CN2401937Y - Image scanning device with DC motor - Google Patents

Abstract

An image scanning device with a DC motor is used to scan an object to be scanned. The image scanning device may include: an optical module, which is used to project an initial optical signal to the object to be scanned and receive a scanned object optical signal generated by the scanned object in response to the initial optical signal; and a DC motor, which is used to cause a relative displacement between the scanned object and the optical module, so that the optical module can perform an action of scanning the scanned object.

Description

Image scanning device with DC motor

The utility model relates to an image scanning device, in particular to an image scanning device with a DC motor which can improve the scanning quality, shorten the scanning time and reduce the production cost by generating a relative displacement between the object to be scanned and the scanning element by the DC motor. scanning device.

At present, when the researchers of the general image scanning device are engaged in the research and development work, they are devoted to how to improve the scanning effect of the image scanning device, shorten the scanning time and reduce the production cost. However, looking at the current image scanning devices on the market, they can be roughly divided into two types: manual type and stepping motor drive mode, and the stepping motor drive mode can be further divided into flat bed type, feeder type, etc. There are several types of paper feed, self-propelled and photo drive (PHD), etc., which are described in detail as follows:

1. By manual traction:

Advantages: the length to be scanned can be determined visually;

Disadvantages: Since the image scanner is operated artificially, it is easy to drop the line (too fast) due to shaking or uncontrollable speed when pulling, which leads to distortion of the scanned image. For example, when scanning a perfect circle Graphics, the scan result may become a vertical flat ellipse; however, if the scrolling is too slow during the scanning process in order to avoid disconnection and ensure the scanning quality, too much time will be wasted.

2. Driven by stepping motor:

Advantages: By using the control of phase change, the number of steps to be rotated can be accurately issued, and the problem of disconnection can be avoided. The technology is relatively simple and mature, so it is still used today and is the current mainstream technology;

Disadvantages: Because of the "stepping", it is intermittent and progressive when turning and walking. Therefore, when each step is started, there will be a period of poor positioning, especially when the high vertical resolution is more serious (see Figure 1 , and explained as follows): If the vertical resolution is higher, the distance △Xi between each scan line will become smaller; at this time, if Xi represents the correct position of the i-th scan line, then X(t )-Xi=Xi _(error) (t); wherein, t in this formula refers to t(i 1)～ts(i); therefore, when the vertical resolution is higher, the distance between every two scanning lines △Xi will become smaller, and the phenomenon of poor positioning: From the formula [Xi _(error) (t)/△Xi], it can be found that the phenomenon of poor positioning becomes more obvious because △Xi becomes smaller.

Therefore, in order to eliminate this phenomenon, a longer time is usually used as a replacement price; if too much time is wasted, the brightness of the light source will change and affect the quality of the scanned image; Larger, and the noise interference and noise caused by the vibration when starting or stopping cannot be ignored.

And by referring to the traditional image scanning device with a stepping motor shown in Figure 1, the position-time relationship diagram of the stepping motor can further understand the defects of the prior art, in which: the horizontal axis represents Time, ti represents the moment when the i-th line is scanned, ts(i) represents the motor steady-state moment when the i-th line can be scanned, and the vertical axis represents the position (and i represents the position when the i-th line is scanned ).

It can be seen from the figure that the scanning time is only: ts(i)~t(i), plus ts(i+1)~t(i+1), ..., plus ts(i+ n)～t(i+n), and the waiting time for the stepper motor to reach a stable position is t(i-1)～ts(i), plus t(i)～ts(i+1),… , plus t(i+n-1)˜ts(i+n), at this time, the scanning operation cannot be performed due to poor line positioning, so too much waiting time is wasted.

For example, assuming that the vertical resolution of the image scanning device is 400dpi, and a 10-inch object to be scanned is equivalent to scanning 400×10=4000 scanning lines, assuming the waiting time t(i-1)～ts (i) is 18ms, and the scanning time ts(i)～t(i) is 2ms, then the real required scanning time is only 2ms×39998 seconds; but the waiting time is 18ms×399972 Seconds, compared with the two, the traditional technology wastes too much time improperly and prolongs the scanning time too much.

