JP6037437B2 - Electronic device, backlight lighting control method and program - Google Patents

Description

  The present invention relates to an electronic device, a backlight lighting control method, and a program, and more particularly to an electronic device and the like that can suppress the generation of noise from a multilayer ceramic chip capacitor that is generated when the backlight of a liquid crystal display unit is turned on.

  Increasing number of portable electronic devices equipped with liquid crystal modules for display, such as mobile phone terminals (smartphones and feature phones), notebook personal computers, tablet terminals, portable game consoles, portable music players, GPS devices, etc. ing. As the light source of the backlight of the liquid crystal module of such an electronic device, two types of systems, that is, a cold cathode tube and an LED (Light Emitting Diode) are mainly used. Since the LED light source does not require a high voltage power source, it is suitable for portable electronic devices, particularly battery-driven devices.

  In such electronic devices, a multilayer ceramic chip capacitor is usually used as a capacitor which is one of basic elements in an electronic circuit. This is because the multilayer ceramic chip capacitor can obtain good characteristics even in a high frequency region, and is also suitable for reducing the size and weight of the device and reducing the price. It is said that there are about 700 billion capacitors produced and used for electronic devices all over the world, and about 80% of them are said to be multilayer ceramic chip capacitors (from Non-Patent Document 1).

  FIG. 13 is an explanatory diagram illustrating a configuration of a general electronic device 910. The electronic device 910 includes a liquid crystal display unit 911 that performs screen display using liquid crystal, a backlight unit 912 that emits light toward the user from behind the liquid crystal display unit 911, and a drive circuit that controls the liquid crystal display unit 911 and the backlight unit 912. Including a control board 913 and a device board 914 responsible for the main processing functions of the electronic apparatus 910 as a whole.

  The control board 913 includes a liquid crystal driving unit 913a and a backlight driving unit 913b for controlling the liquid crystal display unit 911 and the backlight unit 912, respectively. The device board 914 includes a processor 914a that is a main body for executing a computer program, a storage unit 914b that stores data, an operation input unit 914c that receives an input operation from a user, and audio data that can be processed by the processor 914a. Voice input means 914d for input.

  The processing result by the processor 914a is displayed on the liquid crystal display unit 911. Then, in response to a control command from the processor 914a, the liquid crystal drive unit 913a and the backlight drive unit 913b control the liquid crystal display unit 911 and the backlight unit 912, respectively. The operation input unit 914c may be a numeric keypad, a keyboard, a mouse, or the like, or may be a touch screen attached to the surface of the effective display area of the liquid crystal display unit 911. The voice input means 914d is typically a microphone.

  Although many elements are used for the electronic device 910 other than those described here, only the elements necessary for explaining the concept of the present invention are shown here, and other hardware and software are not described. No particular explanation will be given.

  FIG. 14 is an explanatory diagram illustrating adjustment of the luminance of the backlight unit 912 performed by the electronic device 910 illustrated in FIG. 13. The backlight drive unit 913b drives the backlight unit 912 by a PWM (Pulse Width Modulation) method. In other words, the liquid crystal display unit 911 applies a pulse voltage with a constant frequency to the backlight unit 912 to light the backlight unit 912.

  The backlight drive unit 913b adjusts the luminance when the backlight unit 912 is turned on, that is, the brightness of the liquid crystal display unit 911 by changing the duty ratio of the pulse voltage. FIG. 15 is a graph showing the relationship between the duty ratio of the pulse voltage generated by the backlight driving unit 913b and the luminance of the backlight unit 912 in the electronic device 910 shown in FIG. It can be considered that the relationship between the duty ratio and the luminance is almost directly proportional.

  There are the following technical documents related to this. Among them, Patent Document 1 describes a mounting structure for a heat dissipating fin that is difficult to transmit vibration generated in a substrate. Patent Document 2 describes a light emission driving device that removes a resonance frequency from an audible band by turning on / off a switch circuit connected in series to an LED light source in accordance with a pulse signal. Patent Document 3 describes a display device that changes the drive order of display devices when noise is detected by a microphone.

  Patent Document 4 describes an electronic device in which the frequency of a pulse voltage applied to a backlight is changed when a voice call or recording operation is started, and the frequency is restored when the operation is completed. Patent Document 5 describes a backlight drive circuit that maintains a drive voltage in a load circuit even during an off period of a pulse voltage. Patent Document 6 describes a drive circuit that separates a capacitor to prevent the capacitor from being discharged when the pulse voltage has a minimum value.

  Non-Patent Document 1 describes the basic structure and manufacturing method of a multilayer ceramic chip capacitor, and Non-Patent Document 2 describes squeal that is a phenomenon peculiar to capacitors having this structure (details will be described later). ing.

JP 2006-091621 A JP 2006-114324 A JP 2006-145640 A JP 2010-141681 A JP 2011-138666 A Special table 2010-515212 gazette

TDK Public Relations Department, “Multilayer ceramic chip capacitors are made in this way”, May 24, 2012 [Search September 20, 2012], IT Media Co., Ltd., Internet <URL: http: // ednjapan. com / edn / articles / 1205/24 / news099.html> Maekawa Shinmitsu, “How Murata Demonstrates Countermeasures to Deal with Old and New Problems“ Condenser Sound ””, July 25, 2011, [Search September 20, 2012], IT Media Corporation, Internet <URL: http://eetimes.jp/ee/articles/1107/25/news098.html>

  In the electronic device 910 shown in FIG. 13 described above, the capacitor included in the backlight drive unit 913b is often a multilayer ceramic chip capacitor. However, as described in Non-Patent Document 2, a multilayer ceramic chip capacitor has its basic structure, and when a voltage is applied, the electrode itself expands and contracts due to a piezoelectric effect (piezo effect). By continuing to apply a pulse voltage having a constant frequency in the PWM method, the expansion and contraction of the electrode occurs at a constant frequency, and thereby the ceramic capacitor and the control board 913 attached thereto vibrate.

