JP2005176110A - Image scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize various control of a light source even without providing a signal line at each object to be controlled. <P>SOLUTION: In an image scanner, a controller 1 generates a light source control signal S1, and outputs this light source control signal S1 to a light source driver 3. The light source driver 3 generates a drive signal S3 for driving a light source 2 when this light source control signalS1 is inputted, and does not generate the drive signal S3 when the light source control signal S1 is not inputted. The light source driver 3 restarts the generation of the drive signal S3 when the light source control signal S1 is inputted during a period of generating the drive signal S3. The light source driver 3 generates the drive signal S3 so as to lower the illuminance of the light source 3 when the frequency of the light source control signal S1 is high, and generates the drive signal S3 to lower the illuminance when the frequency is low. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus that optically reads a document.

For example, in an image reading apparatus that optically reads an original such as a copying machine or an image scanner, reflected light from the original obtained by an illumination lamp is converted into an electrical signal by a solid-state imaging device such as a CCD (Charge Coupled Device). Thus, the original is read.
Normally, in this type of image reading apparatus, an illumination lamp is driven by controlling an inverter circuit. However, in recent years, in order to improve image quality when reading a document, not only the illumination lamp is turned on / off. The cycle of turning on / off the lamp is controlled (for example, see Patent Document 1), or the illuminance of the lamp is controlled (for example, see Patent Document 2).
JP 2000-4332 A Japanese Patent Laid-Open No. 9-252383

  By the way, when the number of objects to be controlled increases in order to improve the image quality, the number of signals for controlling the inverter circuit increases accordingly. When the number of signals increases in this way, it is necessary to provide a circuit pattern for each signal, resulting in a problem that the substrate size increases and the manufacturing cost increases.

  The present invention has been made under the background described above, and an object of the present invention is to provide a technique that enables various control of a light source without providing a signal line for each control target.

In order to solve the above-described problems, the present invention provides a light source that irradiates light on a document, a control unit that outputs a control signal having a predetermined cycle, a cycle switching unit that switches a cycle of the control signal, and the control signal. Is input, and the light source control means for starting the lighting of the light source and controlling the illuminance of the light source based on the period of the control signal, and the reflection from the document caused by the light irradiation from the light source. An image reading apparatus having reading means for converting light into an electric signal and reading the image is provided.
In this image reading apparatus, the light source control means for controlling the light source starts lighting the light source in response to the input of the control signal and controls the illuminance of the light source based on the cycle of the control signal. Since the light source can be turned on and the illuminance of the light source can be controlled with one control signal, the area of the circuit pattern is reduced and the substrate size is reduced, thereby making it possible to reduce the manufacturing cost.
Further, the present invention provides a light source for irradiating light on a document, a lighting control signal for lighting the light source, a control means for outputting a control signal having a predetermined period, and a period switching means for switching the period of the control signal. When the lighting control signal is input, the lighting of the light source is started, and when the control signal is input, the illuminance of the light source and the lighting timing of the light source are controlled based on the cycle of the control signal. There is provided an image reading apparatus comprising: a light source control means for reading; and a reading means for converting reflected light from the original generated by irradiation of light from the light source into an electric signal for reading.
In this image reading apparatus, the light source control means for controlling the light source starts lighting the light source in response to the input of the lighting control signal, and determines the illuminance of the light source and the lighting timing of the light source based on the period of the control signal. Control. Since the illuminance and lighting timing of the light source can be controlled with a single control signal, the area of the circuit pattern can be reduced, the substrate size can be reduced, and the manufacturing cost can be reduced.

  According to the present invention, various controls of the light source can be performed without providing a signal line for each control target.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[A. First Embodiment]
FIG. 1 is a schematic diagram of an image reading apparatus according to the present embodiment. The image reading apparatus conveys the document 12 placed on the document tray 11 to the reading position 15 on the platen glass 4 one by one by rotating the feed roller 13 on the conveyance path 14 of the document conveying unit 10. To do. The image reading apparatus irradiates the original 12 conveyed to the reading position 15 with light emitted from the light source 2 that is, for example, a fluorescent lamp, and guides the light reflected by the original 12 to the lens 6 by the mirrors 5A to 5C. The image of the document 12 is formed by the lens 6 and read by the photoelectric conversion element 7A included in the image reading unit 7. When the reading is completed, the image reading apparatus moves the document 12 to the document discharge tray 16 using the feed roller 13.

