JPS5961389A - Chromaticity adjusting circuit - Google Patents

Abstract

PURPOSE:To decrease the reduction in the level of a luminance signal and to narrower the range of color where the hue is changed, by decreasing the level of a red primary signal and increasing the level of a blue primary signal when a luminance level is a prescribed level or over. CONSTITUTION:A red color difference signal and a luminance signal are applied to terminals 6R, 7R. The red color difference signal and the luminance signal are applied to an adder 8R, from which the red primary signal is obtained and applied to an adder 9R. Further, luminance signal is applied to the adder 9R via an amplifier 10R. When the luminance signal is at a prescribed level or below, the red primary signal is obtained as it is from the adder 9R and when the luminance signal is at a prescribed level or over, the red primary signal with decreased level is obtained. Further, the level of the blue primary signal is increased when the luminance signal is at a prescribed level or over.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a chromaticity adjustment circuit used in color television receivers to reproduce bright white colors.

Background Art and Problems In the NTSC color television system, the color temperature of white is 6500°, but this makes it appear reddish to the naked eye. Conventionally, attempts have been made to increase the color temperature to make whites more vivid.

A chromaticity adjustment circuit for this purpose has conventionally been configured as shown in FIG. When these levels are controlled to decrease. Then, the blue primary color signal B (hereinafter referred to as B
The signal level has been raised, allowing for vivid white reproduction.

In the same figure, (IR), (IG) and (IB) are
These are terminals to which an R signal, a G signal, and a B signal are respectively supplied. In addition, a threshold level Vth is determined by the resistors (2) and (3), and when the R signal and G signal supplied to the terminals (IR) and (1G) become lower than this threshold level vth, the diodes (4R ) and (4G) are turned on, and the levels of the R and G signals are controlled to decrease. Here, (5R)
, (5G) and (5B) are output terminals, respectively.

Consider the signal processing of this conventional chromaticity adjustment circuit using a luminance-ordered color bar as an example.

Originally, this luminance j-color par (white, yellow, cyan, green,
magenta, red, blue, black), Lj(
, i', G signal and B signal are shown in Figure 2 A and B, respectively.
and C, and the luminance signal Y (=0.
3OR+0.59G+0.11B) is shown in the same figure.

However, due to the signal processing of the conventional chromaticity adjustment circuit, R
If the levels of the R signal and G signal are respectively reduced to about 75%, the R signal, G signal and 13 signal become as shown in FIGS. 3A, B and C, respectively, and the luminance signal Y is as shown in the same figure.

As is clear from this example of luminance-ordered color bars, according to the conventional chromaticity adjustment circuit, 1. When the 11 signal and the G signal exceed a predetermined level, control is performed to lower the levels of these signals, so there is a drawback that the level of the luminance signal is significantly lowered. In addition, the balance between R signal, G signal and 8 signals is wide (white to red)
There are disadvantages in that the color range Cc in which the hue changes is wide.

OBJECTS OF THE INVENTION The present invention is designed to reduce the drop in luminance signal level and narrow the color range in which the hue changes.

Summary of the Invention In order to achieve the above object, the chromaticity adjustment circuit according to the present invention has the following features:
The luminance signal level is detected, and when the luminance signal level exceeds a predetermined level, at least the level of the red primary color signal is lowered by a predetermined amount, and the level of the blue primary color signal is increased by a certain amount. .

The present invention is constructed as described above, and adjusts chromaticity by at least lowering the level of the red primary color signal to a predetermined minimum while increasing the level of the blue primary color signal by a predetermined amount. There is little level drop. Further, when the level of the luminance signal is equal to or higher than a predetermined level, chromaticity adjustment is performed, and only within this narrow range can the balance of each primary color signal be disrupted, and the color range in which the hue changes is narrow.

Embodiment Hereinafter, an embodiment of the chromaticity adjustment circuit according to the present invention will be described from 7 to 7 with reference to FIGS.

FIG. 4 and FIG. 5 show the principle diagram.

