JPH0149235B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a tuning display device for displaying a tuning state on the screen of a cathode ray tube of a color television receiver.

(Constitution of Conventional Example and its Problems) A tuning display device in a conventional color television receiver was constructed as shown in FIG. In FIG. 1, a video intermediate frequency signal a is supplied to one end of a capacitor 1, and bias setting resistors 2 and 3 and the base of a carrier amplification transistor 4 are connected to the other end. The emitter of the carrier wave amplification transistor 4 is grounded,
The collector is connected to a power supply +B via a coil 5 and a capacitor 6 that are connected in parallel with each other. The anode of the rectifier diode 7 is connected to the intermediate tap of the coil 5, and its cathode is connected to the other end of the smoothing capacitor 8 whose one end is grounded, and then to the transistor 10 via the resistor 9. connected to the base. The emitter of the transistor 10 is grounded through a resistor 11 and connected to the negative input terminal of a comparator 12, and the collector is connected to the power supply +B through a resistor 13 and connected to the positive input terminal of a comparator 14. There is. Note that the emitter and collector of the transistor 10 are connected to each other via a resistor 15. On the other hand, a horizontal flyback pulse b of positive polarity is supplied to the base of the sawtooth wave generating transistor 16 via a resistor 17, its emitter is grounded, and its collector is connected to the power supply +B via a resistor 18. and grounded via a capacitor 19, and further connected to the plus input terminal of the comparator 12 and the minus input terminal of the comparator 14. Each output terminal of comparators 12 and 14 is connected to an input terminal of AND gate 20, respectively. In addition, a transistor 21 for green cathode drive and a transistor 22 for red cathode drive
and blue cathode drive transistor 23
, green, red, and blue video signals c, d, and e are supplied to each base, respectively.
Each emitter is grounded through resistors 24, 25 and 26, respectively, and each collector is connected to the power supply + through resistors 27, 28 and 29, respectively.
B, and also connected to the green cathode, red cathode, and blue cathode of the cathode ray tube 30, respectively. And gate 20
The output terminal of is connected to the base of the green cathode drive transistor 21 via the diode 31.

Next, the operation of this embodiment will be explained. The video intermediate frequency signal a applied to one end of the capacitor 1 is amplified by the carrier wave amplifying transistor 4, and is connected to a coil 5 and a capacitor 6 that are selected to resonate at the frequency of the carrier component of the video intermediate frequency signal a. The carrier wave component is extracted by the rectifying diode 7 and the smoothing capacitor 8, and is extracted as a DC voltage, and the voltage is highest at the optimum tuning point. When this DC voltage is applied to the base of the transistor 10 through the resistor 9, the emitter voltage f of the transistor 10 increases as the base voltage increases, and the collector voltage g decreases as the base voltage increases. On the other hand, the horizontal flyback pulse b applied to one end of the resistor 17 is converted into a sawtooth wave voltage h by the sawtooth wave generating transistor 16, the resistor 18, and the capacitor 19. Then, the transistor 1 is connected to the negative input terminal of the comparator 12.
0 emitter voltage f, a sawtooth wave voltage h is input to the positive input terminal, the collector voltage of the transistor 10 is input to the positive input terminal of the comparator 14, and the sawtooth wave voltage h is input to the negative input terminal of the comparator 14. A pulse-like output voltage i as shown in Fig. 2 is generated from each output terminal.
and j are output. Further, these output voltages i and j are inputted to an AND gate 20, and a pulsed output voltage k as shown in FIG. 2 is outputted from the AND gate 20. As is clear from FIG. 2, as the tuning state approaches the optimum tuning point and the emitter voltage f of the transistor 10 increases and the collector voltage g decreases, the pulse width of the output voltage k of the AND gate 20 becomes narrower. In this way, the AND gate 20 whose pulse width changes depending on the tuning state
The output voltage k is supplied to the base of the green cathode drive transistor 21 via the diode 31, mixed with the green video signal, and sent to the cathode ray tube 30.
is input. Here, since the output voltage k of the AND gate 20 is a pulse signal synchronized with horizontal scanning, the television broadcast image is displayed on the screen of the cathode ray tube 30 as a vertical green band with a width corresponding to the pulse width. It is photographed with Therefore, the width of this green band changes depending on the tuning state, and becomes the narrowest at the optimal tuning point.

