CN104282280A - Backlight drive current adjusting device and method thereof - Google Patents

Abstract

The invention provides a backlight drive current adjusting method. The backlight drive current adjusting method includes the steps that PWM signals are input into a port ISET, processed in an electric level conversion mode through an inner PWM controller and then transmitted to a reverse-direction end of a PWM comparer, an integral circuit generates sawtooth signals synchronous with the PWM signals and transmits the sawtooth signals to a same-direction end of the PWM comparer, and after the sawtooth signals are processed through the PWM comparer, the maximum value of the sawtooth signals is provided for an input/output port of a logic control unit in the integral circuit; the maximum value of the sawtooth signals is adjusted by changing the duty ratio of the PWM signals input into the port ISET, and then a backlight drive current is changed.

Description

A kind of adjusting gear of backlight drive electric current and method thereof

Technical field

The present invention relates to lcd technology, be specifically related to a kind of adjusting gear and method thereof of backlight drive electric current.

Background technology

Current, LED-backlit LCD TV has become the main flow of household electrical appliances market flat panel TV.The LED-backlit LCD TV backlight drive current parameter of same or similar dimensions is not quite similar, and same model movement configures the drive current that different back light units needs to adjust according to actual techniques state backlight.

Can realize adjusting the effect of backlight drive by changing hardware parameter on movement, but this mode is difficult to the standardization demand meeting movement design and production.Need propose a kind of newly LED-backlit drive current mode is set.

Summary of the invention

The present invention seeks to: adjusting gear and method thereof that a kind of backlight drive electric current is provided, realize arranging LED-backlit drive current size by software control.

Technical scheme of the present invention is: a kind of adjusting gear of backlight drive electric current, comprise current constant control integrated circuit, comprise backlight drive matrix current adjustment circuit, described backlight drive matrix current adjustment circuit comprises PWM comparer, integrating circuit, PWM controller, described integrating circuit one end connection PWM comparer is held in the same way, connectivity port, one end REF, external 1 electric capacity of port REF, electric capacity other end ground connection; Described PWM controller one end connects PWM comparer backward end, connectivity port, one end ISET; The output terminal of PWM comparer is connected to the I/O port of IC interior logic control element.

Further, the present invention also provides a kind of backlight drive current adjusting method, pwm signal inputs to port ISET, carry out after level translation process through inner PWM controller, transport to PWM comparer backward end, the integrating circuit generation sawtooth signal synchronous with pwm signal is transported to PWM comparer and is held in the same way, after the effect of PWM comparer, the maximal value of sawtooth signal is supplied to the I/O port of IC interior logic control element;

Backlight drive electric current I E numerical value is:

$\mathrm{IE}=\frac{D\×\mathrm{VREF}}{\mathrm{RF}}$

Wherein, VREF is the fixed reference potential that IC interior is arranged, and described fixed reference potential acts on resistance RF, and RF is sample resistance resistance, and D is the dutycycle of the pwm signal that port ISET inputs;

By changing the maximal value of the dutycycle adjustment sawtooth signal inputing to the pwm signal of port ISET, and then change backlight drive electric current.

The invention has the beneficial effects as follows: in current constant control integrated circuit, increase by 2 external-connected port ISET and REF, port REF external capacitor setting reference voltage, control signal PWM inputs to port ISET, changes LED-backlit drive current by changing the dutycycle of pwm signal.Realize the object of software adjustment electric current, by software change backlight specifications parameter, greatly reduce the hardware class of product, the great facility that production and application for product bring.

Accompanying drawing explanation

Accompanying drawing 1:OB3350 type single channel current constant control integrated circuit schematic;

Accompanying drawing 2:OB3350 type single channel constant-current supply pwm chip internal frame diagram;

Accompanying drawing 3: modified single channel constant-current supply pwm chip internal frame diagram.

Embodiment

As shown in Figure 2, traditional this IC interior in back facet current mode that arranges arranges fixed reference potential VREF.Traditional mode arranging back facet current IE is the resistance of adjustment sample resistance RF, that is:

$\mathrm{IE}=\frac{\mathrm{VREF}}{\mathrm{RF}}$

Wherein, VREF arranges fixed reference potential for this IC interior, and this voltage acts on resistance RF, and RF is sample resistance resistance.

