
is realised intemally. In this way only
one tuned circuit needs to be
applied and only one adjustment
has to be carried out. The AFC
output is affected by the
asymmetrical frequency spectrum of
the signal fed to the quadrature
demodulator, which is detemiined by
the SAW filter characteristic. To
overcome this video frequency
dependency of the AFC output, the
demodulator output is followed by a
For the reception of negative-going
signals, the output is sampled only
during peak sync (where a
non-modulated carrier is present).
When receiving signals with positive
modulation the AFC is continuously
active but extensively filtered.
Substantial noise will be present on
the quadrature demodulator Input
signal during reception of very weak
signals. This noise has an
asymmetrical frequency spectrum (
with respect to the IF carrier)
causing an olfset in the AFC output
voltage. This effect can be
minimized by applying a notch in the
demodulator tuned circuit. The
sample-and-hold circuit is followed
by an amplifier with high output
impedance. The steepness of the of
the AFC control voltage can be
lowered by applying load resistors
from the output to the supply and to
ground. The AFC output is switched
off when the AFC sample pin (22) is
connected to ground.
Selection between intemal video
(pin 16) and external video (pin 13)
is made by applying a switching
potential to pin 18 (see Table 3).
Video output (pin 20) from the
device is filtered to remove the
audio carrier and DC~coup|ed to pin
16. The TDA8304 provides the
opportunity for a direct video
connection (e.g. via a peritel
connector) to be made to the device
at pin 13. The AGC detector is not
gated during the extemal video
mode. the first phase detector is
also not gated and operates with a
short time constant. the gain of the
IF amplifier (in the extemal video
mode) is reduced to prevent
Crosstalk of the video amplifier to the
horizontal oscillator during the
The horizontal synchronization
circuit of the TDA8304 provides the
drive pulse for a horizontal
The phase ofthe control loop will
be adapted automatically to the
level of the input signal in order
to achieve an optimum
The control gradient of the
control loop will be low at
reception of weak signals to
reduce the noise bandwidth.
The phase detector control
current is increased during strong
or no-signal reception to obtain a
short catching time and a good
performance during VCR
The TDA8304 embodies a
synchronized divider system for
generating the vertical sawtooth at
pin 3 having several advantages
and features such as:
» The vertical frequency is
alignment free. The divider
automatically adapts to a vertical
frequency of 50 Hz or 60 Hz
including automatic amplitude
correction and its operating
modes offer maximum
A discriminator-window checks
the accuracy ofthe vertical
trigger pulse. Internally
clockpulses are generated by
doubling the line frequency. The
divider operates in the 60 Hz
mode when the trigger pulse
appears before count 576,
otherwise the 50 Hz mode will be
The divider system operates with
a number of different reset
windows. The windows are
activated via an up/down counter.
The counter increases its
counter-value by 1 for each time
the separated vertical sync pulse
appears within the selected
window, otherwise the counter
value is lowered by 1.
Modes of operation
Large search window (divider ratio
between 488 and 722). This mode is
valid for the following conditions:
o Divider is looking for a new
Divider ratio found does not
comply with the narrow window
Up/down counter value of the
divider system, operating in the
narrow window mode, drops:
below count 10
Narrow window mode: divider ratio
between 522 - 528 (60 Hz) or 622 -
628 (50 Hz)
The divider system switches over
to narrow window mode when
the up/down counter has reached
his maximum value of 15 vertical
When the divider operates in the
narrow window mode and a
vertical sync pulse is missing in
the window, the divider is reset at
the end of that window and t1'|e
counter value is lowered by 1.
September 1991 2663
At a counter value below 10 the
divider system switches over to
the large window mode.
The divider system generate also
the so-called anti-top~flutter pulse
which inhibits the phase 1
detector during the vertical sync
pulse. The width of this pulse
depends on the divider mode.
For the large window rhode the
start is generated at the reset of
the divider. ln the narrow window
mode the anti-top-fiutter pulse
starts at the beginning of the first
equalizing pulse. The
anti-top-flutter pulse ends at
count 10 for 50 Hz and at count
12 for 60 Hz.
