JPH0759043B2 - Vertical deflection circuit - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical deflection circuit used in a time-division shutter type stereoscopic television receiver or the like.

2. Description of the Related Art The principle of a conventional stereoscopic television using a time-division shutter system is as shown in FIGS. This uses the binocular parallax of the human eye, and the left and right eyes 10
Images of an object viewed from different angles are projected on the retinas of 0 and 101, and they are merged to be seen as one stereoscopic image.

First, FIG. 9 (a) schematically shows how two points P and Q existing in the horizontal plane are imaged on the retina. When this is applied to the case of shooting with a stereoscopic camera, it becomes as shown in FIG. In the figure, the left camera 102 corresponds to the left eye 100, and the right camera 103 corresponds to the right eye 101. The image (P ' _L ) captured by the left camera 102 is the image (P' _R ) captured by the right camera 103.
The image formed by the left camera 102 and the image formed by the left camera 102 (Q ′ _L ) into the image formed by the right camera 103 (Q ′ _R ). Considering the cathode ray tube surface 104 of the television as shown in FIG. 9C, Q appears in front of the TV and P appears in the back. So the tenth
The figure shows a configuration example of a stereoscopic television system using a time-division shutter system. The left camera 102 and the right camera 103 are the ninth
In the same relationship as the diagram (b), the information L ₁ in the frame unit captured by the left camera 102, L ₂ , L ₃ , ..., L _{n + 1} , the information R in the frame unit captured by the right camera 103 ₁ , R ₂ , R ₃ ,
…, Outputs R _{n + 1} . Information from the left camera 102 is input to the terminal b of the switch 105 that is switched alternately, and information from the right camera 103 is input to the terminal a. Each information is L ₁ , L ₂ ,
_{L 3, ..., L n +} 1, R 1, R 2, R 3, ..., and output a vertical synchronizing signal cycle of R _{n + 1} and 60 Hz. The switch 105 switches between terminals b and c and terminals a and c at a vertical synchronizing signal cycle of 60 Hz, so that a stereoscopic video signal of L ₁ , R ₂ , L ₃ , R ₄ , ... Is output from the terminal c. To be done. That is, the stereoscopic video signal referred to here is a video signal in which one set of left and right information having a 60 Hz vertical synchronizing signal cycle (in units of one frame) is one field. Therefore, the stereoscopic video signal is
When input to the stereoscopic television 106 of FIG. 11, left and right information is displayed in 1/60 cycles for each frame. It is assumed that the display screen is viewed with both eyes through the stereoscopic scope 107. The three-dimensional scope 1
07 is composed of a left shutter 108 and a right shutter 109, and performs opening / closing operations which are opposite to each other in the same vertical synchronization period as the stereoscopic video signal. For example, the signal of the L ₁ frame of the stereoscopic video signal shown in FIG. 10 (information from the left camera) is the stereoscopic television 106 of FIG.
, The left shutter 108 of the stereoscopic scope 107 is open and the right shutter 109 is closed, so that only the information from the left camera 102 can be seen from the left eye 100 through the left shutter 108. Next, when the R ₂ frame signal (information from the right camera) is displayed, the left shutter 108 of the stereoscopic scope 107 is closed, the right shutter 109 is opened, and the right eye 10
Only information from the right camera 103 can be seen from 1 through the right shutter 109. If the above operations are repeated at a vertical synchronizing signal cycle of 60 Hz, it becomes equivalent to watching the image information of the binocular parallax shown in FIG. Can be realized. In other words, the stereoscopic television 106 shown in FIG.
z, horizontal 15KHz raster scan TV can be used.

Problems to be Solved by the Invention A conventional stereoscopic television system using a time-division shutter system usually uses a display having a vertical deflection frequency of 60 Hz, so that the repetition frequency of left and right images is also 60 Hz. Therefore, a flickering flicker appears in the image, which hinders the stereoscopic effect. Therefore, in order to solve the occurrence of the flicker, it is conceivable to change the repetition frequency to 120Hz, which is doubled.However, since the vertical retrace time has little dependence on the frequency, the display screen is distorted only by changing the frequency. I can't get a normal image.

Therefore, when the vertical deflection frequency is changed, the peak value of the vertical deflection voltage during the vertical blanking period is changed. However, if this switching is performed at an arbitrary timing when the operation switch is operated, the peak value is switched when a high back electromotive force is generated in the deflection coil, which may give great stress to the circuit components.

It is an object of the present invention to provide a novel vertical deflection circuit that solves such a problem.

