JP4475285B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus that reads image information from a document, and an image forming apparatus including the image reading apparatus.

  Conventionally, a light source composed of a white fluorescent lamp, an optical element group that collects reflected light that is irradiated from the light source and reflected from the original, and a CCD element that is reflected by the optical element group. A so-called optical reduction type image reading apparatus including an image sensor that acquires image information from an original according to light is known (see, for example, Patent Document 1).

In this optical reduction type image reading apparatus, the amount of light emitted after the start of power supply (hereinafter referred to as the amount of emitted light) is stabilized (that is, the amount of change in the amount of emitted light over a predetermined time is a specified value). The reading of the document is executed (after the following).
Japanese Patent Laid-Open No. 2003-110797

  However, in the image reading apparatus described in Japanese Patent Application Laid-Open No. H10-228707, reading of a document that has a short reading time and is relatively unaffected by changes in the amount of emitted light is also a document that has a long reading time and is relatively affected by changes in the amount of emitted light. There is also a problem that reading is not performed uniformly until the amount of change in the amount of emitted light in a certain time becomes equal to or less than a specified value.

  SUMMARY An advantage of some aspects of the invention is to provide an image reading apparatus capable of reducing the waiting time until the start of reading as much as possible in consideration of the reading time, and an image forming apparatus including the image reading apparatus. .

In the image reading apparatus of the present invention made to achieve the above object, the irradiating means irradiates light toward the original, and the reading means outputs image information from the original based on the reflected light reflected by the original. Read. Then, the estimating means estimates the reading time required for reading the image information by the reading means, the measuring means measures the amount of change in the prescribed amount of light emitted by the irradiating means, and the setting means Based on the estimated reading time estimated by the estimating means and the light amount change amount measured by the measuring means, the control means sets the reading start timing at which the light amount change amount in the estimated reading time is equal to or less than the specified amount. In accordance with the reading start timing set in (1), the reading unit executes reading.
Further, in the image reading apparatus of the present invention, the supply unit supplies power for the irradiation unit to irradiate light, and the supply unit supplies power at the first voltage and then supplies power from the first voltage. In the case where the power supply is performed at the second voltage having a low voltage and the estimated reading time is the first hour, compared to the case where the estimated reading time is the second time longer than the first time, Reduce the time to supply power at the first voltage.

  Generally, the larger the change between the light amount at the start of reading a document and the light amount at the end of reading the document, the larger the difference in reading density within one image information, and the image information is read from the document. The reading quality, which is the quality of time, decreases. For this reason, as shown in FIG. 9, normally, after the rising period has elapsed, that is, after the amount of change in the amount of light in the set time after the start of power supply to the light source becomes equal to or less than the specified amount, the image information Start reading.

However, even before the rising period elapses, if the reading time is less than the set time, the amount of change in the amount of light during the reading time may be less than or equal to the specified amount.
That is, in the image reading apparatus of the present invention, paying attention to this point, the reading start timing is set at which the light amount change amount in the estimated reading time is equal to or less than the predetermined amount based on the light amount change amount measured by the measuring unit. . In other words, in the image reading apparatus of the present invention, when the estimated reading time is less than the set time, reading is started without waiting for the rise period to elapse.

  Therefore, the time (hereinafter referred to as standby time) required from when the power supply to the light source is started until image information is read by the reading unit is shortened (in the figure, standby time 1 is standby time 2). To be shortened).

Therefore, according to the image reading apparatus of the present invention, it is possible to prevent the standby time from becoming longer than necessary.
In particular, in the image reading apparatus of the present invention, first, by supplying power at the first voltage, the amount of light emitted from the irradiating means is increased, and further, the amount of light is changed compared to when the second voltage is applied to the light source. It becomes the specified value or less earlier (that is, the rise time becomes shorter). Therefore, according to the image reading apparatus of the present invention configured as described above, the standby time can be reliably shortened.
However, the specified time is a unit time specified in advance, the reading start timing is the timing at which the reading unit starts reading image information, and the light amount change amount is obtained by dividing the light amount change amount by time. It includes at least the changed rate.

  Note that the above-described rise period is a period from the start of power supply to a light source that requires a waiting time until the amount of light stabilizes, until the change in the amount of light during the set time falls below a specified value. It is.

By the way, the estimation means in the image reading apparatus of the present invention may be configured to estimate the reading time from the reading condition by the reading means as described in claim 2.
That is, the information amount of the image information and the reading time have a correspondence relationship that the reading time becomes longer as the information amount of the image information is larger, and therefore the reading time may be estimated from the reading conditions.

  The reading conditions referred to here are the resolution when reading the document, the reading method when reading the document (for example, whether it is a binary image that does not include intermediate colors or a monochrome image that includes intermediate colors), and the reading conditions. It may be estimated from the length of the original in the sub-scanning direction.