  FIG. 2 is a block diagram showing a hardware configuration of a main part related to image reading in the image reading apparatus. The operation unit 17 has a plurality of keys for operating the image reading apparatus. The operation unit 17 is a key that outputs an instruction to read the document 12 in black and white to the control unit 1 when pressed, and a key that outputs an instruction to read the document 12 in color to the control unit 1 when pressed. And has.

  The control unit 1 controls each unit of the image reading apparatus, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. When the power is turned on, the CPU reads a control program from the ROM, starts up the RAM as a work area, and controls each unit of the image reading apparatus.

  When an instruction to read the document 12 in color or black and white is input from the operation unit 17 after the control program is started, the control unit 1 generates a light source control signal S1 and a reading control signal S2. The reading control signal S <b> 2 is a signal for controlling the timing at which the photoelectric conversion element 7 </ b> A reads an image formed by the lens 6, and is output to the image reading unit 7. The reading control signal S2 is a pulse as shown in FIG. 3, and becomes H level during the reading period in the main scanning direction of the image reading unit 7. The light source control signal S <b> 1 is a signal for controlling on / off of the light source 2, illuminance of the light source 2, lighting timing of the light source 2, and the like, and is output to the light source driving unit 3. The light source control signal S1 is a pulse as shown in FIG. 3 and has a pulse width of 2 to 4 μsec. The repetition cycle of the light source control signal S1 is 10 [kHz] when an instruction to read a document in black and white is input from the operation unit 17, and is 5 [kHz] when an instruction to read in color is input. Become. As shown in FIG. 3, the light source control signal S1 has a falling edge that is synchronized with a falling edge and a rising edge of the reading control signal S2.

  When the reading control signal S <b> 2 is input, the image reading unit 7 controls the photoelectric conversion element 7 </ b> A and reads the image formed by the lens 6. Specifically, reading starts at the rising edge of the reading control signal S2, and reading ends at the falling edge.

  The light source driving unit 3 has an inverter circuit for lighting the light source 2. When the light source control signal S1 is input, the light source drive unit 3 generates a drive signal S3 for turning on the light source 2, as shown in FIG. Note that, when the light source control signal S1 is not input, the light source drive unit 3 does not generate the drive signal S3 as illustrated in FIG. Therefore, in this case, the light source 2 is turned off. Further, when the light source control signal S1 is input while the light source drive unit 3 is generating the drive signal S3, the generation of the drive signal S3 is restarted as shown in FIG. In addition, when the frequency of the light source control signal S1 is 10 [kHz], the light source drive unit 3 generates the drive signal S3 so that the illuminance of the light source 2 is low, and the frequency is 5 [kHz]. In this case, the drive signal S3 is generated so that the illuminance is high.

[Operation of First Embodiment]
Next, the operation of this embodiment will be described. After the user of the image reading apparatus places the document 12 on the document tray 11, for example, when the user presses a key provided on the operation unit 17 that outputs an instruction to read the document 12 in black and white to the control unit 1. An instruction to read 12 in black and white is output from the operation unit 17. When this instruction is input to the control unit 1, the control unit 1 controls the feed roller 13 of the document conveying unit 10 in accordance with this instruction, and the document 12 placed on the document tray 11 is placed on the platen glass 4. It is conveyed to the reading position 15. Next, in order to read the document 12 conveyed to the reading position 15, the control unit 1 generates a reading control signal S2 and a light source control signal S1 at the timing shown in FIG. 5, for example. Here, since the instruction input to the control unit 1 is an instruction to read the document 12 in black and white, the frequency of the light source control signal S1 is 10 [kHz]. The control unit 1 outputs a reading control signal S2 to the image reading unit 7 and outputs a light source control signal S1 to the light source driving unit 3.