  FIG. 16 is an explanatory diagram showing the structure of the multilayer ceramic chip capacitor 921 mounted on the control board 913 (backlight drive unit 913b) of the electronic device 910 shown in FIG. The multilayer ceramic chip capacitor 921 has a structure in which a large number of internal electrodes 921a and ceramic dielectrics 921b are stacked. External electrodes 921c to 92d that are electrically connected to the internal electrode 921a are formed on the left and right sides of the stack. When voltage is applied to the external electrodes 921c to 921d of the multilayer ceramic chip capacitor 921, the piezoelectric effect (piezo effect) causes contraction in the direction parallel to the internal electrode 921a and expansion in the direction perpendicular to the internal electrode 921a. .

  FIG. 17 is an explanatory diagram showing the vibration of the control board 913 generated along with the expansion and contraction of the electrodes generated in the multilayer ceramic chip capacitor 921 shown in FIG. FIG. 17A shows a state where no voltage is applied to the multilayer ceramic chip capacitor 921, and FIG. 17B shows a state where a voltage is applied. When the expansion and contraction of the electrode shown in FIG. 16 occurs in the multilayer ceramic chip capacitor 921 attached to the control board 913, the control board 913 is bent as a result.

  Since a pulse voltage having a constant frequency is continuously applied to the multilayer ceramic chip capacitor 921, this deflection becomes a vibration having a specific frequency. When the frequency of the vibration overlaps with the human audible frequency range, the vibration may be recognized by the human ear as a sound. This phenomenon is generally called “squealing” or “squeaking”. This is an unavoidable phenomenon due to the basic structure of the multilayer ceramic chip capacitor shown in FIG.

  Moreover, the frequency of the vibration is not always equal to the frequency of the pulse voltage. For example, the frequency of vibration depends on the frequency of the pulse voltage, the structure of the control board 913 itself (dimensions, number of layers, wiring pattern, etc.) and the arrangement and mounting state of the capacitor on the control board 913 itself. It is determined. Therefore, it is practically impossible to predict in advance at the design stage whether or not the vibration frequency is an audible frequency (= whether or not sound is produced).

  Since the amplitude of the vibration is fine (less than 1 nm), the sound generated by the squeal is very small and rarely heard directly by the human ear operating the electronic device 910. However, when this vibration is transmitted to the voice input means 914d in the same device, it is picked up and amplified by an amplifier in the device, and mixed in the sound as noise not intended by the user. That is, such noise is included in the sound to be recorded and the sound transmitted to the other party in a voice call.

  As described above, this noise problem is unavoidable due to the basic structure of the multilayer ceramic chip capacitor. Although there is a capacitor that does not generate sound, it cannot replace the multilayer ceramic chip capacitor. In particular, since electronic devices 910 are always required to be smaller and lighter in price and lower in price, capacitors that can eliminate noise by substituting multilayer ceramic chip capacitors that are most suitable for such applications are currently available. not exist.

  Furthermore, in terms of the fact that the electronic device 910 is always required to be smaller and lighter and lower in price, the sound input means 914d is separated from the backlight drive unit 913b, and a sound insulating material is disposed between the two. It is also not practical to solve the problem of sound generation by reducing the size and weight of the equipment and increasing the restrictions on the arrangement of each component. In particular, it becomes difficult to design a device in consideration of usability (ease of use).

  18 to 19 are explanatory views showing the physical arrangement of the voice input means 914d and the backlight drive unit 913b in the electronic device 910 shown in FIG. FIG. 18A shows a state in which the voice input unit 914d and the backlight drive unit 913b are close to each other, and a state in which the voice input unit 914d and the backlight drive unit 913b are separated but the voice input unit 914d cannot be disposed. Each is shown.

  FIG. 19C shows a state in which the voice input unit 914d and the backlight drive unit 913b are separated from each other, but it is against the miniaturization of the apparatus. FIG. 19D shows a state in which the voice input unit 914d and the backlight drive unit 913b are separated. A state in which a sound insulating material 915 is arranged between them is shown.

  As shown in FIG. 18 (a), when the voice input unit 914d and the backlight drive unit 913b are disposed at physically close positions, the sound generated by the backlight drive unit 913b is also transmitted to the voice input unit 914d. Easy to communicate.

  In order to prevent this, as shown in FIG. 18B, a method of arranging the voice input unit 914d as far as possible from the backlight driving unit 913b can be considered. However, since the voice input means 914d may not be arranged at a desired position in the apparatus, the voice input means 914d cannot be arranged at the position shown in FIG. In particular, when the electronic device 910 is a mobile phone terminal, the voice input unit 914d needs to be placed near the user's mouth in a state where the user puts his ear on the speaker. The position will be greatly restricted.

  Further, as shown in FIG. 19 (c), disposing the audio input unit 914d as far as possible from the backlight driving unit 913b within a range in which the audio input unit 914d can be disposed impairs the small size and lightness of the electronic device 910 itself. Is not a practically possible solution. As shown in FIG. 19 (d), there may be a solution that a sound insulating material 915 is disposed between the voice input unit 914d and the backlight driving unit 913b, but this increases the number of parts. This is contrary to the demand for reducing the size and weight of the apparatus, as well as the demand for cost reduction.

  Techniques that can solve this problem are not described in prior art documents. The electronic device described in Patent Document 4 changes the frequency of the pulse voltage applied to the backlight when the voice call or recording operation is started, and returns the frequency to the original state when the operation ends. Although we are trying to reduce the impact, as mentioned above, it is impossible to predict the presence or absence of noise in advance at the design stage, so it is not possible to deny the possibility that noise will occur at the changed frequency. . The same applies to the other patent documents 1 to 3 and 5 to 6. Non-Patent Documents 1 and 2 merely describe the phenomenon of sounding with multilayer ceramic chip capacitors as described above.

