Car mirrors are a very important part of a car, and with the right knowledge, you can have a fulfilling car life.

Table of Contents

(1)Maintaining visibility is the basis of safe driving
There are many parts to a car, and each part plays a role in preventing accidents.
Among them, mirrors are one of the most important parts that play an active role in ensuring visibility while driving and when parking.
In this article, we will explain the basics about car mirrors in an easy-to-understand manner.
With the right knowledge and handling, you can enjoy a safe car life.
(2)What types of mirrors are essential for cars?
There are two types of mirrors in cars.
One is the mirror installed inside the car, called the rearview mirror or back mirror.
The rearview mirror is attached to the upper center of the car’s windshield and serves to check directly behind the car.
The other type of mirror is the door mirror or fender mirror, which is located on the outside of the car.
Door mirrors and fender mirrors are also called side mirrors.
Door mirrors are attached to the doors on both sides of the front seats and are used to check the rear of the car.
Fender mirrors are installed on both sides (symmetrically) of the vehicle hood and play the same role as door mirrors, but nowadays they are mainly installed in cabs and government vehicles.

(3)Basic knowledge of rearview mirrors
3-1.Definition of a rearview mirror
  • ・Rearview mirror refers to the mirror located in the upper center of the front of the car, and is collectively called a back mirror, including door mirrors and fender mirrors
  • ・The term “back mirror” is Japanese English, and is described as “koushakyo” in the legal terminology (Article 44 of the safety standards of the Road Trucking Vehicle Law).
  • ・Rearview mirrors are used to see directly behind the car and are required by the Road Trucking Vehicle Law to be installed.
  • 3-2.Role of rearview mirrors
  • ・Checking for following cars while driving
  • ・Checking the safety of rear seat passengers while driving
  • ・Checking the rear of the car when parking認
  • ・Checking the rear of the car when starting the car
  • 3-3.Characteristics of rearview mirrors
    Rearview mirrors are made of two laminated mirrors so that they do not dazzle even when strong light hits them from behind. Changing the angle of the mirrors reduces dazzle, but when driving at night or in tunnels, the headlights of the following car may reflect and dazzle you.
    In such cases, you can reduce the glare by adjusting the angle of the mirror by pulling the lever at the bottom center of the rearview mirror towards you.
    A room mirror with this lever is called an “anti-glare rearview mirror”.
    In recent years, demand for “automatic anti-glare” mirrors, which detect light and automatically reduce reflectivity, has also increased.
    In order to prevent injury to the occupants in the event of an accident or other impact, the installation standard for rearview mirrors is “adjustable or detachable”.
    3-4.Correct position and adjustment of rearview mirrors
  • ①Sit in the driver’s seat and adjust the position of the seat.
  • ②Once you have decided on your driving position, adjust the position of the rearview mirror.
  • At this time, adjust the angle to a position where you can see the entire rear window while retaining the mirror in a horizontal position.
    3-5.Rearview mirror maintenance, problems and preventive measures
  • Dirty mirror surface
  • If the rearview mirror is dirty, the visibility directly behind you will be poor making it dangerous, so wipe it with water or dry it regularly.
    In particular, if you smoke in the car, the smoke will stick to the car.
    If you smoke in your car, you can’t get rid of it by wiping with water, or use a special cleaner to remove the stains.
  • Damaged or scratched mirror surface
  • If the mirror surface is damaged or scratched, it is dangerous for the occupants, so we recommend replacing it as soon as possible.
  • A Wobbly or swaying rearview mirror
  • Plastic products are susceptible to heat and deterioration, so inspect the mounting area and other parts periodically.

    (4)Basic Knowledge of Side Mirrors
    4-1.Definition of a side mirror
    Door mirrors are often referred to as side mirrors and are required to be installed on the outside left and right sides of the front seat doors according to Article 44 (rear-viewing mirrors) of the safety standards of the Road Vehicles Act.
    In Japan, there was a time when only fender mirrors (mirrors installed on the hood) were allowed, but with the relaxation of the law in 1983, door mirrors have become the norm these days.
    4-2.Role of side mirrors
  • ・Checking the status of following cars while driving
  • ・Checking behind you when changing lanes or turning right or left while driving.
  • ・Checking the distance to obstacles and walls when parking.
  • ・Checking the boundary line when entering a garage.
  • 4-3.Characteristics of side mirrors
    Side mirrors cannot see directly behind you, but they can see behind the right and left sides of the car body, so they are very useful when moving the car, such as when driving, parking, or starting.
    They are characterized by their ability to be adjusted to an angle that is easy for the driver to see, such as when driving or parking, but care must be taken to avoid blind spots if the angle is out of focus.

