CN1122423C - Automatic gain regulator for color video signal of display - Google Patents
Automatic gain regulator for color video signal of display Download PDFInfo
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- CN1122423C CN1122423C CN 98115004 CN98115004A CN1122423C CN 1122423 C CN1122423 C CN 1122423C CN 98115004 CN98115004 CN 98115004 CN 98115004 A CN98115004 A CN 98115004A CN 1122423 C CN1122423 C CN 1122423C
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Abstract
The present invention relates to an automatic gain adjusting device for a displayer, which is used for converting an analog signal of a VGA display card into a digital signal. The device comprises an analog digital converter and a reference voltage processing circuit, wherein the analog digital converter converts the analog signal into the digital signal on the basis of an upper limit reference voltage and a lower limit reference voltage and respectively generates an overflow signal and a borrow signal when the electric potential of the analog signal exceeds the upper limit reference voltage or below the lower limit reference voltage; the reference voltage processing circuit provides the analog digital converter with the upper limit reference voltage and the lower limit reference voltage. When receiving the overflow signal or the borrow signal, the reference voltage processing circuit respectively adjusts the upper limit reference voltage upwards and adjusts the lower limit reference voltage downwards so that the analog signal is effectively converted into the digital signal.
Description
Technical field
The invention provides a kind of automatic gain adjustment device, especially refer to a kind of VGA (Video Graphics Array (Video Graphic Array)) colour signal automatic gain adjustment device that is used for display.
Background technology
LCD projector (LCD projector) often is used to show VGA (VideoGraphic Array) the RGB colour signal that display card produced of PC.Because the RGB colour signal that the VGA display card of each brand is produced has the difference on the amplitude, therefore when different computer that LCD projector is arranged in pairs or groups came display image, different brightness and effect appearred in regular meeting.Yet existing image automatic gain adjustment device (video automatic gain control) only is applicable to the processing of the synthesized image signal (Compositive video signal) that is provided with canonical reference point, can't be suitable for for not having a RGB colour signal of canonical reference point.
With reference to figure 1 and Fig. 2.Fig. 1 is a synthesized image signal 10.Fig. 2 is two analog color signals 20 that a VGA display card is produced.Synthesized image signal 10 includes one and is used for brightness synchronizing signal 12, as the brightness reference and is used for a chrominance synchronization signal 14 (3.58MHz) and an analog color signal 16 as chroma reference.Brightness synchronizing signal 12 can be by existing image automatic gain adjustment device as with reference to converting analog color signal 16 to digital color-signal with the scope of the best, but 20 of the analog color signals that the VGA display card is produced do not have brightness synchronizing signal 12, therefore have no idea to adjust its brightness automatically with existing image automatic gain adjustment device.
Summary of the invention
Therefore, main purpose of the present invention is to provide a kind of automatic gain adjustment device and method that is used for display, and its analog color signal that the VGA display card can be produced converts digital color-signal to after the automatic gain adjustment, to solve the above problems.
The invention provides a kind of automatic gain adjustment device that is used for display, be used for converting the analog color signal that a VGA display card is produced to a digital color-signal, this device comprises: a clamp circuit is used for the lower limit current potential of analog color signal that a VGA display card is produced to be locked in a predetermined reference potential; One analog-digital converter, be used for converting this analog color signal to this digital color-signal, and when the current potential of this analog color signal surpasses this upper limit reference voltage, produce an overflow signal (overflow signal) according to a upper limit reference voltage and a lower limit reference voltage; And the current potential of this analog color signal produces a borrow signal when being lower than this lower limit reference voltage; And a reference voltage treatment circuit, be used for providing this upper limit reference voltage and this lower limit reference voltage to this analog-digital converter; Wherein, when receiving this overflow signal, this reference voltage treatment circuit can be heightened this upper limit reference voltage, so that this analog-digital converter can intactly convert this analog color signal to this digital color-signal.
The present invention also provides a kind of automatic gain method of adjustment that is used for display, be used for converting the analog color signal that a VGA display card is produced to a digital color-signal, it includes: the lower limit current potential that utilizes the analog color signal that clamp circuit locking VGA display card produced; Utilize an analog-digital converter and convert this analog color signal to this digital color-signal according to a upper limit reference voltage and a lower limit reference voltage, and when the current potential of this analog color signal surpasses this upper limit reference voltage, produce an overflow signal, and when being lower than this lower limit reference voltage, the current potential of this analog color signal produces a borrow signal; Utilize a reference voltage treatment circuit to come to provide this upper limit reference voltage and this lower limit reference voltage to this analog-digital converter; And when receiving this overflow signal, utilize this reference voltage treatment circuit to heighten this upper limit reference voltage, so that this analog-digital converter can intactly convert this analog color signal to this digital color-signal.