  The image reading apparatus according to the present invention includes a storage unit that temporarily stores the image information acquired by the reading unit and a transfer unit that transfers the image information stored in the storage unit to an external device. According to the third aspect of the present invention, the estimation means includes the information amount of the image information stored in the storage means per unit time, the information amount of the image information transferred by the transfer means per unit time, and the storage means It is desirable that the reading time is estimated based on at least one of the free capacities.

  That is, the amount of image information stored in the storage unit per unit time (hereinafter referred to as the inflow amount) is more than the amount of information (hereinafter referred to as transfer amount) of the image information transferred to the external device by the transfer unit per unit time. If there is sufficient free space (for example, if there is free space that can store a predetermined amount of information), the reading time can be estimated based on the inflow amount. Further, if the inflow amount is larger than the transfer amount and the free space is insufficient, all the image information in a single document is read and stored in the storage means. Since it is necessary to transfer image information to an external device, the reading time can be estimated based on the transfer amount.

  Furthermore, when the transfer amount is larger than the inflow amount, it is a part of all the image information, and it is possible to prevent the information amount of the image information stored in the storage means from continuing to increase. Can be estimated based on the inflow.

Therefore, the reading time can be estimated if there is such information (inflow amount, transfer amount, free capacity).
If any one or two of these information (inflow, transfer, free capacity) is a fixed value, or if there is a correlation between the information, all the information Even if it is not used, the reading time can be estimated by using any one or two pieces of information.

The supply means definitive image reading apparatus of the present invention, as described in claim 4, the light amount of the illumination means reaches the first light level, supplies power at the second voltage, the first light level After it is determined that the power has reached, power may be supplied at the second voltage.

Its to the supply unit in the image reading apparatus of the present invention, as described in claim 5, may be configured to determine on the basis of the output of the sensor for measuring the amount of light, according to claim 6 As described above, the determination may be made based on the elapsed time from the start of power supply to the irradiation means.

In the latter case, if the characteristics of the change in the amount of light at the time of rising are obtained, it is possible to recognize the elapsed time from the start of power supply in which the amount of light becomes the first amount of light.
By the way, in general, as described above, the reading quality is not only when the change in the amount of light within the reading time is not less than a specified value, but also when the amount of light from the light source is extremely small (that is, dark). descend. That is, the read density in the image information becomes too small, and the image information is dark as a whole and the content of the document is difficult to recognize.

  Therefore, the setting means in the image reading apparatus of the present invention is configured to set the reading start timing so that the light amount of the light source at the reading start timing is equal to or greater than the second light amount. It is desirable that

  According to the image reading apparatus of the present invention configured as described above, when the execution start timing is set, the second light quantity is always ensured, so that the minimum reading quality can be ensured.

However, the second light amount referred to here is a light amount necessary for guaranteeing the reading quality of the image information acquired by the reading unit from the document as a minimum.
The irradiating means in the image reading apparatus of the present invention is preferably a white fluorescent lamp as described in claim 8.

Further, according to the present invention, the irradiating unit irradiates light toward the document, and the reading unit reads image information from the document based on the reflected light reflected by the document. The printing means prints the image information read by the reading means on the recording medium, the estimating means estimates the reading time required for reading the image information by the reading means, and the measuring means is irradiated by the irradiating means. The amount of change in the amount of light to be measured is measured at a specified time, and the amount of change in the estimated reading time is determined based on the estimated reading time estimated by the estimating unit and the amount of light change measured by the measuring unit. Even if the image forming apparatus is configured to set the reading start timing at which the value is equal to or less than the specified amount, and the control unit causes the reading unit to perform reading according to the reading start timing set by the setting unit. There.
However, in the image forming apparatus of the present invention, the supply unit supplies power for the irradiation unit to irradiate light, and the supply unit supplies power at the first voltage and then supplies power from the first voltage. In the case where the power supply is performed at the second voltage having a low voltage and the estimated reading time is the first hour, compared to the case where the estimated reading time is the second time longer than the first time, It is necessary to be configured to shorten the time for supplying power at the first voltage.

  In other words, the present invention may be applied to an image reading apparatus provided in a so-called multifunction machine.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
<overall structure>
FIG. 1 is a perspective view showing the overall configuration of an image forming apparatus to which the present invention is applied.

The image forming apparatus 1 is configured as a so-called multifunction machine having functions as an image scanner, a printer, a copy, and a facsimile machine, and is hereinafter referred to as a multifunction machine.
The multifunction machine 1 includes a paper tray 18 for feeding sheet-like paper, a document reading device 20 (see FIG. 2) that reads information from a document (that is, acquires image data), and reads information from a document. The image forming apparatus 30 (see FIG. 3) that prints an image based on the image data obtained on the sheet is stored, and the body 10 is supported to be openable and closable so as to cover the upper surface of the body 10. The main body cover 12 is provided, and an operation unit 16 into which information necessary for using the multifunction machine 1 is input.

