CN2717147Y - Color temperature calibrating circuit for color television picture tube - Google Patents
Color temperature calibrating circuit for color television picture tube Download PDFInfo
- Publication number
- CN2717147Y CN2717147Y CN 200420061429 CN200420061429U CN2717147Y CN 2717147 Y CN2717147 Y CN 2717147Y CN 200420061429 CN200420061429 CN 200420061429 CN 200420061429 U CN200420061429 U CN 200420061429U CN 2717147 Y CN2717147 Y CN 2717147Y
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- amplifier
- color
- picture tube
- feedback network
- complete machine
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- Processing Of Color Television Signals (AREA)
- Video Image Reproduction Devices For Color Tv Systems (AREA)
Abstract
The utility model relates to the color-temperature calibrating technique for color television picture tube. The utility model discloses a color-temperature calibrating circuit for color television picture tube, comprising a B signal amplifier. The B signal amplifier is connected with a dynamic feedback network. The input end of the dynamic feedback network is connected with the output end of the amplifier and the output end of the dynamic feedback network is connected with the input end of the amplifier. The utility model has the advantages that the effect on the white balance of the complete machine from the primary signal created by the different lighting efficiencies and the difference of transmission losses is compensated; the effect of the white balance of the complete machine is improved; the color distortion of the complete machine is reduced. The color-temperature calibrating circuit has simple circuit structure and low cost and is suitable for the white balance correction of the rear projected TV set which adopts three projective tubes (R, G, B) particularly.
Description
Technical field
The novel image display technology that relates to of this use, particularly color picture tube color temperature correction circuit.
Background technology
CRT projection TV (hereinafter to be referred as PTV) is since coming out, and complete machine white balance effect is relatively poor to be a key factor that influences image quality always.It is inconsistent in different brightness hypograph colour temperatures to be mainly reflected in same complete machine, at low-light level (20-40cd/m
2) time colour temperature higher (22, more than the 000K), at high brightness (200-250cd/m
2) time colour temperature (8,000K following) on the low side, the colour temperature deviation reaches 14, more than the 000K.From the subjective effect of picture, this white picture does not get up in vain, and this is red local redly not to get up, and causes people's the colour of skin blue or green partially, purple partially, and white clouds are white inadequately, and blue sky is indigo plant inadequately also, and the overall color of picture is bad.The inconsistent main cause of complete machine colour temperature is the luminous efficiency difference of three primary colors R (red Red), G (green Green), B (blue Blue) phosphor powder, and R, G, the propagation loss of B light in optical system of different wave length are variant, make that R, G, the B brightness of last arrival screen are inconsistent, particularly the difference of B signal is more obvious.Adopt common white balance correction technology, can not address the above problem.
The utility model content
Technical problem to be solved in the utility model is exactly the shortcoming at above-mentioned prior art, provides a kind of employing dynamical feedback technology, the circuit of correcting color picture tube or projection tube white balance.
The utility model solves its technical problem, and the technical scheme of employing is: the color picture tube color temperature correction circuit comprises the B signal amplifier; On the B signal amplifier, be connected with the dynamical feedback network; Described dynamical feedback network input is connected with amplifier out, and described dynamical feedback network output is connected with amplifier in.
The beneficial effects of the utility model are: remedied primary colour signal because of the influence to the complete machine white balance of luminous efficiency difference and loss difference, improved the white balance effect of complete machine, reduce the complete machine chromatic distortion, and had simple, the with low cost characteristics of circuit structure.
Description of drawings
Fig. 1 is the relation curve of prior art projection TV tristimulus signals amplitude and brightness;
Fig. 2 is the relation curve of brightness of prior art complete machine and colour temperature;
Fig. 3 is the circuit diagram of embodiment;
Fig. 4 is that same type adopts the circuit of embodiment to carry out the relation curve of front and back complete machine brightness of B signal color temperature correction and colour temperature.
Embodiment
Below in conjunction with drawings and Examples, describe the technical solution of the utility model in detail.
From as can be seen shown in Figure 1, under the identical situation of R, G, B signal amplitude of input projection tube, it is bigger that the brightness of the R that obtains on the screen, G, B image differs, B passage particularly, and brightness is obviously lower.For the difference of R, G passage, can proofread and correct by common white balance correcting, because the B channel difference is bigger, and also linear bad, common white balance correcting can not be obtained desirable effect.Above-mentioned difference reaction is on the brightness-colour temperature curve of complete machine, and as shown in Figure 2, colour temperature is higher when low-light level, and tone is colder, and the B component is heavier; Colour temperature is on the low side during high brightness, and tone is warm partially, and B gives short measure.
The utility model adopts the dynamical feedback network, before signal enters projection tube, the B signal is carried out precorrection, and control B primary colours Amplifier Gain makes Amplifier Gain in certain scope, size with input signal changes, low in input signal amplitude hour gain, it is high to gain when input signal amplitude is big, thereby makes the Blue curve among Fig. 1, reach unanimity with the linearity of Red curve and Green curve, improve the white balance effect of complete machine.