However, in the above conventional example, depending on the image of the television broadcast projected on the screen, the green band may be difficult to see and its width may be difficult to judge, or the user may be unable to see the green band on the screen. It is not possible to judge whether the tuning condition is optimal just by looking at the image; it is necessary to operate the adjustment knob on the color television receiver to change the tuning condition and change the width of the green band. It was not possible to clearly know the state of synchronization. Therefore, even though the state of synchronization was optimal, the user had to
I was using the adjustment knob to remove the tuning state from the optimum tuning point and then adjusting it to the optimum tuning point again, which was a wasteful operation.

(Object of the Invention) The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and the display on the screen is easy to see, and it is possible to judge whether or not the synchronization state is optimal just by looking at the screen. The present invention also provides a synchronization display device that can inform the user of what he/she is currently doing through text.

(Structure of the Invention) In order to achieve the above object, the present invention displays characters or figures and their background in different colors on the screen of a cathode ray tube of a color television receiver, and converts a video intermediate frequency signal into a carrier wave. The component is extracted, amplified, and detected, and the color of the background is partially changed depending on the tuning state. When the tuning state is optimal, the background is displayed in a completely uniform color, and when it is not optimal, the background is partially changed. The colors are different.

(Description of Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a diagram showing the configuration of an embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same components. In FIG. 3, 32 is a character generator connected to a microcomputer 33 for control, which generates horizontal flyback pulses b and vertical pulses l.
A character output terminal 34 outputs a pulse-like character output signal of positive polarity for displaying characters, and a background output terminal 34 outputs a pulse-like background output signal of positive polarity for displaying a background. Output terminal 35
It is equipped with. The character output terminal 34 of this character generator 32 is connected via a resistor 36 to the base of another green cathode drive transistor 37 whose emitter and collector are commonly connected to the green cathode drive transistor 21, and also as a background output. The terminal 35 is connected via a resistor 38 to the base of a video signal blanking transistor 39 whose emitter is grounded, and is connected via a resistor 40 to the base of a video signal blanking transistor 39 whose emitter is grounded and whose base is connected to the resistor 40. The collector of the background output control transistor 41 connected to the output terminal of the AND gate 20 through the base of the red cathode drive transistor 22 and another red cathode drive transistor 42 whose emitter and collector are shared. It is connected. The collector of the video signal blanking transistor 39 has cathodes of diodes 44, 45, and 46 whose anodes are connected to the bases of green, red, and blue cathode drive transistors 21, 22, and 23, respectively. Common and connected. Further, the comparator 47 for determining the optimum tuning point has its positive input terminal connected to the cathode of the diode 7, and its negative input terminal connected to the center terminal of a variable resistor 48 for setting a reference voltage. One end of this variable resistor 48 is connected to the power supply +B via a resistor 49, and the other end is grounded via a resistor 50. The output terminal of the comparator 47 is connected to a switching transistor 5 whose emitter is grounded after passing through a resistor 51.
Connected to the base of 2. Note that the collector of the switching transistor 52 is connected to the base of the background output control transistor 42.