Compared with prior art, automatic gain adjustment device of the present invention analog color signal that the VGA display card is produced is converted to digital color-signal effectively.
Description of drawings
Fig. 1 is a synthesized image signal.
The analog color signal that Fig. 2 is produced for the VGA display card.
Fig. 3 is used for the functional block diagram of the automatic gain adjustment device of display for the present invention.
Fig. 4 adjusts the used program of its bound reference voltage for the processor of Fig. 3.
Fig. 5 is the analog color signal that a VGA display card is produced.
Fig. 6 is the output after through a clamp circuit of the analog color signal of Fig. 5.
Fig. 7 and Fig. 8 show how reference voltage treatment circuit of the present invention adjusts its upper limit and lower limit reference voltage.
Embodiment
Please refer to Fig. 3.Fig. 3 is used for the functional block diagram of the automatic gain adjustment device 30 of display for the present invention.Automatic gain adjustment device 30 includes a clamp circuit (clamper) 50, an analog-digital converter (Analog to Digital Converter, ADC) 32 and one reference voltage treatment circuit 34.The analog color signal that automatic gain adjustment device 30 is only produced the VGA display card converts digital color-signal to, because the VGA display card produces R, G, three analog color signals of B, therefore a complete automatic gain adjustment device 30 needs three clamp circuits 50 and three analog-digital converters 32 to handle each analog color signal respectively, and 34 of reference voltage treatment circuits can be handled the upper limit reference voltage and the lower limit reference voltage of three analog-digital converters 32 simultaneously.
The lower limit current potential (position 22 as shown in Figure 2) of the analog color signal that the VGA display card that clamp circuit 50 is used for being imported by input port 48 is produced is locked in a predetermined reference potential.
Analog-digital converter (Analog to Digital Converter, ADC) the 32nd, the analog color signal that is used for being imported from port 56 by clamp circuit 50 converts a digital color-signal to, the analog color signal of port 56 input and the upper limit reference voltage of port 52 and the formed reference voltage range of lower limit reference voltage of port 54 are compared, converting a digital color-signal to, and by output port 46 outputs.When the upper limit current potential of the analog color signal of importing surpassed the upper limit reference voltage of port 52, analog-digital converter 32 produced an overflow (overflow) signals at port 42; And when the lower limit current potential of the analog color signal of importing was lower than the lower limit reference voltage of port 54, analog-digital converter 32 produced a borrow (underflow) signals at port one 4.
Reference voltage treatment circuit 34 is used for providing upper limit reference voltage and lower limit reference voltage to analog-digital converter 32, and heighten the upper limit reference voltage of port 52 output according to the overflow signal that analog-digital converter 32 is produced, and turn down lower limit reference voltage by port 54 output according to the borrow signal that analog-digital converter 32 is produced, so that analog-digital converter 32 can will convert a digital color-signal to by the analog color signal of port 56 inputs in the mode of the best.
Reference voltage treatment circuit 34 comprises a processor 36, a upper limit digital analog converter 38 and a lower limit digital analog converter 40.Processor 36 is used for the borrow signal that overflow signal that receiving port 42 imported and port 44 are imported, and produces limited signal on the relative numeral and produce limited signal under the relative numeral at port 60 at port 58.Upper limit digital analog converter 38 is used for processor 36 is become a upper limit reference voltage in the digital upper limit conversion of signals that port 58 is produced, and lower limit digital analog converter 40 then is used for processor 36 is become a lower limit reference voltage in the digital lower limit conversion of signals that port 60 is produced.
After automatic gain adjustment device 30 is electrically connected on a VGA display card, the lower limit current potential of the analog color signal that clamp circuit 50 is produced the VGA display card earlier is locked on the predetermined reference potential, reference voltage treatment circuit 34 is then by port default initial upper limit reference voltage of 52 outputs and by default initial lower limit reference voltage of port 54 outputs, so that analog-digital converter 32 begins to change the analog color signal by port 56 inputs.Initial upper limit reference voltage and initial lower limit reference voltage are set according to the reference potential of clamp circuit 50, and the mean amplitude of tide of the analog color signal that gap is therebetween then produced than general VGA display card is little.Therefore, behind the analog color signal of automatic gain adjustment device 30 beginning conversion ports 56 inputs, overflow signal and borrow signal that reference voltage treatment circuit 34 can constantly be produced according to analog-digital converter 32 are adjusted its upper limit reference voltage and lower limit reference voltage, so that the upper limit reference voltage that the bound electrical potential energy of the analog color signal of port 56 input and reference voltage treatment circuit 34 are exported is identical with the lower limit reference voltage, the analog color signals that import this moment 56 just can be converted into digital color-signal under best upper limit reference voltage and lower limit reference voltage.