The divider is switched to count
625 when out of sync is detected
by the coincidence detector. This
results in a stable amplitude
when no input signal is available.
The divider is switched to the
large window mode when
enlarged vertical sync pulses are
The transmitter identification/coincidence detector
Pin 25 ol the TDA8304 serves as
the transmitter identification and/or
coincidence detector (see Table 4).
Pin 25 is HIGH (= 9.8 V) when a
transmitter is present and LOW (=
0.3 V) when of no transmitter signal
is detected. When the video switch
is in the internal mode, the signal at
the sync separator input (pin 28) is
the demoduiated iF signal, pin 25
will act as a coincidence detector.
oscillator loop is synchronized with
the video signal and LOW in case of
no synchronization. ln the extemal
video mode and in the text mode,
pin 25 will be active as transmitter
identification. The system relies
upon the detection ol sync pulses on
the incoming IF signal. Pin 25 is
charged with a current of 125 pA by
the separated horizontal sync pulse
and discharged continuously with a
current of 4 uA. The high impedance
of pin 25 should be taken into
amount in the application concept.
The 50/60 Hz identification
The 50/60 Hz information (see Table
5) derived from the divider system is
available at the open collector
output pin 14.
TDA3505 Video control combination circuit with automatic cut-off control
The TDA3505 and TDA3506 are monolithic integrated circuits which perform video control functions in a PAL/SECAM
decoder. The TDA3505 is for negative colour difference signals -(R-Y), -(B-Y) and the TDA3506 is for positive colour
difference signals +(R-Y), +(B-Y).
The required input signals are: luminance and colour difference (negative or positive) and a 3-level sandcastle pulse for
control purposes. Linear RGB signals can be inserted from an external source. RGB output signals are available for
driving the video output stages. The circuits provide automatic cut-off control of the picture tube.
· Capacitive coupling of the colour difference and
luminance input signals with black level clamping in the
· Linear saturation control acting on the colour difference
· (G-Y) and RGB matrix
· Linear transmission of inserted signals
· Equal black levels for inserted and matrixed signals
· 3 identical channels for the RGB signals
· Linear contrast and brightness controls, operating on
both the inserted and matrixed RGB signals
· Peak beam current limiting input
· Clamping, horizontal and vertical blanking of the three
input signals controlled by a 3-level sandcastle pulse
· 3 DC gain controls for the RGB output signals (white
· Emitter-follower outputs for driving the RGB output
· Input for automatic cut-off control with compensation for
leakage current of the picture tube
1. < 110 mA after warm-up.
2. Values are proportional to the supply voltage.
3. When V11-24 < 0,4 V during clamping time - the black levels of the inserted RGB signals are clamped on the black
levels of the internal RGB signals.
When V11-24 > 0,9 V during clamping time - the black levels of the inserted RGB signals are clamped on an internal
DC voltage (correct clamping of the external RGB signals is possible only when they are synchronous with the
4. When pins 21, 22 and 23 are not connected, an internal bias voltage of 5,5 V is supplied.
5. Automatic cut-off control measurement occurs in the following lines after start of the vertical blanking pulse:
line 20: measurement of leakage current (R + G + B)
line 21: measurement of red cut-off current
line 22: measurement of green cut-off current
line 23: measurement of blue cut-off current
6. Black level of the measured channel is nominal; the other two channels are blanked to ultra-black.
7. All three channels blanked to ultra-black.
The cut-off control cycle occurs when the vertical blanking part of the sandcastle pulse contains more than 3 line
The internal blanking continues until the end of the last measured line.
The vertical blanking pulse is not allowed to contain more than 34 line pulses, otherwise another control cycle begins.
8. The sandcastle pulse is compared with three internal thresholds (proportional to VP) and the given levels separate
the various pulses.
9. Blanked to ultra-black (-25%).
10. Pulse duration ³ 3,5 ms.
TDA3827 TV-sound demodulator circuit with SCART switches and AF control
The TDA3827 contains a single FM
demodulator with SCART switches, a
mute function and volume control.