; rS 4 U'H<j is related to the R signal,
Terminals (6R, ) and (7R) have a red difference signal R-Y.
and a luminance signal Y are supplied. These red difference signals R-Y
and the luminance signal Y are supplied to the adder (8R), and the R signal is obtained from the adder (8R), which is supplied to the adder (9I).The luminance signal Y is also supplied to the amplifier (1011).
The signal is supplied to the adder (9ft) via the adder (9ft). This amplifier (
10R), only when the level of the luminance signal Y exceeds a predetermined level, for example, 65% or more of the white peak level, the luminance signal -KIY amplified by 1 (K1) 0) is supplied to the output side. It is made so that it can be obtained. Therefore, the output terminal (
When the level of the luminance signal Y is below a predetermined level, the R signal is obtained as is, and when the level of the luminance signal Y is above the predetermined level, the R signal R whose level is lowered by a predetermined amount is obtained. -KIY is obtained.

Moreover, FIG. 5 is related to the B signal, and the terminal (6B
) and (7B) are supplied with a blue color difference signal B-Y and a luminance signal Y, respectively. These blue color difference signal B-Y and luminance signal Y are supplied to an adder (8B), and a B signal is obtained from this adder (8B), which is supplied to an adder (9B). Further, the luminance signal Y is supplied to the adder (9B) via the amplifier (IOB). This amplifier (IOB) outputs a brightness signal amplified by Kz (K2>O) only when the level of the brightness signal Y exceeds a predetermined level, for example, 65% or more of the white peak level. 1(2
It is designed so that Y can be obtained.

Therefore, the output terminal (11
In B), when the level of the luminance signal Y is below a predetermined level, the B signal is obtained by -1:, and when the level of the luminance signal Y is above the predetermined level, the level is increased by a predetermined amount. A B signal 134-K2Y is obtained.

Therefore, when processing is performed at the color difference signal stage, the configuration is basically as shown in FIG.

In the same figure, terminals (1211), (12G) and (
12B) is supplied with a red difference signal It-Y, a green difference signal G-Y and a blue difference signal B-Y, which are respectively supplied to adders (13R), (13G) and (13B). .

In addition, the luminance signal Y is supplied to the terminal (12Y), which is supplied to the adders (13), (13G), and (13B).
4B) to adders (13R) and (13B). These amplifiers (14R) and (14B) amplify the output by -1 and -2, respectively, only when the level of the luminance signal Y reaches a predetermined level or higher, for example, 65% or higher of the white peak level. Luminance signal - KI
It is designed so that Y and 2Y can be obtained. Therefore,
Output terminals (15R) derived from adder (13R), (1, 3 (3) and (13B)), (15G) and (
15B), when the level of the luminance signal Y is below a predetermined level, the R signal, G signal and B signal are obtained as they are, while when the level of the luminance signal Y is above the predetermined level, the level is changed by a predetermined amount. Reduced R signal R-
KIY, 2Y are obtained from the G signal at the same level and the 13 signal B-4- whose level is increased by a predetermined amount.

Also, when processing at the primary color signal stage, basically the seventh
It is configured as shown in the figure. In the same figure, the terminal (16
11), (16G) and (16B) are supplied with the R signal, G signal and B signal, and the I(signal and B signal are supplied to adders (1, 711) and (17I3), respectively.

Further, these R signal, G signal and B signal are added at a predetermined ratio by a resistance matrix circuit (18),
A luminance signal Y is obtained. This brightness value Y is determined by an amplifier (1
9R) and (19r3) to the boosters (17R) and (17B). These amplifiers (19R) and (19B) amplify the output by a factor of -1 and a factor of two, respectively, only when the level of the luminance signal Y reaches a predetermined level or higher, for example, 65% or higher of the white peak level. The luminance signals -KIY and -2Y can be obtained. Therefore, the output terminals (20I"t) and (2013) derived from the adders (17R) and (17f3)
When the level of the luminance signal Y is below a predetermined level, the R signal and the B signal are obtained as they are, while when the level of the luminance signal Y is above the predetermined level, the level is lowered by a predetermined amount. 1Y is obtained for the R signal R-, and 2Y is obtained for the B signal B-1- whose level is increased by a predetermined amount. Further, the output terminal (20G) receives the G signal at the same level.