  The main body cover 12 includes a placement tray 13 on which a document before being read by the document reading device 20 is placed, and a pair of guides that can be driven according to the size of the document placed on the placement tray 13. A strip 14 and a stacking tray 15 for stacking documents after being read by the document reading device 20 are provided.

Further, the operation unit 16 includes a selection key 16a for selecting a function desired by the user from among a plurality of functions (for example, a scanner function and a copy function) provided in the multifunction device 1, and a function selected by the user. Are provided with a start key 16b for executing processing for realizing the above and a display unit 17 for displaying the state of the multifunction device 1 and the like. The display unit 17 is a liquid crystal panel (so-called touch panel) configured to be able to input settings necessary for realizing the functions of the multifunction device 1 (that is, information, hereinafter referred to as necessary settings).
<Configuration of document reader>
Next, the document reading device 20 will be described.

Here, FIG. 2 is a cross-sectional view for explaining a schematic configuration of the document reading apparatus.
The document reading apparatus 20 includes a reading head 25 provided in the main body 10, a flat bed mechanism (hereinafter also referred to as FB) 31, and an automatic conveyance mechanism 32 provided in the main body cover 12.

  The flat bed mechanism 31 includes a white plate 33 for adjusting white balance, a placement glass 39 disposed so that a reading surface of an original (that is, a surface on which acquired information is printed) is opposed, and a reading head 25. A step motor 38 (see FIG. 3) for driving is provided.

  On the other hand, the automatic conveyance mechanism 32 separates the originals placed on the placement tray 13 one by one and guides them to the conveyance path L, and the original separated by the separation roller 34 is placed on the placement glass 39. A conveyance roller 35 that conveys the document to a predetermined automatic conveyance reading position 3 above and a discharge roller 36 that discharges the document that has been read to the stacking tray 15 are provided. Hereinafter, the main body cover 12 in which the automatic conveyance mechanism 32, the loading tray 13, the guide piece 14, and the stacking tray 15 are incorporated is referred to as an automatic document conveyance device (hereinafter also referred to as an ADF device) 40.

  Further, the reading head 25 includes a light source 26 (an example of an irradiation unit) that irradiates light on the document, an optical element group 27 such as a mirror and a lens that collects reflected light reflected by the document, and information from the document. Is provided with an image sensor 28 (an example of a reading unit) and a light amount sensor 21 for detecting the light amount of the light source 26. In other words, the reading head 25 reads the document by condensing the reflected light reflected by the document by the optical element group 27 and recognizing the collected reflected light by the image sensor 28. It is configured as follows.

  Note that the light source 26 emits a light amount (hereinafter referred to as a light emission amount) that is equal to or greater than a predetermined required light amount after the start of power supply, and a change in the light emission amount at a predetermined time. Is a white fluorescent lamp that requires a waiting time until the value becomes equal to or less than a predetermined value (that is, the amount of emitted light is stabilized).

The image sensor 28 includes a CCD element, and is configured to convert light energy corresponding to the intensity of reflected light into electric charges.
Further, the reading head 25 is capable of reading a document at a position facing the automatic conveyance reading position 3 and is moved in the sub-scanning direction (left and right direction in FIG. 2) along the placement glass 39 by the step motor 22. Is configured to be movable.

  That is, when a document is read using the ADF device 40 (hereinafter, reading by this method is referred to as ADF reading), the reading head 25 is held at a position facing the automatic conveyance reading position 3, and the reading head 25 acquires all information of the original from the original conveyed so as to pass through the automatic conveyance reading position 3 by the automatic original conveyance device 40.

  Further, when reading a document placed so as to cover the placement glass 39 (used as a so-called flat bed type) (hereinafter referred to as FB reading), the reading head 25 is While being moved by the step motor 22, all information of the document placed on the placement glass 39 is acquired.

As described above, the document reading device 20 is configured as a so-called optical reduction type image scanner.
<Internal configuration of MFP>
FIG. 3 is a block diagram for explaining the internal configuration (schematic configuration) of the multifunction machine.

  In addition to the document reading device 20 and the image forming device 30 described above, the multifunction device 1 includes a communication unit 45 (an example of a transfer unit) that communicates with an external device, and power to each unit constituting the multifunction device 1. Power supply unit 60 (an example of a supply unit) and a control unit 50 (an example of a control unit) that controls each unit constituting the multifunction machine 1.

  The image forming apparatus 30 is configured as a so-called laser printer. The image forming apparatus 30 takes in paper from the paper tray 18 and forms an image on the paper. The paper on which the image is recorded is provided on the front surface of the multifunction machine 1. The paper is discharged from the paper discharge port 19 (see FIG. 1).

  In addition, the power supply unit 60 converts a known AC power source directly supplied from the wiring plug connector into a DC power source and inputs it to the light source 26 of the read head 25 that requires power supply, and a light source. 26 is provided with a voltage conversion unit for applying a predetermined voltage to H.26.

