Image reading device

Abstract

To obtain an image reading device that appropriately prevents an increase in temperature without providing a temperature sensor.SOLUTION: A driving unit 21 drives an internal device with a motor. A controller 23 (a) repeatedly derives, in a monitoring period for a predetermined length of period, the ratio of the operating time of the driving unit 21 to the predetermined length of period, and (b) according to the ratio, shifts the operation mode of the driving unit 21 from a normal operation mode to a motor cooling operation mode (an operation mode for reducing the calorific power of the driving unit 21 compared to that in the normal operation mode).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an image reading device. [Background technology]

[0002] One image reading device is equipped with a drive motor that drives a scanning mechanism that scans an illumination lamp and a mirror that reflects light reflected from a document, and in order to suppress heat generation by the drive motor, the repetition period of the scanning operation is controlled according to the continuous operating time of the drive motor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-23514 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned image reading device does not have a temperature sensor, and controls the repetition period of the scanning operation according to the continuous operation time of the drive motor. Even if the drive motor operates intermittently, the temperature will rise if the proportion of the on period of the drive motor is high.

[0005] The present invention has been made in consideration of the above problems, and has an object to provide an image reading device that appropriately suppresses a temperature rise without providing a temperature sensor. [Means for solving the problem]

[0006] The image reading device according to the present invention includes a drive unit that drives an internal device with a motor, and a controller that controls the drive unit, and (a) the controller repeatedly derives a ratio of an operating time of the drive unit during a monitoring period of a predetermined length of time to the predetermined length of time, and (b) in accordance with the ratio, transitions the operating mode of the drive unit from a normal operating mode to a motor cooling operating mode that reduces the amount of heat generated by the drive unit compared to the normal operating mode. Effect of the Invention

[0007] According to the present invention, an image reading device that appropriately suppresses a temperature rise without providing a temperature sensor can be obtained.

[0008] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side view showing the internal configuration of an image reading device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing an electrical configuration of the image reading device shown in FIG. [Diagram 3] FIG. 3 is a diagram showing an example of an operation history of the driving unit 21 in FIG. [Figure 4] FIG. 4 is a flowchart illustrating the operation of the image reading apparatus shown in FIGS. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] Fig. 1 is a side view showing the internal configuration of an image reading device according to an embodiment of the present invention. The image reading device shown in Fig. 1 is a device such as a scanner, a copy machine, a facsimile machine, a multifunction machine, etc. The image reading device shown in Fig. 1 includes contact glasses 1a and 1b, carriages 2 and 3, an imaging lens 4, an image sensor 5, a reference member 6, and a document cover 7.

[0012] The contact glass 1a is installed on the upper surface of the image reading device body, and a document is placed on the contact glass 1a when image reading is performed without using an ADF (Auto Document Feeder) of the document cover 7.

[0013] The contact glass 1b is disposed on the upper surface of the image reading device body, and when an image of a document is read while the document is automatically transported by the ADF of the document cover 7, the document passes over the contact glass 1b.

[0014] The carriage 2 is also installed so as to be movable in the sub-scanning direction by a predetermined drive unit. The carriage 2 has a light source 11 and a mirror 12. The light source 11 is arranged along the main scanning direction, and emits light, for example, from a plurality of light-emitting diodes arranged in an array. The light emitted from the light source 11 is reflected by an original placed on the contact glass 1a, an original passing over the contact glass 1b, a reference member 6 described later, and the like, depending on the position of the carriage 2. The mirror 12 reflects the reflected light from the original, the reference member 6 described later, and the like. When an image of an original is read using the ADF of the original cover 7, the carriage 2 is fixedly arranged below the contact glass 1b.

[0015] Furthermore, the carriage 3 is installed so as to be movable in the sub-scanning direction together with the carriage 2 by a predetermined drive unit. The carriage 3 has mirrors 13 and 14. The mirrors 13 and 14 reflect the light from the mirror 12 of the carriage 2 and emit it along the sub-scanning direction.

[0016] The imaging lens 4 focuses the light from the mirror 14 onto the image sensor 5. The image sensor 5 is a one-dimensional image sensor having a predetermined number of light receiving elements arranged in the main scanning direction, and outputs an electrical signal corresponding to the amount of light received by the pixels of that number of pixels for each line. As the image sensor 5, for example, a CCD (Charge Coupled Device) is used.

[0017] The reference member 6 is a plate-like member arranged on the top surface inside the device to obtain a white reference value for shading correction. The document cover 7 is a member that is rotatably installed so as to be capable of surface contact with the contact glass 1a, and it brings the document into close contact with the contact glass 1a and prevents ambient light from entering the inside of the device through the contact glass 1 during image reading. The document cover 7 also has a built-in ADF, and conveys documents placed on the document tray 7a one by one by conveying rollers 7b driven by a predetermined drive unit, causing them to pass over the contact glass 1b.

