Prius Dash Display - Polarized Output

<div class='quotetop'>QUOTE(baumgrenze @ May 15 2007, 06:24 PM) [snapback]442794[/snapback]</div>

Yep! and so are all LCD displays. You can observe the same effect if your gas station pump has a LCD display, or your laptop, or your flat LCD monitor, or your LCD TV, or ...

 

try taking a pic of a large display (eg a 65" tv like mine) you get only half a picture if taking the pic within 6 feet or so.

 

<div class='quotetop'>QUOTE(DaveinOlyWA @ May 15 2007, 08:00 PM) [snapback]442846[/snapback]</div>

Are you talking about the standard "tube" TVs? Cause I'm pretty sure we all know about that one. If you are talking about an LCD panel, then I'm curious cause I've never seen that.

 

<div class='quotetop'>QUOTE(Alexstarfire @ May 15 2007, 09:14 PM) [snapback]443040[/snapback]</div>

nope not tube or LCD, its DLP....and cant tell you if i can take a pic farther away and have it be ok because i cant get farther away in my current living arrangement, but have tried to take screen shots several times by snapping a digital shot and it goes from bright to multi-color bands down to darkness and have tried several angles

 

<div class='quotetop'>QUOTE(DaveinOlyWA @ May 17 2007, 10:37 AM) [snapback]444172[/snapback]</div>

So, is this a polarization thing, too, since the DLP uses the mirror arrays?

 

<div class='quotetop'>QUOTE(Betelgeuse @ May 17 2007, 10:42 AM) [snapback]444178[/snapback]</div>

Not unless he's using a polarizing filter on his camera.

More likely he's using a shutter speed that is faster than the refresh rate of the screen. Different brnads of DLP screens use different methods of splitting/blending colors and brightness, so without knowing what brand/model, I can't tell you what sort of refresh you are dealing with.

Use a tripod, slow your shutter speed down to 1/4 second or so, and adjust the aperature accordingly and you'll probably find that the image looks ok no matter what brand/model it is.


<div class='quotetop'>QUOTE(baumgrenze @ May 16 2007, 12:04 AM) [snapback]443084[/snapback]</div>

I'm not certain, but I'm pretty sure I've seen other LCDs polarization orientations. Technically it certainly should be possible. However, 45 deg. off verticle is the most common I've seen, and seems to be a standard.

I haven't checked the link you included yet, but if the light from the dash display isn't polarized to start with, then it is probably the reflection off the angled mirror that is polarizing it. No good way to prevent this. Fortunately there is enough unpolarized light after the reflection that the display is still visible (though significantly dimmed).

 

<div class='quotetop'>QUOTE(DaveinOlyWA @ May 17 2007, 11:37 AM) [snapback]444172[/snapback]</div>

DLP displays in home TVs project an entire screen at a time, but the information going to the screen is time multiplexed. Colors are displayed in separate frames, as many as six passes per screen with some brands. Also, if you are using an interlaced signal (such as 1080i) instead of a progressive (1080p), the screen is updated in two passes. Taking a picture with a fast shutter setting will capture part of the screen update. A slow shutter setting will work like human eyes.

Tom

 

Just a non-techie observation- do not use the Blue blocker sunglasses- when hubby buys new ones(clip ons) he gets the lightest polarized ones so he can see the dash. Blue blockers did not work- you could not see the dash.

 

<div class='quotetop'>QUOTE(Danny Hamilton @ May 17 2007, 12:13 PM) [snapback]444199[/snapback]</div>

for your continued viewing pleasure, attached are a few photos showing polarization effects

[attachmentid=8160]
filter adjusted to show light transmission - lcd computer monitor



[attachmentid=8161]
filter adjusted for reduced light transmission - lcd computer monitor



[attachmentid=8162]
filter adjusted to show light transmission - prius mfd



[attachmentid=8163]
filter adjusted to show reduced light transmission - prius mfd



[attachmentid=8164]
filter adjusted to show light transmission - prius mfd



[attachmentid=8165]
filter adjusted to show reduced light transmission - prius mfd

 

<div class='quotetop'>QUOTE(baumgrenze @ May 19 2007, 06:09 PM) [snapback]445829[/snapback]</div>

treeline,
Going back to the article at your hyperlink, the David Carey says "While much of the Toyota Prius's status information and vehicle control functions comes by way of the central touch-screen panel, critical information is delivered from a dedicated display system visible directly behind the steering wheel. The dash module (DM) provides most of the output-only information such as speed, fuel-level, selected gear, and odometer/mileage by way of a digital readout and icon-based vacuum fluorescent display (VFD) panel."

Please note that the author is talking about the DM being lit by a VFD - and that the DM is visible "directly behind the steering wheel". Absolutely, the odometer is bounced thru (or across, or over, or whatever) mirrors before it shows up behind the steering wheel. I agree 100% with David Carey, the author of the article at the link you posted, that the odometer is VFD. No question, no argument.

 

I noticed the same thing the other day when I was driving wearing my polarized Revos. Normally, I only wear my polarized sunglasses on the boat, but have been wearing them to drive lately while my Oakleys were in for a warranty repair issue.

I find polarized sunglasses great for driving, as they have many benefits, especially in removing glare which many drivers find distracting and annoying. However, the trade-off is having trouble looking at some of the displays inside the car, especially if you are just glancing at the displays out of the corner of your eyes. I notice that you almost need to physically turn you head to overcome the effects of the polarization. This makes sense because as has been pointed out, the degree of polarization has to do with the angle of the light.

So, it is really a personal choice of whether the benefits of removing glare outweigh the nuisance you encounter with the LCD display in the car.

 

<div class='quotetop'>QUOTE(baumgrenze @ May 15 2007, 06:24 PM) [snapback]442794[/snapback]</div>

Does it make a difference that the light for the dash is reflected light as opposed to the MFD?

 

<div class='quotetop'>QUOTE(faith2walk @ May 21 2007, 08:32 AM) [snapback]446564[/snapback]</div>

Yes. Reflection tends to induce polarization transverse to the viewing direction.

Tom

 

The conclusion I drew from this years ago was the advantages of polarized glasses are minimal compared to the disadvantages of trying to read LCD screens in today's technology. I got tired of tilting my head to read the MFD or holding my cell phone just right.

My sunglasses now are no longer polarized.