U.S. patent application number 13/306714 was filed with the patent office on 2012-05-31 for display apparatus and electronic equipment.
This patent application is currently assigned to SANYO ELECTRIC CO., LTD.. Invention is credited to Hidenori SATO, Shohei TAKAHASHI, Tomonori YOSHIDA.
Application Number | 20120131936 13/306714 |
Document ID | / |
Family ID | 46125720 |
Filed Date | 2012-05-31 |
United States Patent
Application |
20120131936 |
Kind Code |
A1 |
YOSHIDA; Tomonori ; et
al. |
May 31, 2012 |
DISPLAY APPARATUS AND ELECTRONIC EQUIPMENT
Abstract
A display apparatus has a compressor cooler having a condenser
that condenses refrigerant by radiating heat, an evaporator that
evaporates the refrigerant for heat absorption and
dehumidification, and a compressor that inhales vapor generated by
the evaporator and compresses the vapor to be condensed; a
temperature sensor that monitors temperature of the evaporator; a
backlight; a first control portion that terminates the compressor
when the temperature of the evaporator is a first predetermined
temperature or lower; and a second control portion that increases a
level of the backlight when the temperature of the evaporator is a
second predetermined temperature or lower, wherein the second
predetermined temperature is higher than the first predetermined
temperature.
Inventors: |
YOSHIDA; Tomonori;
(Higashiosaka City, JP) ; TAKAHASHI; Shohei;
(Daito City, JP) ; SATO; Hidenori; (Neyagawa City,
JP) |
Assignee: |
SANYO ELECTRIC CO., LTD.
Moriguchi City
JP
|
Family ID: |
46125720 |
Appl. No.: |
13/306714 |
Filed: |
November 29, 2011 |
Current U.S.
Class: |
62/176.6 ;
62/227 |
Current CPC
Class: |
G09F 9/35 20130101; G09F
27/005 20130101; G09F 13/005 20130101 |
Class at
Publication: |
62/176.6 ;
62/227 |
International
Class: |
F25B 49/02 20060101
F25B049/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 29, 2010 |
JP |
2010-265512 |
Claims
1. A display apparatus comprising: a compressor cooler having a
condenser that condenses refrigerant by radiating heat, an
evaporator that evaporates the refrigerant for heat absorption and
dehumidification, and a compressor that inhales vapor generated by
the evaporator and compresses the vapor to be condensed; a
temperature sensor that monitors temperature of the evaporator; a
backlight; a first control portion that terminates the compressor
when the temperature of the evaporator is a first predetermined
temperature or lower; and a second control portion that increases a
level of the backlight when the temperature of the evaporator is a
second predetermined temperature or lower, wherein the second
predetermined temperature is higher than the first predetermined
temperature.
2. The display apparatus according to claim 1, further comprising:
a humidity sensor that measures humidity; and a third control
portion that activates the compressor cooler at a predetermined
humidity or higher, and further increases a level of the backlight
when the evaporator becomes a second predetermined temperature or
lower.
3. An electronic device comprising: a cooler having at least a
compressor; a temperature sensor that measures temperature; a
humidity sensor that measures humidity; and a control portion that
activates the compressor when the temperature measured by the
temperature sensor is higher than a first temperature and
terminates the compressor when the measured temperature is lower
than a second temperature that is lower than the first temperature,
wherein the control portion also activates the compressor when the
measured temperature is between the first temperature and the
second temperature, and the humidity measured by the humidity
sensor is higher than a predetermined humidity.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on Japanese Patent Application No.
2010-265512 filed on Nov. 29, 2010, the contents of which are
hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a display apparatus and
electronic equipment.
[0004] 2. Description of Related Art
[0005] Recent years, a liquid crystal display apparatus is used for
digital signage. Such display apparatus has a sealed structure,
because the apparatus may be installed outdoors and thus it is
necessary to prevent water or dust from entering into the
apparatus. In addition, these display apparatus can display with
high luminance in order to keep the visibility in the outdoors.
