JPS5836872B2 - Index type color television receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an index type color television receiver that can perform stable and synchronous operation even after the index signal is interrupted.

A color television receiver uses a single electron gun to form index stripes on the screen surface of the picture tube, extracts an index signal by scanning with an electron beam, and uses this index signal to synchronize colors and reproduce images. be.

This index type picture tube consists of a group of color phosphor stripes arranged perpendicularly to the scanning direction of the electron beam, and a group of index stripes arranged in a certain relationship with the color phosphor stripes. For example, a light emitter that generates ultraviolet light by an electron beam is used as the index line group.

In order to reproduce colors using an index type picture tube having such a configuration, it is necessary to add color information corresponding to the color phosphor to the position where the electron beam reaches.

The index line group is used to detect the position of this electron beam.

That is, when hit by an electron beam, the index filament group generates ultraviolet rays, this light is detected externally, and the electron beam is controlled based on the detected signal.

In such an indexing method, the color phosphor stripes and the index stripes are arranged in a certain relationship;
This relationship is very important.

For example, if we consider the case where one triplet of color phosphors (one set of R.G.B color phosphors is referred to as one triplet) is provided with one index line group, the detected index The signal frequency f■ is equal to the triplet frequency fT of the color phosphor strips, and the triplet frequency is equal to the writing frequency controlling the electron beam.

In such a relationship, the phase of the index signal is modulated by the write signal and interferes with each other, resulting in a drawback that an accurate index signal cannot be obtained.

In order to avoid such drawbacks, an arrangement method is generally used in which the triplet frequency and the index frequency are different.

However, if they are arranged in this way, the index signal and the color phosphor stripes will not correspond to each other, so it is necessary to decide in advance which color the index signal corresponds to.

For this purpose, index lines for synchronization are arranged on the screen end side on the start side of horizontal scanning.

This index line for synchronization is called a run-in line or a lead-in line.

Fig. 1 is an enlarged view of the screen surface on the horizontal scanning start side of an index-type color picture tube having the structure described above.
The phosphor strips 2 are arranged on top of the phosphor strips 2, and the metal back 3 is applied on top of the phosphor strips 2.

An index filament 4 is provided on the metal bag 3 in a certain relationship with the phosphor filament 2, and a lead-in filament 5 is further provided on the horizontal scanning start end side of the index filament 4.

6 is a black guard band.

Further, 7 indicates the index filament pitch P■, 8 the index filament width, 9 the triplet pitch PT of the color phosphor filaments, 10 the width of the phosphor filament and one set of guard bands, and 11 indicates the width of the phosphor stripes.

Here, the case of P1:PT=2:3 is shown as one column.

The index line width 8 and the phosphor line width 11 are equal, and the phosphor line width 11 is 1/6 of the triplet pitch 9.

FIG. 2 shows a picture tube 1 having such a screen surface 12.
FIG. 3 is a block diagram showing an example of a color reproduction device using the color reproducing device No. 3.

That is, the picture tube 13 has the above-mentioned screen surface 12 and single electron gun 14, and further includes an index signal detection device 15 using a photoelectric conversion element such as a photomultiplier tube on the side.
is provided.

Then, the index line and the lead-in line are scanned every horizontal scan, and an index signal is taken out from the index signal detection device 15. This signal is led to the face-opening loop circuit 16, where it is synchronized with the phase. A signal of twice the frequency is extracted and applied to frequency divider 17.

This frequency divider 17 divides the input signal frequency into 1/3 and supplies the R. G. It is added as a gate pulse to the gate circuit 1B, 19.20 for guiding the H three primary color signals.

On the other hand, a lead-in signal is extracted by a gate circuit 21 from the index signal extracted by the index signal detection device 15, and is applied to a reset pulse generation circuit 22 to generate a reset pulse.

This reset pulse is applied to frequency divider 17 and resets it.

That is, the frequency divider 17 is reset by the detection of the lead-in signal every horizontal scan, and color synchronization is achieved.