The main purpose of the utility model is to provide an image scanning device with a DC motor that improves the scanning quality.

Another object of the present invention is to provide an image scanning device with a DC motor that shortens the scanning time.

Another object of the present utility model is to provide an image scanning device with a DC motor with reduced noise and low vibration.

Another object of the present invention is to provide an image scanning device with a DC motor that reduces production costs.

The utility model is achieved as follows: an image scanning device with a DC motor, wherein the image scanning device may include: an optical module, which is used to project an initial optical signal to the scanned object, and receive the scanned object A scanned object optical signal generated by the object in response to the initial optical signal; and a DC motor, which is used to generate a relative displacement between the scanned object and the optical module, so that the optical module can scan the scanned object the action of the object.

According to the above idea, the image scanning device can be a platform image scanning device, or a sheet-fed image scanning device, or a self-propelled image scanning device, or a tray image scanning device, or it can be A keyboard image scanning device.

According to the above idea, the scanned object can be a transmissive scanned object or a reflective scanned object.

According to the above idea, the optical module may include: a light source, which is used to provide the initial optical signal, and the initial optical signal is projected to the object to be scanned so as to generate the optical signal of the object to be scanned; a mirror group, It is used to change the optical path of the optical signal of the scanned object; a lens group is used to receive the optical signal of the scanned object and change the optical path of the optical signal of the scanned object; and a sensing element is used to receive the optical signal of the scanned object The optical signal of the scanned object is used to convert the scanned optical signal into an electrical signal output; wherein the sensing element can be a charge-coupled device (CCD).

According to the above idea, the optical module can be a CIS (Contact image Sensor).

According to the above idea, the image scanning device further includes a transmission mechanism connected to the DC motor.

According to the above idea, the transmission mechanism can be used to drive the object to be scanned, so that a relative displacement occurs between the object to be scanned and the optical module.

According to the above idea, the transmission mechanism can be used to drive the optical module to cause a relative displacement between the object to be scanned and the optical module.

According to the above idea, the object to be scanned can be regarded as divided into N scanning lines to perform the scanning action, and the length of each scanning line in the N scanning lines of the object to be scanned can be L'( inch), and the vertical resolution of the image scanning device is K dpi, then the length of each scanning line L'=1/K(inch).

According to the above idea, wherein the scan time of scanning each of the N scan lines can be defined as t line, and wherein the scan time t line can include: a scan integration time t int corresponding to the selected length of the actual scan , plus a tolerance time t torr corresponding to the difference between the scan line length L' and the actual scan selection length.

According to the above idea, during the tolerance time t torr, time can be used to perform image processing actions, or perform actions of the test image scanning device, or other required processing actions.

According to the above idea, the average speed of the DC motor during scanning can be defined as Vi(t), at this time the average relative speed between the object to be scanned and the optical module can be vi(t), and the scan time can be shortened by adjusting the scan integration time t int and the scan time t line of each scan line to adapt to the scan width to be scanned; and the scan line length L' can be approximated to the average relative velocity between the scanned object and the optical module vi(t) is multiplied by the scan time t line of each scan line; since K=1/L'=1/[ vi(t)·tline], therefore, by adjusting the average speed of the DC motor Vi(t), or the transmission device (such as a gear set) connected to the DC motor, and then adjust the average relative speed between the scanned object and the optical module vi(t), and adjust the scanning time t line of each scanning line to meet the required vertical resolution K; and by properly adjusting vi(t) and t line, a satisfactory scanning speed can be obtained.

According to the above idea, the method of shortening the scan time by adjusting the scan integration time t int to adapt to the desired scan width can be applied to an image scanning device with a stepping motor, or a manual image scanning device middle.

According to the above idea, the scanning length during the scanning operation can be known by a detection signal generated by a detection device disposed on the image scanning device.

According to the above idea, the detection device can be a roller for driving the object to be scanned, and the scanning length can be obtained by the number of rotations of the roller.

