KR100260908B1 - Ccd device trigger pulse generator for a head scanner apparatus - Google Patents

Abstract

PURPOSE: An apparatus for generating a trigger signal in a scanner device is to prevent a delay due to an interrupt of a central processing unit when an image capture device required trigger signals of the same period is driven using a timer of the central processing unit and a software. CONSTITUTION: A scanner device scans a document by generating trigger signals to an image capture device in a predetermined period. A central processing unit controls the operations of the scanner device and sets up a predetermined period of a trigger signal and the predetermined number of the trigger signal. A periodic trigger signal generation unit(200) receives the period of the trigger signal and generates the trigger signal according to the period. A trigger signal counting unit(260) receives the predetermined number of the trigger signals and controls the number of the trigger signals generated from the periodic trigger signal generation unit. The first register(220) stores temporarily the period of the trigger signals transmitted from the central processing unit. The second register(230) stores temporarily the number of the trigger signals.

Description

Image sensor trigger signal generator of scanner device

The present invention relates to an image pickup device trigger signal generator of a scanner device, and more particularly, to generate a trigger signal of an image pickup device used in a scanner by a simple control of a dedicated generation circuit and a central processing device rather than a general-purpose central processing device. The present invention relates to an image sensor trigger signal generator of a scanner device, thereby increasing the efficiency of the central processing unit software.

Today, products that perform scanning by using a scanning device are widely used. The light sensitivity of the image reading portion of the scanning device is proportional to the illuminance accumulated in the imaging device just before the trigger signal generating the output signal of the imaging device is applied. do.

Therefore, maintaining a uniform amount of illuminance for each trigger signal period in a scanner device that generates an image by generating a trigger signal at regular intervals plays a very important role in obtaining an image of uniform sensitivity.

In addition, even if a constant illuminance is maintained, if the period of the trigger signal is changed, there is a high probability of obtaining an image of non-uniform sensitivity. Therefore, in order to obtain a good image quality, it is most important to apply a trigger signal of the same period to the image pickup device to maintain a uniform illuminance in the effective reading area.

In the prior art, a method of generating a pulse at a predetermined time by measuring a time of a trigger signal of an image pickup device of the scanner device using a timer of a central processing unit (CPU). In other words, the imaging device is driven by using the software of the general-purpose central processing unit.

The biggest problem with this prior art is that in order to generate the trigger signal, many parts of the central processing unit must be used for signal generation. In addition to the generation of trigger signals, the scanner's central processing unit converts analog signals, which are video signals output from the imaging device, into digital signals, shading correction to compensate for uneven lighting conditions, and nonlinear distortion of the imaging device and the optical system. Many kinds of operations are performed, such as a gamma correction operation for correcting, a job for transmitting a read image to a host computer, and a job for controlling the input / output device of the scanner device.

In order to process these various kinds of tasks in a timely manner, a high performance processor is required, which is a price increase factor of the scanner device.

On the other hand, when the trigger signal generation of the same cycle is driven by the timer and software of the central processing unit, the central processing unit has to perform the interrupt and exception processing every cycle, there is a problem that the central processing unit can not be used efficiently.

Accordingly, an object of the present invention is to automatically generate a trigger signal and to perform only a simplified control in the central processing unit in order to overcome the above-mentioned problems of the prior art, so that a scanner having the same function may be used even if a low performing central processing unit is used. To make the functionality possible.

Another object of the present invention is to solve the delay caused by interrupt and exception processing of the central processing unit, which may occur when the image pickup device requiring the trigger signal of the same period is driven by the timer and the software of the central processing unit. have.

1 is a block diagram showing a connection between a trigger signal generator and a main part of a scanner device according to the present invention;

2 shows an image sensor trigger signal generator of a scanner device according to the present invention;

3 is a time chart illustrating a process of reading and writing data to a corresponding device according to an address according to the present invention;

4 is a time chart illustrating an operation process of an image pickup device trigger signal generator of a scanner device according to the present invention.