Means for Solving the Problems In order to achieve the above object, the present invention provides a vertical deflection circuit in which a peak value of a vertical deflection voltage in a vertical retrace period is switched according to a frequency of a vertical synchronization signal. A crest value changeover switch for changing the crest value of the vertical deflection voltage during the period, a changeover instruction switch, a retrace line detection circuit for detecting a vertical retrace period, a changeover instruction by the changeover instruction switch and the retrace line detection circuit. And a latch circuit for switching the crest value changing switch when the detection signal is input, so that the crest value changing switch is switched at the beginning of the vertical blanking period.

Operation With this configuration, for example, when reproducing a video signal with a vertical sync signal frequency of 120 Hz, the deflection voltage during the vertical blanking period is higher than when it is 60 Hz, so vertical blanking is faster, As a result, the display period is lengthened and distortion does not occur on the screen.

Further, no matter which timing the switch instruction switch is operated, the crest value is switched at the beginning of the vertical blanking period, so that there is no possibility of exerting a large stress on the circuit portion.

Examples The present invention will be described in detail below based on examples. FIG. 1 is an overall block diagram of a crest value switching type vertical deflection circuit in the case where no means for switching crest value when large back electromotive force is not generated in the deflection coil is provided. In the figure, 1 is a vertical oscillation circuit that synchronizes with an input vertical synchronization signal and self-oscillates, and 2 is a sawtooth wave voltage generated in the vertical oscillation circuit 1 and a vertical output circuit 3 in the final stage.
Is an amplifying / shaping circuit for amplifying and shaping the waveform to a signal level that can sufficiently drive the deflection coil 4. The vertical output circuit 3 amplifies electric power so that a sufficient current flows through the deflection coil 4. Reference numeral 5 denotes a pump-up circuit, which switches and supplies each power source to the vertical output circuit 3. The deflection coil 4 scans the electron beam from top to bottom (vertically) by the sawtooth wave current supplied from the vertical output circuit 3.

FIG. 2 shows an embodiment of a portion including the vertical output circuit 3, the pump-up circuit 5, and the deflection coil 4. Here, the vertical output circuit 3 is a transistor power amplifier such as a push-pull amplifier, and causes a deflection current I ₀ to flow through the deflection coil 4, the capacitor C, and the resistor R. Since the power supply voltage Vn from the pump-up circuit 5 is applied to the terminal j of the vertical output circuit 3, the output waveform voltage Vout at the output terminal k becomes Vout≈Vn. The pump-up circuit 5 outputs the voltages V ₁ , V ₂ , V ₃ given by the power source to 60/1.
It is switched by _two switches of 20 Hz switch SW ₁ and pump up switch SW ₂ and supplied as the power supply voltage of the vertical output circuit 3. Pump up switch SW ₂ has terminals d, e, f
And is switched by the detection signal SD from the retrace line detection circuit 6. The retrace line detection circuit 6 is a circuit for extracting only the retrace line period from the output voltage waveform of the vertical output circuit 3, and outputs a pulse which becomes high level only during the retrace line period as the detection signal SD as shown in FIG. . High level, i.e. blanking period of the detection signal SD of the pump up switch SW ₂ terminal d-
The voltage from the terminal g of the 60/120 Hz switch SW ₁ is applied to the terminal j between the terminals e. Pump up switch SW _{2 when the} detection signal SD is at low level
The terminals d and f are turned on and the voltage V ₁ is applied to the terminal j of the vertical output circuit 3. This is because if the power supply voltage is increased, the power consumption of the vertical output circuit 3 increases and problems such as heat generation occur. Therefore, the high power supply voltages V ₃ and V ₂ are added only during the vertical retrace line period, and the display period is the minimum This is because it is possible to reduce the overall power consumption by switching to the voltage V ₁ .

Incidentally, the power supply voltage is in the relation of V ₃ > V ₂ > V ₁ .

The 60 / 120Hz switch SW ₁ is composed of terminals g, h, and i. The terminal h is connected to the power supply V ₃ (for 120Hz) and the terminal i is connected to the power supply V ₂ (for 60Hz). When the vertical deflection is 60 Hz, 12 between terminals g and i
At 0 Hz, turn ON between gh manually. That is, when the vertical deflection is 60 Hz, the power supply voltage V ₂ is guided to the terminal i-g-e and applied as the power supply voltage of the vertical output circuit 3 during the vertical retrace line period. Next, in the case of vertical 120 Hz deflection, the power supply V ₃ is led to the terminals h-g-e and again applied as the power supply voltage of the vertical output circuit 3 during the vertical blanking period. The deflection waveforms and the states of the switches SW ₁ and SW ₂ are shown in FIGS. 3 to 6.
It is a figure.

Incidentally, FIG. 3 shows the deflection waveform in the case of 60 Hz deflection, and FIG. 4 shows the states of the switches SW ₁ and SW ₂ in that case.
On the other hand, FIG. 5 shows the deflection waveform in the case of 120 Hz deflection, and FIG. 6 shows the states of the switches SW ₁ and SW _{2 in} the coupling.