Traditional back facet current mode that arranges is the adjustment realizing drive current by changing hardware element, from design and the production aspect of product, movement versatility can be caused to be deteriorated, and increases buying and production material management and control workload.

Therefore, be necessary to consider to adopt alternate manner, element material need not be changed and realize adjusting backlight drive electric current.

As shown in Figure 1,3, wherein U1 is the adjusting gear of backlight drive electric current of the present invention, and dotted line is with upper part for traditional current constant control integrated circuit, and dotted line take lower part as control section newly-increased after adopting the inventive method.Newly-increased control section comprises backlight drive matrix current adjustment circuit, described backlight drive matrix current adjustment circuit comprises PWM comparer, integrating circuit, PWM controller, described integrating circuit one end connection PWM comparer is held in the same way, connectivity port, one end REF, external 1 electric capacity of port REF, electric capacity other end ground connection, it is relevant that size and the sawtooth wave of this electric capacity change slope, adjustment capacitance size, the slope that sawtooth waveform rises is set to 45 °, to ensure that tooth waveform keeps corresponding relation on time and amplitude; Described PWM controller one end connects PWM comparer backward end, connectivity port, one end ISET; The output terminal of PWM comparer is connected to the I/O port of IC interior logic control element.Pwm signal inputs to port ISET, carry out after level translation process through inner PWM controller, transport to PWM comparer backward end, the integrating circuit generation sawtooth signal synchronous with pwm signal is transported to PWM comparer and is held in the same way, after the effect of PWM comparer, the maximal value of sawtooth signal is supplied to the I/O port of IC interior logic control element.By changing the maximal value of the dutycycle adjustment sawtooth signal inputing to the pwm signal of port ISET, and then change backlight drive electric current.

Set the dutycycle of the pwm signal inputing to port ISET as D in the present invention, back facet current numerical value is:

$\mathrm{IE}=\frac{D\×\mathrm{VREF}}{\mathrm{RF}}$

Wherein, VREF arranges fixed reference potential for this IC interior, and this voltage acts on resistance RF, and RF is sample resistance resistance, and D is the pwm signal dutycycle that port ISET inputs.

Finally, the dutycycle completing the pwm signal be carried on port ISET by the software simulating adjustment of MCU completes the work arranged LED-backlit electric current.That is: by the reconfigurable LED-backlit size of current of adjustment software parameter.

Claims (2)

1. the adjusting gear of a backlight drive electric current, comprise current constant control integrated circuit, it is characterized in that: comprise backlight drive matrix current adjustment circuit, described backlight drive matrix current adjustment circuit comprises PWM comparer, integrating circuit, PWM controller, described integrating circuit one end connection PWM comparer is held in the same way, connectivity port, one end REF, external 1 electric capacity of port REF, electric capacity other end ground connection; Described PWM controller one end connects PWM comparer backward end, connectivity port, one end ISET; The output terminal of PWM comparer is connected to the I/O port of IC interior logic control element.

2. the method for adjustment of a backlight drive electric current, it is characterized in that: pwm signal inputs to port ISET, carry out after level translation process through inner PWM controller, transport to PWM comparer backward end, the integrating circuit generation sawtooth signal synchronous with pwm signal is transported to PWM comparer and is held in the same way, after the effect of PWM comparer, the maximal value of sawtooth signal is supplied to the I/O port of IC interior logic control element;

Backlight drive electric current I E numerical value is:

$\mathrm{IE}=\frac{D\×\mathrm{VREF}}{\mathrm{RF}}$

Wherein, VREF is the fixed reference potential that IC interior is arranged, and described fixed reference potential acts on resistance RF, and RF is sample resistance resistance, and D is the dutycycle of the pwm signal that port ISET inputs;

By changing the maximal value of the dutycycle adjustment sawtooth signal inputing to the pwm signal of port ISET, and then change backlight drive electric current.