JPS6244748B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a television receiver, and particularly to a television receiver that allows the size of the screen to be changed without deteriorating the image quality of the television receiver, thereby saving power consumption. Conventionally, the power consumption of a television receiver has already been determined at the stage of designing the television receiver, so if a battery or storage battery with a certain power capacity is used as a power source, the power consumption will be constant. The television receiver could only operate up to its capacity. Furthermore, although the power required by the signal circuit does not change much depending on the size of the cathode ray tube, it is known that horizontal deflection power, vertical deflection power, and beam power vary significantly depending on the size of the cathode ray tube. . In view of this point, the present invention makes it possible to change the screen size without deteriorating the image quality. Note that the present invention takes the following points into consideration. Generally, the deflection width h is expressed by the following formula. Here, H is the strength of the magnetic field, l is the width of the deflection coil in the electron beam traveling direction, L is the distance from the center of the deflection coil to the center of the fluorescent screen of the cathode ray tube, and E _HV is the anode voltage. Further, the strength H of the magnetic field is proportional to the deflection current I, as shown by the following equation. H∝N・I ∴H∝I ...(2) Here, N is the number of turns of the deflection coil. Further, the deflection current I is proportional to the power supply voltage E _B as shown in the following equation. I=E _B /LyT ∴I∝E _B ...(3) Here, Ly is the inductance of the deflection yoke,
T is the scanning period. Further, as shown by the following equation, the anode voltage E _HV is proportional to the power supply voltage E _B and the speed Va at which the electron beam reaches the screen is proportional to the square root of the anode voltage E _HV . E _HV ∝E _B ……(4) Va∝√ _HV ……(5) Now, using equations (1) to (4), consider the case where, for example, the power supply voltage E _B is doubled by 1/2. . From equation (4), when increasing the power supply voltage E _B by 1/2,
The anode voltage _EHV becomes 1/2. Also, (2), (3)
According to the formula, when the power supply voltage E _B is increased by 1/2, the deflection current I becomes 1/2 and the magnetic field strength H becomes 1/2. In equation (1), 0.3l·L can be considered as a constant, so if we set 0.3l·L=A, it is expressed by the following equation. As mentioned above, when the power supply voltage E _B is increased by 1/2, the anode voltage E _HV and the magnetic field strength H are increased by 1/2, so from equation (6), the deflection width h is

[Formula] double. By the way, if the power supply voltage E _B is increased by 1/2, the anode voltage E _HV will be increased by 1/2, and the beam speed Va will be increased by 1/√2. Since the emission energy of the beam is proportional to the square of the beam speed Va, the power supply voltage E _B
If it is 1/2 times, the emission energy of the beam is 1/2
It will be doubled. Therefore, while the deflection width h is multiplied by √2/2, the emission energy of the beam becomes 1/2, so if left as is, the emission energy of the beam that reaches the phosphor screen per unit time will decrease. The brightness will decrease. In order to prevent brightness reduction, the power supply voltage E _B must be
When it is multiplied by 1/2, the deflection width h may be set to 1/2 by adjusting the deflection current I. That is, from equation (6), when the power supply voltage E _B is 1/2 times, the anode voltage E _HV is 1/2 times, so in order to make the deflection width h 1/2 times, the strength of the magnetic field must be H is 1/
It should be multiplied by 2√2=(1/2). Therefore, from equation (2), the deflection current I should be multiplied by (1/2). In this way, when the power supply voltage E _B is increased by 1/2,
By increasing the deflection current I by (1/2), the deflection width h can be increased by 1/2 while maintaining the original brightness. Generalizing this, the power supply voltage E _B is 1/N
By multiplying the deflection current I by (1/N times), the deflection width h and therefore the screen size can be increased by 1/N times while maintaining the original brightness. An embodiment of the television receiver of the present invention will be described below with reference to the drawings. In the figure, 1 indicates a video signal input terminal to which a video signal is supplied, and the video signal supplied to this video signal input terminal 1 is supplied to the input side of a video drive circuit 3 via a signal system circuit 2. The video output signal obtained from the output side of the video drive circuit 3 is supplied to, for example, the cathode of the cathode ray tube 4, so that the video is reproduced. Further, the horizontal synchronizing signal obtained from the synchronizing signal output terminal of the signal system circuit 2 is supplied to the horizontal oscillating circuit 5 so that the horizontal oscillating circuit 5 oscillates in synchronization with the horizontal synchronizing signal. A horizontal oscillation output signal synchronized with the horizontal synchronization signal obtained on the output side is supplied to the base of a horizontal output transistor 6 constituting the horizontal output circuit, the emitter of this transistor 6 is grounded, and the collector of this transistor 6 is connected to a damper diode 7. and capacitor 8
The collector of the transistor 6 is grounded to one end of the primary winding 9a of the flyback transformer 9.