  When the light source control signal S1 is input, the light source drive unit 3 generates a drive signal S3 (time points t1, t2, t3, t4, t7, t8, t9, t10) and outputs them. When this drive signal S3 is input to the light source 2, the light source 2 is turned on. Since the frequency of the light source control signal S1 is 10 [kHz], the illuminance of the light source 2 is low. On the other hand, the image reading unit 7 starts reading the image formed by the lens 6 at the rising edge of the input reading control signal S2 (time points t1, t7), and the falling edge of the reading control signal S2 (time point). At t4 and t10), the reading is finished.

  When the reading control signal S2 falls, the control unit 1 stops generating the light source control signal S1 until the next main scanning starts (time t4 to t6). When the light source control signal S1 is not input, the light source driver 3 does not generate the drive signal S3 (time points t5 and t11). Therefore, the light source 2 is turned off.

  As described above, according to this embodiment, the light source control signal S1 from the control unit 1 turns on / off the light source 2, changes the illuminance of the light source 2, and restarts the generation of the drive signal S3. . Since these are all performed according to the light source control signal S1, it is not necessary to provide signals and circuit patterns for each control target, and it is possible to reduce the substrate size and the manufacturing cost. Further, since the timing at which the image reading unit 7 starts reading coincides with the timing at which the light source driving unit 3 starts generating the drive signal S3, the illuminance of the light source 2 does not vary depending on the reading timing.

[B. Second Embodiment]
Next, a second embodiment of the image reading apparatus according to the present invention will be described. In the present embodiment, a signal input to the light source driving unit 3 for controlling the light source 2 is different from that in the first embodiment. Hereinafter, differences of the present embodiment from the first embodiment will be described.

  FIG. 6 is a block diagram illustrating a hardware configuration of a main part related to image reading in the image reading apparatus according to the present embodiment. As shown in FIG. 6, the control unit 1 outputs a lighting control signal S4 and a light source control signal S5 to the light source driving unit 3. The light source control signal S5 is a signal similar to the light source control signal S1 of the first embodiment. The light source control signal S5 is different from the light source control signal S1 of the first embodiment in that this signal is used for controlling the illuminance of the light source 2 and the lighting timing of the light source 2. In the first embodiment, the control of turning on / off the light source 2 performed by the light source control signal S1 is performed by the lighting control signal S4 in the present embodiment. The lighting control signal S4 is a pulse as shown in FIG. 7, and becomes H level in the reading period in the main scanning direction of the image reading unit 7.

  When the lighting control signal S4 is input, the light source driving unit 3 generates a driving signal S3 for lighting the light source 2 as shown in FIG. In addition, when the lighting control signal S4 is not input, the light source driving unit 3 does not generate the driving signal S3 as illustrated in FIG. Therefore, in this case, the light source 2 is turned off. When the light source control signal S5 is input while generating the drive signal S3, the light source driver 3 restarts generation of the drive signal S3 as shown in FIG. In addition, when the frequency of the light source control signal S5 is 10 [kHz], the light source drive unit 3 generates the drive signal S3 so that the illuminance of the light source 2 is low, and the frequency is 5 [kHz]. In this case, the drive signal S3 is generated so that the illuminance is high.

[Operation of Second Embodiment]
Next, the operation of this embodiment will be described. In the following description, it is assumed that the user is instructed to read the document 12 in black and white, as in the first embodiment. As in the first embodiment, when the document 12 is transported onto the platen glass 4, the control unit 1 next reads the document 12 transported to the reading position 15, for example, at the timing shown in FIG. Thus, the reading control signal S2, the lighting control signal S4, and the light source control signal S5 are generated. Here, since the instruction input to the control unit 1 is an instruction to read the document 12 in black and white, the frequency of the light source control signal S1 is 10 [kHz]. The control unit 1 outputs a reading control signal S2 to the image reading unit 7, and outputs a lighting control signal S4 and a light source control signal S5 to the light source driving unit 3.