Embodiment
Circuit theory diagrams are seen Fig. 3, there is shown B passage video amplifier circuit schematic diagram.This routine B signal amplifier N1 adopts the TDA6111Q single channel video amplifier of Philips company.Input signal is connected with the input of amplifier N1 by input resistance R1.The dynamical feedback network is made of resistance R _ f, R2 and diode D1.The positive pole of D1 connects input signal, D1 be attempted by on the input resistance R1 after R2 connects, Rf one end is connected with the output of amplifier N1, an end is connected with the input of amplifier N1.Among the figure, R3 is an amplifier N1 input shunt resistance, and R4, C1, C2 constitute peaking network.If the dynamic electric resistor of diode D1 is Rd, the multiplication factor of amplifier N1 is Gb, according to Circuit theory as can be known:
Gb＝Rf/{(R2+Rd)//R1}；
During low-light level, diode D1 ends, Rd=∞;
Then: Gb=Rf/R1;
During high brightness, diode D1 conducting, Rd=0;
Then: Gb=Rf/ (R2//R1).
Be input signal amplitude when changing within the specific limits, the multiplication factor Gb excursion of amplifier is: Rf/R1≤Gb≤Rf/ (R2//R1).
According to input signal amplitude, choose reasonable reference voltage Vref and circuit parameter make the multiplication factor of amplifier N1 inconsistent under different brightness, little when low-light level, big when highlighted, just in time the B signal curve with Fig. 1 forms complementation, improves the white balance effect of complete machine.
Be the actual parameter (as Fig. 3) of the blue signal amplifier of certain model PTV below:
R1＝2.4k；Rf＝100k；R2＝4.7k；R3＝2.7k；
Vin＝2.5Vdc+2Vpp Vout＝190Vdc+125Vpp
Vref＝3.0V
Can calculate the multiplication factor of B signal according to above-mentioned parameter:
During low-light level, diode D1 ends, Gb=41.7;
During high brightness, diode D1 conducting, Gb=62.9.
Fig. 4 is that this type PVT adopts foregoing circuit to proofread and correct the complete machine brightness-colour temperature curve of front and back.Before proofreading and correct among the figure is previous status, and proofreading and correct the back is new state.As can be seen from the figure, after blue signal amplifier adopted the dynamical feedback network, the linearity of brightness-colour temperature curve was improved obviously, and the improvement of particularly low-light level linearity is more outstanding.Brightness is at 15～240cd/m
2The interior variation, colour temperature is almost constant at 10,000K.Measured data sees Table 1.
Table 1
| Brightness | Colour temperature (K) | |
| Cd/ | Previous status 22,226 | New state |
| 8807 | ||
| 30 | 16,358 | 8735 |
| 60 | 14,593 | 8429 |
| 90 | 12,863 | 8623 |
| 120 | 11,565 | 9115 |
| 150 | 10,288 | 9299 |
| 180 | 9,323 | 9387 |
| 210 | 8,059 | 9543 |
| The colour temperature deviation | 14,167 | 1,114 |
Dynamical feedback network of the present utility model, utilize the dynamic characteristic of diode current flow resistance, the gain of control B signal, input signal is carried out precorrection, improve the linearity of B signal amplitude-brightness curve, cooperate the common white method for correcting balance, obviously improved the white balance effect of complete machine, be specially adapted to adopt the back projection television of three (R, G, B) projection tubes to make white balance correction.
Claims (3)
1. the color picture tube color temperature correction circuit comprises the B signal amplifier, it is characterized in that: be connected with the dynamical feedback network on the B signal amplifier; Described dynamical feedback network input is connected with amplifier out, and described dynamical feedback network output is connected with amplifier in.
2. color picture tube color temperature correction circuit according to claim 1 is characterized in that: described dynamical feedback network comprises resistance (Rf), resistance (R2), diode (D1); Resistance (Rf) end is connected with amplifier out, and the other end is connected with amplifier in; Resistance (R2) be connected in parallel on the amplifier input resistance (R1) after diode (D1) is connected, diode D1 positive pole connects input signal.
3. color picture tube color temperature correction circuit according to claim 2 is characterized in that: be parallel with peaking network on the described resistance (R1).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200420061429 CN2717147Y (en) | 2004-09-27 | 2004-09-27 | Color temperature calibrating circuit for color television picture tube |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200420061429 CN2717147Y (en) | 2004-09-27 | 2004-09-27 | Color temperature calibrating circuit for color television picture tube |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2717147Y true CN2717147Y (en) | 2005-08-10 |
Family
ID=34873099
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200420061429 Expired - Fee Related CN2717147Y (en) | 2004-09-27 | 2004-09-27 | Color temperature calibrating circuit for color television picture tube |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2717147Y (en) |
-
2004
- 2004-09-27 CN CN 200420061429 patent/CN2717147Y/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20050810 Termination date: 20130927 |