  Further, although not shown, the power supply unit 60 is based on a conversion command from the control unit 50, and a DC / DC converter that converts a DC power source into any one of a plurality of prescribed voltages prescribed in advance, And an inverter that converts a DC power source converted into a specified voltage by the DC / DC converter into an AC power source. The specified voltage of the DC / DC converter includes a normal lighting voltage (an example of the second voltage) applied to the light source 26 when the original is read, and a quick lighting voltage (first voltage) larger than the normal lighting voltage. One example of one voltage) is set.

That is, in the power supply unit 60, the direct current power converted into the specified voltage by the DC / DC converter is converted into the alternating current power through the inverter and then supplied to the light source 26.
In addition, the communication unit 45 includes a parallel interface (I / F) 46 for inputting / outputting image information and the like with a personal computer (hereinafter referred to as a PC) via a parallel cable, and a PC via a USB cable. A USB interface (I / F) 47 for inputting / outputting image information to / from an external terminal device such as a digital camera, and an NCU 48 for transmitting information to / from an external facsimile device via a general communication line. It has.

The control unit 50 also modulates and demodulates information transmitted by the NCU 43, a ROM 51 that stores a processing program, a RAM 52 that temporarily stores data (an example of storage means), a CPU 53 that executes processing according to the processing program, and the like. The modem 54 is connected to each of these units via a bus, and commands for driving the units (for example, the document reading device 20 and the image forming device 30) constituting the multi-function device 1 according to commands from the CPU 53. And an ASIC 55 functioning as a driver for conversion into a signal.
<Scanning process>
Next, a reading process executed by the CPU 53 of the control unit 50 will be described.

FIG. 4 is a flowchart for explaining the processing procedure of the reading process.
In this reading process, when the selection key 16a is pressed, a function (that is, an image scanner, a copy, and a facsimile) that uses the document reading device 20 is selected, and the start key 16b is used to realize the function in the multifunction device 1. Is pressed (for example, when the multifunction device 1 is used as an image scanner).

  When the reading process is started, first, in S110, a conversion command is transmitted to the DC / DC converter of the power supply unit 60 so that the voltage applied to the light source 26 becomes the normal lighting voltage. Upon receiving the conversion command, the power supply unit 60 starts supplying power to the light source 26. As a result, the power that is converted into the normal lighting voltage by the DC / DC converter and converted into the AC power by the inverter is supplied to the light source 26, and the light source 26 that receives the supply of the AC power starts to emit light. To do.

In S120, a reading time estimation process (described later) for estimating a reading time necessary for acquiring information from the document is executed.
In step S140, a light amount stability determination process (described later) is performed to confirm that the amount of light emitted from the light source 26 is suitable for causing the image sensor 28 to read a document.

If it is confirmed in the light quantity stability determination processing that the image sensor 28 is suitable for reading the document, in S150, the image sensor 28 is read to acquire information from the document. To do. For example, in the case of ADF reading, the document placed on the mounting tray 13 is conveyed so as to pass through the automatic conveyance reading position 3, and in the case of FB reading, the reading head 25 is sub-scanned. By driving in the direction, all information is read from the document.
<Reading time estimation process>
Next, reading time estimation processing (an example of estimation means) will be described.

Here, FIG. 5 is a flowchart showing a processing procedure of the reading time estimation processing.
When this reading time estimation process is started in the previous S120, first, in S210, it is determined whether or not the function selected when the reading process is started is a copy or a facsimile. As a result, if it is determined that the function of the image scanner is selected, neither copying nor facsimile, the process proceeds to S220. Here, the function of the image scanner is a function of acquiring information from the original by the image sensor 28 and transmitting the acquired information to the PC via the communication unit 45. Since the information acquired by the function of the image scanner is displayed on the display of the PC, the resolution when acquiring information from the original by the function of the image scanner is usually set to a high resolution in many cases.

  In S220, whether or not the length of the document placed on the placement tray 13 or the placement glass 39 in the sub-scanning direction (hereinafter referred to as the document length) is equal to or less than a prescribed length specified in advance. If it is determined that the document length is greater than the specified length, the process proceeds to S230.

  Specifically, in this embodiment, during ADF reading, information indicating the size of the document input via the operation unit 16 before the start key 16b is pressed (hereinafter referred to as document size input information). Based on this, the length of the original is recognized. At the time of FB reading, the document length is recognized based on document size input information and the output of a size detection sensor (not shown) for detecting the size of the document placed on the placement glass 39.

Further, in S230, it is determined whether or not the resolution at the time of document reading is equal to or lower than a predetermined resolution. If the determination result shows that the resolution is larger than the predetermined resolution, the process proceeds to S240.
Specifically, in this embodiment, before the start key 16b is pressed, the resolution at the time of document reading is recognized according to the information indicating the size of the resolution input via the operation unit 16.