  First, when the lighting control signal S4 is input, the light source driving unit 3 generates and outputs a driving signal S3 (time points t21 and t26). When this drive signal S3 is input to the light source 2, the light source 2 is turned on. Since the frequency of the light source control signal S1 is 10 [kHz], the illuminance of the light source 2 is low. Next, when the light source control signal S5 is input, the light source drive unit 3 restarts generation of the drive signal S3 (time points t22, t23, t24, t27, t28, t29). On the other hand, the image reading unit 7 starts reading the image formed by the lens 6 at the rising edge of the input reading control signal S2 (time points t22 and t27), and the falling edge of the reading control signal S2 (time point). At t4 and t10), the reading is finished.

  The controller 1 synchronizes the fall of the reading control signal S2 and the fall of the lighting control signal S4, and stops generating the light source control signal S5 until the next main scanning is started. When the lighting control signal S4 is no longer input, the light source driving unit 3 does not generate the driving signal S3 (time points t25 and t30).

  As described above, in the present embodiment, the lighting control signal S4 is provided, whereby the lighting / extinguishing timing of the light source 2 is finely controlled. Further, the illuminance of the light source 2 and the generation of the drive signal S3 are restarted by the light source control signal S5.

[C. Modified example]
As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, It can implement with another various form. For example, the present invention may be implemented by modifying the above-described embodiment as follows.

  In the above-described embodiments, the case where the present invention is applied to an image reading apparatus of a type that reads an image by moving a document has been described as an example. However, like a flatbed type image scanner, a document is scanned on a platen. The present invention may be applied to an image reading apparatus that is fixed on the glass 4 and reads an image while moving the light source 2.

  The illuminance may be high when the frequency of the light source control signal S1 is high, and the illuminance of the light source 2 may be low when the frequency of the light source control signal S1 is low.

1 is a diagram illustrating an image reading apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a main configuration of the image reading apparatus. It is a figure which shows the relationship between the light source control signal S1 and reading control signal S2 in 1st Embodiment. It is a figure which shows the relationship between the light source control signal S1 and drive signal S3 in 1st Embodiment. It is a figure for demonstrating operation | movement of 1st Embodiment. It is a block diagram which shows the structure of the light source drive part 3 concerning 2nd Embodiment of this invention. It is a figure which shows the relationship between the lighting control signal S4 in 2nd Embodiment, the light source control signal S5, and the drive signal S3. It is a figure for demonstrating operation | movement of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Control part, 2 ... Light source, 3 ... Light source drive part, 4 ... Platen glass, 5A, 5B, 5C ... Mirror, 6 ... Lens, 7 ... Image reading Part 7A ... photoelectric conversion element 10 ... document transport part 11 ... document tray 12 ... document 13 ... feed roller 14 ... conveying path 15 ... reading Position, 16 ... Document discharge tray.

Claims (4)

A light source for illuminating the document;
Control means for outputting a control signal having a predetermined period;
Cycle switching means for switching the cycle of the control signal;
When the control signal is input, light source control means for starting lighting of the light source and controlling the illuminance of the light source based on the cycle of the control signal;
An image reading apparatus comprising: reading means for converting the reflected light from the original generated by irradiation of light from the light source into an electric signal and reading the electric signal. The control unit is configured to generate a light source control signal and a read control signal so that an exposure cycle in which the reading unit converts the reflected light into an electrical signal and a lighting cycle in which the light source oscillates by the light source control unit are synchronized. Generate and output,
The image reading apparatus according to claim 1, wherein the reading unit converts reflected light from the document into an electric signal in accordance with the reading control signal.   The image reading apparatus according to claim 2, further comprising a reading cycle varying unit that varies a cycle of the reading control signal. A light source for illuminating the document;
A control means for outputting a lighting control signal for lighting the light source, and a control signal having a predetermined period;
Cycle switching means for switching the cycle of the control signal;
When the lighting control signal is input, the light source starts to be turned on. When the control signal is input, the light source controls the illuminance of the light source and the lighting timing of the light source based on the cycle of the control signal. Control means;
An image reading apparatus comprising: reading means for converting the reflected light from the original generated by irradiation of light from the light source into an electric signal and reading the electric signal.

Images