CN100482472C - Methods and apparatus for driving illuminators in printing applications - Google Patents

Abstract

One embodiment disclosed relates to a method (300) of providing drive signals to an illuminator module (330) having a plurality of channels in a printing application. Binary image data comprising image bits is provided (352) from a data source (202) to the illuminator module. Each image bit is converted (354) to a multi-bit amplitude value within the illuminator module, wherein the conversion of each image bit to the multi-bit amplitude value depends at least on a value of the image bit and which channel is associated with the image bit. Pulse width modulation (PWM) may be applied to the drive signals using programmable transition delays. Apparatus for performing the aforementioned method are also disclosed.

Description

Be used to drive the method and apparatus and the print system of illuminator module

Inventor: David T.Amm, Douglas A.Webb and Gregory A Myatt

The cross reference of related application

It number is that 60/506,492 exercise question is the rights and interests of " Methods and Apparatus for Driving Light Modulators for PrintingApplications " that the present invention has required U.S. Provisional Patent Application that inventor David T.Amm, Douglas A.Webb and GregoryA.Myatt submit on September 26th, 2003.Introduce for your guidance in this disclosure U.S. Provisional Patent Application number 60/506,492.

Technical field

Present invention relates in general to luminaire, comprise optical modulator, and especially rather than only relate to the method and apparatus that is used for using the driving luminaire in printing.

Background technology

Using the optical modulator of Micro Electro Mechanical System (micro electromechanical system MEMS) technology manufacturing is known in general.The example of this optical modulator comprises the Grating LightValve that can obtain from the Silicon Light Machines company of the Sani Wei Er in California ^TM(GLV ^TM) optical modulator.With GLV ^TMBe called as " ribbon light modulator (ribbon light modulator) " below the equipment of optical modulator same type.Described ribbon light modulator in the following discloses content, it is incorporated into this provisional application and for example can be at people's such as Bloom U.S. Patent number 5,311,360, people's such as people's such as Bloom U.S. Patent number 5,841,579 and Bornstein U.S. Patent number 5, find in 661,592.Introduce for your guidance in this disclosure above-mentioned patent.

Can in the various application that comprise optical-fiber network, video and printing, use ribbon light modulator.Should be appreciated that for concrete optimizing application optical modulator be useful.

Ribbon light modulator has been used for printing and has used.In a printing was used, laser beam was rebounded by the reflecting surface from ribbon light modulator and reflexes on the forme (plate).Laser beam has the power level that is enough to make described forme exposure when focusing on.The excitation ribbon light modulator is so that modulating lasering beam and form pattern on described forme.Described forme rolls by inking and on paper so that above pattern transfer arrived.Xcalibur45 from Agfa company ^TMPrint direct platemaking machine (platesetter) and just use this ribbon light modulator.At U.S. Patent number 6,229, the use of ribbon light modulator in printing is used also disclosed in 650.

Summary of the invention

One embodiment of the present of invention relate to a kind of method that is used for providing to the illuminator module with a plurality of channels in the printing application driving signal.The binary picture data that comprises image bit is provided to illuminator module from data source.Each image bit is converted into the multidigit range value in illuminator module, and wherein each image bit depends on the value of image bit at least and which channel is associated with described image bit to the conversion of multidigit range value.Can use programmable transformation delay that pulse width modulated (Pulse width modulation PWM) is applied to the driving signal.

Another embodiment relates to a kind of equipment that is used for driving in the printing application illuminator array with a plurality of channels.Driver IC is configured to receive binary picture data, and provides storage device in described driver IC, is used at least two multidigit range values of each channel storage.The selection circuit of each channel is configured to select one of multidigit range value according to the value of image bit at least.Driver IC can be configured to provide pulse-width-modulated mode, and described pulse-width-modulated mode is applied to the pulse width modulated and drives signal and use independently PWM clock.

Comprise whole disclosures of accompanying drawing and claim when reading after, those of ordinary skills will know these and other feature of the present invention.

Description of drawings

Fig. 1 shows the exemplary output characteristics that is used for ribbon light modulator pixel and may be by the typical operation point of calibrating to determine.

Fig. 2 A schematically shows the example architecture that is used to drive light modulator arrays.

Fig. 2 B is the flow chart of describing to be used to utilize at the driving method of the architecture shown in Fig. 2 A.