    4-4.Correct position of side mirrors and how to adjust them
  • Driver’s side mirror
  • In the up and down field of vision, the ground should be visible about one-third to one-fourth of the time.
    In the left-right field of vision, the mirror should show the car body about one-quarter to one-fifth of the way.
  • Side mirror on the passenger side
  • Make sure that half or one-third of the upward and downward views show the ground, and one-quarter of the left and right views show the car body. Side mirrors are important for checking the presence of motorcycles and bicycles when turning right or left, for checking the status of following vehicles when changing lanes, and for checking boundaries and obstacles when parking.
    It is no exaggeration to say that the angle and position of the side mirrors are crucial to avoid accidents and smooth parking and garage entry. Adjust them for the correct driving position.

    4-5.Side mirror maintenance, problems and preventive measures
  • Fogging of the side mirrors
  • Since side mirrors are installed outside the car, they can easily get dirty or become dull due to rain or snow.
    Dullness and dripping on the mirror surface can reduce visibility and be very dangerous.
    Here are some ways to prevent this from happening.
    Hydrophilic mirror
    Using photocatalytic technology, a crystallized titanium oxide (Ti02) film is deposited on the mirror surface to break down dirt on the mirror surface and make rain drops hydrophilic to ensure rearward visibility.
    This photocatalytic hydrophilic mirror needs to be exposed to sunlight since its performance is enhanced by the ultraviolet rays contained in sunlight.
    In addition, if the surface of the hydrophilic mirror is covered with wax, water repellent coating, or anti-icing material used in car washes, the performance of the mirror will deteriorate.
    In this case, it is necessary to wash the mirror surface thoroughly with neutral detergent. However, depending on the type of wax or coating that has adhered to the mirror, the deterioration in performance may not be reversible, so care must be taken to avoid adhesion as much as possible.
    Installing Heated Door Mirrors
    Heated door mirrors, like rear windows, are equipped with a built-in heating element to prevent water drops at the touch of a button.
    Application and spraying of coating material
    If the mirrors are not coated at the time of purchase, you can apply a coating or spray to make them hydrophilic or water repellent.
    Hydrophilic treatment is a process that blends with the rainwater on the mirror and makes it run off.
    Water repellency is a process in which rainwater that has adhered to the mirror is formed into water droplets and repelled.
    If you think “you have a problem”, take action as soon as possible!

    The operation of side mirrors may fail as the motor and switches deteriorate over time.
    If you notice any of the following problems, consult your dealer or retailer as soon as possible.

  • ・The side mirrors do not move or do not open
  • ・The side mirrors do not move even when the electric switch is turned on
  • ・Only one side mirror moves
  • ・It’s making noise all the time
  • ・Noisy but not moving
  • ・The mirror is scratched or broken
  • (5) Installation standards for automobile mirrors in laws and regulations
    The following are the installation standards for automobile mirrors under Article 44 (rear-view mirrors) of the Safety Standards of the Road Vehicles Act.

    Applicable items
  • ・For mirrors installed on the outside of the car body, the structure must be able to cushion the impact in the event of contact with a pedestrian (variable type, drop type, etc.)
  • ・For mirrors installed inside the car, the structure must be able to fall off in order to prevent injury to occupants in the event of an accident or other impact (variable type or detachable type)
  • ・The mirror is installed so that its function is not impaired by vibration during driving
  • ・Easy to adjust and maintain a constant direction
  • ・Check the status of vehicles up to 50 meters behind the driver’s seat
  • ※Article 224, Section 3 of the Detailed Notice of Article 44 of the Safety Standards for Road Vehicles, Ministry of Land, Infrastructure, Transport and Tourism.
    ※Refer to Article 44 (rear-view mirrors, etc.) of the Safety Regulations for Road Vehicles of the Ministry of Land, Infrastructure, Transport and Tourism.
    Rearview mirrors and side mirrors are essential devices both while driving and when parking.
    Since visibility varies depending on the driver’s posture and the position and height of the seat, it is important to check them before driving.
    It is also important to maintain them on a daily basis to keep your vision safe.