<Description of Symbols of Major Parts of Drawings>

100: central processing unit 200: trigger signal generator

210: address decoder 220: interval register

230: count register 240: control register

250: periodic trigger signal generator 251: down counter

252: short pulse generator 253: OR gate

254: latch 260: trigger signal counter

261: up counter 262: comparator

263: latch 264: flip-flop

According to the present invention for achieving the above object, in the scanning device for generating a predetermined number of trigger signals to the image pickup device to scan a document, controlling all operations of the scanning device and the constant trigger period value and the constant A central processing unit for setting a trigger count value; A periodic trigger signal generator for receiving the constant trigger period value from the CPU and generating the trigger signal at the predetermined trigger period; An image pickup device trigger signal generator of a scanner device including a trigger signal counter for controlling the number of trigger signals generated by the periodic trigger signal generator is received from the central processing unit.

Preferably, the interworm register for temporarily storing the constant trigger period value transmitted from the central processing unit; The number register for temporarily storing the predetermined number of triggers transmitted from the central processing unit.

Preferably, the periodic trigger signal generation unit, a short pulse generator for receiving the control signal for the presence of the trigger signal generation from the central processing unit to control the trigger signal generation; A down counter which loads the constant trigger period value from the interval register and down counts in synchronization with a system clock according to the control of the show pulse generator; The latch unit is configured to latch an overflow (OVF) signal at the moment when the count of the down counter ends and output a trigger signal.

Optionally, the down counter reloads the constant trigger period value from the interval register by the overflow (OVF) signal.

Preferably, the trigger signal counter unit, the counter for counting the trigger signal generated by the periodic trigger signal generator; A comparator for comparing the constant number value stored in the number register with a value counted by the counter; As a result of the comparison of the comparator, when the trigger signal of the predetermined number is generated, the interlock unit for stopping the trigger signal generation of the periodic trigger signal generator.

Hereinafter, the objects, features, and advantages of the present invention described above will be described in more detail with reference to the preferred embodiments of the present invention shown in the accompanying drawings.

The terms to be described below are terms defined in consideration of functions in the present invention, and may vary according to the intention or custom of a person skilled in the art, and the definitions should be made based on the contents throughout the specification.

Referring to Figure 1, the trigger signal generator according to the present invention is connected to the central processing unit of the scanner device to operate.

First, the CPU 100 transmits values for the image sensor trigger signal period T_S_Interval and the number of trigger signals T_S_Number to the trigger signal generator 200, and the trigger signal generator 200 receives the received image sensor trigger. The trigger signal is generated according to the value of the signal period T_S_Interval and the number of trigger signals T_S_Number to transfer charges for illuminance accumulated in the image pickup device to an image processing apparatus (not shown).

Looking at the trigger signal generator 200 according to the present invention in detail with reference to Figure 2, the central processing unit 100 is the imaging device trigger signal period set in the central processing unit 100 in accordance with the address selection of the address decoder 210 ( T_S_Interval) is transmitted to the interval register 220 for temporary storage, and the number of trigger signals (T_S_Number) set in the CPU 100 is temporarily stored in the number register 230.

On the other hand, the control register 240 receives the control information from the central processing unit 100 and temporarily stores.

In addition, when the START signal is generated according to the control information stored in the control register 240, the periodic trigger signal generator 250 loads the image element trigger signal period (T_S_Interval) value from the interval register 220 and transmits the signal to the system clock signal. The synchronized down counter 251 down counts the loaded trigger signal period T_S_Interval value to generate a trigger signal at the time when the counting value becomes '0', and reloads the trigger signal period T_S_Interval value.

On the other hand, since only the trigger signal of the effective read area is required in the actual scanner device, the trigger signal counter unit 260 controls the number of trigger signals of the effective read area.

To this end, the comparator 262 of the trigger signal counter unit 260 counts the trigger signal generated by the periodic trigger signal generator 250 and compares the number value stored in the number register 230 to generate a desired number of triggers. When the signal is generated, the trigger signal generation of the periodic trigger signal generator 250 is stopped. At this time, the down counter 251 and the up counter 261 are synchronized by the same system clock.

Hereinafter, the operation of the trigger signal generator according to the present invention will be described with reference to the time charts of FIGS. 3 and 4.

First, referring to a process of generating a trigger signal by the periodic trigger signal generator 250, as shown in the time chart of FIG. 3, the trigger signal period (T_S_Interval) value from the central processing unit 100 in the DataTo is registered in the interval register. If the data is recorded at 220, the data is held until the next recording time. In this case, it is assumed that the chip select number of the interval register 220 is '1'. In the illustrated control signal, nIOCS is an I / O chip select signal, nRD is a read signal, and nWR is a write signal.