[0006] When the display apparatus is displaying an image with high
luminance, or when it is being irradiated by sunlight, heat is
generated inside the housing of the apparatus. As for the display
apparatus having a sealed structure as described above, it is
difficult for the heat generated inside the housing to dissipate
outside the housing. As a result, temperature inside the housing
may rise and a malfunction of liquid crystal in the liquid crystal
display apparatus may occur.
[0007] One improvement is to employ a compressor-based cooling
system into those LCD displays in order to solve the
above-mentioned problems as described in JP 2010-164884A1 which was
filed by the applicant. The disclosures of which are hereby
incorporated by reference as if set forth in full herein.
[0008] However, in the above-mentioned liquid crystal display
apparatus, since the display apparatus is sealed structured, a
dew-condensation in the housing may occur. In particular, during a
cold winter season, since the outside temperature becomes lower
than the temperature inside the housing, the temperature difference
between the outside and the inside of the housing may cause a
dew-condensation on a protection glass arranged in the front side
of the liquid crystal panel. This dew-condensation decreases
visibility of an image displayed on the liquid crystal panel. In
order to avoid this dew-condensation, one idea is to perform
dehumidification by activating a cooler when a humidity level
becomes a certain level or higher. However, if the cooler is
activated when the ambient temperature is low, its evaporation
temperature decreases and the refrigerant pressure inside the
evaporator becomes too low. This may cause a safety problem for
cooler.
SUMMARY OF THE INVENTION
[0009] A display apparatus according to the present invention
includes a compressor refrigerator including a condenser that
condenses refrigerant by thermal radiation, an evaporator that
evaporates the refrigerant so as to perform heat absorption and
dehumidification, and a compressor that inhales vapor generated by
the evaporator and increases the pressure of the vapor to be
condensed, a temperature sensor that monitors temperature of the
evaporator, a backlight, a first control portion that stops the
compressor when the temperature of the evaporator is a first
predetermined temperature or lower; and a second control portion
that increases a level of the backlight when the temperature of the
evaporator is lower than or equal to a second predetermined
temperature that is higher than the first predetermined
temperature.
[0010] In addition, electronic equipment according to the present
invention includes a cooler including at least a compressor, a
temperature sensor that measures temperature, a humidity sensor
that measures humidity, and a control portion that activates the
compressor when the temperature measured by the temperature sensor
is higher than a first temperature and stops the compressor when
the measured temperature is lower than a second temperature that is
lower than the first temperature, wherein the control portion also
activates the compressor when the measured temperature is between
the first temperature and the second temperature, and the humidity
measured by the humidity sensor is higher than a predetermined
humidity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a perspective view illustrating a structure of a
display apparatus 1.
[0012] FIG. 2 is a first cross sectional view illustrating the
structure of the display apparatus 1.
[0013] FIG. 3 is a second cross sectional view illustrating the
structure of the display apparatus 1.
[0014] FIG. 4 is a diagram illustrating a structure of cooler
30.
[0015] FIG. 5 is a block diagram of the display apparatus 1.
[0016] FIG. 6 is a flowchart illustrating a first example of
temperature and humidity control performed by the display apparatus
1.
[0017] FIG. 7 is a flowchart illustrating a second example of
temperature and humidity control performed by the display apparatus
1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] Hereinafter, an embodiment of a display apparatus according
to the present invention will be described with reference to the
attached drawings. First, a structure of the display apparatus will
be described with reference to FIGS. 1 to 3.
[0019] <Structure of Display Apparatus>
[0020] FIG. 1 is a perspective view illustrating a structure of a
display apparatus 1. The display apparatus 1 has an upper housing
10 which is the housing on the upper part side and a lower housing
20 which is the housing on the lower part side. The upper housing
10 has a window part 11 so that an image displayed on a liquid
crystal panel 12 (described later) arranged inside the upper
housing 10 is viewable. The window part 11 is made of material
which is transparent against a visible light such as glass.