Fig. 3 A schematically shows the architecture that is used to drive light modulator arrays according to the embodiment of the invention.

Fig. 3 B describes to be used to utilize flow chart at the driving method of the architecture shown in Fig. 3 A according to the embodiment of the invention.

Fig. 4 schematically shows the digital printed value of can what use is made of being stored in the driver ASIC of module according to the embodiment of the invention.

Fig. 5 shows example print patterns.

Fig. 6 has schematically illustrated the possible method that is used to realize the PWM function.

Fig. 7 has schematically illustrated possible use to the 3rd range value according to the embodiment of the invention.

Fig. 8 shows the functional block diagram of driver ASIC in an implementation according to the embodiment of the invention.

Fig. 9 shows the functional block diagram of driver ASIC in another implementation according to the embodiment of the invention.

In different accompanying drawings, use identical Reference numeral to show same or similar assembly.

The specific embodiment

In this disclosure, provide many details such as the example of equipment, assembly and method so that thorough understanding of embodiments of the invention is provided.Yet those of ordinary skills will be appreciated that and can implement the present invention under the situation of neither one or a plurality of details.In other example, do not illustrate or describe known details to avoid making each side of the present invention become unclear.

Use ribbon light modulator to describe embodiments of the invention as an example.Yet should be appreciated that the present invention is not limited thereto, and can be used for other application usually, be included in the various printings application and use other type light modulator.In addition, another embodiment is included in employed direct light transmitter in the printing application, such as laser instrument, VCSEL and light emitting diode (lightemitting diodes LED).Here optical modulator and optical transmitting set are known as " luminaire " together.In addition, for present disclosure, term " printing is used " comprises the paper seal, is used for the forme printing and the lithography applications of CTP (computer-to-plate application CTP).

Be used for digital printed range value

For digital printed application, only require two values for each ribbon light modulator pixel.In ideal conditions, those values that are used for 10 systems may be 0 and 1023.Yet may need printing (output) light intensity all is very uniform on whole ribbon light modulator array.Can obtain compensation by calibration process to inhomogeneities in optical device, electronic equipment and ribbon light modulator array itself, distribute 10 unique place values for ON and OFF state to each pixel whereby, so that the output of the light intensity of each pixel is identical.This is called as each pixel " amplitude " data.Fig. 1 shows the output characteristics of ribbon light modulator pixel, and typical operating point, and described operating point can be determined by calibration, and is confirmed as example.Go out as shown, ON or ' 1 ' value are in the position level that is slightly larger than minimum 0 value, and OFF or ' 0 ' value are in the position level that is slightly less than maximum 1023 values.

So the amplitude calibration data comprise two 10 place values for each pixel (or " channel ").Especially should be noted that needn't change these values usually up to the calibration that will look for novelty, this may be from a few minutes to a couple of days or a few weeks longer.

The architecture that needs high bandwidth from data source

Fig. 2 A schematically shows the example architecture 200 that is used to drive light modulator arrays 234.Light modulator board or module 230 comprise driver special IC (ASIC) 232 and driven light modulator arrays 234.In the example of Fig. 2 A, light modulator arrays 234 comprises GLV ^TMLight modulator arrays.

In the example of Fig. 2 A, carry out calibration 204 at input data source " upstream ", described data input is known as " view data " 202.In this architecture 200, send 210 data volume increases when calibration information is provided basically to driver module 230, makes thus to complicate in driver module 230 performed processing.For example, calibration data may comprise 10 for each image bit, therefore can multiply by coefficient 10 to view data.In other implementation, calibration data may comprise other number position for each image bit.

Fig. 2 B is the flow chart of describing to utilize at the driving method 250 of the architecture shown in Fig. 2 A.According to the method 250, receive 252 view data at the calibration module or the parts of data source.This calibration module is searched 254 range values for each position (in other words, for each image bit) in the view data.The range value that is obtained depends on the value of image bit and the channel that is associated (i.e. the light modulator devices that is associated) in array 234.

These range values (range value of each image bit) are sent 256 to light modulator board or module 230 from data source.For example, if range value is 10 place values, so for each image bit, these 10 are sent out 256.In other implementation, range value can have other number position.

At optical modulator module 230, carry out the digital-to-analogue conversion of 258 range values.Use the analog signal that is produced to drive 260 light modulator devices.