Next, the operation of this embodiment will be explained. The character generator 32 is controlled by the microcomputer 33 to generate the characters, for example, "JUST" at a predetermined position on the screen 53 of the cathode ray tube 30 on which the television broadcast image is projected, as shown in FIG. 54
A character output signal and a background output signal are outputted from the character output terminal 34 and the background output terminal 35, respectively, so that the character 54 and the background 55 surrounding the character 54 in a square are displayed. Here, the horizontal flyback pulse b and vertical pulse l input to the character generator 32 are used to set the display positions of the characters 54 and the background 55. This character output terminal 34
The character output signal outputted from the circuit drives the green cathode drive transistor 37 through the resistor 36, and displays the green character "JUST" on the screen 53 as shown in FIG. Further, the background output signal outputted from the background output terminal 35 drives the red cathode drive transistor 43 via the resistor 40, and the screen 53 is output as shown in FIG.
The background 54 surrounding the green text in a square is displayed in red, and the video signal blanking transistor 39 is made conductive via the resistor 38 to blank the video signal while the background output signal is being output. are doing. At this time, the comparator 47 for determining the optimal tuning point has its negative input terminal supplied with the reference voltage set by the variable resistor 48, and its positive input terminal extracts the carrier wave component from the video intermediate frequency signal from the diode 7. A signal corresponding to the amplified and detected tuning degree is supplied, and this reference voltage is set so that the output is high at the optimum tuning point. Therefore, when the tuning state is not optimal, the comparator 47 outputs a low level and the switching transistor 52 is cut off, so the background output control transistor 42 becomes conductive due to the pulsed output voltage k from the AND gate 20. By repeating the interruption, the background output signal is interrupted only while the pulse of the output voltage k of the AND gate 20 is being output, and a part of the red background 55 is changed to a black background 55' as shown in FIG. indicate.
The width of this black background 55' is the width of the AND gate 2
Since it is proportional to the pulse width of the output voltage k of 0, it is wide if the tuning state is far from the optimal tuning point, and becomes narrower as it approaches the optimal tuning point. Note that the width of the red background 55 is set so that even when the width of the black background 55' becomes the widest, it does not exceed the width of the red background 55. Furthermore, when the optimum tuning point has been reached, the output of the comparator 47 for determining the optimum tuning point becomes high, and the switching transistor 5
2 conducts and the background output control transistor 42
cut off. Therefore, the red cathode drive transistor 43 is driven by the background output signal supplied without being cut off from the background output terminal 35 of the character generator 32, and as shown in FIG. A red background 55 is displayed.

In this way, when the tuning state is not optimal, a part of the red background 55 is changed to a black background 55' with a width corresponding to the tuning degree, and when the tuning state reaches the optimal tuning point, the red background 55 is displayed. Since it is displayed in its complete form, the user can correctly judge the state of synchronization just by looking at the display.

In the above embodiment, the display is performed using characters and the background thereof, but instead of the characters, a figure may be displayed, and the synchronization state may be indicated by the figure and the background.

(Effects of the Invention) As explained above, the present invention displays characters or figures and their backgrounds in different colors on the screen of a cathode ray tube, extracts a carrier wave component from a video intermediate frequency signal, and amplifies and detects it. Using signals, the background color is partially changed with a width depending on the synchronization state, and when the optimal synchronization state is reached, the background color is unified and displayed. The display is easy to see due to the contrast with the different colored background, and the user can accurately judge the state of synchronization just by looking at the display, and it can also be used as advertising by displaying trademarks, company names, etc. as text. It has the following effects.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a conventional tuning display device;
The figure is a signal waveform diagram of the main part of FIG. 1, FIG. 3 is a circuit diagram of an embodiment of the present invention, and FIG.
FIG. 5 is a diagram showing the display state of the screen when the synchronization state is not optimal in one embodiment of the present invention.
It is a figure which shows the display when the tuning state of a figure is optimal. 4...Transistor for carrier wave amplification, 7...Diode for rectification, 12, 14, 47...Comparator, 16...Transistor for sawtooth wave generation, 2
0...AND gate, 21,37...Green cathode drive transistor, 22,43...Red cathode drive transistor, 23...Blue cathode drive transistor, 30...Cathode ray tube, 32...Character generator, 33...Microcomputer, 34...Character output terminal, 35...
Background output terminal, 39...Transistor for video signal blanking, 42...Transistor for background output control, 52...Switching transistor, 54
...Character, 55,55'...Background.

Claims (1)

[Claims] 1 A character generator capable of displaying a character string indicating that a tuning operation is being performed on the cathode ray tube screen of a color television receiver by specifying the character color and background color separately, and a video intermediate frequency and a tuning degree detection means for extracting, amplifying and detecting a carrier wave component from a signal, and changing the background color of the character string according to the tuning state by the output of the tuning degree detection means, and making the background color uniform during tuning, A tuning display device characterized in that a part of the background color changes when detuning occurs.