JP2011059828A - Optical information reader and method for controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve measurement accuracy of a system timer at the time of a changeover between an operation mode and a sleep mode in a bar code scanner. <P>SOLUTION: An RTC (Real Time Clock) circuit 19 of the bar code scanner counts a clock signal from a Base circuit 17 operating in the sleep mode and the operation mode to generate prescribed timing, and requests an interrupt for system timer measurement in the timing. Then if the RTC circuit 19 transfers from the operation mode to the sleep mode, for example, a frequency of the clock signal is 32 KHz and is not changed to improve the measurement accuracy of the system timer. The interrupt for the system timer measurement is generated at 1 msec interval in the operation mode, and the interrupt for the system timer measurement is generated at 20 msec interval in the sleep mode. A service life of a battery is thereby improved in the sleep mode. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical information reading apparatus that reads information to be read composed of portions having different light reflectivities such as code symbols, and a control method thereof.

  Conventionally, in product inventory management and sales management, etc., product information is sent and received from the host computer, and code symbols such as barcodes and two-dimensional codes affixed to the products are read, and the information is displayed and managed on a liquid crystal display. Many information terminals are used. These are called handy terminals, and are very convenient for an operator to carry around, collect information from each product shelf, and check information with other operators.

  However, on the other hand, the functions are diversified, and the power consumption increases because of the operation. Since the handy terminal uses a rechargeable battery, the power used by one unit is limited. For this reason, various ideas have been applied to save power consumption as much as possible.

  For example, Patent Document 1 discloses a portable information reader that reads a barcode or the like. According to this portable information reading apparatus, two batteries are provided and power is normally supplied from one battery. However, when a large amount of power is used such as high-speed reading, power is supplied from two batteries. Switching is performed. Thus, Patent Document 1 can supply power under the required voltage and current conditions when high-speed reading processing or the like is required while suppressing power consumption.

  Patent Document 2 discloses a barcode reader. According to this bar code reader, illuminance detection means for detecting ambient illuminance is provided, and the brightness of the backlight and LED is controlled according to the brightness of the place of use. Thus, according to Patent Documents 1 and 2, the power consumption is reduced and the life of the battery is extended.

  FIG. 5A and FIG. 5B are diagrams showing an example of operation in an operation mode and a sleep mode of a handy terminal according to a conventional example as an example of a function for saving power consumption. FIG. 5A shows an operation in the operation mode in which all functions are operable, and FIG. 5B shows an operation in the sleep mode in which some functions are stopped to save power consumption. An OSC (oscillator) 15 shown in FIG. 5A oscillates and outputs a constant clock signal to a PLL (Phase Locked Loop) circuit 16. For example, the OSC 15 outputs a 4 MHz clock signal to the PLL circuit 16.

  The PLL circuit 16 multiplies the clock signal input from the OSC 15 and outputs it to the timer 18. For example, the PLL circuit 16 multiplies the 4 MHz clock signal input from the OSC 15 by 12 and outputs the 48 MHz clock signal to the timer 18. In this example, the count value is set in the timer register of the timer 18 so as to generate 1 msec. The timer 18 receives a 48 MHz clock signal from the PLL circuit 16 and compares the clock signal with the first count value of the timer register to generate a timing of 1 msec.

  In the sleep mode of the handy terminal shown in FIG. 5B, the PLL circuit 16 is stopped (OFF). In this case, the timer 18 receives a 32 KHz clock signal from the Base circuit (reference clock generation circuit) 17 and compares this clock signal with the second count value of the timer register to generate a timing of 1 msec. The system timer is measured by accumulating 1 msec timer interrupts generated by the timer 18.

  In this example, when the operation mode is switched to the sleep mode, the frequency of the clock signal for operating the timer 18 is changed from 48 MHz to 32 KHz. This is because the timer 18 inputs a clock signal from the PLL circuit 16 in the operation mode to generate a 1 msec timing, and in the sleep mode, the timer 18 inputs a clock signal from the Base circuit 17 to generate a 1 msec timing.