  An object of the present invention is to provide an electronic device, a backlight lighting control method, and a program capable of preventing noise caused by the sound of the multilayer ceramic chip capacitor from being mixed into the sound without impairing the small size and lightness of the electronic device. It is to provide.

In order to achieve the above object, an electronic apparatus according to the present invention includes a liquid crystal display unit that displays a screen using liquid crystal, a backlight unit that emits light toward the user from behind the liquid crystal display unit, and voice as audio data. An operation mode for determining whether or not the voice input means is being used, including a backlight drive unit that generates a pulse voltage for lighting the backlight unit. A main control unit having a determination function and a backlight control function for sending a control signal for changing the waveform of the pulse voltage to the backlight drive unit when the voice input unit is used, and the voice input unit is used; If the noise of the audible frequency band is generated in the voice data input by the voice input means, the backlight control function Wherein the sending the control signal to change the frequency without changing the duty ratio of the voltage to the backlight drive section.

In order to achieve the above object, a backlight lighting control method according to the present invention includes a liquid crystal display unit that displays a screen using liquid crystal, a backlight unit that emits light toward the user from behind the liquid crystal display unit, and audio. In an electronic device having voice input means for inputting data, the operation mode determination function determines whether the voice input means is used, and the determination result as to whether the voice input means is used. In response, the backlight control function sends a control signal for changing the waveform of the pulse voltage to the backlight driver, and the backlight driver generates a pulse voltage whose waveform has been changed according to the control signal. characterized by applying to the write unit, when the voice input means is utilized, varying the sound input from the sound input means to the sampling unit is a digital data When the frequency analysis function extracts a frequency with a high sound pressure level from the digital data, the extracted frequency is within the audible frequency region, and the change in the sound pressure level at the frequency is within a predetermined threshold. In addition, when the noise determination function determines that noise has occurred, the voice input means is used, and noise in the audible frequency band is generated in the voice data input by the voice input means In addition, the backlight control function sends a control signal for changing the frequency without changing the duty ratio of the pulse voltage to the backlight driver .

To achieve the above object, a backlight lighting control program according to the present invention includes a liquid crystal display unit that displays a screen using liquid crystal, a backlight unit that emits light toward the user from behind the liquid crystal display unit, and audio. An electronic apparatus having voice input means for inputting data and a backlight driving section for generating a pulse voltage for lighting the backlight section, wherein the voice input means is used for a processor included in the electronic apparatus. And a procedure for sending a control signal for changing the waveform of the pulse voltage to the backlight drive unit in accordance with the procedure for determining whether or not the voice input means is used. and then, the procedure for controlling the operation of converting the sound input from the sound input means into digital data, high-frequency sound pressure level from the digital data And a procedure for determining that noise is generated when the extracted frequency is in the audible frequency region and the change in the sound pressure level at the frequency is within a predetermined threshold. Without further changing the duty ratio of the pulse voltage when the voice input means is used and the noise of the audible frequency band is generated in the voice data inputted by the voice input means. The processor is further caused to execute a procedure for sending a control signal for changing the frequency to the backlight driving unit.

  As described above, the present invention is configured to change the waveform of the pulse voltage in accordance with the determination result of whether or not the voice input means is used. Therefore, the resonance condition is set when the voice input means is used. It can be removed to reduce noise. As a result, it is possible to prevent the noise caused by the sound from entering the sound without impairing the small size and lightness of the electronic device, and the backlight lighting control method having the excellent feature. And can provide programs.

It is explanatory drawing shown about the structure of the electronic device which concerns on the 1st Embodiment of this invention. It is explanatory drawing shown about the more detailed structure of the control board and apparatus board | substrate shown in FIG. 3 is a flowchart illustrating an operation for controlling lighting of a backlight unit of the electronic device illustrated in FIG. 1. FIG. 4 is an explanatory diagram showing a duty ratio of a voltage applied to the backlight unit 12 by the backlight control function shown as step S102 in FIG. FIG. 4A shows a state where the duty ratio is not 100%, and FIG. 4B shows a state where the duty ratio is 100%. It is explanatory drawing shown about the structure of the electronic device which concerns on the 2nd Embodiment of this invention. It is explanatory drawing shown about the more detailed structure of the control board and apparatus board | substrate shown in FIG. FIG. 7 is an explanatory diagram showing pulse voltages having the same duty ratio and different frequencies generated by the backlight drive unit shown in FIG. 6. 7 is a flowchart illustrating an operation of controlling lighting of a backlight unit of the electronic device illustrated in FIG. 6. It is explanatory drawing shown about the structure of the electronic device which concerns on the 3rd Embodiment of this invention. It is explanatory drawing shown about the more detailed structure of the apparatus board | substrate shown in FIG. It is explanatory drawing shown about the normal mode and high quality mode which the operation mode determination function shown in FIG. 10 determines. 10 is a flowchart illustrating an operation of controlling lighting of a backlight unit of the electronic device illustrated in FIG. 9. It is explanatory drawing shown about the structure of a general electronic device. It is explanatory drawing shown about adjustment of the brightness | luminance of a backlight part performed with the electronic device shown in FIG. 14 is a graph illustrating a relationship between a duty ratio of a pulse voltage generated by a backlight driving unit and luminance of the backlight unit in the electronic device illustrated in FIG. 13. It is explanatory drawing shown about the structure of the multilayer ceramic chip capacitor mounted on the control board (backlight drive part) of the electronic device shown in FIG. It is explanatory drawing shown about the vibration of the control board which generate | occur | produces with the expansion-contraction of the electrode which generate | occur | produces in the multilayer ceramic chip capacitor shown in FIG. FIG. 17A shows a state where no voltage is applied to the multilayer ceramic chip capacitor, and FIG. 17B shows a state where a voltage is applied. FIG. 14 is an explanatory diagram showing a physical arrangement of voice input means and a backlight drive unit in the electronic device shown in FIG. 13. FIG. 18A shows a state in which the voice input unit 914d and the backlight drive unit 913b are close to each other, and a state in which the voice input unit 914d and the backlight drive unit 913b are separated but the voice input unit 914d cannot be disposed. Each is shown. It is a continuation of FIG. FIG. 19C shows a state in which the voice input unit 914d and the backlight drive unit 913b are separated from each other, but it is against the miniaturization of the apparatus. FIG. 19D shows a state between the voice input unit 914d and the backlight drive unit 913b. Each shows a state where the sound insulating material 915 is arranged.