· Wide supply voltage range from
4.5 V to 13.2 V
· Wide frequency range from 4 to
· High ripple rejection
· High precision and temperature
· Multiple-input AF operational
amplifiers with offset compensation
· SCART AF input / AF output (low
· External AF input
· High-level AF output voltage with
· External selection of the source
selector AF gain
· Low switching noise between AF
· Wide volume-control range.
SONY KV-M1400U / KV-M1400A CHASSIS SCC-D78J-A (BE-2A) SONY DST EHT FBT TRANSFORMER Bobbin structure for high voltage transformers EHT Output.
A coil bobbin for a fly-back transformer or the like having a bobbin proper. A plurality of partition members or flanges are formed on the bobbin proper with a slot between adjacent ones. At least first and second coil units are formed in the bobbin proper, each having several slots, formed between the flanges, and first and second high voltage coils are wound on the first and second coil units in opposite directions, respectively. A rectifying means is connected in series to the first and second coil units, and a cut-off portion or recess is provided on each of the partition members. In this case, a wire lead of the coil units passes from one slot to an adjacent slot through the cut-off portion which is formed as a delta groove, and one side of the delta groove is corresponded to the tangent direction to the winding direction.
1. A fly-back transformer comprising a coil bobbin comprising a plurality of parallel spaced discs with a first adjacent plurality of said disc formed with delta shaped slots having first edges which extend tangentially to a first winding direction and a first winding wound on said first adjacent plurality of said discs in said first winding direction, a second adjacent plurality of said discs formed with delta shaped slots having first edges which extend tangentially to a second winding direction opposite said first winding direction and a second winding wound on said second adjacent plurality of said discs in said second winding direction, a third adjacent plurality of said discs formed with delta shaped slots having first edges which extend tangentially to said first winding direction and a third winding wound on said third adjacent plurality of said discs in said first winding direction and said second plurality of adjacent discs mounted between said first and third plurality of adjacent discs. 2. A fly-back transformer according to claim 1 wherein adjacent ones of said first adjacent plurality of discs are mounted such that their delta shaped slots are orientated 180 degrees relative to each other. 3. A fly-back transformer according to claim 2 including a first winding turning partition mounted between said first and second adjacent plurality of discs and formed with grooves and notches for changing winding direction between said first and second windings and a second winding turning partition mounted between said second and third adjacent plurality of discs and formed with grooves and notches for changing the winding direction between said second and third windings. 4. A fly-back transformer according to claim 3 wherein said first and second winding turning partitions are formed with winding guiding slots for guiding the winding between the first, second and third adjacent plurality of discs. 5. A fly-back transformer according to claim 2 including a first rectifying means connected between one end of said first winding and one end of said second winding, and a second rectifying means connected between the second end of said second winding and one end of said third winding. 6. A fly-back transformer according to claim 5 wherein the second end of said first winding is grounded and a third rectifying means connected between the second end of said third winding and an output terminal.
1. Field of the Invention
The present invention relates generally to a bobbin structure for high voltage transformers, and is directed more particularly to a bobbin structure for high voltage transformer suitable for automatically winding coils thereon.
2. Description of the Prior Art
In the art, when a wire lead is reversely wound on a bobbin separately at every winding block, a boss is provided at every winding block and the wire lead is wound on one block, then one end of the wire lead is tied to the boss where it will be cut off. The end of the wire lead is tied to another boss, and then the wire lead is wound in the opposite direction. Therefore, the prior art winding method requires complicated procedures and the winding of the wire lead cannot be rapidly done and also the winding can not be performed automatically. Further, the goods made by the prior art method are rather unsatisfactory and have a low yield.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly an object of the invention is to provide a coil bobbin for a fly-back transformer or the like by which a wire lead can be automatically wound on winding blocks of the coil bobbin even though the winding direction is different among the different winding blocks.