The other end is connected to the second power supply voltage output terminal 10. The collector of the transistor 6 is connected to one fixed contact 11b of the changeover switch 11, and the tap provided in the middle of the primary winding 9a of the flyback transformer 9 is connected to the other fixed contact 11c of the changeover switch 11.
Furthermore, the movable contact 11a of this changeover switch 11 is connected to the capacitor 12 and the horizontal deflection coil 13.
and ground through a parallel circuit with the series circuit of capacitor 14. In this case, when the movable contact 11a of the changeover switch 11 is connected to one fixed contact 11c, the power supplied to the horizontal output circuit is greater than when the movable contact 11a of the changeover switch 11 is connected to the other fixed contact 11b. The position of the intermediate tap provided on the primary winding 9a of the flyback transformer 9 is set so that when the voltage is set to 1/N, the current supplied to the horizontal deflection coil 13 is multiplied by (1/N). . Also, the vertical synchronizing signal obtained from the synchronizing signal output terminal of the signal system circuit 2 is supplied to the vertical oscillation circuit 15, and the output side of this vertical oscillation circuit 15 is connected to the resistor 1.
6, 17 and a connection switch 18, and the vertical oscillation output signal obtained at the mutual connection point of the resistors 16 and 17 is sent to the vertical output circuit 19.
The vertical output circuit 19 supplies a vertical deflection current to the vertical deflection coil wound around the neck of the cathode ray tube 4. In this case, when the connection switch 18 is turned on, the connection switch 18
When the power supply voltage supplied to the vertical output circuit 19 is reduced to 1/N through the voltage divider circuit composed of resistors 16 and 17, compared to when the vertical deflection coil is turned off, the vertical deflection coil is A voltage divider circuit including resistors 16 and 17 is set so that the supplied vertical deflection current (1/N) is doubled. Also, one end of the secondary winding 9b of the flyback transformer 9 is connected to the primary winding 9.
a, the other end of this secondary winding 9b is connected to the anode of a rectifying diode 20, and the cathode of this diode 20 is connected to the power supply voltage supply terminal of the drive circuit 3. Also, one end of the tertiary winding 9c of the flyback transformer 9 is connected to a high voltage rectifier diode 21.
The cathode of this diode 21 is connected to the anode terminal of the cathode ray tube 4, and the other end of this tertiary winding 9c is grounded through a series circuit of resistors 22 and 23. Winding wire 9c
One fixed contact 24 of the switch 24 at the other end
c, the mutual connection point of the resistors 22 and 23 is connected to the other fixed contact 24b of the changeover switch 24, and the movable contact 24a of the changeover switch 24 is connected to the control voltage supply of the automatic brightness control circuit 25. A control signal is supplied from the output side of the automatic brightness control circuit 25 to the brightness control terminal of the drive circuit 3. In this case, this automatic brightness control circuit 2
5, it is controlled to always obtain a constant brightness, and prevents excessive current from flowing through the cathode ray tube 4.
By switching the changeover switch 24, the control sensitivity can be changed. Further, one end of the quaternary winding 9d of the flyback transformer 9 is grounded, the other end is connected to the anode of a rectifying diode 26, and the cathode of this diode 26 is connected to the convergence electrode of the cathode ray tube 4. Reference numeral 27 denotes a battery as a DC power source for this television receiver.The negative pole of this battery 27 is grounded, and a positive DC voltage is applied from this positive pole to an output transformer 2 constituting a first power supply circuit 28.