JP 2006-285539 A JP 2008-287647 A

  By the way, when the timer 18 is switched from the operation mode to the sleep mode, the PLL circuit 16 is changed from ON to OFF and the operating frequency is changed from 48 MHz to 32 KHz, and the measurement method of 1 msec is changed when the operating frequency is changed. Since the timing at which the PLL circuit 16 is changed from ON to OFF is not constant, there is a problem that an error occurs when the sleep mode is switched. Similarly, when switching from the sleep mode to the operation mode, the PLL circuit 16 is changed from OFF to ON so that the operating frequency is changed from 32 KHz to 48 MHz, and the measurement method of 1 msec is changed when the operating frequency is changed. Since the timing at which the PLL circuit 16 is changed from OFF to ON is not constant, there is a problem that an error occurs when the operation mode is switched. If an error occurs in this way, it affects the measurement of the system timer and its accuracy is extremely reduced.

  Therefore, the present invention solves such a problem related to the conventional example, and provides an optical information reading apparatus and a control method therefor capable of improving the measurement accuracy of the system timer at the time of mode switching. Objective.

  In order to solve the above-described problems, the optical information reading apparatus according to the present invention sets a state in which some functions are stopped to save power consumption as a sleep mode and operates in a state in which almost all functions can be operated. When the mode is set, a reference clock generation circuit that operates in the sleep mode and the operation mode, and a clock signal input from the reference clock generation circuit is counted to generate a predetermined timing. And a clock circuit for requesting an interrupt.

  In order to solve the above-described problem, the control method of the optical information reading apparatus according to the present invention is an optical information reading method for reading information to be read that is composed of portions having different light reflectances such as code symbols. A method of controlling an apparatus, wherein the optical information reader is set to a sleep mode when a part of functions is stopped to save power consumption, and an operation mode is set to a state where almost all functions can be operated. A step of generating a clock signal by a reference clock generation circuit operating in the sleep mode and the operation mode, a step of generating a predetermined timing by counting the clock signal, and an interrupt for measuring a system timer at the timing Requesting.

  According to the present invention, the clock signal is generated by the reference clock generation circuit that operates in the sleep mode and the operation mode, and the clock signal generated by the reference clock generation circuit is counted in the sleep mode and the operation mode to obtain a predetermined timing. Generate. Request an interrupt for measuring the system timer at the generated timing. Thus, since the frequency of the clock signal to be counted is the same in the sleep mode and the operation mode, no error occurs in the measurement of the system timer even when the operation mode is shifted to the sleep mode, for example.

  According to the optical information reading apparatus and the control method thereof according to the present invention, the clock signal from the reference clock generation circuit operating in the sleep mode and the operation mode is counted to generate a predetermined timing, and the system timer measurement is performed at this timing. Request an interrupt for

  As a result, for example, the frequency of the clock signal to be counted is not changed even when the operation mode is changed to the sleep mode, so that the measurement accuracy of the system timer can be improved.

2 is a block diagram illustrating a configuration example of a barcode scanner 100. FIG. A is an operation in the operation mode in which almost all functions are operable, and B is an operation in the sleep mode in which some functions are stopped to save power consumption. 4 is a flowchart illustrating an operation example of the barcode scanner 100 in a sleep mode. 2 is a block diagram illustrating a configuration example of a barcode scanner 200. FIG. A and B are figures which show the operation example of the operation mode and sleep mode of the handy terminal which concerns on a prior art example.

  Subsequently, an embodiment for carrying out an optical information reading apparatus and a control method thereof according to the present invention will be described with reference to the drawings. The present invention generates a predetermined timing using a clock signal having the same frequency in the sleep mode and the operation mode, and requests an interrupt for measuring the system timer at this timing so that the measurement accuracy of the system timer can be improved. It is what.

  A bar code scanner 100 shown in FIG. 1 is an example of an optical information reader, and is driven by a battery (a rechargeable battery). The barcode scanner 100 includes a laser light source 1, an optical unit 2, a signal processing circuit 3, a CPU 4, a RAM (Random Access Memory) 8, a ROM (Read Only Member) 9, a keyboard 10, a display 11, a switch 12, a power source 13, and a power source. A control circuit 14, an OSC (oscillator) 15, a PLL (Phase Locked Loop) circuit 16, and an RTC (Real Time Clock) circuit 19 are provided.