According to the above idea, the scan start time to and the scan end time tf of the image scanning device can be determined by the microcomputer PC, and the scan time of each scan line is t line, and the scan length is equal to [(tf-to) /t line]×L', and calculate the scan length.

According to the above idea, the scanning time t line of each scanning line for a total of N scans can be calculated by the microcomputer PC, and N is equal to the scanning length multiplied by the vertical resolution, and the scanning length is equal to N divided by the vertical resolution .

According to the above idea, the running period of the DC motor can be divided into three stages: initial period (T1), normal period (T2) and pre-stop period (T3).

According to the above idea, a numerical table can be established through experiments, and it can be concluded that when the running speed V _T2 of the DC motor in the normal period (T2) is reached, the distance driven by the DC motor in the initial period (T1) will be determined by The scanned object is placed at a position beyond the distance traveled during the start period (T1), and the signal of the pre-stop period (T3) is issued at an appropriate time to obtain a correct scan image.

According to the above idea, a numerical table can be established through experiments, and the time required for the initial period (T1) to accelerate from speed zero to speed V _T2 when the DC motor operating speed V _T2 is reached in the normal period (T2) can be summarized or distance, and the time or distance required for the pre-stop period (T3) to decelerate from the speed V _T2 to zero speed, so that it can be known that after the scan is completed, the scanned image data of a certain length should be deleted to obtain a correct scan image result.

According to the above idea, a numerical table can be established through experiments, and the operating speed of the DC motor at each time point in the initial period (T1) and the pre-stop period (T3) can be summarized, and the corresponding corresponding values can be given. Scanning the scanning time t line of each line, the image scanning device can obtain correct scanning image data in the initial period (T1), normal period (T2) or pre-stop period (T3).

The image scanning device provided by the above design can provide an image scanning device with a DC motor that improves scanning quality, shortens scanning time, reduces noise and reduces production costs.

Below in conjunction with accompanying drawing and preferred embodiment, structure, feature and effect of the present utility model are described in detail:

FIG. 1 is a position-time relationship diagram of a stepping motor in a conventional image scanning device with a stepping motor.

Fig. 2 is a position-time relationship diagram of a DC motor in a preferred embodiment of the present invention.

Fig. 3 is a schematic diagram of the scanning principle in a preferred embodiment of the present invention.

Fig. 4 and Fig. 5 are respectively circuit diagrams for supplying power to a DC motor in a preferred embodiment of the present invention.

FIG. 6 and FIG. 7 are diagrams showing the timing relationship diagrams of the scan integration time for the desired scan width in a preferred embodiment of the present invention.

At first, referring to Fig. 2, it is the position-time relationship diagram of DC motor in the preferred embodiment of the present utility model, and horizontal axis represents time among the figure (and ti represents the moment when scanning i line), and vertical axis represents position (and i represents the position when scanning the i-th line); among them, the running period of the DC motor can be divided into three stages: the initial period (T1), the normal period (T2) and the pre-stop period (T3). During the period (T2), it can be used to scan a scanned object, and among them, during the two stages of the initial period (T1) and the pre-stop period (T3), although the speed is slow, there will be nonlinear friction and torque, but this brief time is considered negligible compared to the normal scan time (T2).

Please refer to Fig. 3 again, it is the schematic diagram of scanning principle in the preferred embodiment of the present utility model, comprise a scanned object 31 in the figure, a lens group 32, a charge-coupled device 33, and the scanned object 31 includes To scan a first line i, a second line i+1, and a third line i+2, and when scanning each line, w is the scan width, L' is the scan length, and L is Actual scan selection length.

In order to adapt to the length scanned by the image scanning device, a clock pattern is marked on the right side of the scanned object 31, wherein the clock Tim1 is the entire scan time, and each clock cycle tline included is the time for scanning each line. time, which corresponds to the scan length L'; and the clock Tim2 indicates that in the entire scan time, it includes the scan integration time t int (corresponding to the actual scan length L) and the tolerance error time t torr (corresponding to the scan The difference between the length and the actual scanning length: L'-L).