(First embodiment)
Hereinafter, the structure of the 1st Embodiment of this invention is demonstrated based on attached FIG.
First, the basic content of the present embodiment will be described, and then more specific content will be described.
The electronic apparatus 10 according to the present embodiment includes a liquid crystal display unit 11 that displays a screen using liquid crystal, a backlight unit 12 that emits light from behind the liquid crystal display unit to a user, and an audio input that inputs audio as audio data. An electronic device comprising means 14d. The electronic device 10 includes a backlight driving unit 13b that generates a pulse voltage for lighting the backlight unit, an operation mode determination function 22 that determines whether or not a voice input unit is used, and a voice input. A main control unit (processor 14a) having a backlight control function 21 for sending a control signal for changing the waveform of the pulse voltage to the backlight drive unit when the means is used.

  The backlight control function 21 sends a control signal for setting the duty ratio of the pulse voltage to 100% to the backlight drive unit 13b when the audio input unit 14a is used.

By providing the above configuration, the electronic device 10 can prevent noise caused by sound from being mixed into the sound without impairing the small size and lightness of the electronic device.
Hereinafter, this will be described in more detail.

  FIG. 1 is an explanatory diagram showing the configuration of the electronic device 10 according to the first embodiment of the present invention. The electronic device 10 includes a liquid crystal display unit 11 that performs screen display using liquid crystal, a backlight unit 12 that emits light from behind the liquid crystal display unit 11 toward the user, and a drive circuit that controls the liquid crystal display unit 11 and the backlight unit 12. Including a control board 13 and a device board 14 that bears the main processing functions of the electronic apparatus 10 as a whole. The light source of the backlight unit 12 may be a cold cathode tube or an LED (light emitting diode).

  FIG. 2 is an explanatory diagram showing a more detailed configuration of the control board 13 and the apparatus board 14 shown in FIG. The control board 13 includes a liquid crystal driving unit 13a and a backlight driving unit 13b that control the liquid crystal display unit 11 and the backlight unit 12, respectively. The backlight driving unit 13b generates a voltage for lighting the backlight unit 12.

  The device board 14 includes a processor 14a that is a main body for executing a computer program, a storage unit 14b that stores data, an operation input unit 14c that receives an input operation from a user, and a voice input unit 14d that converts voice into an electrical signal. And sampling means 14e for converting the electrical signal converted from the sound into sound data that can be processed by the processor 14a.

  The processing result by the processor 14 a is displayed on the liquid crystal display unit 11. The operation input unit 14 c may be a numeric keypad, a keyboard, a mouse, or the like, or may be a touch screen attached to the surface of the effective display area of the liquid crystal display unit 11. The voice input unit 14d is typically a microphone.

  The processor 14a operates as the backlight control function 21 and the operation mode determination function 22 by the operation of the LCD control program. The operation mode determination function 22 determines the type of operation being performed by the processor 14a. The backlight control function 21 sends a control signal for determining the waveform of the voltage generated in the backlight drive unit 13b to the backlight drive unit 13b based on the determined type of operation, and through this control signal. The backlight unit 12 is controlled.

  That is, the electronic device 10 is typically a mobile phone terminal (smart phone and feature phone), a notebook personal computer, a tablet terminal, a portable game machine, a portable music player, a GPS device, etc. It is not limited to the equipment of. In short, as long as the electronic device includes the liquid crystal display unit 11 (and the backlight unit 12) and the voice input unit 14d (and the sampling unit 14e), the embodiments described in this specification can be applied. It is.

  Among the elements described above, each of the liquid crystal driving unit 13a, the storage unit 14b, the operation input unit 14c, and the sampling unit 14e is indispensable for the operation of the present embodiment. It is not directly related to new technical content.

  Many hardware elements other than those shown in FIGS. 1 and 2 are used in the electronic device 10. In addition to the one shown in FIG. 2, the processor 14a operates a lot of software such as an OS (Operating System: basic software), various applications, or a device driver. In this specification, only elements necessary for explaining the concept of the present invention are shown, and other hardware and software are not particularly described. The same applies to FIG.

  FIG. 3 is a flowchart illustrating an operation for controlling lighting of the backlight unit 12 of the electronic device 10 illustrated in FIG. 1. When the processor 14a of the electronic device 10 starts an operation for displaying something on the liquid crystal display unit 11, first, the operation mode determination function 22 determines whether the operation being performed in the processor 14a is the “specific operation mode”. (Step S101). Here, the “specific operation mode” refers to an operation mode using the voice input unit 14d (and the sampling unit 14e) such as moving image shooting, voice recording, and voice call. If it is not a specific operation mode (No in step S101), the operation is continued as it is.

  If the operation mode is a specific operation mode (Yes in step S101), the operation mode determination function 22 passes control to the backlight control function 21, and the backlight control function 21 receives this and controls the backlight drive unit 13b to perform the backlight operation. The brightness of the light unit 12 is controlled. More specifically, the display duty is adjusted to the brightest “duty ratio 100%” (step S102), and the operation returns to step S101 to continue the operation.

  FIG. 4 is an explanatory diagram showing the duty ratio of the voltage applied to the backlight unit 12 by the backlight control function 21 shown as step S102 in FIG. FIG. 4A shows a state where the duty ratio is not 100%, and FIG. 4B shows a state where the duty ratio is 100%. As shown in FIG. 4B, when the duty ratio is 100%, the PWM on / off operation is not performed, and a constant voltage that is not a pulse waveform is always applied to the backlight unit 12. Means the state.