9 to one end of the primary winding 29a, and the other end of this primary winding 29a constitutes a switching element.
It is connected to the collector of an npn transistor 30, and the emitter of this transistor 30 is grounded. Further, the cathode ray tube 4 is connected to the secondary winding 29b of the power transformer 29.
Heater power supply terminals 31a and 31b that supply heater voltage to the heater of
One end of the tertiary winding 29c is grounded, and the other end is grounded through a series circuit of a rectifier diode 32 and a smoothing capacitor 33 that constitute a rectifier circuit, and the connection point between the diode 32 and the capacitor 33 is connected to the ground. From this, the first power supply voltage output terminal 34 is derived. Also, this diode 32 and capacitor 33
The pulse width modulation circuit 3 uses a comparison signal between the output voltage and the reference voltage obtained from the mutual connection points as a control signal.
5, and the pulse width of the pulse signal supplied from the pulse signal generator 36 is modulated according to the level of this control signal. A pulse width modulated signal obtained from the output side of the pulse width modulation circuit 35 is supplied to the base of the transistor 30 to switch the transistor 30. In this case, the output transformer 29, transistor 30, diode 3
2. A first power supply circuit 28 is composed of a capacitor 33, a pulse width modulation circuit 35, and a pulse signal generator 36, and the first power supply voltage obtained from the connection point of the diode 32 and the capacitor 33 is pulsed. Since control is performed by feeding back to the control voltage supply terminal of the width modulation circuit 35, the first power supply voltage obtained at the first power supply voltage output terminal 34 is kept constant. Further, the first power supply voltage obtained at the first power supply voltage output terminal 34 is supplied to the power supply terminals of the signal system circuit 2, horizontal oscillation circuit 5, vertical oscillation circuit 15, etc., respectively. Further, a positive DC voltage is supplied from the positive terminal of the battery 27 to one end of a primary winding 38a of an output transistor 38 that constitutes a second power supply circuit 37, and the other end of this primary winding 38a constitutes a switching element.
It is connected to the collector of an npn transistor 39, and the emitter of this transistor 39 is grounded. Further, one end of the secondary winding 38b of the output transformer 38 is grounded, and the other end is grounded through a series circuit of a rectifying diode 40 and a smoothing capacitor 41 that constitute a rectifying circuit.
1 to the second power supply voltage output terminal 10 from the mutual connection point of
Derive. Further, the voltage obtained at the mutual connection point of the diode 40 and the capacitor 41 is connected to the output side of the first detection circuit 42 and the second detection circuit 42 to one fixed contact 44b of the changeover switch 44,
The output side of the second detection circuit 43 is connected to the other fixed contact 44c of the changeover switch 44, and the movable contact 44a of the changeover switch 44 is connected to the control voltage supply terminal of the pulse width modulation circuit 45. This pulse width modulation circuit 45 performs pulse width modulation on the pulse signal supplied from the pulse signal generator 36 under the control of the control voltage supplied to the control voltage supply terminal. A pulse width modulated signal obtained from the output side of the pulse width modulation circuit 45 is supplied to the base of the transistor 39 to perform switching. In this case, output transformer 3
8. A second power supply circuit 37 is composed of a transistor 39, a diode 40, a capacitor 41, a first detection circuit 42, a second detection circuit 43, a pulse width modulation circuit 45, and a pulse signal generator 36. By switching the switch 44, the second power supply voltage obtained from the connection point of the diode 40 and the capacitor 41 is connected to the pulse width modulation circuit 4 via the first detection circuit 42 or the second detection circuit 43.