FIG. 8 is a connection diagram showing an embodiment of the present invention, in which the signals are processed after being converted into primary color signals.

In the same figure, terminals (21R), (21G) and (2
1B) is supplied with the R signal, G (i and B signals,
These signals are sent to the drive circuit (3(
npn type transistor (3) composing D, R),
(31G) and (3], supplied to the base of B). Further, these R signal, G signal, and B(i) are each supplied to a resistance matrix circuit (40), where they are corrected at a predetermined ratio, and a luminance signal Y is generated.

This luminance signal Y is transmitted to the gain control circuit (!1(1
lli tf? be done. The collector of this transistor 51) is grounded via a resistor M, and the emitter thereof is connected to a power supply terminal +81 (to which a DC voltage of +12 V is supplied, for example) via a resistor 63). Further, the emitter of this transistor 61) is an npn type transistor C1
It is connected to the base of 4) and 5). transistor 6
Are the collectors of Tsugo resistant? ! 7F (+Gl) is connected to the power supply terminal +81, and its emitter is connected via a resistor 67) to the emitter of a pnp type transistor C)8). Further, the emitter of the transistor 651 is connected to the emitter of the transistor 651 via the resistor 9), and the collector of the pnp transistor 651 is grounded. In addition, a threshold setting resistor (fil) and a series circuit of (6 points) are connected between the power supply terminal 1B1 and the ground.The voltage Vthl obtained at the connection point of this resistor (6I) and the iron is the control voltage. as transistors 58) and (
60). In this case, the control voltage v
thl is a transistor (5C
, ei5), (5 to (60)) start to conduct.

Furthermore, the emitters of the transistors (31R), (31G), and (31B) constituting the drive circuit (3tr) are connected to resistors (32R), (32G), and (32B), respectively.
), and the collector of the husband is grounded through npn transistors p (33I-L), (33G) and (33
B) is connected to the emitter of The collectors of these transistors (331), (33G) and (33B) are connected to a power supply terminal +82 (for example, a DC voltage of +200 V is supplied to the collectors of the transistors (331, 33G) and (33B) through resistors (34R), (34G) and (34B). ), and their respective bases are connected to the voltage terminal +Bl.At that (-, Ito No. 1 obtained at the collectors of these transistors (331S, (33G), and (33B)) is Cathode I<R related to the electron beam of light, cathode K related to the green electronic beam
It is supplied to the cathodes KH related to the G and blue electronic beams 11.

Further, the collector of the differential transistor e'i5) constituting the gain control circuit (50) is connected to the drive circuit 0 (1
) is connected to the emitter of the transistor (33B) that constitutes the drive circuit (3o), and the collector of the transistor 6 (to) that constitutes the gain controller) roll circuit (5tl) is connected to the emitter of the transistor (31R) that constitutes the drive circuit (3o). Connected.

This example is configured as described above, and has a resistance matrix circuit (4
The level of the luminance signal Y obtained from 0 is applied to the control 7 (voltage Vt)
When the level is below a predetermined level determined by +1, the gain control circuit (50) controls the transistors (54),
(55), ('ill, (io) are placed in a non-conducting state and are in an inactive state.

Therefore, the red, green, and blue electron beams are density modulated by the R, G, and B signals at their respective levels.

On the other hand, when the level of the luminance signal Y exceeds a predetermined level, the transistors (5a, (55), C13
) and (IiO) are in a conductive state, and currents I corresponding to the level of the luminance signal Y are applied to ) and transistors ω and y, respectively.
B1 and IRl begin to flow. transistor 05
), the transistor (33B) constituting the drive circuit (3F+)
In addition to the current flowing through 31B), this current ■ Let the old flow 1! ;:,reactor. Therefore, the blue electronic beer l is density-modulated by the B signal B+2Y whose level has been increased by a predetermined amount.

