frank@odetics.com (Frank Merrow) (02/07/91)
Hi, I am planning on buying a Super VGA board and CRT soon. I keep seeing things about dot pitch with numbers like .3? and .2?. What is pitch? I gather lower numbers are better, but what does it really mean to me when I look at the CRT? Frank
millernw@clutx.clarkson.edu (Neal Miller,,,) (02/08/91)
From article <1991Feb6.234713.17376@odetics.com>, by frank@odetics.com (Frank Merrow): > Hi, > > I am planning on buying a Super VGA board and CRT soon. I keep seeing > things about dot pitch with numbers like .3? and .2?. What is pitch? > I gather lower numbers are better, but what does it really mean to me > when I look at the CRT? From what I understand, the pitch of a monitor is the distance be- tween the pixels. The best pitches that are commonly found on the market are in the .28mm range or so. A lower pitch is definately better. A hypothetical 15-foot diagonal 1024x768 monitor would have a pretty lousy pitch (also called dot pitch), while a 10" 1024x768 monitor would have an excellent dot-pitch, but then you'd be straining the eye. I'd recommend a 14" monitor with a .28mm dot pitch. If I'm mistaken in any of the above, please correct me. ------------------------------------------------------------------------------ Neal Miller | "Why not go mad?" | millernw@clutx.clarkson.edu Clarkson University | - Ford Prefect | millernw@clutx.bitnet ------------------------------------------------------------------------------
smsmith@hpuxa.ircc.ohio-state.edu (Stephen M. Smith) (02/08/91)
millernw@clutx.clarkson.edu writes: >frank@odetics.com (Frank Merrow): >> I am planning on buying a Super VGA board and CRT soon. I keep seeing >> things about dot pitch with numbers like .3? and .2?. What is pitch? >> I gather lower numbers are better, but what does it really mean to me >> when I look at the CRT? > > From what I understand, the pitch of a monitor is the distance be- >tween the pixels. The best pitches that are commonly found on the market >are in the .28mm range or so. A lower pitch is definately better. A >hypothetical 15-foot diagonal 1024x768 monitor would have a pretty lousy >pitch (also called dot pitch), while a 10" 1024x768 monitor would have an >excellent dot-pitch, but then you'd be straining the eye. I'd recommend a >14" monitor with a .28mm dot pitch. If I'm mistaken in any of the above, >please correct me. I'm no expert on this, but I think two things are being confused here. "Pixels" (1024x768 for example) are NOT the same thing as "dot pitch." You can disply 300x200, 640x480, 800x600, etc. at different times on a multisync monitor, but your "dot pitch" will always remain the SAME. In other words, a "pixel" has to do with the resolution (1024 *pixels* x 768 *pixels*), but the dot pitch has to do with the holes in the mesh which are just behind the tube screen on your monitor. The best dot pitch available is 25 "dpi" (Sony Trinitron 14" tube). This means that the tube is physically constructed with a "mesh" which has "25 holes in the mesh for every inch across." (I think that's the way it's figured, or could mean that each hole is .25mm in size.) In any case, the more "holes" in the mesh, the sharper the picture. The reason for the holes is to narrow the beams so as to hit smaller patches of the phosphor coating on the backside of your screen's surface so that colors won't bleed into one another and to make the picture "sharp." (If that's wrong, somebody please correct.) The pixels are something entirely different. One "pixel" is one increment of scan on one line (one of the 1024 "increments" on one of 768 horizontal lines given a 1024x768 resolution). Thus the larger the screen, the larger the pixel becomes (at the same resolution). But the dot pitch will be determined not by the software, nor by the video card's capabilities, nor by the resolution being displayed, but by the physical makeup of the TUBE. The reason that higher resolutions and smaller dot pitches are more expensive for a given monitor is that 1) higher resolutions need more exacting electronic "circuitry" (for higher vertical scan capabilities), and 2) it costs more to make the tube with more holes in its "mesh." Therefore...the construction of the TUBE will determine the dot pitch, but the electronic "capabilities" built into the circuitry of the monitor will determine RESOLUTION (i.e., how many pixels it can display). S. "Stevie" Smith \ + / <smsmith@hpuxa. \+++++/ " #*&<-[89s]*(k#$@-_=//a2$]'+=.(2_&*%>,,@ ircc.ohio-state. \ + / {7%*@,..":27g)-=,#*:.#,/6&1*.4-,l@#9:-) " edu> \ + / BTW, WYSInaWYG \ + / --witty.saying.ARC
bobmon@iuvax.cs.indiana.edu (RAMontante) (02/08/91)
smsmith@hpuxa.ircc.ohio-state.edu (Stephen M. Smith): | I'm no expert on this, but I think two things are being confused here. | "Pixels" (1024x768 for example) are NOT the same thing as | "dot pitch." You can disply 300x200, 640x480, 800x600, etc. at | different times on a multisync monitor, but your "dot pitch" will | always remain the SAME. In other words, a "pixel" has to do with | the resolution (1024 *pixels* x 768 *pixels*), but the dot pitch | has to do with the holes in the mesh which are just behind the tube | screen on your monitor. The best dot pitch available is 25 "dpi" | (Sony Trinitron 14" tube). This means that the tube is physically | constructed with a "mesh" which has "25 holes in the mesh for every | inch across." (I think that's the way it's figured, or could mean | that each hole is .25mm in size.) In any case, the more "holes" [ ... ] Close. The pitch (typically .28mm) is the spacing between discrete "dots" on the screen. Note that in a color tube a "dot" is composed of *three* phosphor patches, a Red, a Green, and a Blue one. Many of the best tubes (maybe all, these days) use a perforated mask around these phosphor triplets, which keeps the electron beam from stimulating more than one set of phosphors at a time. (To put it another way, the mask makes sure that the dots are less than .28mm in diameter, so they don't overlap.) At .28mm/dot, a horizontal line of 1024 dots is 287mm long. This fits well with the active area of a 13" (diagonal) CRT tube, so is nicely suited to a 1024x768 sVGA image. Consider a .38mm dot pitch: a 1024-dot line needs a screen 389 millimeters wide, while 287mm holds only 755 dots. So if you tried to display a 1024-pixel-wide image, either 1) 35% of the image would overrun the edge of the screen, 2) the 1024 image pixels have to be mapped over only 755 screen dots, resulting in blurriness and loss of image quality, or 3) images greater than 755 pixels width must be rejected. On the other hand, a horizontal line on a 19" (diagonal) monitor is about 390mm, so a .38mm dot pitch on a 19" monitor is fine for images up to 1024 pixels width.
mikek@col.hp.com (Mike Karin) (02/14/91)
> From what I understand, the pitch of a monitor is the distance be- >tween the pixels. The best pitches that are commonly found on the market Not exactly. The pitch is the horizontal distance between pixels of the same color. ie. The distance between two RED pixels on a color display. Mike Karin Hewlett-Packard Co. Colorado Springs Division mikek@col.hp.com