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OLED or LCD as a replacement display for synthesizer (English)

A question that is asked again and again to me as a spare parts dealer for electric pianos, music workstations and synthesizers, is the question of whether it makes more sense to replace the original display with an OLED or whether it makes more sense to stay with LCD. In the following article I would like to shed light on this question from different angles. First of all, for me there is no clear yes for one solution. As always, it depends on the individual case

1. Restoration or replacement

At the very beginning of the considerations each musician has to decide for himself, if I want to stay as close to the original as possible with the replacement display or is it just me that I have a readable display in the instrument again. If I want to stay as close as possible to the state of delivery of the synthesizer, then I speak of a restoration. Or is it as a musician "only" to have a readable display in the instrument again. In that case, I like to rely on current technology and can use the advantages of an OLED in good conscience.

2. Restoration

When we will do a restoration, it is also clear that I have to install an LCD display. The majority of music workstations and synthesizers where displays are replaced today were built in the late 1980's and 1990's. LCD displays were the state of the art during this time. Some of these LCDs had no backlight or, in most cases, a backlight in the form of an EL foil. That lifetime of EL foil is quite limited, today knows anyone who has a synthesizer with an LCD display.
But also in the restoration I allow myself to use actual LCD displays. The up to date LCD's today are always with a backlight on LED basis. This extends the lifetime considerably.

3. How LCD works

An LCD is a liquid crystal display. In this technique, liquid crystals are switched by means of an electrical voltage in two different states. The one state prevents the light from shining through, in the other state light can shine through. For this to work, an LCD will necessarily need a backlight.

4. How OLED works

The abbreviation OLED stands for organic light emitting diode. This technique uses an electrical voltage to light up an organic material. This means that every single pixel lights up like a subminiature lightbulb.

5. Which display sizes are available as OLEDs

Basically, I can say that OLED displays are available in many different sizes. In this context, the term size for the resolution of the display. For graphic displays, the resolution is specified in pixels. For alphanumeric displays, the number of characters and the number of rows are mentioned. An alphanumeric display with a resolution of 16x2 has 16 characters by 2 rows.
Problematic in our case is that we not only have to consider the resolution. A replacement display for a synthesizer needs to meet additional parameters so it can be used as a replacement. First, the display must have the same mechanical dimensions. No one wants to drill new holes in his synth or in the new display. Whatever must be same between old and new display, is the used interface. If the interface does not fit and synthesizer and display speak in different languages, the data exchange between the components will not work.
For the above reasons, OLED displays are only available as a replacement for alphanumeric displays up to a maximum of 40x2 characters. The status of these findings is the year 2018.

6. Lifespan

A decision criterion for or against an OLED could be e.g. be lifespan.
First, I would like to explain how the specification of the lifetime is defined: The indication of the lifetime is given in operating hours. However, after the specified operating hours, the display is still readable. According to the manufacturer, the display still has more than 50% of the original brightness after the specified operating hours.

For the lifetime of OLEDs I found two different details. The manufacturers themselves indicate values ​of 50,000 to 80,000 operating hours for a display type. In scientific articles, when looking at the lifespan, there are differences very clearly between the luminous color. According to these data, there are marked differences in lifetime as a function of the luminous color and in dependence on the operating temperature. Blue displays have the shortest lifespan. All in all, the lifetime of a blue OLED is given as half the life of a white OLED. We can neglect the ambient temperature with e-pianos and synthesizers because it is very rare here for increased ambient temperatures.

The same statement of 50,000 hours, I found by manufacturer of LCD displays. For LCD it should be said that this information applies to displays with LED backlight. The lifetime of the previously used EL foils is much lower.

7. Response time

In the reaction times of the two display variants clearly scores OLED. Under laboratory conditions, OLEDs are 1,000 times faster than classic LCD displays.

8. Comparison OLED – LCD

If I now compare these two display variants, then OLED has three important advantages over the LCD. On the one hand, the readability of an OLED in daylight or in the sun is much better than with an LCD. The second advantage is that an OLED can be read from many different angles. Especially the reading angle I feel in LCD's as a disadvantage. As soon as I no longer look at the display at a right angle it becomes more difficult with the readability. The third advantage of the OELD is the greatly improved reaction speed compared to the LCD. Although this plays a minor role for the here considered displays for musical instruments.

As an advantage of the LCD, I appreciate that this technique has been in use for many years. The technique is well known, well developed and mature. During the years of operation of a synthesizer, no negative surprises are to be expected here. In comparation, OLED technique is new and lifetime data are laboratory values.

Another advantage of the known LCD technology is the low price of the modules.

9. Summary

There are many advantages to the OELD in the summary. Assuming I do not speak of a restoration of the instrument which limits me greatly in the selection of the display.
The OLED reacts faster. Lights by itself, which greatly improves the readability and the reading angle.

As a major disadvantage remains lifetime. The small OLED displays considered here are also cited by manufacturers with good lifetime range. In scientific articles or Wikipedia, the lifetime is called a major disadvantage.

For the LCD speak the favorable price and the mature technology.

What remains to be said is that there are no OLED alternatives for many graphics displays built in the 1990's. For many popular instruments such as the Yamaha SY99, Korg Wavestation and 01 / W or Roland D70, there are only modern LCD displays. Today, these have without exception an LED backlight which prolongs the lifespan and there are 4 good color variants. The selection has improved a lot here.

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