  That is, if the “duty ratio is 100%”, the ceramic capacitor built in the backlight driving unit 13b does not vibrate, and the “sounding” as described above does not occur. Therefore, noise caused by sounding does not enter the voice input means 14d.

(Overall operation of the first embodiment)
Next, the overall operation of the above embodiment will be described.
The backlight lighting control method according to the present embodiment includes a liquid crystal display unit that performs screen display using liquid crystal, a backlight unit that emits light toward the user from behind the liquid crystal display unit, and audio input that inputs audio as audio data. The operation mode determination function determines whether or not the voice input means is used (step S101 in FIG. 3) and determines whether or not the voice input means is used. Depending on the result, the backlight control function sends a control signal for changing the waveform of the pulse voltage to the backlight drive unit (FIG. 3, step S102), and the pulse voltage whose waveform has been changed according to the control signal is sent to the backlight drive unit. Is generated, and this pulse voltage is applied to the backlight portion. In this case, when the voice input means is used, the backlight control function sends a control signal for setting the duty ratio of the pulse voltage to 100% to the backlight driving unit.

Here, each of the above-described operation steps may be programmed to be executable by a computer and executed by the processor 14a of the electronic device 10 that directly executes the steps. The program may be recorded on a non-temporary recording medium, such as a DVD, a CD, or a flash memory. In this case, the program is read from the recording medium by a computer and executed.
By this operation, this embodiment has the following effects.

  According to the present embodiment, when the voice input means is used, the duty ratio of the pulse voltage is set to 100%, so that the sounding phenomenon itself does not occur. Therefore, noise caused by sounding does not enter the voice input means 14d. For this reason, it is not necessary to dispose the voice input unit 14d at a position away from the backlight drive unit 13b (which is a source of noise), and problems such as the above-described reduction in size and weight, cost reduction, and usability of the device. Also disappear.

  The “specific operation mode” means “an operation mode using the voice input unit 14d” as described above. This includes situations where the electronic device 10 is often used outdoors, such as video shooting and voice calls. In general, since strong sunlight is exposed to the display surface outdoors, the display content on the liquid crystal display unit 11 is difficult to see. In the present embodiment, the luminance of the backlight unit 12 is maximized with a “duty ratio of 100%” in the case of “video shooting and voice call”, etc., so that the visibility of the liquid crystal display unit 11 in the outdoors is improved. The following effects can also be obtained.

(Second Embodiment)
The second embodiment of the present invention uses voice input means in addition to the configuration of the first embodiment described above, and noise in the audible frequency band is included in the voice data input by the voice input means. When this occurs, the backlight control function 221 sends a control signal for changing the frequency with the same duty ratio of the pulse voltage to the backlight drive unit 213b.

  In addition, a sampling unit 14e that converts the sound input from the voice input unit 14d into digital data, and a main control unit (processor 14a) controls a sampling control function 223 that controls the operation of the sampling unit, and a sound from the digital data. Noise is generated when the frequency analysis function 224 extracts a frequency with a high pressure level and the extracted frequency is within the audible frequency range and the change in the sound pressure level at the frequency is within a predetermined threshold. It is assumed that a noise determination function 225 for determining that the image is being processed is provided.

Even with this configuration, in addition to obtaining the same effect as in the first embodiment, it is not necessary to maximize the luminance of the backlight unit 12, and thus it is possible to obtain an effect of suppressing power consumption. become.
Hereinafter, this will be described in more detail.

  FIG. 5 is an explanatory diagram showing the configuration of the electronic apparatus 210 according to the second embodiment of the present invention. The electronic device 210 has substantially the same hardware configuration as the electronic device 10 according to the first embodiment described above, and only the software configuration is partially changed. That is, the control board 13 and the device board 14 are merely replaced with different control boards 213 and device boards 214, respectively. Accordingly, the same elements are referred to by the same names and reference numerals, and the description thereof is omitted in principle.

  6 is an explanatory diagram showing a more detailed configuration of the control board 213 and the device board 214 shown in FIG. In the control board 213, as compared with the control board 13 of the first embodiment, the backlight driving unit 13b is replaced with another backlight driving unit 213b.

  The device substrate 214 includes a processor 14a, a storage unit 14b, an operation input unit 14c, an audio input unit 14d, and a sampling unit 14e, as in the device substrate 14 of the first embodiment. The processor 14a operates a backlight control function 221, an operation mode determination function 22, a sampling control function 223, a frequency analysis function 224, and a noise determination function by operating an LCD control program different from the first embodiment. It operates as 225.

  The sampling control function 223 controls the operation of the sampling unit 14e that samples the sound input from the voice input unit 14d and converts it into digital data. The frequency analysis function 224 detects a sound pressure level for each frequency from the digital data converted by the sampling unit 14e by a known method such as FFT (Fast Fourier Transform), and extracts a frequency having a high sound pressure level. .

  The noise determination function 225 determines whether noise (which may be caused by squealing) is generated from the sound pressure level for each frequency detected by the frequency analysis function 224. More specifically, since the sound pressure level at the same frequency should be constantly changing in the case of a sound that is not noise, “a threshold value in which the change of the sound pressure level within the audible frequency range and with time is given in advance” Sounds that are “within” can be determined to be noise.

  As in the first embodiment, the operation mode determination function 22 determines whether or not the type of operation performed by the processor 14a is a specific operation mode, that is, an “operation mode using the voice input unit 14d”. To do.

  The backlight control function 221 applies pulse voltages having the same duty ratio and different frequencies to the backlight unit 12 when it is determined that noise is generated in a specific operation mode. Thus, the backlight driving unit 213b is controlled. The backlight driving unit 213b has a function of generating such “pulse voltages having the same duty ratio and different frequencies”. Details of this will be described next.