However, in this method, the phase is matched by a lead-in signal at the start of horizontal scanning, but if the index signal is interrupted midway, synchronization will be lost from then on until the horizontal scanning is completed, and color reproduction will not be possible.

Therefore, it is necessary to take measures such that the index signal can be detected in any state.

For example, a small amount of electron beam is sent even in the black part of the image (
The need arises (called dark current).

If the amount of dark current is too large, the contrast deteriorates, so it must be strictly controlled.

Furthermore, considering that the cutoff characteristics of the picture tube change due to changes over time, the dark current control described above is extremely difficult.

This invention has been made in consideration of these points, and is designed to detect the index line at two different frequencies. Index type color that cuts off the signal applied to the picture tube, detects a synchronization signal without phase modulation, and uses this to create a reset pulse, allowing stable color synchronization and normal color reproduction even after the index signal is interrupted. The company provides television receivers.

An example of the present invention will be described below with reference to the drawings.

FIG. 3 is an enlarged view of the screen surface of the picture tube used in the color television receiver according to the present invention. G. A color phosphor line 32 of color B is formed, and a metal bag 33 is placed on this color phosphor line 32.
An index filament 34 is provided through the layer, and a lead-in filament 35 is provided on the horizontal scanning start end side from this.

The index filament 34 is the first index filament 3
41 and a second index filament 342 formed wider than this, and arranged so that, for example, the second index filament 342 is arranged every second index filament 341. be done.

Note that 36 is a guard band. 37 is the index pitch P, 38 is the triplet pitch, 39 is the pitch of each color phosphor line, which is 1/3 of the triplet pitch 38, and the color phosphor line width 40 is equal to 1/6 of the triplet pitch 38. It becomes.

Further, 41 is the first index line width, which is equal to 1/3 of the index pitch 37, and 42 is the second index line width, which is equal to 1/2 of the index pinch 37.

A circuit of a picture receiver according to the present invention using a picture tube having such a screen surface is constructed as shown in FIG.

As shown in FIG. 4, the picture tube 43 has a screen surface 44 and a single electron gun 45 as described above, and is also equipped with an index signal detection device 46 made of a photoelectric conversion element such as a photomultiplier tube on the side. This index signal detection device 4
At the output end of 6, there is a phase-locked loop 47 that synchronizes with the phase of the detected index signal and generates a signal with twice the frequency, and divides the frequency signal obtained by this phase-locked loop 47 into 1/3. A frequency divider 48 is connected in series.

Also, the output terminal of this frequency divider 48 has R. G. Gate circuits 49, so and si to which each primary color signal of B is added are connected,
A gate circuit 52 is inserted and connected between the output ends of the gate circuits 49, so, si and the picture tube 43.

Further, the index signal detection device 46 includes a gate circuit 53 for extracting a lead-in signal from the output signal thereof, and a reset pulse generator for generating a reset pulse for resetting the frequency divider 48 using the output signal of the gate circuit 53. Circuits 54 are connected in series.

Further, a detection circuit 55 for detecting a lack of an index signal and a gate pulse generation circuit 56 that reacts at the falling edge of the output pulse of this detection circuit 55 are connected in series to the output terminal of the index detection device 46 to generate the gate pulse. The output end of the circuit 56 is connected to the gate circuit 52.

Further, at the output terminal of the index signal detection circuit 46,
A frequency selection circuit 57 extracts the third harmonic of the index signal obtained from the second index line 342 in the output signal, and the reset pulse generation circuit generates an auxiliary synchronization pulse from the output signal of the frequency selection circuit 57. 54 and a gate pulse generation circuit 58 are connected in series.

The operation of such a structure will be explained with reference to the waveform diagram of FIG. 5.

First, as shown in FIG. 3 in the picture tube 43, when the screen surface is scanned in the direction of arrow 59 by an electron beam,
A signal as shown in FIG. 5a is taken out by the index signal detection device 46.

This detected index signal 60 is applied to a phase-locked loop circuit 47, where a double frequency signal locked to the phase of this signal is generated and taken out as an output as shown in FIG. 5b. is applied to frequency divider 48.