Among them, t line=t int+t torr,

And t int > 0; t torr ≥ 0 is meaningful.

The time t line for scanning each line can be generated by software design or software combined with hardware design; similarly, the scan integration time t int and the tolerance time t torr can also be generated by software design or software combined with hardware design and generated; and during the tolerance time t torr, the time can be used to perform image processing actions, or perform actions of the test image scanning device, or other actions that require processing.

Furthermore, it is assumed that the average speed of the DC motor during scanning is Vi(t), the average relative speed between the scanned object and the optical module at this time is vi(t), and the vertical resolution of the image scanning device is K dpi, then:

The scanning length L’ of each line vi(t) t line;

The scanning length of each line L'=1/K inch;

→K · vi(t)·(t int+t torr)＝1

Therefore, if you want to get a better vertical resolution (K dpi), you can directly control the DC voltage supplied to the DC Motor (DC Motor) in exchange for a better vertical resolution with a smaller motor speed; Or, by shortening the time setting of t line by software or hardware design, better vertical resolution can also be obtained; and by properly adjusting t 1ine and vi(t), more satisfactory scanning speed can be obtained.

Please refer to Fig. 4 and Fig. 5 again, which are circuit diagrams for supplying power to a DC motor in a preferred embodiment of the present invention. In Fig. 4, by controlling the voltage V supplied to the DC motor, the DC motor can be controlled. The rotation speed of the DC motor, and through the output terminals C and C, the forward and reverse rotation of the DC motor can be further controlled.

As for how to control the voltage V supplied to the DC motor, the circuit design shown in Figure 5 can be used to determine the current Ic flowing through the resistor R by controlling bit0~bit5, then: the voltage V supplied to the DC motor =V ^* Ic·R, therefore, the motor speed can be easily controlled to satisfy the vertical resolution of the image scanning device.

And another technical characteristic of the present utility model, then can be learned clearly by referring to shown in Fig. 6, Fig. 7, and wherein, shown in Fig. 6, Fig. 7 respectively is that the present utility model adapts to desired in preferred embodiment Timing diagram of scan integration time for scan width.

In Figure 6, when the required scan width is W1, the scan integration time t int and t line can be changed by software or hardware design, and at the same time, the average between the scanned object and the optical module can be changed. Relative velocity vi(t), so that the scanned image can obtain the required vertical resolution; similarly, in Figure 7, if the required scanning width is W2, the scanning integration time t can also be changed by software or with hardware design int and t line, and change the motor speed at the same time, so that the scanned image can obtain the required vertical resolution.

Because in the utility model, this scan integration time t int can adapt to the required scan width and adjust flexibly, and because this scan integration time t int only needs to be equal to or greater than what is required when the charge-coupled element serially outputs data corresponding to the desired scan width The required time is enough, so the utility model can adjust t int, t line and vi(t), effectively shortens the scanning time; however, in the traditional method, because the scanning integration time t int is fixed, time must be wasted in the scanning process, and then time is wasted in the image data selection process; therefore, this practical Compared with the traditional technology, the new type has a progress that cannot be ignored.

Of course, the above-mentioned technical feature of shortening the scanning time by adjusting the scanning integration time t int and t line to adapt to the desired scanning width should not be limited to the image scanning device with a DC motor of the present invention, and its design concept And the embodiments can also be applied to image scanning devices with stepping motors in the conventional technology, or manual image scanning devices.

And for how to obtain the mode of scanned length with the image scanning device of the present utility model with DC motor, now describe in detail as follows:

First, assuming that the designed vertical resolution is K dpi, the average rotational speed of the DC motor during scanning is Vi(t), and the average relative speed between the scanned object and the optical module is vi(t). The length of each line scanned is L', and the object to be scanned can be divided into N scanning lines, and the total length to be scanned is L"; then: L ^* = (tf to) vi(t)

＝(tf to)·(L’/t line)

＝N/K

Method 1: Determine the scan start time to and the scan end time tf by the microcomputer PC; that is, by controlling the scan start time to and the scan end time tf, and via (tf-to)=L ^* /vi(t )=L ^* ·t line·K is calculated to obtain the desired total scanning length L ^* ; of course, how many scanning lines N have been scanned can be known through conversion.