Subsequently, while applying the trigger signal period (T_S_Interval) value to the data input signal of the down counter 251 of FIG. 2, the down counter 251 is operated by the START signal generated from the CPU 100 and the count is increased. At the moment of termination, the overflow OVF flows into the latch 254 to generate a trigger signal.

Looking at this process in more detail, when the value of the "n-th" bit of the control data transmitted from the central processing unit 100 to the control register 240 is 1, input the START signal to the short pulse generator 252, short The pulse generator 252 generates a short pulse based on the system clock to enable the down counter 251 of the periodic trigger signal generator 250 through an OR gate 253 operation, and the down counter 251. Loads a trigger signal period (T_S_Interval) value from the interval register 220 to perform a down count in synchronization with the system clock.

Next, when the count of the down counter 251 ends, the overflow OVF flows into the latch 254 to generate a trigger signal, and simultaneously transmits an enable signal to the LOAD DATA terminal of the down counter 251. The trigger signal period (T_S_Interval) value is reloaded from the interval register 220.

This process is repeated until the STOP signal, ie, '0', is input from the control register 240 to the short pulse generator 252.

Meanwhile, referring to a process of controlling the number of trigger signals, when the trigger signal number T_S_Number is recorded in the number register 230 from the CPU 100, data is maintained until the next recording time.

As shown in the time chart of FIG. 3, the value of the trigger signal number T_S_Number is read from the number register 230 selected by the address bus and transmitted to the comparator 262. In this case, it is assumed that the chip selection number of the number register 230 is '2'.

Next, the comparator 262 is a count value of the up counter 261 of FIG. 2 synchronized with the system clock (that is, the number of trigger signals generated so far) and the number of trigger signals transmitted from the number register 230 (T_S_Number). ), The trigger generation is stopped by holding the reset of the latch 254 of the periodic trigger signal generator 250 in the same case.

In this case, the latch 263 and the flip-flop 264 of the trigger signal counter 260 are used to interlock with the periodic trigger signal generator 250, and their operations are as shown in the time chart of FIG. 4. .

As described above, according to the present invention, a trigger signal is automatically generated in the image pickup device and only a simplified control can be performed in the central processing unit, thereby realizing a scanner function having the same function even when a low performing central processing unit is used. In addition, there is an effect of resolving the delay caused by the interrupt and exception processing of the central processing unit, which may occur when the imaging device requiring the trigger signal of the same period is driven by the timer and the software of the central processing unit.

Although the preferred embodiments of the present invention have been described in detail above, those skilled in the art will appreciate that the present invention may be modified without departing from the spirit and scope of the invention as defined in the appended claims. It will be appreciated that modifications or variations may be made. Therefore, changes in the future embodiments of the present invention will not be able to escape the technology of the present invention.

Claims (5)

A scanning device for scanning a document by generating a predetermined number of trigger signals at a predetermined period in an image pickup device, A central processing unit controlling all operations of the scanning device and setting the constant trigger period value and the constant trigger number value; A periodic trigger signal generator for receiving the constant trigger period value from the central processing unit and generating the trigger signal at the constant trigger period; And a trigger signal counter unit configured to receive the predetermined number of triggers from the central processing unit and control the number of the trigger signals generated by the periodic trigger signal generator. The method of claim 1, An interworm register temporarily storing the constant trigger period value transmitted from the CPU; And a number register for temporarily storing the constant trigger number value transmitted from the central processing unit. The method of claim 2, wherein the periodic trigger signal generator, A short pulse generator that receives a control signal for whether a trigger signal is generated from the central processing unit and controls the generation of a trigger signal; A down counter which loads the constant trigger period value from the interval register and down counts in synchronization with a system clock according to the control of the show pulse generator; And a latch unit configured to output a trigger signal after latching an overflow (OVF) signal at the moment when the count down of the down counter is completed. The method of claim 3, wherein And the down counter reloads the constant trigger period value from the interval register by the overflow (OVF) signal. The method of claim 2, wherein the trigger signal counter unit, A counter for counting a trigger signal generated by the periodic trigger signal generator; A comparator for comparing the constant number of triggers stored in the number register with a value counted by the counter; And an interlock unit for stopping the generation of the trigger signal of the periodic trigger signal generator when a trigger signal corresponding to the predetermined number of triggers is generated as a result of the comparison of the comparator.

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