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Back to working on the HP Officejet Pro 8000

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  • vrsculptor@hotmail.com
    Some good news and some bad news. The good news is that the encoder (Avago AEDS-964X) has enough drive to feed both the printer and a breakout board. This
    Message 1 of 7 , Jan 20, 2010
      Some good news and some bad news.

      The good news is that the encoder (Avago AEDS-964X) has enough drive to feed both the printer and a breakout board. This means that your controller can tell exactly when the printer is moving and how much so you can coordinate the motion of the X axis with what the printer expects.

      Also good news that you can definitely tell when the dance is over and the paper feed cycle is to begin. When the dance is done the head moves all the way to the left and the encoder starts to count up. You can sense the head position with a micro switch.

      The bad news is that the printer goes through an elaborate power up and head alignment cycle whenever you change a print head or the printer has been off for a while. The cycle takes 20 minutes. This would be bad enough but the printer prints an alignment page and scans the output to make sure that the heads are properly aligned. I see two really huge problems here.

      1. The print output will be on plaster in our application. Not sure that printer would properly "see" alignment. Could probably get around this by laying a sheet of paper on top of plaster.

      2. If we are not using pigmented ink but a binder like vodka/water the alignment will fail as it wont "see" its alignment marks.

      I wonder if printing with ink (in a gray scale) instead of binder is a problem. From looking at the recipes I think it might be.

      I guess I need to resolve this before going any farther.

      Roger
    • John
      ... Roger How does it scan for alignment?, what optical system does it have for doing this, would it be possible to lift up the scanning optics and have
      Message 2 of 7 , Jan 21, 2010
        --- In diy_3d_printing_and_fabrication@yahoogroups.com, vrsculptor@... wrote:
        >
        > Some good news and some bad news.
        >
        > The good news is that the encoder (Avago AEDS-964X) has enough drive to feed both the printer and a breakout board. This means that your controller can tell exactly when the printer is moving and how much so you can coordinate the motion of the X axis with what the printer expects.
        >
        > Also good news that you can definitely tell when the dance is over and the paper feed cycle is to begin. When the dance is done the head moves all the way to the left and the encoder starts to count up. You can sense the head position with a micro switch.
        >
        > The bad news is that the printer goes through an elaborate power up and head alignment cycle whenever you change a print head or the printer has been off for a while. The cycle takes 20 minutes. This would be bad enough but the printer prints an alignment page and scans the output to make sure that the heads are properly aligned. I see two really huge problems here.
        >
        > 1. The print output will be on plaster in our application. Not sure that printer would properly "see" alignment. Could probably get around this by laying a sheet of paper on top of plaster.
        >
        > 2. If we are not using pigmented ink but a binder like vodka/water the alignment will fail as it wont "see" its alignment marks.
        >
        > I wonder if printing with ink (in a gray scale) instead of binder is a problem. From looking at the recipes I think it might be.
        >
        > I guess I need to resolve this before going any farther.
        >
        > Roger
        >
        Roger
        How does it scan for alignment?, what optical system does it have for doing this, would it be possible to lift up the scanning optics and have something fixed below to kid it somehow.
      • vrsculptor@hotmail.com
        Hi John, The scanner is mounted on the side of the print head. A lot of the HP s had a sensor for automatic paper type sensing and edge of page. This one, only
        Message 3 of 7 , Jan 21, 2010
          Hi John,
          The scanner is mounted on the side of the print head. A lot of the HP's had a sensor for automatic paper type sensing and edge of page. This one, only during alignment, shines a high intensity blue LED on the paper. The alignment procedure prints a whole page of blocks in primary colors and I guess adjusts print head timing so that the edges line up. The alignment process also adjust the micro line feed spacing (guess encoder ticks) to prevent streaking. Its got to have some sort of CMOS image sensor.

          I've heard from other sources that the print data is sent to the head serially via SPI and not parallel. The cable has a lot of connections and there is an ASIC/FPGA in the print head so lord knows what its doing.

          I'm afraid this printer is just way too smart to mess with.

          Roger


          > How does it scan for alignment?, what optical system does it have for doing this, would it be possible to lift up the scanning optics and have something fixed below to kid it somehow.
          >
        • Boman33
          Roger, Are you sure that it actually checks the printing? Is it possible a paper edge detector to make sure it correctly finds the edge of the paper? Bertho
          Message 4 of 7 , Jan 21, 2010
            Roger,
            Are you sure that it actually checks the printing?
            Is it possible a paper edge detector to make sure it correctly finds the
            edge of the paper?
            Bertho
            ====

            From: vrsculptor@... Sent: Thursday, January 21, 2010 10:10
            Hi John,
            The scanner is mounted on the side of the print head. A lot of the HP's had
            a sensor for automatic paper type sensing and edge of page. This one, only
            during alignment, shines a high intensity blue LED on the paper. The
            alignment procedure prints a whole page of blocks in primary colors and I
            guess adjusts print head timing so that the edges line up. The alignment
            process also adjust the micro line feed spacing (guess encoder ticks) to
            prevent streaking. Its got to have some sort of CMOS image sensor.

