Striving to provide the joys of photography through a viewfinder is the core of the X series' identity. This time around, we were successful in responding to the wishes of our customers to have photography information displayed within the viewfinder of the premium compact camera FUJIFILM X20. This includes information such as the focus point, shutter speed, aperture value, exposure correction, and image stabilizer alert.
However, the road toward realizing an unobtrusive and simple information display within a compact optical zoom viewfinder was not an easy one. Here, we will tell you a few of the hurdles we had to overcome during the development.
Display within compact film camera viewfinder
Technologically speaking, it's no easy task to display words and lines within the OVF of a non-single lens reflex compact camera – that is, one without mirrors or pentaprisms. Most cameras on the market either have nothing show up in the OVF or only show figures outside the frame, and neither can display information such as the focal point.
But that wasn't the only problem. With FUJIFILM X20, the OVF must change magnifications according to the lens zoom level, and any information display would have to consider the problem of parallax. These were among the numerous issues that had to be faced.
The method we settled on was to place a Digital Trans panel between the two large glass prisms within the viewfinder. The first issue to be tackled was how to place a Digital Trans Panel in this space of less than 1.0mm.
An eye sensor was also placed within the little space left within the viewfinder. This allowed the viewfinder display and LCD monitor display behind it to be automatically switched by simply putting your eye near it.
Display within FUJIFILM X20 viewfinder
Increasing the transparency rate of the LCD panel itself was vital to ensure the viewfinder to remain clear and easy to see, even with a digital trans placed between its two prisms. Various materials were tested, ultimately leading to the development of the Digital Trans Panel.
Switching of LCD panels is normally controlled by changing the alignment of the orientation within its polarization plates through application of voltage. This means that when light passes through, the panel becomes transparent with voltage, and when light does not pass through, light scatters due to no voltage. This is a different mechanism from those used in LCD TVs and monitors.
The major difference between the Digital Trans Panel and others is the lack of a polarization plate. This allowed the achievement of a 90% transparency rate, compared to the approx. 10% for normal LCD panels. A high transparency rate was the key to realizing clear OVF display. An anti-reflective coating was also applied to each side of the panel, to further heighten transparency rate.
A characteristic of LCD panels is that when voltage is not applied, or when the power is off, the orientation makes light scatter and results in reduced clarity. But FUJIFILM X20 includes a circuit where orientation turns on and the LCD panel activates to make the viewfinder clear, all by simply inserting battery. Thus, the viewfinder can immediately be used even when the power is off. The amount of current used in this process is but a few microamperes, and has nearly zero effect on features such as the number of photos that can be taken.
The orientation makes light scatter and results in reduced clarity.
Light passes through
The FUJIFILM X20 Digital Trans Panel can display a total of 128 lines and icons (segments). This number is determined by the function and size of the drive IC in charge of turning displays on or off. While a single drive IC contained within an average single lens reflex camera viewfinder controls 50 segments, the X20 viewfinder contains a high-functioning drive IC which allows displaying over double that number.
*1 Segment: Unit for the lines or icons which can turn on, flicker, or turn off simultaneously when an ON/OFF signal is received. For example, parallax alerts such as “!” and “Flower” are always displayed at the same timing, so they are regarded as 1 segment. There is no relation to design complexity.
Chip on Glass technology used to place drive IC on glass
Furthermore, to ensure the viewfinder does not take up too much space, Chip on Glass technology was used to place the drive IC directly onto the glass surface of the LCD panel. This is the first time in the world use this technology on a Digital Trans Panel.
An internal GUI (Graphic User Interface) designer that oversees various types of design within Fujifilm was in charge of effectively utilizing the 128 display segments of the Digital Trans Panel, and ensuring an easy-to-understand design which showed information that users want to see while taking photos.