Another object of the invention is to provide a coil bobbin for a fly-back transformer or the like in which a bridge member and an inverse engaging device for transferring a wire lead from one wiring block to an adjacent wiring block of the coil bobbin and wiring the wire lead in opposite wiring directions between adjacent wiring blocks, and a guide member for positively guiding the wire lead are provided.
According to an aspect of the present invention, a coil bobbin for a fly-back transformer or the like is provided which comprises a plurality of partition members forming a plurality of slots, a first coil unit having several slots on which a first high voltage coil is wound in one winding direction, a second coil unit having several slots on which a second high voltage coil is wound in the other direction, a rectifying means connected in series to the first and second coil units, and a cut-off portion provided on each of the partition members, a wire lead passing from one slot to an adjacent slot through the cut-off portions, each of the cut-off portions being formed as a delta groove, and one side of the delta groove corresponding to a tangent to the winding direction.
The other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings through which the like reference numerals and letters designate the same elements and parts, respectively.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram showing the construction of a fly-back transformer;
FIG. 2 is a connection diagram showing an example of the electrical connection of the fly-back transformer shown in FIG. 1;
FIG. 3 is a schematic diagram showing an example of a device for automatically winding a wire lead of the fly-back transformer on its bobbin;
FIG. 4 is a perspective view showing an example of the coil bobbin according to the present invention;
FIG. 5 is a plan view of FIG. 4;
FIGS. 6 and 7 are views used for explaining recesses or cut-off portions shown in FIGS. 4 and 5; and FIGS. 8A and 8B cross-sectional views showing an example of the inverse engaging means according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
When the high voltage winding of a fly-back transformer used in a high voltage generating circuit of a television receiver is divided into plural ones and then wound on a bobbin, the divided windings (divided coils) are connected in series through a plurality of rectifying diodes.
When the winding is divided into, for example, three portions, such as divided coils La, Lb and Lc, they are wound on a bobbin proper 1 from, for example, left to right sequentially in this order as shown in FIG. 1. In this case, if the divided coils La and Lc are selected to have the same sense of turn and the middle coil Lb is selected to have the opposite sense of turn from the coils La and Lc, the distance between the terminal end of coil La and the start of coil Lb and the distance between the terminal end of coil Lb and the start of coil Lc can be got relatively long. Therefore, diodes Da and Db can be mounted by utilizing the space above the block on which the middle coil Lb is wound as shown in FIG. 1, so that it becomes useless to provide spaces for diodes between the divided coils La and Lb and between the divided coils Lb and Lc and hence the bobbin proper 1 can be made compact.
FIG. 2 is a connection diagram showing the connection of the above fly-back transformer. In FIG. 2, reference numeral 2 designates a primary winding (Primary coil) of the fly-back transformer, reference letter L designates its high voltage winding (secondary coil), including divided coils La, Lb and Lc, 3 an output terminal, and 4 a lead wire connected to the anode terminal of a cathode ray tube (not shown), respectively.
An example of the bobbin structure according to the invention, which is suitable to automatically wind coils, which are different in sense of turn in each winding block as shown in FIG. 1, on the bobbin, will be hereinafter described with reference to the drawings.
FIG. 3 is a diagram showing an automatic winding apparatus of a wire lead on a coil bobbin. If it is assumed that the wire lead is wound in the order of winding blocks A, B and C in FIG. 1 and the wire lead is wound on the block A with the bobbin proper 1 being rotated in the counter-clockwise direction as shown in FIG. 3, the relation between the bobbin proper 1 and the wire lead becomes as shown in FIG. 3. In this figure, reference numeral 6 designates a bobbin for feeding the wire lead.
Turning to FIG. 4, an example 10 of the bobbin structure or coil bobbin according to the present invention will be described now. In this example, the winding blocks A, B and C for the divided coils La, Lb and Lc are respectively divided into plural slots or sections by plural partition members or flanges 11, and a cut-off portion or recess 12 is formed on each of the flanges 11 through which the wire lead in one section is transferred to the following winding section.