Please refer to Fig. 4.Fig. 4 is that the processor 36 of Fig. 3 is adjusted its upper limit reference voltage and the employed program 70 of lower limit reference voltage.In program 70, suppose that the lower limit current potential of the analog color signal that clamp circuit 50 has been produced the VGA display card is locked in 2.95V.Program 70 includes the following step:
Step 71: set initial upper limit reference voltage and initial lower limit reference voltage, as 3.5V and 3.0V;
Step 72: check whether received the overflow signal; If not, then skip to step 75;
Step 73: check that whether upper limit reference voltage is to a preset upper limit, as 3.8V; If then skip to step 75;
Step 74: upper limit reference voltage is increased by a predetermined amount, as 0.01V;
Step 75: check whether received the borrow signal; If not, then skip to step 72;
Step 76: check that whether the lower limit reference voltage is to a default lower limit, as 2.9V; If then skip to step 72;
Step 77: the lower limit reference voltage is reduced a predetermined amount,, skip to step 72 as 0.01V.
Please refer to Fig. 5 and Fig. 6.Fig. 5 is the analog color signal 80 that a VGA display card is produced.Fig. 6 is the output of signal 80 through clamp circuit 50.The amplitude of Fig. 5 shows signal 80 is 0.6V
P-p, after the process processing of clamp circuit 50, its bound becomes 3.55V and 2.95V.At this moment, if the initial upper limit reference voltage of reference voltage treatment circuit 34 and initial lower limit reference voltage are set to 3.55V and 2.95V, then analog-digital converter 32 just can intactly convert signal 80 to a digital color-signal.
Please refer to Fig. 7 and Fig. 8.Fig. 7 and Fig. 8 show how reference voltage treatment circuit 34 of the present invention adjusts its upper limit and lower limit reference voltage.Fig. 7 shows that the initial upper limit reference voltage of reference voltage treatment circuit 34 is 3.5V, and initial lower limit reference voltage is 3.0V.Because 82 and 84 parts of signal 80 exceed 3.5V, and 86 parts are lower than 3.0V, so analog-digital converter 32 meetings generation overflow signal when 82 and 84 parts of switching signal 80, and when 86 parts of switching signal 80, produce the borrow signal.Reference voltage treatment circuit 34 can be adjusted its upper limit reference voltage and lower limit reference voltage at once when receiving overflow signal or borrow signal.Fig. 8 shows that reference voltage treatment circuit 34 is adjusted into 3.51V with its upper limit reference voltage, and its lower limit reference voltage is adjusted into 2.99V.Constantly adjust through repeating, reference voltage treatment circuit 34 can make clamp circuit 50 all fall between upper limit reference voltage and the lower limit reference voltage from the analog color signal upper and lower limit current potential of port 56 inputs at last, so that the analog color signal 80 that analog-digital converter 32 can intactly be transmitted clamp circuit 50 converts digital color-signal to.
The above only is preferred embodiment of the present invention, and all equalizations of doing according to claims of the present invention change and modify, and all should belong to the scope that comprises of patent of the present invention.
Claims (11)
1. an automatic gain adjustment device that is used for display is used for converting the analog color signal that a VGA display card is produced to a digital color-signal, and this device comprises:
One clamp circuit is used for the lower limit current potential of analog color signal that a VGA display card is produced to be locked in a predetermined reference potential;
One analog-digital converter, be used for converting this analog color signal to this digital color-signal according to a upper limit reference voltage and a lower limit reference voltage, and when the current potential of this analog color signal surpasses this upper limit reference voltage, produce an overflow signal, and the current potential of this analog color signal produces a borrow signal when being lower than this lower limit reference voltage; And
One reference voltage treatment circuit is used for providing this upper limit reference voltage and this lower limit reference voltage to this analog-digital converter,
Wherein, when receiving this overflow signal, this reference voltage treatment circuit can be heightened this upper limit reference voltage, so that this analog-digital converter can intactly convert this analog color signal to this digital color-signal.
2. automatic gain adjustment device as claimed in claim 1, wherein, described analog-digital converter produces a borrow signal when the current potential of described analog color signal is lower than described lower limit reference voltage, and described reference voltage treatment circuit is when receiving this borrow signal, can turn down this lower limit reference voltage, so that this analog-digital converter can intactly convert this analog color signal to this digital color-signal.