The triplet frequency fT is 2/3 times the index frequency f when viewed from the arrangement shown in FIG. R of frequency fT. G. Create a gate pulse corresponding to B,
This is applied to each gate circuit 49, 50, 51.

On the other hand, the read-in signal 61 is taken out from the output of the index signal detection device 46 by the gate circuit 53 and applied to the reset pulse generation circuit 54.

This causes the reset pulse generation circuit 54 to operate and generate a reset pulse.

This reset pulse is applied to the frequency divider circuit 48, and the frequency divider 4
8 is reset every horizontal scan to perform frequency division.

Therefore, if synchronization is achieved at the start of horizontal scanning, no synchronization will occur unless the index signal is lost.

Now, if we consider the case where a black image state occurs during a certain period 63 as shown in FIG. With those, you will be able to synchronize after that.

That is, the screen surface 4 of the picture tube 43 in this device
4, the index filament 34 is divided into the first index filament 341 and the second index filament 342 as described above, and the second index filament 342 is divided into two of the first index filament 341. The second index line width 42 is set to 1/2 of the index pitch 37, so that the duty ratio of the detected index signal (62 in FIG. 5a) is l:1. I have to.

Further, the first index line width 41 is set to 1/3 of the index pitch 37, so that the duty ratio of the detected index signal is 2:1.

Generally, a signal with a duty ratio of 2:1 (1 Therefore, the third harmonic becomes A3=0.

Therefore, if all the screens are arranged in a 2:1 arrangement, the third harmonic of the index signal will not be detected.

However, on the screen with the above configuration, a signal with a duty ratio of 1 is detected for every two index lines in the section 37, so the output of the frequency selection circuit 57 is changed as shown in FIG. 5C. The third harmonic is extracted.

Since the position from which this third harmonic is extracted corresponds to the color phosphor, this signal can be used for synchronization after the index signal is interrupted.

However, since the period at which this third harmonic is detected is twice the triplet period, that is, twice the write signal period,
Since it is phase modulated by the write signal, it cannot be used as is.

Therefore, this device cuts off the image from when the index signal is interrupted and is detected again until the first third harmonic is obtained, making it a mere gray raster, and extracting the third harmonic without undergoing phase modulation from the write signal. , generates auxiliary synchronization pulses.

Therefore, the detection position of the third harmonic in this case is shown in Figure 5C.
66, which is much more accurate than the third harmonic shown at 64.

That is, when the index signal disappears for a period indicated by 63 in FIG. 5a, the detection circuit 55 generates a pulse as shown in FIG. 5 eφ during the period when the index signal is missing.

A gate pulse that rises synchronously at the falling edge 67 of this pulse, that is, at the end of the signal missing period, and falls synchronously with the falling edge 68 of the output pulse of the auxiliary synchronizing pulse generating circuit is sent from the gate pulse generating circuit 56 to the fifth gate pulse. This occurs as shown in Figure f.

This gate pulse is applied to the gate circuit 52 to cut off the write signal, and on the other hand, the auxiliary synchronization pulse generation circuit 58
, and resets this circuit at the rising edge of the gate pulse.

Then, when the first third harmonic 66 after the index signal missing period, which is completely unaffected by the write signal, is obtained,
This is applied to the auxiliary synchronization pulse generation circuit 58 via the frequency selection circuit 57, and therefore the auxiliary synchronization pulse generation circuit 58
B generates the auxiliary synchronization pulse again as shown in FIG. 5d.

This auxiliary synchronizing pulse is applied to the gate pulse generating circuit 56, and at its falling edge 68, the output pulse of the gate pulse generating circuit 56 falls.

Therefore, the gate pulse to the gate circuit 52 disappears, and the gate circuit 52 releases the cutoff of the write signal.

At the same time, the auxiliary synchronizing pulse is applied to the reset pulse generating circuit 54, setting it, generating a reset pulse, applying the reset pulse to the frequency divider 48, resetting it, and causing the frequency dividing operation to be performed again.