[0021] FIG. 2 is a diagram illustrating an A-A cross sectional view
of the display apparatus 1 illustrated in FIG. 1.
[0022] As illustrated in FIG. 2, inside the upper housing 10, the
liquid crystal panel 12 displaying an image, a backlight 13
irradiating light to the panel 12, fans 14a and 14b circulating air
inside the upper housing 10, temperature sensors 15a and 15b
detecting temperature inside the upper housing 10 (see FIG. 3 for
detail), humidity sensors 17a and 17b detecting humidity inside the
upper housing 10, and an evaporator 31 cooling the inside of the
upper housing 10 so as to perform dehumidification are
arranged.
[0023] Further, as illustrated in FIG. 2, inside the lower housing
20, a compressor 32 compressing refrigerant, a condenser 33
condensing the refrigerant compressed by the compressor 32 by heat
radiation, and an expansion valve 34 that expands the refrigerant
condensed by the condenser 33 are arranged. The evaporator 31
absorbs heat by evaporating the refrigerant expanded by the
expansion valve 34. The compressor 32 compresses the refrigerant
evaporated by the evaporator 31. Hereafter, group that consist of
the evaporator 31, the compressor 32, the condenser 33, and the
expansion valve 34 is referred to as a cooler 30. Details of this
cooler 30 will be described later.
[0024] The liquid crystal panel 12 controls orientation of liquid
crystal so as to selectively transmit light from the backlight 13,
and hence an image is displayed. The image displayed on the liquid
crystal panel 12 is viewable from the outside of the upper housing
10 through the window part 11. The backlight 13 is constituted of,
for example, a fluorescent tube or light emitting diodes. The
backlight 13 may comprise a diffuser panel that diffuses light
emitted from the light source so as to irradiate a plane (or
uniform) light to the liquid crystal panel 12, and a reflector
plate that reflects light emitted from the light source.
[0025] The fan 14b is arranged at a lower portion of the upper
housing 10 and blows cooled air cooled by the evaporator 31 towards
a front surface of the liquid crystal panel 12. The fan 14a is
arranged at an upper portion of the upper housing 10 and blows air
which has passed the front surface side of the liquid crystal panel
12 to the rear side of the panel 12. Then, this air further passes
the rear side of the liquid crystal panel 12 and reaches the
evaporator 31. By circulating the air inside the upper housing 10
using the fans 14b and 14a, the liquid crystal panel 12 is cooled
effectively. The number or arrangement of the fans 14b and 14a are
not limited to the above example. Hereafter, the fans 14b and 14a
are generically referred to as a fan 14.
[0026] FIG. 3 is a diagram illustrating a B-B cross sectional view
of the display apparatus 1.
[0027] As illustrated in FIG. 3, four temperature sensors 15a, 15b,
15c, and 15d are arranged inside the upper housing 10. Further,
four humidity sensors 17a, 17b, 17c, and 17d are also arranged
inside the upper housing 10. Each of the temperature sensors 15a,
15b, 15c, and 15d is constituted of a temperature detecting element
such as a thermistor for example. Each of the humidity sensors 17a,
17b, 17c, and 17d is constituted of a humidity detecting element
such as a high polymer humidity sensing element, which is an
element that detects humidity based on a variation of an electrical
characteristic (such as resistance or capacitance) of high polymer
according to moisture). As illustrated in FIG. 2, each of the
above-mentioned temperature sensors 15a to 15d and the humidity
sensors 17a to 17d are disposed between the window part 11 and the
liquid crystal panel 12.