As shown in FIG. 6, each recess 12 is so formed that its one side extends in the direction substantially coincident with the tangent to the circle of the bobbin proper 1 and its direction is selected in response to the sense of turn of the winding or wire lead. In this case, the direction of recess 12 means the direction of the opening of recess 12, and the direction of recess 12 is selected opposite to the sense of turn of the winding in the present invention.
Now, recesses 12A, which are formed in the winding block A, will be now described by way of example. The positions of recesses 12A formed on an even flange 11Ae and an odd flange 11A 0 are different, for example, about 180° as shown in FIGS. 6A and 6B. Since the bobbin proper 1 is rotated in the counter-clockwise direction in the winding block A and hence the sense of turn of the wire lead is in the clockwise direction, the recess 12A is formed on the even flange 11Ae at the position shown in FIG. 6A. That is, the direction of recess 12A is inclined with respect to the rotating direction of bobbin proper 1 as shown in FIG. 6A. In this case, one side 13a of recess 12A is coincident with the tangent to the circle of bobbin proper 1, while the other side 13b of recess 12A is selected to have an oblique angle with respect to the side 13a so that the recess 12A has a predetermined opening angle.
The opening angle of recess 12A is important but the angle between the side 13a of recess 12A and the tangent to the circle of bobbin proper 1 is also important in the invention. When the wire lead is bridged or transferred from one section to the following section through the recess 12A, the wire lead in one section advances to the following section in contact with the side 13a of recess 12A since the bobbin proper 1 is rotated. In the invention, if the side 13a of recess 12A is selected to be extended in the direction coincident with the tangent to the circle of bobbin proper 1, the wire lead can smoothly advance from one section to the next section without being bent.
In the invention, since the middle divided coil Lb is wound opposite to the divided coil La, a recess 12B provided on each of flanges 11B of the winding block B is formed to have an opening opposite to that of recess 12A formed in the winding block A as shown in FIGS. 6C and 6D.
As shown in FIG. 5, terminal attaching recesses 14 are provided between the winding blocks A and B to which diodes are attached respectively. In the illustrated example of FIG. 5, a flange 15AB is formed between the flanges 11A 0 and 11B 0 of winding blocks A and B, and the recesses 14 are formed between the flanges 11A 0 and 15AB and between 15AB and 11B 0 at predetermined positions. Then, terminal plates 16, shown in FIG. 4, are inserted into the recesses 14 and then fixed there to, respectively. The terminal plates 16 are not shown in FIG. 5. Between the winding blocks B and C and between the blocks A and B, similar terminal attaching recesses 14 are formed, and terminal plates 16 are also inserted thereinto and then fixed thereto.
As described above, since the divided coil Lb is wound opposite to the divided coils La and Lc, it is necessary that the winding direction of the wire lead be changed when the wire lead goes from the block A to block B and also from the block B to block C, respectively.
Turning to FIG. 7, an example of the winding or wire lead guide means according to the present invention will be now described. In FIG. 7, there are mainly shown a bridge member for the wire lead and an inverse member or means for the wire lead which are provided between the winding blocks A and B. At first, a bridge means 20 and its guide means 21, which form the bridge member, will be described. The bridge means 20 is provided by forming a cut-out portion or recess in the middle flange 15AB located between the winding blocks A and B. In close relation to the bridge means or recess 20, the guide means 21 is provided on a bridge section X A at the side of block A. This guide means 21 is formed as a guide piece which connects an edge portion 20a of recess 20 at the winding direction side to the flange 11A 0 of block A in the oblique direction along the winding direction through the section X A .
Next, an inverse engaging means 22 will be now described with reference to FIGS. 7 and 8. If the flange 11B 0 of FIG. 7 is viewed from the right side, the inverse engaging means 22 can be shown in FIG. 8A. In this case, the tip end of one side 13a of recess 12B 1 is formed as a projection which is extended outwards somewhat beyond the outer diameter of flange 11B 0 . The inverse engaging means 22 may take any configuration but it is necessary that when the rotating direction of the bobbin proper 1 is changed to the clockwise direction, the wire lead can be engaged with the recess 12B 1 or projection of one side 13a and then suitably transferred to the next station.