Require the architecture of less bandwidth from data source

Fig. 3 A schematically shows the architecture 300 that is used to drive light modulator arrays according to the embodiment of the invention.In the architecture 300 of Fig. 3 A, carry out calibration (replacing as shown in the architecture 200 of Fig. 2 A, outside data source is plate, carrying out) among the driver ASIC 332 on light modulator board or module 300.Preferably, after carrying out any data compression/decompression algorithms, carry out calibration.This makes the data input quantity that will be provided to module 330 minimize valuably, and the data of having simplified in module 330 are handled.

According to an embodiment, view data is provided 310 from image data source 202 to the driver ASIC of optical modulator module 330 332 serials according to ground of each image bit.The digital printed value 333 of each can be stored locally on the driver ASIC332 in the optical modulator module 330, perhaps can be stored on the outer chip of described driver ASIC 332.Digital printed value comprises the pulse width modulation (PWM) of driving signal of each light modulator devices that is used to show light modulator arrays 234 and the data of range value.Digital printed value is converted into analog drive signal, and it is provided for corresponding optical modulator.Be appreciated that valuably to be that the architecture 300 of Fig. 3 A also do not require from image source 202 and carry out high-speed data transfer to optical modulator module 330, and can (via cable) pass on carrying out simpler data between the module and in module.Be that the architecture 300 of Fig. 3 A can also be passed on more multidata for given communication bandwidth valuably.

Fig. 3 B is the flow chart of describing to utilize at the driving method of the architecture shown in Fig. 3 A.According to the method 350, view data (not being amplitude data) is sent 352 to light modulator board or module 330 from image data source 202.This has reduced desired bandwidth between data source 202 and optical modulator module 330 valuably.

In the driver ASIC 332 of optical modulator module 330, image bit is converted 354 and is range value.For example, can use 10 range values.Carry out conversion with respect to the described circuit of Fig. 4 below for example can using.

Certainly, also in driver ASIC 332, carry out the digital-to-analogue conversion of 258 range values, and use the analog signal that is produced to drive the light modulator devices of 260 arrays 234.

Select digital printed value by driver ASIC

Fig. 4 schematically shows the digital printed value (being range value) that can use the circuit according to the embodiment of the invention to come what use is made of to be stored in the driver ASIC 332 of optical modulator module 330.In the example of Fig. 4, memory register 402 is for each channel (being each light modulator devices in the array 234) storage 10 ON/OFF (on/off) range value in the chip.The position 405 of depending on view data is to select 10 digital printed values of ON or 10 digital printed values of OFF at logical one or at logical zero cause multiplexer 404, for output.Digital to analog converter (digital to analog converter DAC) 406 is converted to the simulate press value to selected digital printed value, and described then simulate press value is used as high pressure simulation signal 408 and offers the optical modulator that is associated.

Can utilize in the pulse width of about 5 μ s (5 microsecond) and come function driver ASIC 332.In one embodiment,---per 5 μ s---are loaded into whole calibration data among the driver ASIC 332 to utilize each burst length.10 x 272 channels that produced require very wide and data/address bus at a high speed.These data rates become for high speed operation more and have more challenge, for example near 2 μ s pulse widths.In another embodiment, for data rate being minimized and the permissible velocity increase, driver ASIC 332 can be stored in calibration data in the chip itself.After calibration, only need single 1 place value to show the ON/OFF state of drive channel.This can make overall data rates reduce about 10 times, and will allow to use shorter pulse and/or simpler data/address bus.

Pulse width modulation data values

For digital printed, ribbon light modulator is switched between two states (" ON " and " OFF ") so that print the binary pattern of picture in the simple checkerboard shown in Fig. 5.Fig. 5 (a) shows simply, even checkerboard pattern.For a given pixel of when row chien shih is ON, and is OFF for the next one.This example produces the pattern of 50% gray level on big zone.