In S240, it is estimated that the reading time is equal to or longer than a predetermined time, and the estimated reading time obtained by estimating the reading time is set to a second time longer than the predetermined time, and the process returns to the reading process.

  On the other hand, if the selected function is copy or facsimile as a result of the determination in S210, the determination result in S220 indicates that the document length is equal to or shorter than the specified length, and the determination result in S230 indicates that the resolution is If the resolution is less than the specified resolution, the process proceeds to S250.

In S250, it is estimated that the reading time is less than the specified time, the estimated reading time is set to a first time shorter than the specified time, and the process returns to the reading process.
That is, in the reading time estimation process, the reading time is equal to or longer than a predetermined time based on the size of the document, the resolution at the time of reading (that is, an index for determining the amount of information acquired by reading the document). It is estimated whether it becomes. Then, if it is estimated that the read time is equal to or greater than the prescribed time, the second time, when it is estimated that the read time is less than the prescribed time, the short first time than the second time, sets the estimated read time .
<Light intensity stability judgment processing>
Next, light quantity stability determination processing (an example of measurement means and setting means) will be described.

Here, FIG. 6 is a flowchart showing a processing procedure of the light quantity stability determination processing.
When this light quantity stability determination process is activated in the previous S140, first, in S410, the first timer is activated.

  In subsequent S420, it is determined whether or not the measurement time measured by the first timer indicates that a preset rising period has elapsed, and as a result of the determination, the measurement time indicates that the rising period has elapsed. If not, the process proceeds to S430.

However, the rising period is equal to or greater than the light amount for guaranteeing the minimum reading quality at the time of reading the document (hereinafter referred to as the guaranteed light amount) and the power supply to the light source 26 is started. This is a period until the change in the amount of light at a preset time (see FIG. 9) that is prescribed in advance is equal to or less than a prescribed value that is prescribed in advance. Note that the set time referred to here is a time equal to or longer than the second time , and the specified value is the maximum variation in the amount of emitted light during the reading time (hereinafter, referred to as “allowed” to guarantee the minimum reading quality). This corresponds to the “specified amount” in FIG.

  That is, if the amount of emitted light is greater than or equal to the guaranteed amount of light, and the amount of fluctuation between the amount of emitted light at the start of reading the document and the amount of emitted light at the end of reading the document is less than the guaranteed variation, Limit reading quality is guaranteed.

In S430, the light quantity sensor 21 (see FIG. 3) is detected at a predetermined time interval, and the detection result is acquired.
In subsequent S440, based on the acquired light quantity acquired in S430, the fluctuation amount of the light quantity in a unit time (corresponding to the “prescribed time” in FIG. 9) defined in advance as a time shorter than the first time is calculated. A light quantity fluctuation rate obtained by dividing the light quantity fluctuation amount by a unit time is calculated (an example of measuring means).

In S450, it is determined whether or not the light amount fluctuation rate calculated in S440 is equal to or less than the second fluctuation rate defined in advance. As a result of the determination, it is determined that the light amount fluctuation rate is equal to or less than the second fluctuation rate. If so, the process proceeds to S460. The second fluctuation rate is obtained by dividing the guaranteed fluctuation amount (corresponding to the “specified amount” in FIG. 9) by the first time .

Further, in S460, whether the estimated read time is the first time, to determine whether the second time, as a result of the judgment, if the second time, the process proceeds to S470.
In S470, it is determined whether or not the light amount fluctuation rate calculated in S440 is equal to or less than the first fluctuation rate defined in advance. As a result of the determination, it is determined that the light amount fluctuation rate is greater than the first fluctuation rate. If YES, return to S420. Note that if it is determined in S450 that the light quantity variation rate is greater than the second variation rate, the process returns to S420.

The first variation rate is obtained by dividing the guaranteed variation amount by the second time . Therefore, the first variation rate is smaller than the second variation rate.
On the other hand, if it is determined as a result of determination in S470 that the light quantity variation rate is equal to or less than the first variation rate, or if it is determined as a result of determination in S460 that it is the first time , the process proceeds to reading processing. And return. That is, when it is determined that the light amount fluctuation amount in the estimated reading time is larger than the guaranteed fluctuation amount, the process returns to the reading process and the reading is executed.

Note that, as a result of the determination in S420, the process returns to the reading process also when the measurement time indicates that the rising period has elapsed.
That is, in the light quantity stability determination process, if the fluctuation amount of the light quantity in the estimated reading time is equal to or less than the guaranteed fluctuation quantity, the minimum reading quality is guaranteed even before the rising period has passed, Assuming that reading is possible, the process proceeds to S150 of the reading process.
[Effect of the first embodiment]
As described above, according to the multifunction device 1 of the present embodiment, when the estimated reading time is the first time , the reading process is started (that is, the light source 26 emits light) until the reading is started. It is possible to shorten the waiting time required for the operation.

