JPH0119787B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a video mixing amplification device.

In a conventional video mixing amplification device, a so-called mix mode transition is performed by operating a fader lever and continuously changing the mixing ratio from a first video signal to a second video signal. A split feeder is used in which the lever is divided into left and right parts, and when you hold both levers and move them in the same way, the first,
You can move the gain so that the sum of the gains of the 2 video signals is always 1, and if you move the left and right levers independently,
This is because it has the feature that the levels of two video signals can be adjusted independently.

In a split fader, if the same signal is supplied as the input video signal to the mixing amplifier and the two left and right levers are grasped and moved, the level of the output signal may change slightly. This causes errors due to the mechanical precision of the fader, changes in grip, etc., and the gains of the two gain control circuits in the mixing amplifier have a relationship of K and (1-K), that is, the sum of both is always 1. This is because the gain after mixing does not become 1 because the relationship deviates from the above relationship.

FIG. 1 is a block diagram of a conventional video mixing amplification device. Signals from input terminals 1 and 2 are level controlled by gain control circuits 3 and 4 according to control signals from fader volumes 7 and 8, and mixed. After being mixed in circuit 5, it is output from output terminal 6. Here, the gain control signal from the split fader
Ideally, V ₁ and V ₂ will change so that the sum of both levers is always equal to 1 if you hold the two levers and move them at the same time, but as mentioned above, it depends on how you hold the levers and the mechanical precision of the feeder. Therefore, ideal effects could not be obtained.

There is also a system in which one fader lever moves two fader volumes in a complementary manner so that the sum of both gains is always 1. This eliminates errors caused by human grip, but in this case the two It is rarely used because the signal level cannot be changed independently. Furthermore, if the mechanical precision is poor, errors may still occur.

Therefore, an object of the present invention is to maintain the relationship between the gains of the two gain control circuits K and (1-K) when using split faders and operate both at the same time, thereby suppressing fluctuations in the output level. To provide a video mixing and amplifying device which operates independently when both fader levers are separated and operated independently.

According to the present invention, control signals corresponding to the two levers of the split fader are received, and when the two levers are in positions close to each other corresponding to the case where they are grasped and operated together, the feeder signal of one side is received. A video mixing device is obtained in which a fader signal control circuit is added that changes the other fader signal based on , and makes the gain of the gain control circuit have a relationship between 1 and (1-K).

Furthermore, in the present invention, if the two fader levers are moved widely apart and operated independently, it is also possible to change the levels of the two video signals independently. Therefore, with the feeder signal control circuit according to the present invention, in the case of a slight positional deviation between the two levers of the split feeder, the operation will be as if the feeder had only one feeder lever, and the two feeder levers would operate as if there were only one feeder lever. When the position of the feeder is shifted significantly, it becomes a conventional swing feeder operation.

Next, the present invention will be described in detail with reference to the drawings of an embodiment of the present invention. FIG. 2 is a diagram showing an embodiment of the present invention, in which the video signals supplied to the video signal input signals 31 and 32 are transmitted to the gain control circuit 3.
After the gain is changed in 3 and 34, the mixing circuit 3
7 and is sent to the video signal output terminal 39. A signal from the fader volume 35 is supplied to a gain control circuit 33 and a fader signal control circuit 38. The fader signal control circuit 38 receives signals from the fader volumes 35 and 36, and when the positions of the two fader levers are close, the gains of the gain control circuits 33 and 34 are set to K, (1-K).
A signal that maintains this relationship is sent to the gain control circuit 34. Of course, each of the fader volumes 35 and 36 is mechanically connected to a fader lever (not shown). The outputs of the fader volumes 35 and 36 change as shown in FIGS. 3A and 3B when the two fader levers are mechanically connected and moved, that is, in an ideal state where there is no gripping error.

In practice, if there is a grip error, the two gains do not have a relationship of K, (1-K), so for example, when the output of the fader volume 35 is at point E in FIG. 3, only the fader volume 36 moves slightly. The output voltage is controlled by the fader signal control circuit 38 so that the output voltage during that period is constant, and the output is as shown in FIG. 2D. Although FIG. 3 shows a case where the output of the feeder volume 36 is kept constant near point E, it goes without saying that such an effect is not limited to point E, but is possible in all possible ranges of the feeder position. It is.

FIG. 4 shows one example of the configuration of the fader signal control circuit 38 in FIG. Further, FIG. 5 shows voltage changes at each part a to g in FIG. 4. Also the fifth
In the illustrated example, it is assumed that the voltage at the fader signal input terminal 51 is constant and the voltage at the fader signal input terminal 52 changes. First, FIG. 4 will be explained. The inverting amplifier circuit 56 inverts the input b from the input terminal 52, for example, when the input is 0.
When the input voltage is 1.0 volts, the output is 1.0 volts, and when the input is 1.0 volts, the output is 0 volts. A subtraction circuit 57 receives a signal 9 supplied from the output signal C of the inverting amplifier circuit 56 to the fader signal input terminal 51.
Output signal d is obtained by subtracting . The high level clip circuit 58 clips the input signal that is higher than the voltage set at the input terminal 53 (output e), and the low level clip circuit 59 clips the input signal that is lower than the voltage set at the input terminal 54 and outputs it. (output f). The adder circuit 60 adds the signal b supplied to the fader signal input terminal 52 and the signal f from the low level clip circuit 59 and sends a gain control signal g to the output terminal 55. signal g
As is clear from the figure, the voltage of the output g is fixed constant within a predetermined range according to the voltage set by the clip circuits 58 and 59.

Although the example shown in FIG. 4 is constructed of analog circuits, it is clear that similar signal processing can be applied to digital faders to achieve more accurate and stable processing than analog faders. Furthermore, in the example shown in FIG. 5, the amplitude of the signal sent from the output terminal 55 is small, but this control signal can change the gain of the subsequent gain control circuit from 0% to 100%.
There is no problem as long as it can be changed up to.

[Brief explanation of drawings]

FIG. 1 shows an example of the configuration of a conventional video mixing amplification device. FIG. 2 is a diagram showing an embodiment of the present invention, FIG. 3 is a diagram explaining the operation of the present invention, FIG. 4 is a block diagram of the fader signal control circuit of FIG. 2, and FIG. FIG. 3 is a diagram showing the operation of the fader signal control circuit shown in FIG. In the figure, 1, 2...video signal input terminals,
3, 4... Gain control circuit, 5... Mixing circuit, 6... Video signal output terminal, 7, 8... Fader volume, 31, 32... Video signal input terminal, 33, 34... Gain control circuit, 3
5, 36...Fader volume, 37...Mixing circuit, 38...Fader signal control circuit, 39...Video signal output terminal, 51, 52...Fader signal input terminal, 53...Input terminal, 54...Input terminal ,
55... Output terminal, 56... Inverting amplifier circuit, 57
...Subtraction circuit, 58...High level clip circuit,
59...Low level clip circuit, 60...Addition circuit.

Claims (1)

[Claims] 1. A fader including two levers for controlling a mixing ratio of video signals, means for outputting two gain control signals corresponding to the positions of the two levers of the fader, and means for receiving the two gain control signals and controlling the fader. When the relative positions of the two levers are within a certain range that is a neighborhood relationship, the gain is K and (1-K).
a fader signal control circuit that generates two correction gain control signals having the relationship of; a fader signal control circuit that receives the video signal input;
1. A video mixing amplification device comprising: two gain control circuits that change gains in accordance with two correction gain control signals; and a mixing circuit that mixes outputs of the two gain control circuits.