  The switch 12 switches the power source 13 of the barcode scanner 100 on / off. The barcode scanner 100 has an operation mode and a sleep mode. The sleep mode is a state in which some functions are stopped to save power consumption, and the operation mode is a state in which almost all functions are operable. For example, the switching method of each mode is switched by a function key (not shown) of the keyboard 10. The switching method of each mode is not limited to this, and it may be controlled to automatically switch to the sleep mode when the non-operation time of the barcode scanner 100 elapses for a fixed time and to switch from the sleep mode to the operation mode by sensor detection.

  The power supply control circuit 14 controls the power supply voltage supplied from the power supply 13 to the CPU 4. For example, in the sleep mode, the power supply control circuit 14 stops some functions of the CPU 4 to save power consumption. In this example, in the sleep mode, the power supply control circuit 14 stops the power supply voltage supplied to the OSC 15 and the PLL circuit 16.

  The laser light source 1 irradiates light toward a bar code which is an example of a code symbol composed of portions having different light reflectivities. For example, the laser light source 1 emits a laser beam from the light emitting point toward the condenser lens 2 a of the optical unit 2. The condensing lens 2 a condenses the laser beam emitted from the laser light source 1. A scan mirror 2b is arranged at the subsequent stage of the condenser lens 2a. The scan mirror 2b deflects the laser beam collected by the condenser lens 2a.

  In a state where the barcode scanner 100 is directed to the barcode, the laser beam deflected by the scan mirror 2b is applied to the barcode to scan the barcode. The imaging lens 2 c receives the reflected light reflected from the barcode and forms an image of the reflected light on the photoelectric converter 3 a of the signal processing circuit 3. The photoelectric converter 3a receives the reflected light, converts it into an electrical signal corresponding to the intensity, and outputs it to the binarization processing unit 3b. The binarization processing unit 3b differentiates this electric signal to obtain a binarized signal. For example, the binarization processing unit 3b performs amplification gain adjustment, noise processing, and the like of the electric signal, and differentiates the electric signal to obtain a differential signal. The binarization processing unit 3b obtains an inflection point indicating the boundary between the black bar and the white bar of the barcode from the differential signal, obtains a binarization signal from the inflection point, and outputs it to the CPU 4.

  The CPU 4 generates an interrupt at the edge timing of the binarized signal and obtains the barcode length. The CPU 4 compares the obtained bar code width length with a threshold value to discriminate a thick bar / thin bar or the like and converts it into a bar code character.

  In this example, the CPU 4 includes an interrupt controller 5 and a timer 6. The interrupt controller 5 generates an interrupt to the timer 6 at the timing of the rising edge in the binarized signal. The timer 6 obtains the edge interval (time interval) of the binarized signal when an interrupt occurs, and obtains the width of the barcode from this edge interval.

  The OSC 15 shown in FIG. 1 oscillates and outputs a constant clock signal to the PLL circuit 16. For example, the OSC 15 outputs a 4 MHz clock signal to the PLL circuit 16. The PLL circuit 16 multiplies the clock signal input from the OSC 15. For example, the PLL circuit 16 multiplies the 4 MHz clock signal input from the OSC 15 by 12 to generate a 48 MHz clock signal. The CPU 4 operates with a 48 MHz clock signal generated by the PLL circuit 16.

  The Base circuit 17 (see FIG. 2) operates in the sleep mode and the operation mode. The RTC circuit 19 is an example of a clock circuit and functions as a real time clock. The RTC circuit 19 counts the clock signal input from the Base circuit 17 to generate a predetermined timing, and requests an interrupt for measuring the system timer at this timing. As a result, for example, the frequency of the clock signal to be counted is not changed even when the operation mode is changed to the sleep mode, so that the measurement accuracy of the system timer can be improved. The Base circuit 17 is an example of a reference clock generation circuit.