[0018] Fig. 2 is a diagram showing the electrical configuration of the image reading device shown in Fig. 1. As shown in Fig. 2, in addition to the image sensor 5, the image reading device includes a drive unit 21, a temperature sensor 22 that detects the outside air temperature (room temperature), and a controller 23.

[0019] The drive unit 21 drives the internal device (here, the above-mentioned carriages 2 and 3) with a motor. The temperature sensor 22 is a sensor that detects the outside air temperature (room temperature). The controller 23 includes a processor that executes a program, an ASIC (Application Specific Integrated Circuit), and the like, and (a) electrically controls the drive unit 21 and the like to control the operation of the transport rollers 12 and 13 and the like, and (b) receives an electrical signal indicating the original image from the image sensor 5, generates image data corresponding to the electrical signal, and performs predetermined image processing on the image data.

[0020] FIG. 3 is a diagram showing an example of an operation history of the driving unit 21 in FIG.

[0021] In addition, the controller 23 (a) repeatedly derives the ratio of the operating time of the drive unit 21 during a monitoring period of a predetermined time length (here, 30 minutes) to the predetermined time length, and (b) transitions the operating mode of the drive unit 21 from the normal operating mode to the motor cooling operating mode according to that ratio.

[0022] Here, it is determined whether or not the driving unit 21 is operating for each unit time (one minute) in the monitoring period, and the above-mentioned ratio is derived.

[0023] Here, the motor cooling operation mode is an operation mode in which the amount of heat generated by the drive unit 21 is reduced compared to the normal operation mode, and causes the drive unit 21 to perform intermittent operation with a predetermined pause time for every predetermined number of sheets.

[0024] Specifically, (a) when the above-mentioned ratio becomes equal to or greater than a predetermined first threshold (e.g., 65%), the controller 23 transitions the operation mode of the drive unit 21 from the normal operation mode to the motor cooling operation mode, and (b) when the above-mentioned ratio becomes equal to or less than a predetermined second threshold (e.g., 60%) that is lower than the first threshold, the controller 23 transitions the operation mode of the drive unit 21 from the motor cooling operation mode to the normal operation mode.

[0025] For example, in the case of operation history #1 in Fig. 3, the total motor operation period is 20 minutes, the above-mentioned ratio is 66% (=20 / 30 x 100), and the operation mode of drive unit 21 is shifted from the normal operation mode to the motor cooling operation mode. Also, for example, in the case of operation history #2 in Fig. 3, the total motor operation period is 15 minutes, the above-mentioned ratio is 50% (=15 / 30 x 100), and the operation mode of drive unit 21 is shifted from the motor cooling operation mode to the normal operation mode.

[0026] Furthermore, the controller 23 adjusts the first and second thresholds according to the above-mentioned outside air temperature. For example, when the outside air temperature is 25 degrees Celsius (i.e., equal to or lower than the first reference temperature), the controller 23 increases the first and second thresholds by 10% each (in the above-mentioned example, the first threshold is 75% and the second threshold is 70%), and when the outside air temperature is 33 degrees Celsius (i.e., equal to or higher than the second reference temperature; lower than the first reference temperature<lower than the second reference temperature), the controller 23 decreases the first and second thresholds by 5% each (in the above-mentioned example, the first threshold is 60% and the second threshold is 55%).

[0027] When continuous reading of original sheets is performed, if the number of continuously read sheets reaches a predetermined threshold value (e.g., 400 sheets) or more, the controller 23 immediately and forcibly shifts the operation mode of the drive unit 21 from the normal operation mode to the motor cooling operation mode, regardless of the above-mentioned ratio. As a result, even if the temperature of the drive unit 21 rises due to continuous reading of original sheets during the monitoring period, the operation mode is appropriately shifted to the motor cooling operation mode.

[0028] The controller 23 may (a) derive the adjusted operating time by multiplying the operating time by a weighting coefficient corresponding to the operating speed of the drive unit 21, and (b) derive the ratio of the adjusted operating time to the above-mentioned specified time length as the above-mentioned ratio.

[0029] In that case, for example, if the drive unit 21 has a high-speed mode and a low-speed mode with different motor rotation speeds, and the weighting coefficient for the high-speed mode is 1 and the weighting coefficient for the low-speed mode is 0.8, then, as in operation history #3 in Figure 3, when the operation time in high-speed mode is 15 minutes and the operation time in low-speed mode is 5 minutes out of a monitoring period of 30 minutes, the adjusted operation time will be 19 minutes (=15×1+5×0.8), and the above-mentioned ratio will be 63% (=19 / 30×100).

[0030] Furthermore, in the motor cooling operation mode, the controller 23 (a) causes the drive unit 21 to perform intermittent operation with a pause for each sheet when the number of read original sheets is equal to or greater than a predetermined threshold, and (b) causes the drive unit 21 to perform intermittent operation with a pause for every predetermined number of sheets when the number of read original sheets is less than the predetermined threshold. That is, for example, when the number of read sheets is 20 or less, a pause is taken for every 5 sheets, and when the number of read sheets is 21 or more, a pause is taken for every sheet.

