JPH03132280A - Integrated circuit - Google Patents

Abstract

PURPOSE:To reduce number of terminals by using a terminal for signal input/ output not used when the operating mode is switched in common for a terminal for the mode changeover. CONSTITUTION:When a signal inputted and outputted between a selection circuit 26 and 1st terminals T15-T17 is selected among signals WR, WG, WB inputted and outputted between the selection circuit 26 and a 1st signal processing circuit 30 or among signals WR, WG, CL inputted and outputted between the selection circuit 26 and a 2nd signal processing circuit 26 based on the result of comparison between a voltage VT at a 2nd terminal T18 inputting and outputting the signal CL and a prescribed reference voltage VREF, the 2nd terminal T18 is used effectively to decrease number of terminals. That is, an output terminal of the signal CL at a clamp level not required at the check of a gamma correction circuit 30 is used in common for a changeover control terminal of the selection circuit 26. Thus, the terminal not in use is utilized effectively to reduce number of terminals.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to integrated circuits, and can be applied, for example, to integrated circuits for signal processing of television cameras.

B. Summary of the Invention The present invention makes effective use of terminals in integrated circuits by sharing signal input/output terminals that become unused when the operating mode is switched as terminals for mode switching. The number can be reduced.

C. Prior Art Conventionally, in integrated circuits, in order to effectively avoid an increase in the number of terminals as the degree of integration increases, terminals for signal input and output have been switched for use.

For example, as shown in FIG. 4, in a signal processing integrated circuit l of a television camera, signal output terminals TI, T
2, T3 via selection circuit 2.

They are designed to be able to output color signals R, G, and B, respectively.

On the other hand, the terminal T4 receives the mode switching signal SEL of the integrated circuit 1 and switches the contacts of the selection circuit 2, thereby converting the color difference signals R-Y and B-Y output from the matrix circuit 3 into color signals. Terminal T2 instead of G and B,
Output from T3.

Thus, the terminals Tl, T2, T3 are connected to the color difference signals RY, .
Since the B-Y output terminal and the color signal R, . . . GSB output terminal are shared, an increase in the number of terminals can be effectively avoided even if the degree of integration of the integrated circuit 1 is increased accordingly.

Problem to be solved by the invention D However, even if the terminals are switched and used in this way, the terminal T1 is left unused when the color difference signals R-Y and B-Y are output, and in the end, the terminal is not used effectively. However, there was still an insufficient problem in reducing the number of terminals.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose an integrated circuit that can reduce the number of terminals by effectively utilizing terminals that are no longer used when the operating mode is switched.

E Means for Solving the Problem In order to solve the problem, in the present invention, the first terminals T15, T16, T17 and the second terminal 718,
Signals WR, WG, W
A first signal processing circuit 30 that inputs and outputs B, and a selection circuit 2
6 and the second terminal 718, the signals WR and WGSWB
, a second signal processing circuit 24 that inputs and outputs CL,
Based on the comparison result SEL1 between the predetermined reference voltage VOF and the voltage VT of the second terminal T1B, the selection circuit 26 is switched and a signal WR is input/output between the selection circuit 26 and the first signal processing circuit 30. A signal WR input/output between WG, WB or the selection circuit 26 and the second signal processing circuit 24,
From WG, WB, CL, the selection circuit 26 and the first terminal T
15, T16, and T17.

Input/output is performed between the selection circuit 26 and the first signal processing circuit 30 based on the comparison result between the voltage VT of the second terminal 71B that inputs/outputs the F action signal CL and a predetermined reference voltage Signals WR, WC, , WB or signals WR, WGSWB input/output between the selection circuit 26 and the second signal processing circuit 24
, CL, the selection circuit 26 and the first terminals T15, T1
6. If you select the signal to be input/output between T17, the second
The number of terminals can be reduced by effectively utilizing the terminal T1B.