  The ROM 9 stores a real-time OS (for example, μITron) of the barcode scanner 100 and is referred to by the CPU 4. The execution unit of real-time processing is roughly divided into tasks and handlers. The task is activated, interrupted, resumed, and terminated by the real-time OS. On the other hand, the handler is a program unit that is activated without going through the OS by various events occurring inside and outside the CPU 4. When the CPU 4 detects the occurrence of an interrupt, it switches the execution state to the interrupt processing execution state, and executes the interrupt handler registered in the CPU 4. Since the OS cannot control the execution of the interrupt handler, the interrupt handler has a higher priority than the task to which the normal execution state of the CPU 4 is applied.

  The RAM 8 is used as a work memory for the CPU 4. Various instructions are input to the keyboard 10 from an operator. The display 11 displays the operation state of the barcode scanner 100, an instruction from the operator, and the like.

  Next, an operation example of the barcode scanner 100 will be described. In this example, in the operation mode, the RTC circuit 19 generates a predetermined timing (for example, 1 msec) by counting the clock signal input from the Base circuit 17 (see FIG. 2), and interrupts for system timer measurement at this timing. Is requested to the interrupt controller 5. When receiving the interrupt request for measuring the system timer, the interrupt controller 5 generates an interrupt to the CPU 4.

  In an operation mode, when a trigger switch (not shown) is turned on by an operator with the barcode scanner 100 facing the barcode, a laser beam is emitted from the light emission point of the laser light source 1 of the barcode scanner 100. This laser beam is condensed by the condensing lens 2 a of the optical unit 2. The condensed laser beam is deflected by the scan mirror 2b and applied to the barcode to scan the barcode.

  Light is reflected from the barcode, and the reflected light is imaged on the photoelectric converter 3a by the imaging lens 2c. The reflected light imaged on the photoelectric converter 3a is converted into an electric signal corresponding to the intensity by the photoelectric converter 3a. This electric signal is differentiated by the binarization processing unit 3b to obtain a binarized signal. The interrupt controller 5 generates a laser interrupt to the timer 6 at the edge timing in the binarized signal. The timer 6 obtains the edge interval (time interval) of the binarized signal when the laser interruption occurs, and obtains the width of the barcode from this edge interval.

  When a trigger switch (not shown) is turned off, the laser beam emitted from the laser light source 1 is stopped and the barcode scanning process is stopped.

  When the mode is switched to the sleep mode by a function key (not shown) of the keyboard 10, the power supply control circuit 14 stops some functions of the CPU 4 and saves power consumption. In this example, in the sleep mode, the power supply control circuit 14 stops the power supply voltage supplied to the OSC 15 and the PLL circuit 16 and supplies the power supply voltage to the RTC circuit 19.

  In this sleep mode, the RTC circuit 19 counts the clock signal input from the Base circuit 17 (see FIG. 2) to generate a predetermined timing, and requests an interrupt for system timer measurement to the interrupt controller 5 at this timing. To do. For example, in the sleep mode, an interrupt for measuring the system timer is generated at a later timing (for example, 20 msec) than in the operation mode. When receiving the interrupt request for measuring the system timer, the interrupt controller 5 generates an interrupt to the CPU 4. The CPU 4 activates the interrupt handler and measures the system timer.

  As described above, the present invention measures the system timer using the RTC circuit 19 that is driven at the same frequency in the sleep mode and the operation mode. As a result, since the frequency of the clock signal for measuring the system timer is not changed even when the operation mode is shifted to the sleep mode, the measurement accuracy of the system timer can be improved. Also, in sleep mode, the system timer measurement interrupt is generated at the timing of 20msec and the sleep mode is kept long, so the battery life can be improved compared to the case of generating the system timer measurement interrupt at the timing of 1msec. .

  Next, the system timer measurement process in the operation mode and the sleep mode will be described with reference to FIGS. 2A and 2B. FIG. 2A shows an operation in an operation mode in which almost all functions are operable. In the operation mode, the OSC 15 shown in FIG. 2A oscillates and outputs a constant clock signal, for example, a 4 MHz clock signal to the PLL circuit 16. The PLL circuit 16 multiplies the clock signal input from the OSC 15 by, for example, 12 times to generate a 48 MHz clock signal. This 48 MHz clock signal is used as an operation clock of the CPU 4.