Another guide means 23 is provided on a bridge section X B at the side of winding block B in close relation to the inverse engaging means 22. The guide means 23 is formed as a guide surface which is a projected surface from the bottom surface of section X B and extended obliquely in the winding direction. This guide means or guide surface 23 is inclinded low into the means 22 and has an edge 23a which is continuously formed between the middle flange 15AB and the flange 11B 0 .
In this case, it is possible that the guide means 21 and guide surface 23 are formed to be the same in construction. That is, both the guide means 21 and 23 can be made of either the guide piece, which crosses the winding section or guide surface projected upwards from the bottom surface of the winding section. It is sufficient if the guide means 21 and 23 are formed to smoothly transfer the wire lead from one section to the next section under the bobbin proper 1 being rotated.
Although not shown, in connection with the middle flange 15BC between the winding blocks B and C, there are provided similar bridge means 20, guide means 21, inverse engaging means 22 and another guide means 23, respectively. In this case, since the winding direction of the wire lead is reversed, the forming directions of the means are reverse but their construction is substantially the same as that of the former means. Therefore, their detailed description will be omitted.
According to the bobbin structure of the invention with the construction set forth above, the wire lead, which is transferred from the block A to the section X A by the rotation of bobbin proper 1, is wound on the section X B from the section X A after being guided by the guide piece 21 to the recess 20 provided on the middle flange 15AB, and then transferred to the recess 22 provided on the flange 11B 0 guide surface 23, bridged once to the first section of winding block B through the recess 22 (refer to dotted lines b in FIG. 7). Then, if the rotating direction of the bobbin proper 1 is reversed, the wire lead is engaged with the bottom of recess 22 (refer to solid lines b in FIG. 7). Thus, if the above reverse rotation of bobbin proper 1 is maintained, the wire lead is wound on the block B in the direction reverse to that of block A. When the wire lead is transferred from the block B to block C, the same effect as that above is achieved. Therefore, according to the present invention, the wire lead can be automatically and continuously wound on the bobbin proper 1.
After the single wire lead is continuously wound on blocks A, B and C of bobbin proper 1 as set forth above, the wire lead is cut at the substantially center of each of its bridging portions. Then, the cut ends of the wire lead are connected through diodes Da, Db and Dc at the terminal plates 16, respectively by solder.
In the present invention, the projection piece, which has the diameter greater than that of the flange 11B, is provided in the bridge recess 12 to form the inverse engaging means 22 as described above, so that when the winding direction is changed, the wire lead engages with the inverse engaging means 22 without errors when reversing the winding direction of the wire lead.
If the diameter of the projection piece of means 22 is selected, for example, to be the same as that of the flange 11B, it will not be certain that the wire lead engages with the means 22 because it depends upon the extra length of the wire lead and hence errors in winding cannot be positively avoided.
Further, in this invention, the bridge means is provided on the flange positioned at the bridging portion of the bobbin which has a number of dividing blocks separated by flanges, and the inverse engaging means is provided and also the guide means is provided at the former winding section to cooperate with the inverse engaging means. Therefore, the wire lead can be positively fed to the bridge means, and the transfer of the wire lead to the following winding section can be carried out smoothly.
Further, in this invention since one side of the recess 12 is selected coincident with the tangent of the outer circle of the bobbin proper 1 and also with the winding direction, the wire lead can be smoothly bridged to the following section. Due to the fact that the direction of recess 12 is changed in response to the winding direction, even if there is a block on which the wire lead is wound in the opposite direction to that of the other block, the wire lead can be continuously and automatically wound through the respective blocks.
The above description is given for the case where the present invention is applied to the coil bobbin for the high voltage winding of a fly-back transformer, but it will be clear that the present invention can be applied to other coil bobbins which require divided windings thereon with the same effects.
It will be apparent that many modifications and variations could be effected by one skilled in the art without departing from the spirits or scope of the novel concepts of the present invention, so that the spirits or scope of the invention should be determined by the appended claims only.