Method 2: The time t line of scanning each line for N times can be directly calculated by the microcomputer PC, or by cooperating with circuit design and structural design (such as grating, light transmitter-receiver and related structures), the total The time t line of scanning each line for N times is determined, and the total scanning length L ^* of the desired scanning can be obtained by L ^* =N/K→N=L ^* ·K.

Method 3: adapt to the total scanning length L ^* to be scanned, and generate a detection signal at an appropriate position; for example, in a general tray-type image scanning device, it can be known by the contact of the scanned object with the light emitting-receiver Scanning starts, and when the scanned object leaves a light transmitter-receiver, the light transmitter-receiver responds to the detection signal sent by the light source signal received, and knows the end of the scan; or, in the paper-fed image scanning device , the total length L ^* of the scan can be known by the number of turns of the roller that drives the object to be scanned.

Since the running period of the DC motor can be divided into three stages: the initial period (T1), the normal period (T2) and the pre-stop period (T3), therefore, how to choose the scanned image data to obtain the correct scanning result , it can be done by:

Method 1: A numerical table can be established through experiments to sum up the time required for the initial period (T1) when the DC motor operating speed V _T2 in the normal period (T2) is reached, and calculate it in the initial period (T1) , the distance traveled by the DC motor, and then the object to be scanned can be placed at the position after the distance traveled during the initial period (T1), and the signal of the pre-stop period (T3) is issued at an appropriate time , so that the image scanning device can scan the scanned object at the DC motor operating speed V _T2 in the normal period (T2);

Method 2: It is also possible to establish a numerical table through experiments, and conclude that when the DC motor operating speed V _T2 in the normal period (T2) is reached, the time required for the initial period (T1) to accelerate from speed zero to speed V _T2 or distance, and the time or distance required for the pre-stop period (T3) to decelerate from the speed V _T2 to zero speed, so that it can be known that after the scan is completed, the scanned image data of a certain length should be deleted to obtain a correct scan image result;

Method 3: Of course, it is also possible to establish a numerical table through experiments, and conclude that in the initial period (T1) and the pre-stop period (T3), at each time point t ₁₁ , t ₁₂ , t _1n , t ₃₁ , At t ₃₂ ,..., t _3n , when the average rotational speed of the DC motor is Vi(t), and the corresponding average relative speed between the scanned object and the optical module is vi(t), and Give corresponding scanning time t line ₍₁₁₎ , t line ₍₁₂₎ , t line _(1n) , t line ₍₃₁₎ , t line ₍₃₂₎ , t line _{( 3n)} , no matter the image scanning device is in the initial period (T1), normal period (T2) or pre-stop period (T3), the obtained scanned image data is correct.

And the attached table one will be aimed at the preferred embodiment of the image scanning device with a DC motor of the present invention and the traditional image scanning device with a stepping motor, and make a distinction and arrangement of technology and effect: attached table one: Image scanning device with stepping motor Image scanning device with DC motor positioning problem Because of "stepping", there will be a problem of poor positioning, and the effect is more obvious when the vertical resolution is higher; the solution is to trade longer scanning time for scanning quality. The DC motor is continuously driven, and there is no disadvantage of poor positioning, so there is no need for waiting time for the motor to run stably, and the scan time can be greatly shortened. Vertical resolution K The running speed of the stepping motor has nothing to do with the vertical resolution, that is, the vertical resolution cannot be controlled by adjusting the speed of the stepping motor. K·vi(t)·t line=1 Therefore, the average speed Vi(t) of the DC motor can be adjusted, or the transmission device (such as a gear set) connected to the DC motor, and then the scanned object and the optical model can be adjusted. The average relative velocity vi(t) between groups or the time t line to scan each line to satisfy the vertical resolution. scanning speed When limited by the requirement of high vertical resolution, the derived problems must consume too long waiting time, and the scanning speed is obviously slow. K·vi(t)·t line=1 By adjusting vi(t) and t line, the required vertical resolution can be satisfied and the scanning time can be shortened. Cost of production The unit price of stepper motors is higher. The unit price of a DC motor is about 1/2 to 1/3 of that of a stepping motor.