3. automatic gain adjustment device as claimed in claim 2, wherein, described automatic gain adjustment device is after being electrically connected on described VGA display card, described reference voltage treatment circuit can be exported a default initial upper limit reference voltage and a default initial lower limit reference voltage, so that described analog-digital converter begins to change described analog color signal.
4. automatic gain adjustment device as claimed in claim 3, also comprise a clamp circuit, being used for the lower limit current potential of analog color signal that described VGA display card is produced is locked in a predetermined reference potential, and the initial upper limit reference voltage of described reference voltage treatment circuit and initial lower limit reference voltage are set according to the reference potential of this clamp circuit.
5. automatic gain adjustment device as claimed in claim 1, wherein, the colour signal that described VGA display card is produced can be redness, green or blue signal.
6. automatic gain adjustment device as claimed in claim 1, wherein, described display is a LCD projector.
7. automatic gain adjustment device as claimed in claim 2, wherein, described reference voltage treatment circuit comprises:
One processor is used for receiving overflow signal and the borrow signal that described analog-digital converter produces, and produces a numeral upward a limited signal and a digital limited signal down;
One upper limit digital analog converter, the digital upper limit conversion of signals that is used for described processor is produced becomes described upper limit reference voltage; And
One lower limit digital analog converter, the digital lower limit conversion of signals that is used for described processor is produced becomes described lower limit reference voltage.
8. automatic gain adjustment device as claimed in claim 7, wherein, when receiving described overflow signal, described processor can be heightened limited signal on the described numeral, to promote described upper limit reference voltage, and when receiving described borrow signal, this processor can be turned down limited signal under the described numeral, to reduce described lower limit reference voltage.
9. automatic gain adjustment device as claimed in claim 7, wherein, described automatic gain adjustment device is after being electrically connected on described VGA display card, limited signal under a limited signal and the initial number of presetting on the initial number that described processor output one is preset, to produce an initial upper limit reference voltage and an initial lower limit reference voltage, so that described analog-digital converter begins to change described analog color signal.
10. an automatic gain method of adjustment that is used for display is used for converting the analog color signal that a VGA display card is produced to a digital color-signal, and it includes:
Utilize the lower limit current potential of the analog color signal that clamp circuit locking VGA display card produced;
Utilize an analog-digital converter and convert this analog color signal to this digital color-signal according to a upper limit reference voltage and a lower limit reference voltage, and when the current potential of this analog color signal surpasses this upper limit reference voltage, produce an overflow signal, and when being lower than this lower limit reference voltage, the current potential of this analog color signal produces a borrow signal;
Utilize a reference voltage treatment circuit to come to provide this upper limit reference voltage and this lower limit reference voltage to this analog-digital converter; And
When receiving this overflow signal, utilize this reference voltage treatment circuit to heighten this upper limit reference voltage, so that this analog-digital converter can intactly convert this analog color signal to this digital color-signal.
11. automatic gain method of adjustment as claimed in claim 10 wherein, when described analog-digital converter is lower than described lower limit reference voltage at the current potential of described analog color signal, produces a borrow signal, this method includes in addition:
When receiving described borrow signal, utilize described reference voltage treatment circuit to turn down described lower limit reference voltage, so that described analog-digital converter can intactly become described digital color-signal with described analog signal conversion.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98115004 CN1122423C (en) | 1998-06-19 | 1998-06-19 | Automatic gain regulator for color video signal of display |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98115004 CN1122423C (en) | 1998-06-19 | 1998-06-19 | Automatic gain regulator for color video signal of display |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1239857A CN1239857A (en) | 1999-12-29 |
| CN1122423C true CN1122423C (en) | 2003-09-24 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 98115004 Expired - Fee Related CN1122423C (en) | 1998-06-19 | 1998-06-19 | Automatic gain regulator for color video signal of display |
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| CN (1) | CN1122423C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7084795B2 (en) * | 2004-06-02 | 2006-08-01 | Mstar Semiconductor, Inc. | Video signal processing system with a dynamic ADC calibration loop and related methods |
| JP5709629B2 (en) * | 2011-04-19 | 2015-04-30 | キヤノン株式会社 | Imaging apparatus and control method |
| CN106791839B (en) * | 2016-12-19 | 2020-03-27 | 中国航空工业集团公司洛阳电光设备研究所 | Method and device for digitally sampling CCIR (China center IR) or EIA (electronic article Association) standard analog video |
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1998
- 1998-06-19 CN CN 98115004 patent/CN1122423C/en not_active Expired - Fee Related
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| Publication number | Publication date |
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| CN1239857A (en) | 1999-12-29 |
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