At the time of 60 HZ deflection, t ₁ + t ₂ is the display period and t ₃ is the vertical retrace line period. The voltage applied during the t ₃ period is V ₂ and the voltage applied during the display period t ₁ + t ₂ is V ₁ . On the other hand, at 120 Hz, vertical blanking period t
_The voltage V ₃ applied to ₃ ′ and the voltage applied to the display period t ₁ ′ + t ₂ ′ are
Become V ₁ . Here, each waveform period at the time of 120 Hz deflection must be able to become about half with respect to the synchronization of each waveform (a) at the time of 60 Hz deflection. This can be achieved by doubling the frequency of the vertical synchronizing signal input to the vertical oscillating circuit 1 and the frequency of the vertical oscillating circuit 1, but the vertical retrace line is changed by the abrupt sawtooth wave of the deflection current I ₀ to cause deflection coil deflection. Since the counter electromotive force is generated in No. 4, the power supply voltage must be increased to release the counter electromotive force energy in order to shorten the blanking period. The voltage V ₂ when the flyback period t ₃ of So 60 Hz, when a 120Hz flyback period t ₃ 'is to add a high voltage V ₃ from V _2. As a result, a necessary and sufficient display period can be secured even when the vertical deflection is doubled to 120 Hz. Therefore, it is possible to realize a vertical deflection circuit that does not cause distortion on the screen regardless of whether the vertical deflection is 60 Hz or 120 Hz.

By the way, when increasing the peak value of the vertical deflection voltage by applying a high power supply voltage only during the vertical blanking period as described above, operate the 60 / 120Hz switch SW ₁ when high back electromotive force is generated in the deflection coil. There is a possibility that the power supply voltage may be switched, and a large electrical stress is applied to each circuit component.

Therefore, in the embodiment of the present invention shown in FIG. 7, the power supply voltage applied during the vertical retrace period is switched when a large back electromotive force is not generated in the deflection coil.
In the figure, the pump-up circuit 5 further includes a latch circuit 7 and a 60/120 Hz instruction switch 8 in the configuration of the embodiment shown in FIG. The output of the blanking detection circuit 6 is applied to the clock terminal CK of the latch circuit 7, and the output of the 60/120 Hz instruction switch 8 is applied to the data terminal D. The relationship between these inputs and the Q output is shown in FIG. According to this configuration, 60
No matter what timing the / 120Hz indicating switch 8 is switched, the 60 / 120Hz switch SW ₁ is always switched at the beginning of the vertical blanking period (hence, when the high back electromotive force is not generated in the deflection coil). Therefore, no large electrical stress is applied to the circuit components.

As described above, according to the present invention, vertical deflection can be properly performed at both frequencies of, for example, 60 Hz and 120 Hz with an extremely simple circuit configuration, and the vertical deflection voltage is adjusted according to the frequency only during the vertical blanking period. Since the crest value of is changed, it is possible to realize a vertical deflection circuit that reduces power consumption and that does not cause flicker and screen distortion.

Further, according to the present invention, since the peak value of the vertical deflection voltage during the vertical blanking period is switched when the high back electromotive force is not generated in the deflection coil, a large electrical stress can be applied to the circuit components. Absent.

[Brief description of drawings]

FIG. 1 is a block diagram of a vertical deflection circuit according to the present invention, FIG. 2 is a diagram showing an embodiment of its main part, and FIGS. 3, 4, 5, and 6 are explanatory diagrams thereof. Is. FIG. 7 is a view showing another embodiment of the main part in FIG.
The figure is an explanatory diagram thereof. FIG. 9, FIG. 10 and FIG. 11 are diagrams for explaining a time-division shutter type stereoscopic television. 3 …… vertical output circuit, 4 …… deflection coil, 5 …… pump up circuit, 6 …… vertical return detection circuit, 7 …… latch circuit, 8 …… 60 / 120Hz indicator switch, SW ₁ …… 60 / 120Hz switch, SW ₂ …… Pump up switch, V ₁ , V ₂ , V ₃ …… Power supply voltage.

Claims (1)

[Claims] 1. A vertical deflection circuit for switching the peak value of a vertical deflection voltage during a vertical blanking period according to the frequency of a vertical synchronizing signal, for switching the peak value of a vertical deflection voltage during a vertical blanking period. A peak value changeover switch, a changeover instruction switch, a retrace line detection circuit for detecting a vertical retrace period, a changeover instruction by the changeover instruction switch and a detection signal of the retrace line detection circuit A vertical deflection circuit comprising: a latch circuit for switching a switch, wherein the switching of the crest value switching switch is performed at the beginning of a vertical blanking period.