Furthermore, the utility model adjusts the scan integration time t int and the time t line of scanning each line to adapt to the desired scan width and shorten the scan time. It should not be limited to the utility model having a DC motor In the image scanning device, its design concept and implementation method can also be applied to the image scanning device with stepping motor in the traditional technology, or in the manual image scanning device; and the utility model can avoid the problem of poor positioning and reduce unnecessary waste of time, speed up the scanning speed, and can achieve extremely high vertical resolution; the utility model uses a direct current motor drive method and a traditional stepping motor drive method. Compared with the two, the utility model can greatly reduce the Possible signal noise interference and noise problems.

In summary, the utility model discloses an image scanning device with a DC motor that is different from and superior to the traditional technology, which can not only improve the scanning quality, but also greatly shorten the scanning time, and has low vibration and low noise Efficacy, and can reduce production costs, a breakthrough in technology, is an invention with industrial value.

Claims (31)

1. An image scanning device with a DC motor, wherein the image scanning device may include: an optical module, which is used to project an initial optical signal to the object to be scanned, and receive a response from the object to be scanned An optical signal of the scanned object generated by the initial optical signal; and a DC motor, which is used to cause a relative displacement between the scanned object and the optical module, so that the optical module can scan the scanned object action. 2. The image scanning device with a DC motor as claimed in claim 1, wherein the image scanning device is a flatbed image scanning device. 3. The image scanning device with a DC motor as claimed in claim 1, wherein the image scanning device is a paper-fed image scanning device. 4. The image scanning device with a DC motor as claimed in claim 1, wherein the image scanning device is a self-propelled image scanning device. 5. The image scanning device with a DC motor as claimed in claim 1, wherein the image scanning device is a tray type image scanning device. 6. The image scanning device with a DC motor as claimed in claim 1, wherein the image scanning device is a keyboard type image scanning device. 7. The image scanning device with a DC motor as claimed in claim 1, wherein the object to be scanned can be a transmissive object to be scanned. 8. The image scanning device with a DC motor as claimed in claim 1, wherein the object to be scanned is a reflective object to be scanned. 9. The image scanning device with a DC motor as claimed in claim 1, wherein the optical module includes: a light source for providing the initial optical signal, and the initial optical signal is projected to the A scanning object, so as to generate the optical signal of the scanned object; a mirror group, which is used to change the optical path of the optical signal of the scanned object; a lens group, which is used to receive the optical signal of the scanned object, and change the scanned object an optical path of the object optical signal; and an inductive element for receiving the scanned object optical signal so as to convert the scanned optical signal into an electrical signal for output. 10. The image scanning device with a DC motor as claimed in claim 9, wherein the inductive element is a charge-coupled element. 11. The image scanning device with a DC motor as claimed in claim 1, wherein the optical module is a contact image sensor. 12. The image scanning device with a DC motor as claimed in claim 1, further comprising a transmission mechanism connected to the DC motor. 13. The image scanning device with a DC motor as claimed in claim 12, wherein the transmission mechanism can be used to drive the object to be scanned, so that the object to be scanned and the optical module produce a relative displacement. 14. The image scanning device with a DC motor as claimed in claim 12, wherein the transmission mechanism can be used to drive the optical module to cause a relative displacement between the object to be scanned and the optical module. 15. The image scanning device with a DC motor as claimed in claim 1, wherein the object to be scanned can be regarded as being divided into N scanning lines for performing the scanning action. 16. The image scanning device with a DC motor as claimed in claim 15, wherein the length of each of the N scanning lines of the scanned object can be L' (inch), and the image The vertical resolution of the scanning device is K dpi, and the length of each scanning line L'=1/K(inch). 17. The image scanning device with a DC motor as claimed in claim 16, wherein the scanning time for scanning each of the N scanning lines can be defined as tline, and the scanning time tline can be defined as Including: the scan integration time t int corresponding to the actual scan selection length, plus the tolerance error time t torr corresponding to the difference between the scan line length L' and the actual scan selection length. 