About The Auto Light Switch; Charging Precautions; Charging Guide; Operating Conditions - Casio 2531 Operation Manual

Operation Guide 2531

About the Auto Light Switch

Turning on the auto light switch causes the backlight to turn on for about one second,
whenever you position your wrist as described below in any mode. Note that this
watch features a "Full Auto EL Light," so the auto light switch operates only when
available light is below a certain level. It does not turn on the backlight under bright
light.
Moving the watch to a position that is parallel to the ground and then tilting it towards
you more than 40 degrees causes the backlight to turn on.
Parallel to
ground
Warning!
• Always make sure you are in a safe place whenever you are reading the
display of the watch using the auto light switch. Be especially careful when
running or engaged in any other activity that can result in accident or injury.
Also take care that sudden illumination by the auto light switch does not
surprise or distract others around you.
• When you are wearing the watch, make sure that its auto light switch is turned
off before riding on a bicycle or operating a motorcycle or any other motor
vehicle. Sudden and unintended operation of the auto light switch can create a
distraction, which can result in a traffic accident and serious personal injury.
To turn the auto light switch on and off
In the Timekeeping Mode, hold down D for about two seconds to toggle the auto light
switch on (AUTO EL displayed) and off (AUTO EL not displayed).
• The auto light switch on indicator (AUTO EL) is on the display in all modes while the
auto light switch is turned on.
Battery
This watch is equipped with a solar cell and a rechargeable battery (secondary
battery) that is charged by the electrical power produced by the solar cell. The
illustration shown below shows how you should position the watch for charging.
Example: Orient the watch so its
face is pointing at a light source.
• Note that charging efficiency
drops when any part of the solar
cell is blocked by clothing, etc.
• The illustration shows how to
position a watch with a resin band.
Important!
• Storing the watch for long periods in an area where there is no light or wearing it in
such a way that it is blocked from exposure to light can cause rechargeable battery
power to run down. Be sure that the watch is normally exposed to bright light
whenever possible.
• This watch employs a solar cell that converts light into electricity, which charges a
built-in rechargeable battery. Normally, the rechargeable battery should not need
replacement, but after very long use over a number of years, the rechargeable
battery may lose its ability to achieve a full charge. Should you notice problems with
getting the rechargeable battery to a full charge, contact your dealer or CASIO
distributor about having the rechargeable battery replaced.
• The rechargeable battery should be replaced with a CASIO-specified CTL1616
battery only. Other rechargeable batteries can cause damage to the watch.
• All data stored in memory is deleted, and the current time and all other settings
return to their initial factory defaults whenever battery power drops to Level 5 and
when you have the battery replaced.
• Turn on the watch's Power Saving function and keep it in an area normally exposed
to bright light when storing it for long periods. This helps to keep the rechargeable
battery from going dead.
Battery Power Indicator
The battery power indicator on the display shows you the current status of the
rechargeable battery's power.
Battery power indicator Level Battery Power
Indicator
1
2
3
4
(Charge Soon Alert)
5
• The flashing
indicator at Level 4 tells you that battery power is very low, and that
exposure to bright light for charging is required as soon as possible.
• At Level 5, all functions are disabled and settings return to their initial factory
defaults. Functions are enabled once again after the rechargeable battery is
charged, but you need to set the current time, date, and all other settings after the
battery is recharged to Level 3 from Level 5. Though the time appears on the display
after the battery is charged to Level 4, you will not be able to change the time setting
until the battery reaches Level 3.
• Leaving the watch in direct sunlight or some other very strong light source can
cause the battery power indicator to temporarily show a reading that is higher than
the actual battery level. The correct battery power indicator should appear after a
few minutes.
• If you use the backlight or any of the alarm functions a number of times during a
short period, RECOVER appears on the display and the following operations
become disabled until battery power recovers.
Backlight
Beeper tone
After some time, battery power will recover and RECOVER will disappear, indicating
that the above functions are enabled again.