Also, according to the multifunction device 1, since the reading start timing is determined so that the amount of fluctuation of the light amount in the estimated reading time is equal to or less than the guaranteed fluctuation amount, the reading start time and the reading end time are determined. A difference in density in the read image can be suppressed.
[Second Embodiment]
Next, a second embodiment of the present invention will be described.

The image forming apparatus shown in the first embodiment is different from the image forming apparatus of the second embodiment only in the reading process executed by the image forming apparatus. For this reason, the same components as those of the image forming apparatus shown in the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and description will be made focusing on reading processing different from that of the first embodiment.
<Scanning process>
Here, FIG. 7 is a flowchart showing the processing procedure of the reading process in the present embodiment.

  In this reading process, when the selection key 16a is pressed, a function (that is, an image scanner, a copy, and a facsimile) that uses the document reading device 20 is selected, and the start key 16b is used to realize the function in the multifunction device 1. Is pressed (for example, when the multifunction device 1 is used as an image scanner).

  When the reading process is started, first, in S510, a conversion command is transmitted to the DC / DC converter of the power supply unit 60 so that the voltage applied to the light source 26 becomes the normal lighting voltage, and the light source Supply of power is started at 26. Thus, the voltage source is converted by the DC / DC converter, the AC power source of the normal lighting voltage converted to the AC power source by the inverter is supplied to the light source 26, and the light source 26 that receives the supply of the AC power source is Start flashing.

In S520, a reading time estimation process for estimating a reading time necessary for acquiring information from the document is executed.
Further, in S530, a rapid lighting voltage application process (described later) for supplying an AC power supply for rapid lighting to the light source is executed so that the amount of light from the light source 26 increases more quickly.

  In step S540, a light amount stability determination process is performed to confirm that the amount of light emitted from the light source 26 is in a state suitable for causing the image sensor 28 to read a document.

  Subsequently, in S550, when it is confirmed in the light quantity stability determination processing that the image sensor 28 is in a state suitable for reading the document, the image sensor 28 is read to read information from the document. To get.

Note that the reading time estimation process and the light amount stability determination process are the same as those in the first embodiment, and thus description thereof is omitted here.
<Rapid voltage application process>
Next, the rapid lighting voltage application process will be described.

Here, FIG. 8 is a flowchart showing a processing procedure of the rapid lighting voltage application processing.
When the rapid lighting voltage application process is started in S530, first, in S310, the voltage applied to the light source 26 is changed from the normal lighting voltage only to the normal lighting voltage and the rapid lighting voltage. A conversion command is transmitted to the DC / DC converter of the power supply unit 60 so as to be switched. As a result, the AC power of the rapid lighting voltage, which is converted by the DC / DC converter and converted into the AC power by the inverter, is supplied to the light source 26 together with the AC power of the normal lighting voltage. The supplied light source 26 increases the amount of emitted light.

Subsequently, in S320, a second timer for measuring the time during which the rapid lighting voltage is applied to the light source 26 is started.
In S330, it is determined whether or not the measurement time measured by the second timer is equal to or longer than a preset time. If the measurement time is shorter than the set time as a result of the determination, the process proceeds to S340. move on. Note that the set time corresponds to the characteristic of the light emission amount of the light source 26 obtained in advance by experiments or the like (that is, the time from the start of supplying the normal lighting voltage AC power supply to the light source 26 and the light emission amount). The time is set so that the light emission quantity becomes a predetermined upper limit light quantity according to (Relationship).

In S340, the light amount emitted from the light source from the light amount sensor 21 (hereinafter, the acquired light amount is referred to as an acquired light amount) is acquired.
Then, in S350, it has been acquired light acquired in S340, it is determined whether a predefined first threshold value is a value of the light emission amount (however, the first threshold value <the upper limit amount) or more, the determine the constant As a result, if the amount of acquired light is greater than or equal to the first threshold, the process proceeds to S360.

In S360, it is determined whether the estimated reading time is the first time or the second time , and if it is determined that the reading time is the second time , the process proceeds to S370.

  In S370, it is determined whether or not the acquired light amount acquired in S340 is equal to or greater than a second threshold value that is preset as a value larger than the first threshold value (where the second threshold value is less than the upper limit light amount).

As a result of the determination, if the acquired light amount is less than the second threshold value, the process returns to S330. Note that, if the result of determination in S350 is that the amount of acquired light is less than the first threshold, processing returns to S330.
On the other hand, the result of the determination in S370, if the acquired light is a second threshold value or more, or the result of the determination in S330, if the measured time is longer than the specified time, or the result of the determination in S360, the reading time first If it is determined that it is one hour , the process proceeds to S380.

  In S380, a conversion command is transmitted to the DC / DC converter so that the voltage applied to the light source 26 is changed from the normal lighting voltage and the rapid lighting voltage to only the normal lighting voltage.

Then, the process returns to the reading process.
Here, FIG. 10 is an explanatory diagram showing the light emission characteristics of the light source when the rapid lighting voltage application process is executed.