  FIG. 7 is an explanatory diagram showing pulse voltages having the same duty ratio and different frequencies generated by the backlight driving unit 213b shown in FIG. As described above, the duty ratio is a ratio of time during which the PWM signal is turned on during the PWM on / off operation cycle. Therefore, even if the frequency of the pulse voltage applied to the backlight unit 12 is changed, the luminance of the backlight unit 12 does not substantially change as long as the duty ratio is the same. In this case, the frequency of the pulse voltage may be changed in the direction of increasing or decreasing the frequency.

  As described above, whether or not sound is generated depends on a large number of conditions. Therefore, when the generation of sound is observed, the pulse voltage that is an element related to the lighting of the backlight unit 12 is detected. If the frequency is changed, if the duty ratio is the same, it is possible to easily avoid the noise by removing the resonance condition without changing the substantial display luminance. If noise (ie, sounding) continues in the audible frequency range even after the frequency is changed, the frequency may be further changed.

  FIG. 8 is a flowchart illustrating an operation for controlling lighting of the backlight unit 12 of the electronic apparatus 210 illustrated in FIG. 6. When the processor 14a of the electronic device 210 starts an operation of displaying something on the liquid crystal display unit 11, first, the operation mode determination function 22 is performed by the processor 14a as in step S101 of the first embodiment (FIG. 3). It is determined whether the detected operation is a “specific operation mode” (step S301).

  If it is a specific operation mode (Yes in step S301), the operation mode determination function 22 passes control to the sampling control function 223, and the sampling control function 223 controls the operation of the sampling means 14e, from the voice input means 14d. The input sound is sampled and converted into digital data (step S302). Then, from the digital data obtained by sampling, the frequency analysis function 224 detects the sound pressure level for each frequency and extracts a frequency having a high sound pressure level (step S303).

  The noise determination function 225 determines whether the extracted frequency is in the audible frequency region and whether the change in the sound pressure level at the frequency is within a given threshold, that is, the possibility of the noise It is determined whether or not a certain noise is generated (step S304). If it is determined that no noise is generated, the operation from step S301 is repeated.

  If it is determined that noise is generated (Yes in step S304), the backlight control function 221 performs backlighting so as to generate “pulse voltages having the same duty ratio and different frequencies” shown in FIG. The write driver 213b is controlled (step S305). Thereafter, the operation from step S301 is continued, and if the generation of noise in the audible frequency region continues, the frequency of the pulse voltage is further changed.

  In the above-mentioned “specific operation mode”, a certain time (for example, 1 second) from the start of the recording operation is recorded without sound, and the processing shown in steps S301 to S305 in FIG. 8 is completed during this time. It is also possible to configure. In this way, noise at the start of recording can be made inconspicuous.

(Overall operation of the second embodiment)
Next, the overall operation of the above embodiment will be described.
In the backlight lighting control method according to the present embodiment, when the voice input unit is used in the backlight lighting control method according to the first embodiment, the sampling unit converts the sound input from the voice input unit into digital data. (FIG. 8, step S302), and the frequency analysis function extracts a frequency with a high sound pressure level from the digital data (FIG. 8, step S303).
When the extracted frequency is within the audible frequency region and the change in the sound pressure level at the frequency is within a predetermined threshold, the noise determination function determines that noise is occurring (FIG. 8). In addition to step S304), when the voice input means is used and noise in the audible frequency band is generated in the voice data input by the voice input means, the frequency is changed with the same duty ratio of the pulse voltage. The backlight control function sends the control signal to be sent to the backlight driver (FIG. 8, step S305).
By this operation, this embodiment has the following effects.

  According to the present embodiment, it is determined whether or not noise is generated in the audible frequency range by using the voice input means 14d that is actually used for recording or voice call as it is. By changing the frequency of the pulse voltage, it is possible to remove the resonance condition and avoid the noise. At this time, since the duty ratio is not changed, the luminance of the backlight unit 12 is not substantially changed.

  Therefore, it is possible to suppress the occurrence of noise in the audible frequency region that may be caused by sounding without changing anything about the visual display. Further, unlike the first embodiment, since the luminance of the backlight unit 12 is not maximized in order to prevent noise, there is also a secondary effect that an increase in power consumption can be suppressed.

(Third embodiment)
In the third embodiment of the present invention, in addition to the second embodiment described above, the sampling control function 423 includes a plurality of operation modes having different sampling frequencies, and the operation mode determination function 422 is used by the voice input means. When the operation mode is an operation mode with a higher sampling frequency, the backlight control function is controlled to change the waveform of the pulse voltage.

With this configuration, in addition to obtaining the same effect as in the second embodiment, the pulse voltage is applied only when the operation mode has a higher sampling frequency, that is, the operation mode in which noise caused by sound is easily picked up. Since the waveform is changed, it is possible to obtain an effect of further reducing power consumption.
Hereinafter, this will be described in more detail.

  FIG. 9 is an explanatory diagram showing the configuration of the electronic device 410 according to the third embodiment of the present invention. The electronic device 410 has the same hardware configuration as the electronic device 210 according to the second embodiment described above, and only the software configuration is partially changed. That is, the device substrate 214 is only replaced with another device substrate 414. Accordingly, the same elements are referred to by the same names and reference numerals, and the description thereof is omitted in principle.

  FIG. 10 is an explanatory diagram showing a more detailed configuration of the device substrate 414 shown in FIG. A control board 213 is also shown, but this is the same as in the second embodiment. The device board 414 includes the same processor 14a, storage means 14b, operation input means 14c, and voice input means 14d as the device boards 14 and 214 of the first and second embodiments, but the first and second implementations. A sampling means 414e different from the configuration is provided.

  Then, when the processor 14a operates an LCD control program different from the first and second embodiments, the backlight control function 221, the operation mode determination function 422, the sampling control function 423, the frequency analysis function 224, and It operates as a noise determination function 225. Of these, the operation mode determination function 422 and the sampling control function 423 are all the same as those in the second embodiment.