Furthermore, if the current IRI is made to flow through the transistor (transistor, distal 8), the current flowing through the transistor (33R) constituting the drive circuit (3o) is reduced in accordance with this current IR1. Therefore, the red electron beam is density-modulated by the R-1-IY whose level is lowered by a predetermined amount. Furthermore, the green electron beam is
The density is modulated by the G signal at its original level.

According to this example, when the level of the luminance signal Y becomes equal to or higher than a predetermined level, the red electron beam is added to the R signal 1t- whose level has been lowered by a predetermined amount (KIY), and the density of The modulated blue electron beam has a level of 1 (
K2Y) is driven by the raised B signal B1I (2Y), so the color temperature is raised and a clear white color is reproduced.

Let's take a look at the signal processing of the chromaticity adjustment circuit in the example shown in Figure 8 in terms of color pars. In this case, if the level of the luminance signal Y is 75% above the white level, the key control circuit t50) is activated, and the R signal, G signal and B signal are, for example, shown in FIGS. 9A and 9B, respectively. and C, and the luminance signal Y is as shown in (■) in the figure.

As is clear from this example of the luminance-ordered color bar, the 8th
According to the chromaticity -p, y, 1 adjustment circuit shown in the figure, the chromaticity adjustment is performed by lowering the level of the R signal by a predetermined amount and increasing the level of the B signal by 2. The level drop of the luminance signal Y is extremely small, and the luminance signal Y
chromaticity is adjusted when the level of
The balance of the R signal, G signal, and B signal is lost only in a narrow ν range, and the image range Cc in which the hue changes is narrow ℃. In addition, the predetermined amount that is increased or decreased in the 13 signal and the R signal is the brightness signal Y.
(-KIY, 2Y), and the above-mentioned imbalance occurs when the level of the luminance signal Y is
The change in hue is so large that it becomes noticeable, so you can barely feel the change in hue.
FIG. 0 is a connection diagram showing another embodiment of the present invention, in which the signals are processed after being converted into primary color signals, similar to the example in FIG. In FIG. 10, parts corresponding to those in FIG. 8 are designated by the same reference numerals.

In the same figure, terminals (2i t), (21G) and (
The R signal, G signal, and B signal supplied to the drive circuit (30) are supplied to the bases of transistors (31), (31G), and (31B), respectively, which constitute the drive circuit (30). These signals are also supplied to a +7x circuit (40') where the signal, G signal and B signal are each resistor masked, where they are added at a predetermined ratio (31:) to obtain a luminance signal Y.

The signal Y is supplied to the base of the npn transistor (7) constituting the gain control circuit (10). The collector of this transistor (71) is connected to the power supply ☆11'-B1 via a resistor CI'lJ. 1 Also, power supply i'i! Connect the threshold setting resistors (731 and (74) between the a-+-I31 and the ground.
A series circuit is connected, and the voltage Vt112 obtained at the connection point of this resistor (Tai and (74)) is connected to the transistor (tl
) is applied to the emitter of In this case, voltage Vth2
When the level of the luminance signal Y reaches a predetermined level or higher, for example, 75% or higher of the white level, the transistor (TI)
Set it to a value such that it begins to conduct.

In other words, the collector of the transistor (7J) is connected to the base of the npH transistor (1), the collector of this transistor (7) is connected to the power supply terminal +81, and its emitter is connected to the resistor (7J) and ( The connection point of this resistor (71'j and (77)) is connected to the emitter of the transistor (31B) forming the drive circuit (3(1)). , when the transistor (rl) is non-conducting, the transistor (31
The resistance values of resistors (7G), (17), etc. are set so that an appropriate emitter bias is applied to the emitter of B). Still, the connection point of the resistors (73) and (14) (74) is connected to the base of the pnp transistor (7al),
The collector of this transistor (Kasumi) is grounded through the resistor (r9), and its emitter is connected to the resistor (80) and (8
I) through the series circuit? Mj 9: Connected to 4A child B1. The connection point between the resistors 910) and 1) is the transistor (3) R that constitutes the drive circuit (30).
, ) is connected to the emitter of the In this case, the resistance values of the resistors (8tl), (81), etc. are set so that an appropriate emitter bias is applied to the emitter of the transistor (31ft) when the transistor (71) is non-conductive.