That is, in the quick lighting voltage application process, as shown in FIG. 10, if the estimated reading time is the first time , the estimated reading time is the second time when the acquired light amount becomes the first threshold. When the amount of acquired light reaches the second threshold value, the voltage applied to the light source 26 is switched to only the normal lighting voltage.
[Effects of Second Embodiment]
As described above, according to the multifunction device of the present embodiment, in the rapid lighting voltage application process, in addition to the normal lighting voltage AC power supply, the rapid lighting voltage AC that is larger than the normal lighting voltage is used. Since the power is supplied to the light source 26, the rising period, that is, the time from when the power is supplied to the light source 26 until the light amount is determined to be stable can be shortened.

As a result, according to the MFP of the present embodiment, even when the estimated reading time is the second time , it is possible to reduce the waiting time required to start reading the document information after the reading process is activated. it can. That is, according to the multifunction machine of the present embodiment, the standby time can be reliably shortened.

Furthermore, according to the MFP of the present embodiment, when the estimated reading time is the first time , it is possible to start reading even during the rising period, so the standby time is set to the second time. The time during which the rapid lighting voltage is applied to the light source 26 can be shortened while maintaining the same level as the standby time.

Therefore, according to the MFP of this embodiment, if the estimated reading time is the first time , the power consumption is suppressed without making the waiting time longer than the waiting time when the estimated reading time is the second time. can do.
<Other embodiments>
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it is possible to implement in various aspects.

  For example, in the reading time estimation process of the above embodiment, when the document length is less than the specified length and the resolution is less than the specified resolution, the estimated reading time is shorter than the specified time. The estimated reading time may be shorter than the specified time when either the length or less and the resolution is less than the specified resolution are satisfied. That is, only one of the reading time estimation processes S220 and S230 may be performed.

  In the reading time estimation process of the above embodiment, the amount of information acquired by reading the document is determined using the size or resolution of the document as an index. However, the index for determining the information amount is It is not limited to.

  For example, a reading method when reading a document (for example, a binary image that does not include intermediate colors or a black and white image that includes intermediate colors) may be used as an index, and the amount of information stored in the RAM 52 per unit time (hereinafter, referred to as a binary image) Inflow amount), at least one of the amount of information transferred from the MFP 1 to the external device per unit time (hereinafter referred to as transfer amount) and the free capacity of the RAM 52 may be used as an index.

  In the latter case, if the inflow amount is larger than the transfer amount and the free space is sufficient, the reading time can be estimated based on the inflow amount. Further, if the inflow amount is larger than the transfer amount and the free space is insufficient, in order to obtain all the image information in one original, it is a part of all the image information and stored in the storage means. Since it is necessary to transfer image information to an external device, the reading time can be estimated based on the transfer amount.

  Furthermore, when the transfer amount is larger than the inflow amount, it is a part of all the image information, and it is possible to prevent the information amount of the image information stored in the storage means from continuing to increase. Can be estimated based on the inflow.

In the reading time estimation process of the above embodiment, it is estimated whether the reading time is equal to or longer than the specified time, and either the second time or the first time is set as the estimated reading time. The time itself may be estimated and derived directly. In this case, for example, the estimation may be performed using a map in which the information amount and the reading time are associated in advance.

  In the light quantity stability determination process of the above embodiment, the light quantity fluctuation rate is calculated by dividing the fluctuation quantity of the light quantity acquired in S430 by the unit time, and the light quantity fluctuation rate is the first fluctuation rate or the second fluctuation rate. If the rate is less than or equal to the rate, reading is executed. However, in addition to this condition, reading may be executed when the amount of acquired light is equal to or greater than the guaranteed amount of light. That is, before returning to the reading process, a step of confirming that the acquired light quantity is equal to or greater than the guaranteed light quantity may be added to the light quantity stability determination process.

  Furthermore, in the light quantity stability determination process of the above embodiment, it was confirmed that the fluctuation amount of the light quantity at the estimated reading time is equal to or less than the guaranteed fluctuation quantity by calculating the light quantity fluctuation rate. It is not limited. For example, the amount of fluctuation of the light amount in the estimated reading time may be directly derived and confirmed using the amount of fluctuation.

  In the light quantity stability determination process in the above embodiment, the light quantity fluctuation rate is calculated based on the output of the light quantity sensor 21, but the light quantity fluctuation rate calculation method is not limited to this. For example, the elapsed time from the start of power supply in which the light amount variation rate is equal to or less than the first variation rate or the second variation rate may be recognized according to the characteristics of the light amount change during the rising period.

  In the above-described embodiment, the multifunction apparatus 1 has been described. However, the present invention may be applied to the image reading apparatus 20 alone.