Some application needs " ON " state by changing given pixel duration---this is known as pulse width modulation or PWM, change effective duty cycle.Fig. 5 (b) and 5 (c) illustrate the trailing edge of change " ON " pulse so that form 75% " ON " respectively and the effect of 25% " ON " greyscale pattern.In example illustrated in fig. 5, all pixels in each example all have identical " ON " pulse width.In Fig. 5 (b), the ON pulse is lengthened to 1.5 times of pulse among Fig. 5 (a) so that produce 75% greyscale pattern.In Fig. 5 (c), the ON pulse is shortened 0.5 times of pulse among Fig. 5 (a) so that produce 25% greyscale pattern.In practice, owing to run through system by the inhomogeneities that Several Factors caused, thereby cause may needing to change independently the pulse width of each pixel.Fig. 6 shows several extreme example and illustrates some possible methods that are used to realize this PWM function.

Fig. 6 shows five pixels or the channel in the ribbon light modulator array of the pulse width with variation.Pixel 1,3 and 5 has the pulse width that is suitable for 50% greyscale pattern, and pixel 2 is set to 75% gray scale, and pixel 4 is in 25% gray scale.Fig. 6 illustrates the distinct methods of the pulse width that is used for application change.In Fig. 6 (a), the trailing edge of modulation " ON " pulse.In Fig. 6 (b), modulate the rising edge of described pulse.And in Fig. 6 (c), on the rising and falling edges of " ON " pulse, modulate described pulse symmetrically.

Four kinds of possible timings (timing) schemes of having applied for artificial pulse width modulation design:

(i) rising (preceding) edge of change " ON " pulse;

(ii) change decline (back) edge of " ON " pulse;

(iii) changing two edges comparably changes with the duty cycle that produces symmetry; With

(iv) change two edges, to each along adopting different values at random to form any output of wanting.

In one embodiment, driver ASIC is designed to realize above-mentioned the 4th kind of scheme---promptly change two edges independently with precision up to 8.Except that variable pulse width, this scheme also allows to change pixel regularly with respect to neighbor, keeps constant pulse width simultaneously.

Can during calibration process, determine the data value of PWM according to the similar mode that is used for previously described amplitude data values.Driver ASIC can use arbitrarily that (type iv) scheme comes each edge for each channel to modulate the rising and falling edges of ON pulse up to 8 precision.

Applies amplitude and PWM data

By amplitude and PWM calibration data are stored in driver ASIC originally on one's body, come reproduced image by sending binary system (1 or 0) pattern to optical modulator module 330 (referring to Fig. 3) simply.The value of view data will determine to use which range value (ON or OFF).

Optical modulator module 330 can also be configured to storage " current " and " next one " view data pixel value so that the transformation of prediction from ON to OFF or from OFF to ON.Use " transformation type " to select PWM data value and amplitude data values then.For example, suppose three PWM data values are arranged, if the view data pixel is converted to ON from OFF, can select a PWM data value so, if the view data pixel is converted to OFF from ON, can select the 2nd PWM data value so, and if the view data pixel change (for example from OFF to ON then to ON) with specific 3 bit patterns, can select the 3rd PWM data value so.

The 3rd or more a plurality of amplitude level

In order to provide maximum flexibility to driver ASIC, described driver ASIC can be designed to have two-stage above amplitude and length of delay.Illustrate the example of the 3rd range value in Fig. 7, wherein the 3rd range value comprises second " ON " value.Can use this 3rd amplitude level with respect to the timing of the rising edge of data-signal.Similarly, can provide the 4th amplitude level and use it with respect to the timing of the trailing edge of data-signal.The rising and falling edges (for example adding more amplitude step) that extra level outside four can be used to further control signal maybe can be used to come the described signal of modulation in predetermined pattern in response to the binary picture data sequence of being discerned.

Specific implementation

Figure 8 illustrates functional block diagram according to the selection circuit among the driver ASIC of specific implementation.As drawn, described circuit comprises global logic and pixel channels (showing a pixel channels).Global logic comprises PWM interface and data-interface and various counter and register.Data and address bus provides the communication from global logic to each pixel channels.

Described specific implementation provides the independently PWM pattern of PWM clock of using.In the PWM pattern, for digital printed application, utilize single bit image data switch 10 range values of storage inside (Amp1, Amp2, Amp3).Can change on the edge in data by programmable delay and realize pulse width modulation.Provide three transformation able to programme edges to postpone (postpone 1, postpone 2, postpone 3), each postpones up to 8 precision.

Other pattern that comprises video mode and test pattern also is provided in this specific implementation.In video mode, adopt 10 bit data bus at a high speed, and forbid PWM.In test pattern, simulation output is multiplexed to test lead.