[0028] The temperature sensor 15a and the humidity sensor 17a are
arranged on the upper right side of the window part 11. The
temperature sensor 15b and the humidity sensor 17b are arranged on
the lower right of the window part 11. The temperature sensor 15c
and the humidity sensor 17c are arranged on the upper left side of
the window part 11. The temperature sensor 15d and the humidity
sensor 17d are arranged on the lower left side of the window part
11. However, the arrangement of the temperature sensors or the
humidity sensor is not limited to the above. For instance, only a
single humidity sensor may be arranged near the evaporator 31.
[0029] <Schematic Structure of Cooler>
[0030] With reference to FIG. 4, a structure of the cooler 30 will
be described.
[0031] The cooler 30 includes an evaporator 31, the compressor 32,
the condenser 33, and the expansion valve 34. In this cooler 30,
the refrigerant circulates in a closed loop, and there is no need
to exchange the refrigerant.
[0032] The compressor 32 compresses the refrigerant evaporated by
the evaporator 31 so that the refrigerant becomes a high
temperature and high pressure state. The condenser 33 condenses the
refrigerant compressed by the compressor 32, by heat exchange (heat
radiation). The cooler 30 may include a fan for expediting the heat
exchange in the condenser 33.
[0033] The expansion valve 34 expands the refrigerant condensed by
the condenser 33 so that the refrigerant becomes a low temperature
and low pressure state. Then, the evaporator 31 evaporates the
refrigerant expanded by the expansion valve 34 by heat exchange
(heat absorption). Here, moisture contained in the air inside the
upper housing 10 is dew-condensed on the evaporator 31. Then,
moisture dew-condensed on the evaporator 31 is drained outside the
upper housing 10. The cooler 30 may include a fan for expediting
heat exchange or dehumidification in the evaporator 31.
[0034] As described above, the cooler 30 cools and dehumidify the
inside of the upper housing 10, by changing the state of the
refrigerant between liquid and gas repeatedly and by the exchanging
heat (heat absorption and radiation).
[0035] At inlet of the evaporator 31 in a flow path of the
refrigerant, evaporator temperature sensor 311 detecting
temperature of the evaporator 31 or evaporator pressure sensor 312
detecting pressure of the evaporator 31 is arranged. Further, at
outlet of the condenser 33, a condenser temperature sensor 332
detecting temperature of the condenser 33 and a condenser pressure
sensor 331 detecting pressure of the condenser 33 are arranged.
[0036] Each of the evaporator temperature sensor 311 and the
condenser temperature sensor 332 has a temperature detecting
element (e.g., a thermistor). The evaporator temperature sensor 311
indirectly detects temperature of the refrigerant flowing into the
evaporator 31. In detail, the sensor 311 detects temperature of the
refrigerant between outgoing from expansion valve 34 and ingoing to
evaporator 31. The condenser temperature sensor 332 detects
temperature of the refrigerant flowing out from the condenser 33.
In detail, the sensor 332 indirectly detects temperature of the
refrigerant condensed by the condenser 33 before it is expanded by
the expansion valve 34.
[0037] In the cooler 30, if the flow path of the refrigerant is in
a "closed loop", a relationship between the pressure and the
temperature of the refrigerant is uniquely determined. Therefore,
by referring to the temperature detected by the evaporator
temperature sensor 311, the pressure of the refrigerant can be
estimated.
[0038] Instead, the pressure of the refrigerant may be measured
directly using pressure sensors 312 and 331 may be adopted. These
pressure sensors have a pressure detecting element such as a strain
gage (which detects deformation of diaphragm caused by pressure of
the refrigerant).
[0039] <Control of Temperature and Humidity>
[0040] The control of temperature and humidity of the display
apparatus 1 is described with reference from FIGS. 5 to 7. FIG. 5
is a block diagram illustrating a schematic structure of the
apparatus 1.
[0041] As illustrated in FIG. 5, the display apparatus 1 has a
control portion 16 that controls operations of the cooler 30, the
liquid crystal panel 12, the backlight 13, and the fan 14. The
control portion 16 obtains information detected by the temperature
sensor 15, the humidity sensor 17, the evaporator temperature
sensor 311, and the condenser temperature sensor 332.