  The sampling control function 423 can perform sampling in two types of operations, “normal mode” and “high-quality mode”, when the sound input from the audio input unit 14d via the sampling unit 414e is captured. The operation mode determination function 422 has a function of determining whether or not the operation performed by the processor 14a is the “specific operation mode” and the “high quality mode”. Here, the “high quality mode” refers to an operation mode in which the sampling frequency when capturing the sound input from the sound input means 14d is high, that is, a sound in a wider frequency band is processed.

  FIG. 11 is an explanatory diagram showing the normal mode and the high quality mode determined by the operation mode determination function 422 shown in FIG. The sampling means 414e can operate at two kinds of sampling frequencies, for example, 4 kHz and 8 kHz. Here, the former is a “normal mode” and the latter is a “high-quality mode”.

  In general, even with noise of the same sound pressure level, a higher frequency is easier to hear. Further, when the sampling frequency is high, a sound having a wider frequency band is taken in. Therefore, when the sound is generated, the sound input unit 14d can easily pick up the sound. In the example shown in FIG. 11, noise due to squeaking is generated in the vicinity of 6 kHz. This noise is not picked up in the normal mode, but is picked up in the high quality mode.

  Therefore, the operation mode determination function 422 performs the operation of changing the waveform of the pulse voltage shown in and after step S302 in FIG. 8 only when the mode is the “specific operation mode” and the “high quality mode”. . If the waveform of the pulse voltage is changed, the power consumption is slightly increased as compared with the case where the pulse voltage is not changed, so that an effect of reducing the increase can be obtained.

  FIG. 12 is a flowchart illustrating an operation for controlling lighting of the backlight unit 12 of the electronic apparatus 410 illustrated in FIG. 9. This operation is only the operation of the first step is replaced as compared with the operation of the second embodiment shown in FIG. That is, the operation mode determination function 422 determines whether the operation performed by the processor 14a is the “specific operation mode” and the “high quality mode” (step S501). Is simply replaced. Accordingly, the same operations are denoted by the same reference numerals and description thereof is omitted.

  The present invention has been described with reference to the specific embodiments shown in the drawings. However, the present invention is not limited to the embodiments shown in the drawings, and any known hitherto provided that the effects of the present invention are achieved. Even if it is a structure, it is employable.

  Regarding the embodiment described above, the main points of the new technical contents are summarized as follows. In addition, although part or all of the said embodiment is summarized as follows as a novel technique, this invention is not necessarily limited to this.

(Supplementary Note 1) Electronic device including a liquid crystal display unit that displays a screen using liquid crystal, a backlight unit that emits light toward the user from behind the liquid crystal display unit, and a voice input unit that inputs voice as voice data Because
With a backlight drive unit that generates a pulse voltage for lighting the backlight unit,
An operation mode determination function for determining whether or not the voice input means is used;
An electronic apparatus comprising a main control unit having a backlight control function for sending a control signal for changing a waveform of the pulse voltage to the backlight drive unit when the voice input means is used .

(Supplementary note 2) The backlight control function is characterized in that when the voice input means is used, a control signal for setting the duty ratio of the pulse voltage to 100% is sent to the backlight drive unit. The electronic device according to attachment 1.

(Supplementary Note 3) When the voice input unit is used and noise in an audible frequency band is generated in the voice data input by the voice input unit, the backlight control function is set to the pulse The electronic apparatus according to appendix 1, wherein a control signal for changing a frequency without changing a voltage duty ratio is sent to the backlight driving unit.

(Additional remark 4) While providing the sampling means which converts the sound input from the said voice input means into digital data,
The main control unit
A sampling control function for controlling the operation of the sampling means;
A frequency analysis function for extracting a frequency with a high sound pressure level from the digital data;
A noise determination function for determining that the noise is generated when the extracted frequency is in an audible frequency region and the change in the sound pressure level at the frequency is within a predetermined threshold value; The electronic apparatus according to Appendix 3, further comprising:

(Supplementary Note 5) The sampling unit includes a plurality of operation modes having different sampling frequencies,
The operation mode determination function is configured to change the pulse voltage waveform of the backlight control function when the voice input unit is used and the operation mode is an operation mode having a higher sampling frequency. The electronic apparatus according to appendix 4, wherein the electronic apparatus is controlled.

(Appendix 6) An electronic apparatus including a liquid crystal display unit that displays a screen using liquid crystal, a backlight unit that emits light toward the user from behind the liquid crystal display unit, and an audio input unit that inputs audio as audio data There,
The operation mode determination function determines whether or not the voice input means is used,
Depending on the determination result of whether or not the voice input means is used, a backlight control function sends a control signal to change the waveform of the pulse voltage to the backlight drive unit,
The backlight driver generates a pulse voltage whose waveform has been changed according to the control signal,
A backlight lighting control method, wherein the pulse voltage is applied to the backlight unit.

(Supplementary note 7) The supplementary note is characterized in that, when the voice input means is used, the backlight control function sends a control signal for setting the duty ratio of the pulse voltage to 100% to the backlight driving unit. 6. The backlight lighting control method according to 6.

(Supplementary Note 8) When the voice input means is used, the sampling unit converts the sound input from the voice input means into digital data,
A frequency analysis function extracts a frequency with a high sound pressure level from the digital data,
When the extracted frequency is in the audible frequency region and the change in the sound pressure level at the frequency is within a predetermined threshold, the noise determination function determines that the noise is occurring. ,
The frequency is changed without changing the duty ratio of the pulse voltage when the voice input means is used and noise in the audible frequency band is generated in the voice data input by the voice input means. The backlight lighting control method according to appendix 6, wherein the backlight control function sends a control signal to be sent to the backlight driving unit.