Figure 9 illustrates another implementation of circuit among the driver ASIC.Slightly revise by comparison but the circuit of this implementation and Fig. 8 is similar.

Though above argumentation is in the background of optical modulator module, alternate embodiment described circuit application in direct light emitter module.In this direct light emitter module, light modulator arrays can be replaced by the direct light transmitter array.In other words, embodiments of the invention more relate to illuminator module generally, and wherein illuminator module can be optical modulator module or direct light emitter module.

Though specific embodiments of the invention are provided, be to be understood that these embodiment only to be used to illustrate purpose and and unrestricted.The those of ordinary skills that read this disclosure can draw many additional embodiments.

Claims (24)

1. one kind is used for using the method that the driving signal is provided to the illuminator module with a plurality of channels in printing, and described method comprises:

The binary picture data that comprises image bit is provided to illuminator module from data source; And

In described illuminator module, each image bit is converted to the range value with a plurality of,

Wherein the conversion that each image bit is converted to the range value with a plurality of is depended on the value of described image bit at least and which channel is associated with described image bit.

2. the method for claim 1, wherein the driver IC in described illuminator module provides binary picture data, and carries out in described driver IC each image bit is converted to the range value with a plurality of.

3. method as claimed in claim 2 wherein provides two range values with a plurality of for each channel.

4. method as claimed in claim 2 wherein provides three or more the range values with a plurality of for each channel.

5. the method for claim 1 also comprises:

The pulse width modulated is applied to described driving signal.

6. method as claimed in claim 5 wherein uses programmable transformation edge to postpone to apply pulse width modulation.

7. method as claimed in claim 6, wherein rising and falling edges all is programmable.

8. the method for claim 1 is wherein printed application and is comprised the paper printing.

9. the method for claim 1 is wherein printed application and is comprised lithographic printing.

10. the method for claim 1, wherein said printing are used and are comprised and be used for the forme that CTP is used.

11. the method for claim 1 wherein drives light modulator arrays by the driving signal that described illuminator module produced.

12. the method for claim 1 wherein drives the direct light transmitter array by the driving signal that described illuminator module produced.

13. one kind is used for using the equipment that drives the illuminator module with a plurality of channels in printing, described equipment comprises:

Driver IC is configured to receive binary picture data;

Storage device is used for being at least two range values with a plurality of of each channel storage in described driver IC; With

The selection circuit that is used for each channel is configured to select to have one of range value of a plurality of according to the value of image bit at least.

14. equipment as claimed in claim 13, wherein said selection circuit comprises multiplexer, and the output of multiplexer is determined by the value of described image bit.

15. equipment as claimed in claim 13, wherein said driver IC are configured to three or more range values with a plurality of of each channel storage.

16. equipment as claimed in claim 13, wherein said driver IC is configured to provide pulse-width-modulated mode, and described pulse-width-modulated mode is applied to the pulse width modulated and drives signal and use independently pulse width modulation clock.

17. equipment as claimed in claim 16 wherein in pulse-width-modulated mode, is realized pulse width modulation by programmable delay on data transformation edge.

18. equipment as claimed in claim 17, wherein rising and falling edges all is programmable.

19. equipment as claimed in claim 16, wherein said driver IC also is configured to have the video mode of inhibit pulse width modulated.

20. equipment as claimed in claim 13, wherein said driver IC is configured to have the pixel channels circuit and the global logic circuit of each channel of illuminator module, and wherein data and address bus provides the communication of the pixel channels circuit from the global logic circuit to each channel.

The application in one group of application that 21. equipment as claimed in claim 13, wherein said printing application come free paper printing, lithographic printing and CTP to use to be constituted.

22. equipment as claimed in claim 13, wherein said illuminator module comprises optical modulator module.

23. equipment as claimed in claim 13, wherein said illuminator module comprises direct light emitter module.

24. a print system wherein provides the driving signal to the illuminator module with a plurality of channels, described print system comprises:

Be used for comprising that the binary picture data of image bit is provided to the device of illuminator module from data source; With

Be used in described illuminator module, each image bit being converted to the device of range value with a plurality of,

Wherein the conversion that each image bit is converted to the range value with a plurality of is depended on the value of described image bit at least and which channel is associated with described image bit.

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