18. The image scanning device with a DC motor as claimed in claim 17, wherein during the tolerance time t torr, time can be used to perform image processing actions or to perform test image scanning device actions, or other actions that need to be processed. 19. The image scanning device with a DC motor as claimed in claim 17, wherein the average rotational speed of the DC motor during scanning can be defined as Vi(t), at this time the average relative speed between the object to be scanned and the optical module can be vi(t). 20. The image scanning device with a DC motor as claimed in claim 19, wherein the scanning line length L' can be approximated to the average relative speed between the scanned object and the optical module vi(t) is multiplied by the scan time t line of each scan line. 21. The image scanning device with a DC motor as claimed in claim 20, wherein K=1/L'=1/[ vi(t)·t line], by adjusting the average speed of the DC motor Vi(t), and then adjust the average relative speed between the scanned object and the optical module vi(t) and the scan time t line of each scan line to meet the required vertical resolution K. 22. The image scanning device with a DC motor as claimed in claim 17, wherein the scanning integration time t int and the scanning time tline of each scanning line can be adjusted to adapt to the desired scanning width , thereby shortening the scan time. 23. The image scanning device with a DC motor as claimed in claim 1, wherein the method of shortening the scan time by adjusting the scan integration time t int to adapt to the scan width can be applied to An image scanning device with a stepping motor, or a manual image scanning device. 24. The image scanning device with a DC motor as claimed in claim 1, wherein the scanning length of the scanning action can be determined by a detection signal generated by a detection device provided on the image scanning device and learned. 25. The image scanning device with a DC motor as claimed in claim 24, wherein the detection device can be a roller for driving the object to be scanned, and by the number of rotations of the roller, it can Know the scan length. 26. The image scanning device with a DC motor as claimed in claim 1, wherein the scanning start time to and the scanning end time tf of the image scanning device can be determined by a microcomputer PC, and the time of each scanning line The scan time is t line, and the scan length is obtained by calculating the scan length equal to [(tf to)/t line]×L'. 27. The image scanning device with a DC motor as claimed in claim 1, wherein the scanning time tline of each scanning line for a total of N scans can be calculated by a microcomputer PC, and N is equal to the scanning length multiplied by The vertical resolution, and the derived scan length is equal to N divided by the vertical resolution. 28. The image scanning device with a DC motor as claimed in claim 1, characterized in that: the running period of the DC motor can be divided into three stages: initial period (T1), normal period (T2) and pre-stop period (T3). stage. 29. The image scanning device with a DC motor as claimed in claim 28, characterized in that: a numerical table can be established through experiments, and it can be concluded that when the DC motor operating speed V _T2 in the normal period (T2) is reached, the starting point The distance traveled by the DC motor in the initial period (T1), and the scanned object is placed at a position after the distance traveled during the initial period (T1), and the signal of the pre-stop period (T3) is issued at an appropriate time , the correct scanned image can be obtained. 30. The image scanning device with a DC motor as claimed in claim 28, characterized in that: a numerical table can be established through experiments, and it can be concluded that when the DC motor operating speed V _T2 in the normal period (T2) is reached, the starting point The time or distance required for the initial period (T1) to accelerate from speed zero to speed V _T2 , and the time or distance required for the pre-stop period (T3) to decelerate from speed V _T2 to speed zero, so that it can be known during scanning After the end, several lengths of scanned image data should be deleted to obtain correct scanned image results. 31. The image scanning device with a DC motor as claimed in claim 28, characterized in that: a numerical table can be established through experiments, and it can be concluded that in the initial period (T1) and the pre-stop period (T3) stages, in each At this point in time, the average speed of the DC motor vi(t), the average relative speed between the scanned object and the optical module at this time vi(t), and given the corresponding scanning time t ine of each line, the image scanning device can obtain correct scanned image data.

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