Charging Precautions

Certain charging conditions can cause the watch to become very hot. Avoid leaving
the watch in the areas described below whenever charging its rechargeable battery.
Also note that allowing the watch to become very hot can cause its liquid crystal
display to black out. The appearance of the LCD should become normal again when
the watch returns to a lower temperature.
Warning!
Leaving the watch in bright light to charge its rechargeable battery can cause it
to become quite hot. Take care when handling the watch to avoid burn injury.
The watch can become particularly hot when exposed to the following
conditions for long periods.
• On the dashboard of a car parked in direct sunlight
More than • Too close to an incandescent lamp
40° • Under direct sunlight

Charging Guide

After a full charge, timekeeping remains enabled for up to about nine months, while
the watch is used under the conditions described below.

Operating Conditions

• Watch is not exposed to light
• Display on 18 hours per day, sleep state 6 hours per day
• 1 backlight operation (1.5 seconds) per day
• 10 seconds of alarm operation per day
• 1 countdown timer operation per day
Charge Times
Exposing the watch to light for the periods shown below each day restores the power
used by the above operating conditions.
Exposure Level (Brightness)
Outdoor Sunlight (50,000 lux)
Sunlight Through a Window (10,000 lux)
Daylight Through a Window on a Cloudy Day
(5,000 lux)
Indoor Fluorescent Lighting (500 lux)
• Stable operation is promoted by frequent charging.
Recovery Times
The table below shows the amount exposure that is required to take the battery from
one level to the next.
Solar cell
Exposure Level
(Brightness)
Outdoor Sunlight (50,000 lux)
Sunlight Through a Window
(10,000 lux)
Daylight Through a Window
on a Cloudy Day (5,000 lux)
Indoor Fluorescent Lighting
(500 lux)
• The above exposure time values are all for reference only. Actual required exposure
Reference
This section contains more detailed and technical information about watch operation.
It also contains important precautions and notes about the various features and
functions of this watch.
Power Saving Function
Function Status
All functions enabled.
All functions enabled.
To recover from the sleep state
All functions enabled.
Perform any one of the following operations.
• Move the watch to a well-lit area. It can take up to five seconds for the display to turn
Beeper tone, backlight,
display, and buttons are
• Press any button.
disabled.
• Angle the watch towards your face for reading.
All functions, including
timekeeping, are disabled. To turn Power Saving on and off
Moon Phase Indicator
The Moon phase indicator of this watch indicates the current phase of the Moon as
shown below.
Moon Phase
Indicator
Moon Age
Moon Phase
Approximate Exposure Time
Level 5
65 minutes
4 hours
7 hours
60 hours
times depend on lighting conditions.
When turned on, the Power Saving function automatically
puts the watch into a sleep state whenever it is left in an
area where it is dark for 30 to 35 minutes. The sleep state
is indicated by a blank screen with SLEEP flashing on it.
In the sleep state, all functions are enabled, except for the
display.
• Wearing watch inside the sleeve of clothing can cause it
to enter the sleep state.
on.
1. In the Timekeeping Mode, hold down C until the
seconds start to flash, which indicates the setting
screen.
2. Press B seven times until the Power Saving on/off
screen appears.
3. Press D to toggle Power Saving on (ON) and off
(OFF).
4. Press C twice to exit the setting screen.
• The Power Saving on indicator (SAVE) is on the display
in all modes while the Power Saving is turned on.
(part you cannot see)
0, 1, 29 2 - 5 6 - 9 10 - 13 14 - 16 17 - 20 21 - 24 25 - 28
New First
Moon Quarter
(Waxing)
Approximate Exposure Time
5 minutes
24 minutes
48 minutes
8 hours
Level 4 Level 3 Level 2 Level 1
18 hours 4 hours
98 hours 19 hours
– – –
– – –
Moon phase (part you can see)
Full Last
Moon Quarter
(Waning)
4