1 is a perspective view illustrating an overall configuration of a multifunction machine. 1 is a cross-sectional view illustrating a schematic configuration of an image reading apparatus. It is a block diagram which shows the structure of a control part. It is a flowchart which shows the process sequence of the reading process in 1st embodiment. It is a flowchart which shows the process sequence of a reading time estimation process. It is a flowchart which shows the process sequence of a light quantity stability determination process. It is a flowchart which shows the process sequence of the reading process in 2nd embodiment. It is a flowchart which shows the process sequence of the voltage application process for quick lighting. It is explanatory drawing for demonstrating the outline | summary of this invention. It is explanatory drawing which showed the light emission characteristic of the light source when the voltage application process for rapid lighting was performed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multifunction machine (image forming apparatus) 3 ... Automatic conveyance reading position 10 ... Main-body part 12 ... Main-body cover 13 ... Loading tray 14 ... Guide piece 15 ... Accumulation tray 16 ... Operation part 16a ... Selection key 16b ... Start key 17 ... Display unit 18 ... Paper tray 19 ... Paper discharge port 20 ... Document reading device 22 ... Step motor 25 ... Reading head 26 ... Light source 27 ... Optical element group 28 ... Image sensor 29 ... Light sensor 30 ... Image forming device 31 ... Flatbed mechanism 32 ... Automatic conveyance mechanism 33 ... White plate 34 ... Separation roller 35 ... Conveyance roller 36 ... Discharge roller 38 ... Step motor 39 ... Placed glass 40 ... Automatic document conveyance device (ADF device) 45 ... Communication unit 46 ... Parallel I / F 47 ... USB I / F 48 ... NCU 50 ... Control part 51 ... ROM 52 ... RAM 53 ... PU 54 ... modem 55 ... ASIC 60 ... power supply unit

Claims (9)

Irradiating means for irradiating light toward the document;
Reading means for reading image information from the document based on the reflected light irradiated by the irradiation unit and reflected by the document;
Estimating means for estimating a reading time required for reading image information by the reading means;
Measuring means for measuring the amount of change in the amount of light emitted by the irradiating means in a specified time;
Setting means for setting a reading start timing at which the light amount change amount in the estimated reading time is equal to or less than a predetermined amount based on the estimated reading time estimated by the estimating unit and the light amount change amount measured by the measuring unit;
Control means for causing the reading means to perform reading according to the reading start timing set by the setting means;
Supply means for supplying power for the irradiation means to irradiate light,
The supply means includes
After power supply at the first voltage, power supply at the second voltage lower than the first voltage,
When the estimated reading time estimated by the estimating means is the first time, power is supplied at the first voltage compared to the case where the estimated reading time is a second time longer than the first time. An image reading apparatus characterized by shortening the time for performing . The estimation means includes
The image reading apparatus according to claim 1, wherein the reading time is estimated from a reading condition by the reading unit. Storage means for temporarily storing image information acquired by the reading means;
Transfer means for transferring image information stored in the storage means to an external device,
The estimation means includes
At least one of the amount of image information stored in the storage unit per unit time, the amount of image information transferred by the transfer unit per unit time, and the free capacity of the storage unit The image reading apparatus according to claim 1, wherein the reading time is estimated based on the reading time. Before Symbol supply means,
When the light amount of the irradiation means reaches the first light amount, power is supplied at the second voltage, and after it is determined that the first light amount has been reached, power is supplied at the second voltage. The image reading apparatus according to claim 1. The supply means includes
The image reading apparatus according to claim 4, characterized in that that the light amount of the illumination means has reached a first light level, determined on the basis of the output of the sensor for measuring the amount of light. The supply means includes
The image reading apparatus according to claim 4 in which the light amount of the illumination means that reaching the first light level, and judging on the basis of the elapsed time from the start of power supply to the illumination means. The said setting means sets the said reading start timing so that the light quantity of the said irradiation means in the said reading start timing may become more than a 2nd light quantity, The any one of Claim 1 thru | or 6 characterized by the above-mentioned. Image reading apparatus.   8. The image reading apparatus according to claim 1, wherein the irradiation unit is a white fluorescent lamp. Irradiating means for irradiating light toward the document;
Reading means for reading image information from the document based on the reflected light irradiated by the irradiation unit and reflected by the document;
Printing means for printing image information read by the reading means on a recording medium;
Estimating means for estimating a reading time required for reading image information by the reading means;
Measuring means for measuring the amount of change in the amount of light emitted by the irradiating means in a specified time;
Setting means for setting a reading start timing at which the light amount change amount in the estimated reading time is equal to or less than a predetermined amount based on the estimated reading time estimated by the estimating unit and the light amount change amount measured by the measuring unit;
Control means for causing the reading means to perform reading according to the reading start timing set by the setting means;
Supply means for supplying power for the irradiation means to irradiate light,
The supply means includes
After power supply at the first voltage, power supply at the second voltage lower than the first voltage,
When the estimated reading time estimated by the estimating means is the first time, power is supplied at the first voltage compared to the case where the estimated reading time is a second time longer than the first time. An image forming apparatus characterized in that the time for performing is shortened .

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