G example An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, lO indicates the television camera as a whole, and CCD (charge coupled d
An image pickup signal Sl outputted from a solid-state image pickup device 11 made of a solid-state image pickup device (device) is applied to a preprocessing circuit 12.

The preprocessing circuit 12 drives the solid-state imaging device 11 and performs preprocessing such as signal level correction on the imaging signal 31 and outputs the signal to the integrated circuit 14 .

The integrated circuit 14 receives the imaging signal St via an input signal terminal TIO, performs predetermined signal processing, and outputs a luminance signal Y and color difference signals RY and BY.

That is, in the integrated circuit 14, the luminance signal processing circuit 1
6 synthesizes the luminance signal Y from the image signal S1, performs processing such as contour correction, and outputs it from the terminal T11.

The matrix circuit 18 receives the color signal R from the image signal S1.
, G, and B, and then output to the variable gain amplifier circuit 20.

The variable gain amplifier circuit 20 switches the gain based on a control signal input from the control circuit 22 via terminals TI2 to T14, and thereby outputs color signals WR, WG, and WB corrected to predetermined signal levels. .

The clamp circuit 24 receives the color signals WR, WC;, WB output from the variable gain amplifier circuit 20, and clamps them at a predetermined signal level to produce the color signals WRSWG, WB.
maintains the black level at a predetermined level.

Further, the clamp circuit 24 includes the clamped color signals WR,
WG, WB, selection circuit 26, terminals T15, T16, T
17 to the control circuit 22, and also outputs the clamped clamp level CL to the control circuit 22 via the amplifier circuit 27 and the terminal 71B.

The control circuit 22 outputs a control signal so that the signal levels of the color signals WRSWG and WB become a predetermined ratio based on the input clamp level CL, and thereby the color signal WR
,,WG%Adjust the WB white balance.

The T correction circuit 30 corrects the gamma of the color signals WR and WGSWB output from the clamp circuit 24 and then outputs them to the matrix circuit 32 and to the remaining contacts of the selection circuit 26.

The matrix circuit 32 generates color difference signals R-Y and B-Y from the color signals WR and WGSWB output from the T correction circuit 30.
are synthesized and terminal T20. Output via T21.

Thus, in the television camera 1, the color difference signal R
-Y and BY are converted into a video signal together with the luminance signal Y and output.

The comparison circuit 36 compares the reference voltage output from a predetermined reference power supply 38 with the signal level of the terminal 71B, and switches the contact of the selection circuit 26 based on the comparison result.

That is, as shown in FIG. 2, the reference power supply 38 has a diode 40 and a constant current source 41 connected in series, and thereby a reference voltage Vmtr (Vcc Vat
) is applied to the inverting input terminal of the comparison circuit 36.

Therefore, the comparison circuit 36 outputs the selection signal 5ELI when the voltage VT at the terminal T1B rises from the reference voltage ■Feng□, thereby switching the contacts of the selection circuit 26, and the color signals WR, WG output from the clamp circuit 24. , WB, the color signals WR, WGSW output from the T correction circuit 30
B is output.

On the other hand, the amplifier circuit 27 has emitter resistors 42 and 4.
3. Transistors 45 and 46 having a constant current source 44 constitute a differential amplifier circuit, and the collector resistor 4
The collector output of the transistor 46 obtained through the transistor 7 is outputted through the transistor 48 having a common emitter circuit configuration.

Further, the amplifier circuit 27 connects the emitter of the transistor 48 to a protection diode 49 and a constant current source 50, and outputs a clamp level signal CL via the protection diode 49.

Thus, in the amplifier circuit 27, if the current value of the constant current source 44 is I and the resistance value of the collector resistor 47 is R, the base voltage of the transistor 48 changes in the range of VCC to VcC-R1, so the protective diode is The output terminal voltage of 49 changes in the range of voltages VCC2VIE to Vcc2V□-R1 in accordance with the base voltages of transistors 45 and 46, thereby outputting a clamp level signal CL.