(Additional remark 9) The liquid crystal display part which displays a screen with a liquid crystal, the backlight part which emits light toward the user from the back of the said liquid crystal display part, the audio | voice input means which inputs an audio | voice as audio | voice data, and the said backlight part An electronic device having a backlight drive unit that generates a pulse voltage for lighting
In the processor included in the electronic device,
A procedure for determining whether or not the voice input means is used;
And a procedure for sending a control signal for changing a waveform of the pulse voltage to the backlight driving unit according to a determination result of whether or not the voice input unit is used. program.

(Additional remark 10) When the said audio | voice input means is utilized, the control signal which makes the duty ratio of the said pulse voltage 100% is sent to the said backlight drive part, The backlight of Additional remark 9 characterized by the above-mentioned. Lighting control program.

(Additional remark 11) The procedure which controls the operation | movement which converts the sound input from the said audio | voice input means into digital data,
A procedure for extracting a frequency with a high sound pressure level from the digital data;
And a procedure for determining that the noise is generated when the extracted frequency is in an audible frequency range and the change in the sound pressure level at the frequency is within a predetermined threshold. And let it run further,
The frequency is changed without changing the duty ratio of the pulse voltage when the voice input means is used and noise in the audible frequency band is generated in the voice data input by the voice input means. The backlight lighting control program according to appendix 9, further comprising causing the processor to further execute a procedure of sending a control signal to be sent to the backlight driving unit.

  The present invention can be widely applied to any electronic device that includes a liquid crystal display unit (and a backlight unit) and audio input means. The present invention can be applied regardless of whether the light source of the backlight unit of the electronic device is a cold cathode tube or an LED (light emitting diode). In particular, it is particularly suitable when the electronic device is portable or battery driven. Typically, mobile phone terminals (smartphones and feature phones), notebook personal computers, tablet terminals, portable game machines, portable music players, GPS devices, and the like are suitable applications of the present invention.

10, 210, 410 Electronic equipment 11 Liquid crystal display unit 12 Backlight unit 13, 213 Control board 13a Liquid crystal drive unit 13b, 213b Backlight drive unit 14, 214, 414 Device board 14a Processor 14b Storage unit 14c Operation input unit 14d Audio input unit Means 14e, 414e Sampling means 21, 221 Backlight control function 22, 422 Operation mode judgment function 223, 423 Sampling control function 224 Frequency analysis function 225 Noise judgment function

Claims (5)

An electronic apparatus including a liquid crystal display unit that displays a screen using liquid crystal, a backlight unit that emits light toward the user from behind the liquid crystal display unit, and an audio input unit that inputs audio as audio data,
With a backlight drive unit that generates a pulse voltage for lighting the backlight unit,
An operation mode determination function for determining whether or not the voice input means is used;
A main controller having a backlight control function for sending a control signal for changing the waveform of the pulse voltage to the backlight driver when the voice input means is used;
When the audio input unit is used and noise in an audible frequency band is generated in the audio data input by the audio input unit, the backlight control function is configured to change the duty ratio of the pulse voltage. An electronic apparatus characterized in that a control signal for changing the frequency without changing the frequency is sent to the backlight drive unit. A sampling means for converting the sound input from the voice input means into digital data;
The main control unit
A sampling control function for controlling the operation of the sampling means;
A frequency analysis function for extracting a frequency with a high sound pressure level from the digital data;
A noise determination function for determining that the noise is generated when the extracted frequency is in an audible frequency region and the change in the sound pressure level at the frequency is within a predetermined threshold value; The electronic device according to claim 1, further comprising: The sampling means comprises a plurality of operation modes having different sampling frequencies,
The operation mode determination function is configured to change the pulse voltage waveform of the backlight control function when the voice input unit is used and the operation mode is an operation mode having a higher sampling frequency. The electronic device according to claim 2, wherein the electronic device is controlled. An electronic apparatus comprising a liquid crystal display unit that displays a screen using liquid crystal, a backlight unit that emits light toward the user from behind the liquid crystal display unit, and a voice input unit that inputs voice as voice data.
The operation mode determination function determines whether or not the voice input means is used,
Depending on the determination result of whether or not the voice input means is used, the backlight control function sends a control signal for changing the waveform of the pulse voltage to the backlight drive unit,
The backlight driver generates a pulse voltage whose waveform has been changed according to the control signal,
A backlight lighting control method characterized by applying this pulse voltage to the backlight unit,
When the voice input means is used, the sampling unit converts the sound input from the voice input means into digital data,
A frequency analysis function extracts a frequency with a high sound pressure level from the digital data,
When the extracted frequency is in an audible frequency region and the change in the sound pressure level at the frequency is within a predetermined threshold, the noise determination function determines that noise is occurring, and
The frequency is changed without changing the duty ratio of the pulse voltage when the voice input means is used and noise in the audible frequency band is generated in the voice data input by the voice input means. The backlight lighting control method, wherein the backlight control function sends a control signal to the backlight driving unit. A liquid crystal display unit that displays a screen using liquid crystal, a backlight unit that emits light toward the user from behind the liquid crystal display unit, audio input means that inputs audio as audio data, and for lighting the backlight unit An electronic device having a backlight drive unit that generates a pulse voltage of
In the processor included in the electronic device,
A procedure for determining whether or not the voice input means is used;
And according to the determination result of whether or not the voice input means is used, to execute a procedure to send a control signal to change the waveform of the pulse voltage to the backlight drive unit,
A backlight lighting control program characterized by
A procedure for controlling the operation of converting the sound input from the voice input means into digital data;
A procedure for extracting a frequency with a high sound pressure level from the digital data;
And when the extracted frequency is in an audible frequency region and the change in the sound pressure level at the frequency is within a predetermined threshold value, a procedure for determining that noise has occurred is sent to the processor. And let it run
The frequency is changed without changing the duty ratio of the pulse voltage when the voice input means is used and noise in the audible frequency band is generated in the voice data input by the voice input means. A backlight lighting control program for causing the processor to further execute a procedure of sending a control signal to be sent to the backlight driving unit.

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