[0042] The cooler 30 is designed to terminate its operation when
the pressure of the evaporator 31 becomes lower than a
predetermined pressure. The cooler 30 is designed to terminate
because when the refrigerant pressure inside the evaporator is too
low, it may make cooler 31 harmful. A decrease of the refrigerant
pressure is equivalent to a decrease of the refrigerant temperature
inside the evaporator. In addition, the cooler 30 is specified to
stop at the safety point of view when the pressure of the condenser
33 detected by the condenser pressure sensor 331 becomes Pc 1 or
higher.
[0043] [First Example of Temperature and Humidity Control]
[0044] FIG. 6 is a flowchart showing an example of temperature and
humidity control performed by the display apparatus 1. This
flowchart shows the control performed recursively by the control
portion 16. This flowchart can be roughly divided into a process of
Steps S1 to S6 and a process of Steps S7 to S11. The former one is
for preventing a malfunction due to an increase of temperature in
the housing, and the latter is a process for preventing a
malfunction due to a decrease of temperature in the housing.
[0045] First, the former process is discussed. As shown in FIG. 6,
first, in Step S1, the control portion 16 detects the temperature
inside the upper housing 10, referring to outputs of the
temperature sensors 15.
[0046] In Step S2, the control portion 16 determines whether the
temperature detected in Step S1 is temperature Th-or-higher or not.
For instance, it determines whether at least one of the sensors 15a
to 15d measures the temperature Th or higher. Here, Th is a
temperature that is lower than an upper limit temperature that
normal display on the liquid crystal panel 12 is guaranteed. For
example, the temperature is 43 degrees centigrade.
[0047] If the temperature inside the housing 10 is Th or higher
(Yes in Step S2), the control portion 16 proceeds to Step S3 and
drives the cooler 30. Here, if the cooler 30 is already being
driven, this driving state is maintained. In this case, the control
portion 16 may drive the fan 14 together with the driving of the
cooler 30.
[0048] On the other hand, if the temperature inside the housing 10
is lower than Th (No in Step S2), the control portion 16 proceeds
to Step S4 and detects humidity inside the housing 10.
[0049] In Step S5, the control portion 16 determines whether the
humidity inside the housing 10 is Hh-or-higher or not. For
instance, it determines whether at least in one of the sensors 17a
to 17d measures a humidity Hh-or-higher or not(Hh is for example,
80%).
[0050] If the humidity inside the housing 10 is Hh or higher (Yes
in S5), assuming that the dew-condensation may occur, the control
portion 16 proceeds to Step S3 and drive the cooler 30. Thus, the
dew-condensation can be prevented. If the humidity inside the
housing 10 is lower than Hh (No in S5), the driving of the cooler
30 is stopped in Step S6. Because the temperature inside the upper
housing 10 is in a normal range and there is no risk of the
condensation, the control portion 16 stops the driving of the fan
14 in synchronization with the cooler 30.
[0051] Next, the latter process is discussed. First, in Step S7,
the control portion 16 detects temperature of the evaporator 31
referring to an output of the evaporator temperature sensor
311.
[0052] In Step S8, the control portion 16 determines whether the
temperature detected in Step S7 is Te2-or-lower or not. Here, Te2
is a temperature a little higher than a lower limit temperature
that normal operation of the evaporator 31 is guaranteed. This
temperature is referred to as temperature Te1.
[0053] When the temperature of the evaporator 31 is Te2 or lower
(Yes in Step S8), the control portion 16 controls an output level
of the backlight 13 to be a level higher than a normal level so as
to prevent the temperature from decreasing down to the temperature
Te1.