Since control is performed by feedback to the control voltage supply terminal 5, the second power supply voltage obtained from the second power supply voltage output terminal 10 is kept constant. Further, this second power supply voltage is supplied to the power supply terminals of the horizontal output circuit and the vertical output circuit 19. In this case, different reference voltages are applied to each of the first detection circuit 42 and the second detection circuit 43, and the reference voltage and the output voltage are compared, and the first detection circuit 42 and the second detection circuit 43 Since the comparison output is output as the output of the detection circuit 43, the movable contact 44a of the changeover switch 44 is connected to one fixed contact 44b, and the first
When the control voltage is supplied to the control voltage supply terminal of the pulse width modulation circuit 45 through the detection circuit 42 of It is constructed so that the power supply voltage is equal to that required by the horizontal output circuit and the vertical output circuit 19 when an inch screen is obtained, and the movable contact 44a of the changeover switch 44 is connected to the other fixed contact 44c. detection circuit 4
3 to the control voltage supply terminal of the pulse width modulation circuit 45, the second power supply voltage obtained at the second power supply voltage output terminal 10 is applied to a normal size screen, for example, a 10-inch screen. The configuration is such that the power supply voltage required by the horizontal output circuit and vertical output circuit 19 when the screen is 1/N times larger is obtained, that is, the power supply voltage is 1/N times the normal power supply voltage. Since the present invention is configured as described above, in order to obtain a normal size screen, for example, a 10-inch screen, it is necessary to connect the movable contact 11a of the changeover switch 11 to one of the fixed contacts 11b, and to connect the connection switch 1.
8 to OFF, connecting the movable contact 24a of the changeover switch 24 to one fixed contact 24b, and further connecting the movable contact 44a of the changeover switch 44 to one of the fixed contacts 24b.
is connected to one fixed contact 44b. In this case, the first power supply voltage output terminal 3
4 to the power supply terminals of the signal system circuit 2, horizontal oscillation circuit 5, vertical oscillation circuit 15, etc., as usual, and the second power supply voltage output terminal 10 is supplied with a diode 40 and a capacitor. 41
The signals obtained at the mutual connection points of the first detection circuit 4
2 to the control voltage supply terminal of the pulse width modulation circuit 45, the power required by the horizontal output circuit and the vertical output circuit 19 to obtain a normal size screen, for example, a 10-inch screen. A voltage is obtained and supplied to the horizontal output circuit and vertical output circuit 19. Therefore, the horizontal deflection current necessary to obtain a normal screen size, for example, a 10-inch screen, flows through the horizontal deflection coil 13 from the horizontal output circuit.
Further, the vertical deflection current necessary to obtain a normal screen size, for example, 10 inches, flows through the vertical deflection coil from the vertical output circuit 19, and the vertical deflection current necessary to obtain a normal screen size, for example, 10 inches, flows through the cathode ray tube 5. A screen can be obtained, and the secondary winding 9a of the flyback transformer 9 can be connected to the power supply voltage supply terminal of the drive circuit 3.
The power supply voltage is controlled by supplying a voltage corresponding to a higher voltage, and the brightness is controlled by supplying a control signal from the automatic brightness control circuit 25 to the brightness control terminal of the drive circuit 3, thereby achieving good image quality. Obtainable. Next, when reducing the screen size to save power consumption of this television receiver, connect the movable contact 11a of the changeover switch 11 to the other fixed contact 11c, and turn on the connection switch 18. , the movable contact 24a of the changeover switch 24
Connecting the switch to the other fixed contact 24c and further connecting the movable contact 44a of the changeover switch 44 to the other fixed contact 44c are performed in conjunction with each other.
In this case, the heater voltage supplied to the heater of the cathode ray tube 4 and the first power supply voltage output terminal 34 are obtained,
Signal system circuit 2, horizontal oscillation circuit 5, vertical oscillation circuit 1
The first power supply voltage supplied to each power supply terminal 5, etc. is the same as when obtaining a normal size screen, for example, a 10-inch screen, but is obtained from the second power supply voltage output terminal 10, The second power supply voltage supplied to the power supply terminals of the horizontal output circuit and the vertical output circuit 19 is a control voltage that is obtained from the output side of the second detection circuit 43 and is supplied to the control voltage supply terminal of the pulse width modulation circuit 45. Therefore, the size of the normal screen is 1/N times the size of a 10-inch screen, so the cathode ray tube 4 supplied from the tertiary winding 9c and the quaternary winding 9d of the flyback transformer 9.