  The Base circuit 17 shown in FIG. 2A outputs a 32 KHz clock signal to the RTC circuit 19. The RTC circuit 19 counts the clock signal input from the Base circuit 17 to generate a 1 msec timing, and requests an interrupt for system timer measurement from the interrupt controller 5 (see FIG. 1) at this timing. In this example, in order to operate the function of the RTC circuit 19 that generates an interrupt every 1 sec at 1000 times, the register of the RTC circuit 19 is set with a first count value that generates an interrupt every 1 msec. Yes. The RTC circuit 19 receives a 32 KHz clock signal from the Base circuit 17 and compares the clock signal with the first count value of the register to generate a timing of 1 msec. The system timer is measured by accumulating 1 msec interrupts generated by the RTC circuit 19.

  FIG. 2B shows an operation in the sleep mode in which some functions are stopped to save power consumption. In the sleep mode, the OSC 15 and the PLL circuit 16 shown in FIG. 2B are stopped, and the Base circuit 17 and the RTC circuit 19 are driven. In the sleep mode, a second count value for generating an interrupt every 20 msec is set in the register of the RTC circuit 19. The RTC circuit 19 inputs a clock signal of 32 KHz from the Base circuit 17, compares the clock signal with the second count value of the register, and requests an interrupt at a timing of 20 msec. The system timer is measured by accumulating 20 msec timer interrupts generated by the RTC circuit 19.

  In this example, when the operation mode is switched to the sleep mode, the frequency of the clock signal for operating the RTC circuit 19 is unified to 32 KHz, and the frequency of the clock signal is changed from 48 MHz to 32 KHz as shown in FIGS. 5A and 5B. Not changed. This is because the RTC circuit 19 inputs the clock signal from the same Base circuit 17 in the operation mode and the sleep mode. As described above, since the frequency of the clock signal to be counted is not changed even when the operation mode is shifted to the sleep mode, the measurement accuracy of the system timer can be improved. Further, in the sleep mode, an interrupt for measuring the system timer is generated at a timing of 20 msec, so that the battery life can be improved as compared with a case where an interrupt for measuring the system timer is generated at a timing of 1 msec.

  Next, an example of the operation of the barcode scanner 100 in the sleep mode will be described with reference to FIG. In this example, the mode is switched to the sleep mode by a function key (not shown) of the keyboard 10. In the sleep mode, the OSC 15 and the PLL circuit 16 shown in FIG. 2B are stopped, and the Base circuit 17 and the RTC circuit 19 are driven.

  When the mode is switched to the sleep mode, in step ST1 shown in FIG. 3, the CPU 4 sets a second count value for generating an interrupt every 20 msec in the register of the RTC circuit 19, and proceeds to step ST2.

  In step ST2, the power supply control circuit 14 stops the power supply voltage supplied to the OSC 15 and the PLL circuit 16, and proceeds to step ST3. In step ST3, the OSC 15 and the PLL circuit 16 are stopped, and the sleep mode in which the Base circuit 17 and the RTC circuit 19 are driven is set. Subsequently, the process proceeds to step ST4.

  In step ST4, the RTC circuit 19 inputs a clock signal of 32 KHz from the Base circuit 17, compares this clock signal with the second count value of the register, and requests an interrupt to the interrupt controller 5 at a timing of 20 msec. . The interrupt controller 5 receives an interrupt request from the RTC circuit 19, generates an interrupt to the CPU 4, and proceeds to step ST5.

  In step ST5, the power supply control circuit 14 supplies the power supply voltage to the OSC 15 and the PLL circuit 16, and proceeds to step ST6. In step ST6, the CPU 4 activates the interrupt handler based on the interrupt input from the interrupt controller 5, measures the system timer, and proceeds to step ST7.