Therefore, in the amplifier circuit 27, the voltage VT at the terminal 718
However, the voltage vcc Vl! When the voltage rises above this level, the protection diode 49 switches to the OFF state and stops the clamp level signal output operation.

Thus, the voltage VT at terminal T18 becomes the voltage VCC-V0C
When the C-type is lifted up, the amplifier circuit 27 is switched to the OFF state, and the T-corrected color signals WR,
WG and WB can be output.

On the other hand, if no voltage is applied to terminal 718,
A clamp level signal CL is output from the terminal 718, and color signals WR, WG, and WB before T correction are output from the terminals T15 to T17.

Therefore, the terminal 718 can be used in common as an output signal switching control terminal and a clamp level signal output terminal.

In practice, this type of integrated circuit 14 needs to be incorporated into the television camera 10 for white balance control, and in this case, the color signals WR, WG, WB before γ correction are
It is also necessary to output a clamp level signal CL.

On the other hand, in product inspection of integrated circuits, it is necessary to output the color signals WR, WG, and WB output from the T correction circuit 30 in order to check the operation of the T correction circuit 30.

Therefore, while four signals are required for white balance control, three signals are required to confirm the operation of the T correction circuit 30.

Therefore, if the necessary output signals are assigned to separate terminals, a total of seven terminals will be required just for white balance control and checking the operation of the T correction circuit 30.

However, if the color signals WR, WG, WB output from the T correction circuit 30 and the color signals WR, WG, WB before T correction are switched and outputted via the selection circuit 26, the number of output terminals can be reduced accordingly. Although the number can be reduced by three, an input terminal for controlling switching of the selection circuit 26 is required, and five terminals are required in total.

On the other hand, if the terminal 71B is shared by the switching control terminal of the selection circuit 26 and the clamp level signal output terminal as in this embodiment, there will be a total of four terminals T15.
~ At T1B, white balance control and T correction circuit 30
operation can be confirmed, and the number of terminals can be reduced accordingly.

Thus, when checking the operation of the T correction circuit 30, by using the unnecessary terminal T18 as the switching control OII terminal of the selection circuit 26, it is possible to effectively utilize the terminals and reduce the number of terminals.

In the above configuration, the image signal S1 output from the solid-state image sensor 11 is transmitted to the integrated circuit 1 via the preprocessing circuit 12.
4, and the color signals R, G,
B and luminance signal Y are combined.

The luminance signal Y is output from the integrated circuit 14 via the terminal Tll and is combined with the video signal.

The color signals R and GSB are subjected to white balance adjustment via the variable gain amplifier circuit 20 and then output to the clamp circuit 24.

Color signal WR clamped by the clamp circuit 24.

WG and WB are output to the control circuit 22 via the selection circuit 26 and terminals T15 to T17, and at the same time, a clamp level signal CL is output to the control circuit 22 via the terminal 71B.

As a result, a control signal is created in the control circuit 22, and the terminal T
The color signals WR and WGS are applied to the variable gain control circuit 20 via I2 to T14, and thus the color signals WR and WGS are
The WB white balance is adjusted.

Color signal WR clamped by the clamp circuit 24.

WC;, WB are gamma-corrected in the T correction circuit 30 and then converted into color difference signals R-Y in the matrix circuit 32.

It is converted into B-Y and output from the integrated circuit 14, and is converted together with the luminance signal Y into a video signal.

On the other hand, at the stage of product inspection of the integrated circuit 14, a voltage equal to or higher than the voltage VCC-V0 is applied to the terminal T1B, the contacts of the selection circuit 26 are switched, and the amplifier circuit 27 is switched off.

As a result, the output of the clamp level signal CL is controlled to stop, and the gamma-corrected color signals WR and WGSWB are
However, instead of the color signals WR1wc and WB before gamma correction,
The signal is output from the terminals T15 to T17, and thereby the T correction circuit 30 can be inspected.