[0054] For instance, if the guaranteed temperature Te1 is -15
degrees centigrade, the control portion 16 controls the level of
the backlight 13 to be 65% of the maximum value when the
temperature of the evaporator 31 lowers -10 degrees. If the
temperature lowers -12 degrees, the level of the backlight 13 is
controlled to be 80%. By making the output level of the backlight
high, inside the display apparatus 1 is heated and the temperature
of the refrigerant rises. As a result, a decrease of the
evaporation temperature (evaporate pressure) is prevented, and
hence it can prevent the cooler from terminating unintentionally.
Further, since the cooler is prevented from termination,
dew-condensation at a low temperature can be avoided.
[0055] When the temperature of the evaporator 31 is Te1 or lower
(Yes in Step S10), the cooler 30 is terminated in Step S11.
[0056] In this case, the control portion 16 may also terminate the
operation of the liquid crystal panel 12 and the backlight 13.
[0057] According to this example, it is possible to prevent
dew-condensation, while safety of the cooler 30 is maintained.
[0058] [Second Example of Temperature and Humidity Control]
[0059] FIG. 7 is a flowchart showing another example of the
temperature and humidity control performed by the display apparatus
1. In the first example described above, the level of the backlight
is controlled based on the detection result of the temperature of
the evaporator. However, this example differs that the level of the
backlight is controlled based on the humidity inside the upper
housing 10 rather than based on the detection result of the
temperature of the evaporator.
[0060] As shown in FIG. 7, first, in Step S21, the control portion
16 detects the temperature inside the upper housing 10. In Step
S22, the control portion 16 determines whether the temperature
detected in S21 is Th-or-higher or not. If the temperature is lower
than Th (NO in S22), the humidity inside the upper housing 10 is
detected (S23). If the humidity is lower than Hh (NO in S24), the
cooler 30 is terminated (S25).
[0061] On the other hand, if the temperature inside the upper
housing 10 is Th or higher (YES in S22), the control portion 16
drives the cooler 30 (S26).
[0062] If the temperature inside the upper housing 10 is lower than
Th (NO in S22) and the humidity is Hh or higher (YES in S24), the
cooler 30 is driven (S27). Further, the backlight 13 is controlled
so as to increase its output level (S28). As described above, the
level of the backlight is increased when the cooler 30 (compressor)
is driven based on the humidity in the housing. Thereby, it can
increase the heat load even when the temperature inside the housing
is low.
[0063] In this case, the control portion 16 adjusts the level of
the backlight 13 to a predetermined level (80%, for example)
regardless of the temperature of the evaporator 31. If the level of
the backlight 13 is already larger than predetermined value, the
control portion 16 may maintain the level of the backlight 13.
[0064] <Variations>
[0065] In order to prevent the cooler 30 from frequent activation
and termination, the control portion 16 may additionally perform
following control in the flowchart shown in FIG. 6 or 7. For
example, in Step S2 of FIG. 6 and Step S22 of FIG. 7, the threshold
value temperature Th may be set different value depending on
whether the cooler 30 is to be activated or to be terminated. For
example, 43 degrees centigrade may be adopted when driving, and 38
degrees centigrade when terminating. In other words, the threshold
value temperature Th may have a hysteresis. The control portion 16
may perform a control so as not to terminate the cooler 30 while a
predetermined time period (for example, ten minutes) has not
elapsed since the activation of the cooler 30. The vice-versa
control may be performed (i.e. do not activate while a
predetermined time has not elapsed since the termination)
[0066] Instead of steps S7 to S10 shown in FIG. 6, in which the
backlight or the cooler 30 are controlled according to the
temperature of the evaporator 31, these controls may be performed
according to temperature of the condenser 33. However, it is
preferable, to perform control based on temperature of the
condenser 33 after a predetermined time period (for example, 10
minutes) has elapsed from the activation of the cooler 30 so that
the temperature of the condenser 33 is raised and stabilized.
[0067] The embodiment of the present invention is described above,
however, the scope of the present invention is not limited to this.
It can be modified variously within the scope of the present
invention without deviating from the spirit thereof.
* * * * *