            I've heard from other sources that the print data is sent to the head
            serially via SPI and not parallel. The cable has a lot of connections and
            there is an ASIC/FPGA in the print head so lord knows what its doing.

            I'm afraid this printer is just way too smart to mess with.

            Roger

            > How does it scan for alignment?, what optical system does it have for
            doing this, would it be possible to lift up the scanning optics and have
            something fixed below to kid it somehow.
          • John
            Hello Roger, I wonder if its the same type of sensors that are in optical mice,16 or 32 pixels, or even a line sensor, unless someone has written a utility to
            Message 5 of 7 , Jan 21, 2010
              Hello Roger,
              I wonder if its the same type of sensors that are in optical mice,16 or 32 pixels, or even a line sensor, unless someone has written a utility to switch callibration of it sounds like a whole world of pain, would it be possible to add some food colouring to the binder, if so, you could let it do its callibration thing, put down a few layers and build on top, I may be talking rubbish here as I have never seen the HP Officejet Pro 8000.

              --- In diy_3d_printing_and_fabrication@yahoogroups.com, vrsculptor@... wrote:
              >
              > Hi John,
              > The scanner is mounted on the side of the print head. A lot of the HP's had a sensor for automatic paper type sensing and edge of page. This one, only during alignment, shines a high intensity blue LED on the paper. The alignment procedure prints a whole page of blocks in primary colors and I guess adjusts print head timing so that the edges line up. The alignment process also adjust the micro line feed spacing (guess encoder ticks) to prevent streaking. Its got to have some sort of CMOS image sensor.
              >
              > I've heard from other sources that the print data is sent to the head serially via SPI and not parallel. The cable has a lot of connections and there is an ASIC/FPGA in the print head so lord knows what its doing.
              >
              > I'm afraid this printer is just way too smart to mess with.
              >
              > Roger
              >
              >
              > > How does it scan for alignment?, what optical system does it have for doing this, would it be possible to lift up the scanning optics and have something fixed below to kid it somehow.
              > >
              >
            • vrsculptor@hotmail.com
              Hi Bertho, I m reasonably sure. I wish there was a way to get real information on these printers from HP without having to be an OEM. Everything I have been
              Message 6 of 7 , Jan 21, 2010
                Hi Bertho,
                I'm reasonably sure. I wish there was a way to get real information on these printers from HP without having to be an OEM. Everything I have been able to pick up has been through observation and testing. I would love to be wrong.

                My HP 990cxi has a blue LED that is used to find edge of paper. It comes on every paper feed cycle.

                The HP 8000 is different. The blue LED only comes on during its alignment cycle. The manual says that the 20 minute alignment cycle aligns the print heads and adjusts for streaking. When aligning it prints 24 lines of boxes with composite (kind of like lithograph targets) markers at the start and end of each line. If it isn't looking at what its printing I can't imagine what its doing.

                Roger

                >
                > Roger,
                > Are you sure that it actually checks the printing?
                > Is it possible a paper edge detector to make sure it correctly finds the
                > edge of the paper?
                > Bertho
                > ====
              • Charles Fernando
                Hi, My HP 5550 also has a blue led beside the ink carriage, for paper type sensor, the owner s manual said so, but this feature is unrealiable.... Charles ...
                Message 7 of 7 , Jan 21, 2010
                  Hi,
                  My HP 5550 also has a blue led beside the ink carriage, for paper type sensor, the owner's manual said so, but this feature is unrealiable....

                  Charles

                  --- On Fri, 1/22/10, vrsculptor@... <vrsculptor@...> wrote:

                  From: vrsculptor@... <vrsculptor@...>
                  Subject: [diy_3d_printing_and_fabrication] Re: Back to working on the HP Officejet Pro 8000
                  To: diy_3d_printing_and_fabrication@yahoogroups.com
                  Date: Friday, January 22, 2010, 7:50 AM

                   

                  Hi Bertho,
                  I'm reasonably sure. I wish there was a way to get real information on these printers from HP without having to be an OEM. Everything I have been able to pick up has been through observation and testing. I would love to be wrong.

                  My HP 990cxi has a blue LED that is used to find edge of paper. It comes on every paper feed cycle.

                  The HP 8000 is different. The blue LED only comes on during its alignment cycle. The manual says that the 20 minute alignment cycle aligns the print heads and adjusts for streaking. When aligning it prints 24 lines of boxes with composite (kind of like lithograph targets) markers at the start and end of each line. If it isn't looking at what its printing I can't imagine what its doing.

                  Roger

                  >
                  > Roger,
                  > Are you sure that it actually checks the printing?
                  > Is it possible a paper edge detector to make sure it correctly finds the
                  > edge of the paper?
                  > Bertho
                  > ====


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