According to the above configuration, by sharing the output terminal of the clamp level signal CL, which is not required when testing the T correction circuit 30, as the switching control terminal of the selection circuit 26,
The number of terminals can be reduced by effectively utilizing unused terminals.

In the above embodiment, the selection circuit 26 selects the inspection signal of the T correction circuit 30 and the white balance adjustment signal.
The case where the present invention is applied to an integrated circuit for selective output has been described, but the present invention is not limited to this. For example, as shown in FIG.
The present invention may be applied to an integrated circuit that selectively outputs Y.

That is, as shown by assigning the same reference numerals to the parts common to those in FIG. is output from the terminals T2 and T3 via the selection circuit 61.

Further, among the color signals R, G, and B, the red color signal R is applied to the comparison circuit 36 and the terminal T1 via the amplifier circuit 27.

Furthermore, the integrated circuit 60 outputs the color difference signals R-Y and B-Y output from the matrix circuit 3 via the selection circuit 61 from terminals T2 and T3.

In this way, by raising the voltage of the terminal l, the contacts of the selection circuit 61 are switched and the color difference signals R-Y, B are switched.
-Y can be selectively output.

In this way, the terminal 1 can be shared as the output terminal of the red color signal R and the switching control terminal of the selection circuit 61,
The number of terminals of the integrated circuit 60 can be reduced accordingly.

Furthermore, in the above-described embodiment, a case was described in which one terminal is shared for signal output and selection circuit switching, but the present invention is not limited to this, and a signal input terminal is shared for selection circuit switching. You can.

Further, in the above-described embodiment, a case has been described in which a desired signal is selectively outputted from the selection circuit, but the present invention is not limited to this, and can be applied to a case where input signals are selectively inputted.

Further, in the above-described embodiment, a case was described in which one comparison circuit was connected to a shared terminal, but the present invention is not limited to this, and a plurality of comparison circuits may be connected.

In this way, the plurality of selection circuits can be switched and controlled based on the plurality of comparison results obtained from the plurality of comparison circuits.

Further, in the above-described embodiment, a case has been described in which the mode of white balance adjustment operation and the mode of integrated circuit inspection are switched by switching the selection circuit, but the present invention is not limited to this, and can include various modes. It can be widely applied to integrated circuits.

Furthermore, the present invention is not limited to switching the selection circuit, but can be widely applied to cases other than switching the selection circuit as a controlled object.

Furthermore, the number of terminals shared for switching control is not limited to one, and a plurality of terminals may be shared to control a plurality of controlled objects.

Further, in the above-described embodiments, a case has been described in which the present invention is applied to a signal processing integrated circuit for a television camera, but the present invention is not limited to this and can be widely applied to various integrated circuits.

H Effects of the Invention As described above, according to the present invention, unused terminals can be effectively utilized by sharing signal input/output terminals that become unused when the operation mode is switched as mode switching terminals. Thus, it is possible to obtain an integrated circuit in which the number of terminals can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a television according to an embodiment of the present invention, and FIG. 4 is a block diagram illustrating the prior art. 1.14.60・old・・integrated circuit, 2.26.61・・
...Selection circuit, 27...Amplification circuit, 36.
...Comparison circuit, T1 to T21...Terminal. Agent Megumi Tanabe Accumulation Map Y1 Mo28 0 Certain Anger Day Rei G3 Diagram Conventional Ze11 Vine 4 Diagram

Claims (1)

[Claims] A first terminal, a second terminal, a selection circuit connected to the first terminal, and a first signal processing circuit that inputs and outputs signals between the selection circuit. , a second signal processing circuit that inputs and outputs signals between the selection circuit and the second terminal, and based on the comparison result between the predetermined reference voltage and the voltage of the second terminal, The selection circuit is switched, and from the signal input/output between the selection circuit and the first signal processing circuit or the signal input/output between the selection circuit and the second signal processing circuit, An integrated circuit characterized in that a signal to be input/output to/from the first terminal is selected.