This period, that is, the period T0 from the end of the index signal missing period to the restart of frequency division, is the maximum 2 triplets, so it does not pose any particular problem in terms of image reproduction.

In this way, in this device, the write signal is cut off from the time when the first index signal is interrupted and starts to be detected again until the first second index signal is obtained, and the second index signal is processed without interference of the write signal. detect,
By resetting the frequency divider using the auxiliary synchronization pulse generated from this signal, stable color synchronization can be achieved even after the first index signal is interrupted.

Therefore, there is no need to control the dark current so that a dark current is always obtained, and normal image reproduction can be performed without any accompanying deterioration in contrast.

In the embodiment, the presence or absence of the third harmonic of the index signal was used as a means for detecting a signal corresponding to the color phosphor stripe, but the present invention is not limited to this. The arrangement 1 is appropriately arranged so that there is a difference in the width of each index line of 2, and the presence or absence of the n-th harmonic occurs.
It is sufficient if a signal corresponding to the red phosphor stripes can be obtained.

Also, index pinch P■ and triplet pitch PT
Although the ratio is set to 2:3, it is not limited to this.

As described above, according to the present invention, it is possible to provide an index-type color television receiver that can stably achieve color synchronization even if there is an interruption in the index signal, and can reproduce images with good contrast.

[Brief explanation of the drawing]

Figure 1 is an enlarged view showing the screen structure of a conventional index-type color picture tube, and Figure 2 is a circuit diagram of a conventional index-type color television receiver using a picture tube with the screen structure shown in Figure 1. FIG. 3 is an enlarged view showing the screen structure of an index type picture tube used in an index type color television receiver according to the present invention.
4 is a circuit diagram of an index-type color television receiver according to the present invention using a picture tube having the screen structure shown in FIG. 3, and FIG. 5 is a diagram of the index-type color television receiver shown in FIG. 4. It is a signal waveform diagram of each part of a receiver. 31... Glass, 32... Phosphor stripe, 33... Metal back, 34... Index stripe, 35... Lead Instriatum, 3
41...First index line, 342...
...Second index line, 36... Card band, 37... Index pitch, 3
8... Triplet pitch, 39...
Color phosphor line pitch, 40... Color phosphor line width, 41... First index line width, 42.
...Second index line width, 43...
・Picture tube, 44...Screen surface, 45...
... Single electron gun, 46 ... Index signal detection device, 47 ... Phase locked loop, 4
8... Frequency divider, 49, 50, 5L52, 53.
... Gate circuit, 54 ... Reset pulse generation circuit, 55 ... Detection circuit, 56 ...
. . . Gate pulse generation circuit, 57 . . . Frequency selection circuit, 58 . . . Auxiliary synchronization pulse generation circuit.

Claims (1)

[Scope of Claims] A first index filament group arranged at an index pitch having a non-integer relationship with the triplet pitch of the one-color phosphor filament, and this index filament group is a first index filament; An index type color picture tube configured of second index filaments that are wider than the first index filaments and are arranged at predetermined intervals, and the index of the index signal detected by the index signal detection device. a clock generating means for generating a clock having a frequency corresponding to the pitch; a frequency divider for dividing the output of the clock generating means to generate a gate pulse that determines the scanning timing of the electron beam with respect to the color phosphor strip; a detection circuit for detecting a period of missing index signal; auxiliary index signal detection means for detecting a signal obtained by irradiating the second index filament with an electron beam; and detecting a missing period of the index signal by the detection circuit. and an auxiliary synchronization pulse generation circuit that detects phase information due to the difference in the width of the second index filament and the first index filament by the auxiliary index signal detection means and generates an auxiliary synchronization pulse. and a reset means for resetting the frequency divider and performing color synchronization after the index signal is lost, using the auxiliary synchronization pulse output from the auxiliary synchronization pulse generation circuit, even if the index signal is lost. The above second index'
An index-type color television receiver characterized in that color synchronization is performed using a signal obtained by irradiating electron beams onto the Socus rays.