The anode voltage and convergence voltage are respectively 1/N times as large as when obtaining a normal size screen, for example, a 10-inch screen. Also, in this case, the horizontal deflection current flowing from the horizontal output circuit to the horizontal deflection coil 13 is obtained from an intermediate tap provided on the primary winding 9a of the flyback transformer 9, and is used for a normal size screen, for example, a 10-inch screen. The vertical deflection current flowing from the vertical output circuit 19 to the vertical deflection coil is (1/N) times the current when the vertical output circuit 19 is obtained.
The vertical oscillation output signal obtained from the output side of the is supplied to the input side of the vertical output circuit 19 through a voltage divider circuit consisting of resistors 16 and 17. The current will be (1/N) times as much as when it is obtained. Therefore, as the power supply voltage changes by a factor of 1/N, the horizontal deflection current and vertical deflection current increase by a factor of (1/N). While maintaining the original brightness as explained using
The screen size is 1/N times larger, that is, 10/N inches. In this case, the movable contact 2 of the changeover switch 24
4a is connected to the fixed contact 24c, and a new control voltage is applied to the control voltage supply terminal of the automatic brightness control circuit 25, so that a constant brightness is always obtained regardless of changes in screen size. Since the bias voltage is controlled by supplying a power supply voltage that varies with the power supply voltage E _B to the power supply voltage supply terminal of the drive circuit 3, good image quality can be obtained even when the screen size changes. It will be done. Then, when the screen size becomes 1/N times larger as described above, the deflection power and the like become smaller, so the power consumption becomes smaller. As described above, according to the television receiver of the present invention, the screen size can be changed while maintaining good image quality, and the power consumption of the television receiver can be saved. In the above embodiment, the case where a battery is used as the power source 27 has been described, but even when this television receiver is driven using a commercial power source, the same operation and effect as described above can be obtained by using the same configuration. can. In addition, large-sized receivers whose demand has been increasing in recent years, such as 27
If the present invention is applied to a TV receiver with an inch screen, and if you are enjoying the game alone or you do not need to view it on such a large screen, you can reduce the screen size each time. can save you a lot of money. In addition, in the case of the above embodiment, the power consumption of the receiver is reduced to 2
Three or more detection circuits are provided to supply a control voltage to the control voltage supply terminal of the pulse width modulation circuit 45 of the second power supply circuit 37, although the value is variable.
The second value obtained by switching the detection circuits such as
If the configuration is such that a vertical deflection current and a horizontal deflection current flow such that a vertical deflection magnetic field and a horizontal deflection magnetic field proportional to (E _B ) are obtained according to the power supply voltage E _B of It is easy to understand that the size of the playback screen and the power consumption of the machine can be set in multiple stages. It goes without saying that the present invention is not limited to the above-described embodiments, and can take various other configurations without departing from the gist of the present invention.

[Brief explanation of the drawing]

The figure is a configuration diagram showing an embodiment of the television receiver of the present invention. 1 is a video signal input terminal, 2 is a signal system circuit, 3 is a video drive circuit, 4 is a cathode ray tube, 9 is a flyback transformer, 10 is a second power supply voltage output terminal,
11, 24 and 44 are changeover switches, 13 is a horizontal deflection coil, 18 is a connection switch, 19 is a vertical output circuit, 25 is an automatic brightness control circuit, 27 is a battery, 28 is a first power supply circuit, and 34 is a first 37 is the second power supply circuit, 42 is the first power supply voltage output terminal.
43 is a second detection circuit.

Claims (1)

[Claims] 1. A first power supply circuit that supplies a power supply voltage to a signal system circuit, and a second power supply circuit that supplies a power supply voltage to a deflection system circuit and a bias circuit of a cathode ray tube, The voltage obtained from the power supply circuit is 1/N
means that can vary the vertical and horizontal deflection currents obtained from the deflection system circuit by a factor of 1/N (N is a positive number) as the voltage obtained from the second power supply circuit changes by a factor of 1/N. means for varying the voltage obtained from the second power supply circuit by 1/N times, thereby varying the vertical and horizontal deflection widths by 1/N times. A television receiver characterized by: