The backlight module and the display that comprise adjusting control circuit
Technical field
The present invention relates to a kind of adjusting control circuit, particularly a kind of adjusting control circuit that is applied to backlight module.
Background technology
Because photoelectricity science and technology is flourish, more and more chances touch communication miscellaneous or electronic product in the life, for example: personal digital assistant (personal digital assistant; PDA), mobile phone, mobile computer, desktop display, automobile-used display or the like.Wherein, display unit is answered the common device that possesses for these communications or electronic product, so the concerning quality of these communications or electronic product of the quality of display unit.High image quality, volume are little, in light weight so display unit can possess, low driving voltage, with advantage such as low consumpting power be urgently in the target of making great efforts.
Generally speaking, present display all is equipped with backlight module to provide backlight, and backlight module then is equipped with adjusting control circuit, with the brightness of control backlight.
Please refer to Fig. 1, it is the function block schematic diagram that illustrates known backlight module 10.Backlight module 10 comprises light source 12, converter (inverter) 14, pulse width modulation module (PWM module) 16, current sensing means 18 and adjusting control circuit 20, and wherein current sensing means 18 is in order to the operating current of detection light source 12.In backlight module 10, the brightness of light source 12 is controlled by converter 14, and the electric current that converter 14 provides is big more, and the brightness of light source 12 is just strong more, otherwise if the electric current that converter 14 provides is more little, the brightness of light source 12 is just more little.The size of current that adjusting control circuit 20 is exported in order to control converter 14.Adjusting control circuit 20 is according to the external signal S of user's input
rThe current detection signal S that is fed back with current sensing means 18
fNumber export brightness control signal S
c, to utilize brightness control signal S
cControl the electric current that converter 14 is exported.Pulse width modulation module 16 is electrically connected between adjusting control circuit 20 and the converter 14, in order to brightness control signal S
cBe modulated into pulse signal, and input to converter 14.
Please refer to Fig. 2, it is the electrical block diagram that illustrates known adjusting control circuit 20.Adjusting control circuit 20 comprises comparator 22, resistance 24,26,28 and 30.The anode of comparator 22 is in order to receive the external signal S that the user imported
rExternal signal S
rAfter inputing to comparator 22, comparator 22 just can calculate external signal S
rWith reference voltage V
rDifference, and export this difference to resistance 28.Resistance 30 is electrically connected to current sensing means 18, with received current detection signal S
f, and utilize resistance 28 with current detection signal S
fBe coupled into brightness control signal S with the difference of comparator 22 outputs
c
As shown in the above description, adjusting control circuit 20 can make brightness control signal S
cValue along with the external signal S of user input
rValue and linear change, to change the brightness of light source 12.Generally speaking, the user can only be by three kinds of external signal S
rSelect an output in the value, promptly 0 volt, 1.6 volts and 3.3 volts, wherein 1.6 volts correspond to normal brightness, and 0 volt corresponds to lower brightness, and 3.3 volts correspond to higher brightness.Though adjusting control circuit 20 can make brightness control signal S
cValue along with external signal S
rValue and be linear change, but signal S externally
rValue is changed under the condition of limited, brightness control signal S
cValue also be limited, in other words, the resolution of 12 brightness that can present of light source is also less relatively, and can't satisfy user's demand.
Therefore, need a kind of external signal S that adjusts
rThe adjusting control circuit of corresponding current value can satisfy user's demand with the resolution of the brightness of guaranteeing light source.
Summary of the invention
Therefore, an aspect of of the present present invention provides a kind of adjusting control circuit, and it can adjust the pairing current value of external signal according to user's demand.
Another aspect of the present invention provides a kind of backlight module, and it can adjust the pairing current value of external signal according to user's demand.
One side more of the present invention provides a kind of display, and it can adjust the pairing current value of external signal according to user's demand.
According to one embodiment of the invention, this adjusting control circuit comprises current changeover switch, at least one resistance, voltage changeover switch, level judging circuit and comparator.Current changeover switch is in order to choose an electric current.Resistance is electrically connected to current changeover switch, to produce a corresponding magnitude of voltage according to this electric current.Voltage changeover switch is in order to receive this corresponding voltage value and to export a reference voltage.Level judging circuit is come Control current diverter switch and voltage changeover switch according to the size of external input voltage.Comparator is in order to receiving a feedback voltage and this reference voltage, and exports a brightness control signal.
According to one embodiment of the invention, this backlight module comprises above-mentioned adjusting control circuit, light source and converter, and wherein converter is electrically connected between light source and the adjusting control circuit, to control the size of current that exports light source to according to brightness control signal.
According to one embodiment of the invention, this display comprises an above-mentioned backlight module and a display floater, and wherein display floater is arranged on the backlight module, comes display image in order to receive the light that backlight module provided.
Description of drawings
For above-mentioned and other purposes of the present invention, feature and advantage can be become apparent, above especially exemplified by a preferred embodiment, and conjunction with figs., be described in detail below:
Fig. 1 is the function block schematic diagram that illustrates known backlight module.
Fig. 2 is the electrical block diagram that illustrates known adjusting control circuit.
Fig. 3 illustrates the electrical block diagram of adjusting control circuit according to an embodiment of the invention.
Fig. 4 illustrates the electrical block diagram of adjusting control circuit according to an embodiment of the invention.
Fig. 5 illustrates the function block schematic diagram of backlight module according to an embodiment of the invention.
Fig. 6 illustrates the function block schematic diagram of display 400 according to an embodiment of the invention.
[main element symbol description]
10: backlight module 12: light source
14: converter 16: the pulse width modulation module
18: current sensing means 20: adjusting control circuit
22: comparator 24: resistance
26: resistance 28: resistance
30: resistance 100: adjusting control circuit
110: current source 120: current source
130: current changeover switch 150: voltage changeover switch
150a: voltage input end 150b: voltage input end
150c: voltage output end 160: level judging circuit
170: comparator 300: backlight module
310: light source 320: converter
330: pulse width modulation module 340: current sensing means
350: adjusting control circuit 400: display
410: display floater 420: preceding frame
S
c: brightness control signal S
r: external signal
S
f: detection signal V
A: reference voltage
V
r: reference voltage V
g: reference voltage
I
1: electric current I
2: electric current
R1: resistance R 1a: end points
R1b: end points R2: resistance
Embodiment
Please refer to Fig. 3, it is to illustrate the electrical block diagram of adjusting control circuit 100 according to an embodiment of the invention.Adjusting control circuit 100 comprises current source 110, current source 120, current changeover switch 130, resistance R 1, voltage changeover switch 150, level judging circuit 160 and comparator 170.Current changeover switch 130 is electrically connected to current source 110 and current source 120, to export first electric current I
1Or second electric current I
2, wherein current source 110 is in order to export first electric current I
1, and current source 120 is in order to export second electric current I
2Resistance R 1 is electrically connected to current changeover switch 130, and with first electric current or second electric current that received current diverter switch 130 is exported, wherein the end points R1a of resistance R 1 is electrically connected to reference voltage V
g, and end points R1b is electrically connected to current changeover switch 130.Voltage changeover switch 150 has voltage input end 150a, 150b and voltage output end 150c.Voltage input end 150a is electrically connected to the end points R1b of resistance R 1, and voltage input end 150b is electrically connected to reference voltage V
r, with from voltage output end 150c output reference voltage V
rOr the voltage of end points R1b.The negative terminal of comparator 170 is electrically connected to the voltage output end 150c of voltage changeover switch 150, and anode then is transfused to a feedback signal S
f, this feedback signal S
fCan for example be the current feedback signal of light source.Level judging circuit 160 is in order to judge the external signal S of user's input
rSize, with the switching state of decision current changeover switch 130 and voltage changeover switch 150.In the following description, will illustrate that adjusting control circuit 100 is the brightness control signal S that how to adjust its output
c
By above circuit connecting relation as can be known, when deciding current changeover switch 130 outputs first electric current I
1The time, voltage level V can appear in the end points R1b of resistance R 1
Min, and when current changeover switch 130 outputs second electric current I
2The time, voltage level V can appear in end points R1b
Max, V wherein
Min=I
1* R1+V
g, and voltage level V
Max=I
2* R1+V
gIf set first electric current I
1Value less than first electric current I
2Value, voltage level V then
MinValue can be less than voltage level V
MaxValue.Then, with reference voltage V
rValue be designed between voltage level V
MaxWith voltage level V
MinBetween, so level judging circuit 160 can be according to external signal S
rCome the switching state of Control current diverter switch 130 and voltage changeover switch 150, so that voltage changeover switch 150 output reference voltage level V
Min, V
MaxWith reference voltage V
rThen, the signal and the feedback signal S that are exported of 170 calculating voltage diverter switches 150 of comparator
fBetween difference, and export brightness control signal S according to this difference
c
By above-mentioned explanation as can be known, suitably with external signal S
rValue correspond to voltage level V
Min, V
MaxWith reference voltage V
r, for example: S
rIn the time of=3.3 volts, voltage changeover switch 150 output-voltage levels V
MaxS
rIn the time of=1.6 volts, voltage changeover switch 150 output reference voltage V
rS
rIn the time of=0 volt, voltage changeover switch 150 output-voltage levels V
Min, so can make brightness control signal S
cAlong with external signal S
rVariation and change, and this variation is not to be linear change.Moreover the user can change voltage level V easily by the value of changing resistance R 1
MinAnd V
MaxValue, make brightness control signal S
cValue have more elasticity.
In addition, what one of value was carried is, because in integrated circuit, the realization of current source is quite easy, therefore current source 110, current source 120, current changeover switch 130, voltage changeover switch 150, level judging circuit 160 and comparator 170 can be integrated into a chip, and, so not only can significantly dwindle the volume of adjusting control circuit 100 with resistance R 1 outer this chip that is connected on, more can change the value of resistance R 1 according to user's demand at any time.
Please refer to Fig. 4, it is to illustrate the electrical block diagram of adjusting control circuit 200 according to an embodiment of the invention.Adjusting control circuit 200 is similar to adjusting control circuit 100, also comprises resistance R 2 but difference is adjusting control circuit 200, and wherein an end of resistance R 2 is electrically connected to the end points R1b of resistance R 1, and the other end is electrically connected to reference voltage V
AIn adjusting control circuit 200,, therefore can obtain by Kirchhoff's law owing to added resistance R 2:
I
2+(V
A-V
min)/R1-(V
min-V
g)/R2=0 ...........(1)
I
1+(V
A-V
max)/R1-(V
max-V
g)/R2=0 .........(2)
Just can try to achieve V easily by equation (1) and (2)
MinAnd V
MaxValue.In the present embodiment, because the influence of resistance R 2, make voltage level V
MinAnd V
MaxCorrelation each other descends, and then has increased voltage level V
MinAnd V
MaxElasticity in the design.
Please refer to Fig. 5, it is to illustrate the function block schematic diagram of backlight module 300 according to an embodiment of the invention.Backlight module 300 comprises light source 310, converter 320, pulse width modulation module (PWMmodule) 330, current sensing means 340 and adjusting control circuit 350, and wherein adjusting control circuit 350 can for example be above-mentioned adjusting control circuit 100 or 200.In backlight module 300, converter 320 is electrically connected to light source 310, gives me a little bright light source 310 to provide current to light source 310.Pulse modulation module 330 is electrically connected between adjusting control circuit 350 and the converter 320, in order to brightness control signal S
cBe modulated into pulse signal and input to converter 320.Current sensing means 340 is in order to the operating current of detection light source 310, and output feedback signal S
fTo adjusting control circuit 350.
In the present embodiment, because above-mentioned adjusting control circuit 350 has the advantage of adjusting control circuit 100 or 200, so the brightness of backlight module 300 can be adjusted to the required brightness of user easily.
Please refer to Fig. 6, it is to illustrate the function block schematic diagram of display 400 according to an embodiment of the invention.Display 400 comprises backlight module 300, display floater 410 and preceding frame 420.Backlight module 300 is in order to provide light to display floater 410, and display floater 410 then is arranged on the backlight module 300, comes display frame to utilize this light.Preceding frame 420 is arranged on the display floater 410 and is sticked on the outer rim of backlight module 300.Because display 400 utilizes backlight module 300 that backlight is provided, so the brightness of display 400 can be adjusted to the required brightness of user easily.
Though the present invention with embodiment openly as above; right its is not in order to qualification the present invention, those skilled in the art, without departing from the spirit and scope of the present invention; when can being used for a variety of modifications and variations, so protection scope of the present invention is as the criterion when looking the appended claims person of defining.