The objective was to create simple and easy to understand information display., The optimal display method for each functions contained within FUJIFILM X20 was investigated accordingly, but the large number of patters made the task difficult. However, by creatively utilizing display methods such as “lighting up,” “flickering,” and “display switching,” all sorts of information were able to be displayed. These included not only exposure displays such as aperture and shutter speed, but also switching to exposure display after switching of elements such as ISO sensitivity or exposure correction, in addition to the display of alerts for parallax, AF errors and image stabilization. The finer details were also given consideration to in creating a layout consistent with the LCD monitor display, such as situating exposure displays on the lower half of the screen and error displays on the right.
A display at a bright place
At the time of AF error
Ath the time of AF lock
A Display at dark place
At the time of AF error
Ath the time of AF lock
Segment displays are normally black, but this makes them hard to see in the dark. Therefore, the three colored LEDs (R/G/B) on the side of the Digital Trans Panel were used to ensure that in darker areas, the display is green when normal, blue during AF/AE lock, and red when an AF error occurs. The switching of these colors utilizes the trait where light reflected off LCD panel orientation when it scatters light (or is black, in other words) changes the color of said light. By utilizing several colors of light, we made it possible for the OVF to be used in all types of situations.
We took the opinions of professional photographers into consideration when deciding on display design, design layout, and display method within the viewfinder. We received some particularly harsh opinions regarding the focus area display method, which only made us realize anew the importance of the viewfinder to photographers. But this also allowed us to realize a design which proved satisfactory for everyone.
As the viewfinders for the X series of cameras are known for providing a clear and beautiful view, the structural design of the Digital Trans Panel was full of innovations, keeping the manufacturing process in mind.
For example, to ensure an even distribution of LED lights over the entire LCD panel which is used to display colors for the Digital Trans Panel, the angle set for the light guide was 112.5°. This ensured optimal form for the light guide when compared to the 90⁰ angle that is normally used in light guides for single lens reflex cameras. This also achieved both conservation of space and increase in LED lighting efficiency. Yet another innovation is the covering of the LCD panel in a frame to ensure LED lights not to leak into the eyepiece of the viewfinder.
A particularly problematic issue was how to limit the out-of-focus state of the viewfinder FOV frame and LCD image when matching the viewfinder image focus surface to the Digital Trans Panel display surface. Instead of attaching the FOV frame to the LCD as a separate piece, chrome vapor was onto the LCD panel. This allowed the viewfinder display surface and FOV frame surface to be kept at the same level, and chrome vapor ensured a slim silhouette. Thus, both clarity and ease of viewing were realized for the OVF.
Since parts such as the glass prism, high zoom eyepiece lens, and Digital Trans Panel would be handled together during manufacturing, multiple measures to ensure precision and dustproofing are in place. Use of a sealed structure for the Digital Trans Panel to prevent foreign material intrusion and reducing the number of parts comprising said Panel to the bare minimum required are but a few examples of these measures. As the viewfinder can zoom in up to 15x magnification, even the slightest debris or mismatching can appear to be enormous. The chrome vapor plating used for the FOV frame explained above was but one of the measures used to reduce the number of component parts. Ultimately, this contributed not only to dustproofing but also to ease of viewing.
In order for a viewfinder camera to correctly display viewfinder area, it is of the utmost importance that the optical axes of the lens and viewfinder match. Toward this end, the optical axes of each and every single lens and viewfinder are matched using both machines and human eyes to enhance precision. This is a process that we proudly proclaim to be possible due to the product being made in Japan.
As you can see, the Advanced OVF used in FUJIFILM X20 is a culmination of technology and brains. We are certain that we have increased the usefulness of the viewfinder and thus, increased its enjoyability. We hope you will experience the new sensations and ease of use of the beautiful X20 viewfinder.
Advanced OVF development project leader: Shigeru Kondo, Electronic Image Product Development Center Senior Engineer
Advanced OVF display design: Takeharu Omata, Design Center Chief
Digital Trans Panel development leader: Masanari Asano, Electronic Image Product Development Center Senior Engineer
Advanced OVF structure design: Takao Sasaki, Optical Device Business Div.