The rest of the structure is the same as the example shown in FIG.

The example in FIG. 10 is configured as described above, and when the level of the brightness signal Y obtained from the resistance matrix circuit (40') is below a predetermined level determined by the control voltage vth2, the transistor (71) is rendered non-conductive. The gain control circuit (7()) is inactive. Therefore, the red, green, and evening electron beams are R signal and G signal at the same level, respectively.
The density is modulated by the signal and the B signal.

On the other hand, when the level of the luminance signal Y reaches a predetermined level or higher, the transistor (71) becomes conductive. The transistor (75) and the (1 mark) have currents IB2 and In2 which become smaller as the level of the luminance signal Y becomes more dog-like.
There is a current. Therefore, the voltage at the emitter of transistor (31B) decreases as the level of signal Y increases,
The current flowing through the transistor (33B) increases by that amount, and the blue electron beam is density-modulated by the B signal B+2Y whose level has been increased by a predetermined amount.

In addition, the emitter voltage of the transistor (3], n,) increases as the level of the luminance signal Y increases, and the current flowing through the transistor (33ft) decreases by that amount. Quantitative decrease of R signal R-
The density will be modulated by Y.

Note that the green electron beam is density-modulated by the G signal at the same level.

In this way, in the example of FIG. 10 as well, when the luminance signal Y level exceeds a predetermined level, the red electron beam is added to the R signal R- whose level has been lowered by a predetermined 1 (KIY), and the density is increased by Y. It'd been changed, and in the evening's electronic binoculars, the level of the B signal B- was increased by a predetermined amount (K2 Y).
Since the density is modulated by 2Y on 1-, the color temperature is raised,
Able to reproduce vivid white color. It is clear that the same effect as the above-mentioned example of FIG. 8 can be obtained in this example of FIG. 10 as well.

According to the above-described embodiment, the amount by which the B signal and the R signal are increased or decreased varies depending on the level of the luminance signal Y (K
2Y, -1gtY), but it may be a constant amount that does not depend on the level of the luminance signal Y. Further, according to the above-mentioned embodiment, the level of the G signal is left as is, but if the level of this 0.1 signal is slightly increased, it becomes even more effective in reproducing vivid white. can be taken as a thing.

Effects of the Invention As is clear from the embodiments described above, the chromaticity adjustment circuit according to the present invention lowers the level of the red primary color signal (R signal) by a predetermined amount, while lowering the level of the blue primary color signal (B signal). Since the chromaticity adjustment is performed by increasing the level by a predetermined amount, there is little decrease in the level of the luminance signal. In addition, when the level of the luminance signal exceeds a predetermined level, chromaticity adjustment is performed, and only within this narrow range can the balance of each primary color signal be disrupted.
The color range in which the hue changes is narrow.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram showing an example of a conventional color adjustment circuit; FIGS. 2, 3, and 9 are diagrams for explaining a comparison between the present invention and a conventional example; FIGS. 4 and 5 The figures are the original drawings, FIGS. 6 and 7 are basic configuration diagrams, and FIG. 8 is the chromaticity ii! according to the present invention! Connection diagram showing the actual circuit of the tJ rectifying circuit, No. 10
The figure is a connection diagram showing another embodiment of the present invention. (211S, (21G) and (2113) are respective terminals, ('j[l) is an l-uv circuit, (40) is a resistance matrix circuit, and (', +lυ is a 4-gain control circuit). Agent Ito fi, 'J1
(1

Claims (1)

[Claims] A luminance signal level is detected, and when the luminance signal level exceeds a predetermined level, at least the level of the red primary color signal is lowered by a predetermined amount, and the level of the blue primary color signal is increased by a predetermined amount. Chromaticity adjustment circuit.