[0031] It should be noted that the image reading device does not include a temperature sensor for measuring the internal temperature, and a cooling device (such as a cooling fan) for forcibly cooling the internal device.

[0032] Next, the operation of the image reading apparatus will be described with reference to FIG 4. FIG 4 is a flow chart for explaining the operation of the image reading apparatus shown in FIG 1 and FIG 2.

[0033] The controller 23 sets the operation mode of the drive unit 21 to the normal operation mode at the start of scanning the original (step S1), and then derives the ratio of the motor operation period for each monitoring period (here, 30 minutes) as described above (step S2), and determines whether the ratio of the motor operation period is equal to or greater than a first threshold value (here, 65%) (step S3). If the ratio of the motor operation period is not equal to or greater than the first threshold value, the controller 23 continues to keep the operation mode of the drive unit 21 in the normal operation mode, and if the ratio of the motor operation period is equal to or greater than the first threshold value, the controller 23 transitions the operation mode of the drive unit 21 from the normal operation mode to the motor cooling operation mode (step S4).

[0034] Similarly, in the motor cooling operation mode, the controller 23 derives the ratio of the motor operation period for each monitoring period (here, 30 minutes) as described above (step S5), and determines whether or not the ratio of the motor operation period is equal to or less than a second threshold value (here, 60%) (step S6). If the ratio of the motor operation period is not equal to or less than the second threshold value, the controller 23 continues to keep the operation mode of the drive unit 21 in the motor cooling operation mode, and if the ratio of the motor operation period is equal to or less than the second threshold value, the controller 23 transitions the operation mode of the drive unit 21 from the motor cooling operation mode to the normal operation mode (step S1).

[0035] As described above, according to the embodiment, the drive unit 21 drives the internal device with a motor. The controller 23 (a) repeatedly derives the ratio of the operation time of the drive unit 21 in a monitoring period of a predetermined length of time to a predetermined length of time, and (b) shifts the operation mode of the drive unit 21 from the normal operation mode to a motor cooling operation mode (an operation mode that reduces the amount of heat generated by the drive unit 21 compared to the normal operation mode) according to the ratio.

[0036] As a result, the operation mode is switched according to the above-mentioned ratio, which is correlated with the amount of heat generated by the driving unit 21, so that the temperature rise is appropriately suppressed without providing a temperature sensor.

[0037] It should be noted that various changes and modifications to the above-described embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing its intended advantages. In other words, such changes and modifications are intended to be included within the scope of the claims.

[0038] For example, in the above embodiment, the temperature sensor 22 may not be provided, and the user may input the value of the outside air temperature to the image reading device by operating an input device.

[0039] In the above embodiment, the above ratio may be the ratio of the motor operation period of the drive unit of the transport roller 7b. [Industrial Applicability]

[0040] The present invention is applicable to, for example, an image reading device. [Explanation of symbols]

[0041] 2 Carriage (an example of an internal device) 12,13 Transport roller 21 Drive unit 22 Temperature Sensor 23 Controller

Claims

1. A drive unit that drives the internal device with a motor; A controller for controlling the drive unit, The controller (a) repeatedly derives a ratio of an operation time of the drive unit during a monitoring period of a predetermined time length to the predetermined time length, and (b) transitions an operation mode of the drive unit from a normal operation mode to a motor cooling operation mode in accordance with the ratio, the motor cooling operation mode reducing an amount of heat generated by the drive unit compared to the normal operation mode. An image reading device comprising:

2. The image reading device according to claim 1, characterized in that the controller (a) transitions the operating mode of the drive unit from the normal operating mode to the motor cooling operating mode when the ratio becomes equal to or greater than a predetermined first threshold, and (b) transitions the operating mode of the drive unit from the motor cooling operating mode to the normal operating mode when the ratio becomes equal to or less than a predetermined second threshold that is lower than the first threshold.

3. Further equipped with a temperature sensor to detect the outside air temperature, The controller adjusts the first threshold value and the second threshold value in response to the outside air temperature; 3. The image reading device according to claim 2, wherein:

4. The original sheet is a plurality of original sheets, the controller, when performing continuous reading of the document sheets, when the number of the continuously read sheets becomes equal to or greater than a predetermined threshold, forcibly shifts the operation mode of the drive unit from the normal operation mode to the motor cooling operation mode regardless of the ratio; 2. The image reading device according to claim 1,

5. The image reading device according to claim 1, characterized in that the controller (a) derives an adjusted operating time by multiplying the operating time by a weighting coefficient for the operating speed of the drive unit, and (b) derives the ratio of the adjusted operating time to the specified time length as the ratio.

6. The image reading device described in claim 1, characterized in that, in the motor cooling operation mode, (a) when the number of the original sheets read is equal to or greater than a predetermined threshold, the controller causes the drive unit to perform intermittent operation with a pause for each sheet, and (b) when the number of the original sheets read is less than the predetermined threshold, the controller causes the drive unit to perform intermittent operation with a pause for every predetermined number of sheets.

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