  In step ST7, the CPU 4 determines the cause of the interrupt. If the cause of the interrupt is an RTC interrupt, the CPU 4 returns to step ST2, maintains the sleep mode, generates an interrupt every 20 msec, and measures the system timer. If the cause of the interrupt is other than the RTC interrupt, the process proceeds to step ST8. In step ST8, the CPU 4 sets the first count value for generating an interrupt every 1 msec in the register of the RTC circuit 19 to cancel the sleep mode.

  Thus, according to the barcode scanner 100 and the control method thereof according to the present invention, the RTC circuit 19 counts the clock signal from the Base circuit 17 that operates in the sleep mode and the operation mode, and generates a predetermined timing. At this timing, an interrupt for system timer measurement is requested. As a result, for example, the frequency of the clock signal to be counted is not changed even when the operation mode is changed to the sleep mode, so that the measurement accuracy of the system timer can be improved.

  In the operation mode, an interrupt for measuring the system timer is generated in 1 msec, and in the sleep mode, an interrupt for measuring the system timer is generated in 20 msec. This can improve the battery life in the sleep mode. For example, if a system timer measurement interrupt is generated at 1 msec in sleep mode, the battery life is about 70 hours. If a system timer measurement interrupt is generated at 20 msec in sleep mode, the battery life is about 100 hours. Improved.

  In the embodiment, the description is based on the specification of μ, but the real-time OS to be applied is not limited to μITron. In the embodiment, the optical unit using the scanning mirror is used, but the same effect can be obtained even in an apparatus incorporating a camera module that captures a code symbol with a solid-state imaging device such as a CMOS sensor.

  For example, the barcode scanner 200 shown in FIG. 4 is an example of an optical information reading device including a CMOS sensor, and includes a lens 21, a CMOS sensor 22, a signal processing circuit 23, a CPU 4, a RAM 8, a ROM 9, a keyboard 10, a display 11, and a switch. 12, a power supply 13, a power supply control circuit 14, and an OSC15. The same components as those of the barcode scanner 100 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The lens 21 shown in FIG. 4 forms an image on the CMOS sensor 22 of the reflected light of the barcode irradiated by an unillustrated LED or the like. The CMOS sensor 22 converts the reflected light into an electric signal and outputs it to the signal processing circuit 23. The signal processing circuit 23 binarizes the electric signal and outputs a binarized signal to the CPU 4. The CPU 4 generates an interrupt at the edge timing of the binarized signal and obtains the barcode length. The CPU 4 compares the obtained bar code width length with a threshold value to discriminate a thick bar / thin bar or the like and converts it into a bar code character. The present invention can achieve the same effect even in an apparatus incorporating a camera module that images a code symbol with a solid-state imaging device such as a CMOS sensor.

  The present invention is extremely suitable when applied to an optical information reading apparatus that reads information to be read, which is composed of portions having different light reflectivities such as code symbols.

  4 ... CPU, 5 ... interrupt controller, 17 ... Base circuit (reference clock generation circuit), 19 ... RTC circuit (clock circuit), 100 ... barcode scanner (optical information reading) apparatus)

Claims (4)

When the sleep mode is set to save some power by stopping some functions, and the operation mode is set to a state where almost all functions can be operated.
A reference clock generation circuit that operates in the sleep mode and the operation mode;
An optical information reading apparatus comprising: a clock circuit that counts a clock signal input from the reference clock generation circuit to generate a predetermined timing, and requests an interrupt for measuring a system timer at the timing.   The optical information reading apparatus according to claim 1, wherein the clock circuit functions as a real-time clock.   The optical information reader according to claim 1, wherein in the sleep mode, an interrupt for measuring the system timer is generated at a timing later than that in the operation mode. A method of controlling an optical information reader that reads information to be read that is composed of parts having different light reflectivities such as code symbols,
The optical information reader is
When the sleep mode is set to save some power by stopping some functions, and the operation mode is set to a state where almost all functions can be operated.
Generating a clock signal by a reference clock generation circuit operating in the sleep mode and the operation mode;
Counting the clock signal to generate a predetermined timing;
Requesting an interrupt for system timer measurement at the timing;
A method for controlling an optical information reading apparatus, comprising:

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