Patent Publication Number: US-9892713-B2

Title: Display device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 12/365,465, filed on Feb. 4, 2009, which claims priority Japanese Patent Application No. 2008-040820, filed on Feb. 22, 2008, the disclosures of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention is one that pertains to technology providing a display device. 
     Description of the Related Art 
     In recent years, along with the spread of Personal Computers as well as IT (Information Technology) infrastructure development, projection type image display devices, starting with projectors, have spread with high speed in various settings such as at conference presentations and for lectures at education sites. 
     Moreover, accompanying the spread, the trend toward higher luminance is advancing together with a reduction in price. As a result hereof, since it has not been possible in the past to obtain sufficient brightness for display images of projection type image display devices, it has been necessary to project on a dedicated screen to make the projection. Under present conditions, since it is possible to procure projection type image display devices comparatively inexpensively and with high luminance, it is possible to ensure sufficient brightness even without making a projection on a dedicated screen, so cases in which projections are made on recording facilities such as whiteboards and blackboards have also gradually become more numerous. 
     On the other hand, a recording facility onto which a projection is made is an important tool with which tables and characters are recorded to carry out communication of intent, but since there are different objectives at the time of recording, there is a situation in which it cannot be said that guide displays such as to make tables easy to write or record characters by alignment in either the horizontal or vertical direction are sufficient. As far as whiteboards are concerned, there are box-shaped guide displays or printed guide letters which are put to practical use as recording aids, but since the objectives of use at the time of recording are diverse, the situation is one which cannot be said to be sufficient. 
     Accordingly, the situation is one in which settings of use where a projection type image display device projects onto the aforementioned facility to display an image are becoming numerous and it is possible to display arbitrary auxiliary lines from the projection type image display device to carry out assistance in recording. Regarding the concerned functionality, it is one that is disclosed in JP-A-2005-250391. 
     SUMMARY OF THE INVENTION 
     Regarding JP-A-2005-250391, as things stand today, it only covers a test pattern display for aligning a projected image position with respect to a screen. 
     As for the display of auxiliary lines targeting assistance in recording, there is a need to hold the display position for a long time, but as far as liquid crystal devices used in projection type image display devices are concerned, there is, in the case of displaying a luminance or a color that is different from the background region for a long time in the same position, the problem that a persistent image (burn-in) occurs, since a DC voltage component remains. Consequently, in this invention, a way of solving this problem is regarded as an issue requiring attention. 
     With respect to the aforementioned problem, in the present invention, the system is devised, in a display device provided with a frame memory developing an auxiliary line image as a display image and a means of reading out and displaying the image data developed in the aforementioned frame memory, so that the aforementioned auxiliary line image is constituted by background color and dashed auxiliary lines constituted by pixels which have luminance or color that is different from that of the background color and pixels with have nearly identical luminance or color to that of the background color. 
     By carrying out the display of the dashes so as to move, at fixed time intervals or arbitrary time intervals, the dash display areas of the aforementioned auxiliary lines on the trajectory of the figure described by the aforementioned auxiliary lines, the system is devised to display the auxiliary lines so that the display of an identical pixel of the display device is reduced. 
     Also, the system is devised to carry out display of auxiliary lines, so that, at fixed time intervals or arbitrary time intervals, for the dash display areas of the auxiliary lines, the pixel areas whose luminance or color differs from that of the background color are changed into a luminance or color that is nearly identical to that of the background color and, moreover, the pixel areas whose luminance or color is nearly identical to that of the background color are changed into a luminance or color that differs from that of the background color. 
     Moreover, the system is devised to: comprise an operation means for operating the display device; a frame memory read means detecting input information from the aforementioned operation means, changing the display color of the auxiliary line image in accordance with the input information, and developing the same in the frame memory; and a storage means storing settings data about auxiliary line image display colors; and, with respect to the input information from the aforementioned operation means, to take the background color or luminance level of the auxiliary line image as well as the display color or luminance level of the auxiliary lines to be adjustable; and store the present settings data in the aforementioned storage means to hold the settings state thereof. 
     In addition, the system comprises: an operation means for operating a display device; a frame memory read means detecting the input information from the aforementioned operation means, modifying the display intervals between the auxiliary lines of an auxiliary line image in accordance with the input information, and developing the same in frame memory; and a storage means storing the settings data of the auxiliary line display intervals of the auxiliary line image; and is devised to take the interval between auxiliary lines of the auxiliary line image to be adjustable with respect to the input information from the aforementioned operation means, store the present settings data in the aforementioned storage means, and hold the settings state thereof. 
     Moreover, the system comprises: an auxiliary line image storage means having pre-stored an auxiliary line image with a plurality of shapes; an operation means for operating a display device; a frame memory read means detecting the input information from the aforementioned operation means, reading out the auxiliary line image data selected from the aforementioned auxiliary line image storage means in accordance with the input information, and developing the same in frame memory; and a storage means storing selected information about auxiliary line image data that have been selected from the auxiliary line image storage means; and is devised, with respect to the input information from the aforementioned operation means, to take the same to be selectively displayable from a pre-stored auxiliary line image, store the present selected information in the aforementioned storage means to hold the settings state thereof. 
     Also, the system comprises: an image transformation means carrying out auxiliary line image size enlargement or reduction; and a frame memory read control means controlling the positions of reads to the frame memory and controlling the display positions of the auxiliary line image; and is devised, with respect to the input information from the aforementioned operation means, to modify, and take to be displayable, the auxiliary line size and display position that had been pre-stored, and store the present selected information in the aforementioned storage means to hold the settings state thereof. 
     In addition, in a display device provided with: a light source provided with a light adjusting means adjusting the quantity of light of the display image; a fan targeting the tracking of changes in the aforementioned quantity of light and the carrying out of the cooling of a heat generation block; and a fan drive circuit driving the aforementioned fan; the system is devised to increase or decrease the quantity of light of the display image and make the rotation rate of the aforementioned fan track and control the changes in the aforementioned quantity of light during auxiliary line image display, in conjunction with the auxiliary line image. 
     Also, in a display device provided with a function of implementing distortion correction by means of transforming an image displayed on the display device, the system is devised so that, in the image displayed on the recording facility, the spaces between the dashes constituting the auxiliary line are set so that the dashes of the auxiliary lines of the auxiliary line image do not join to become a solid line, even in the case where distortion correction has been carried out. 
     Moreover, in a display device provided with a function of implementing distortion correction by means of transforming an image displayed on the recording facility, the system is devised so that, in conjunction with the amount of distortion correction, the spaces between dashes are adjusted so that the dashes of an auxiliary line of the auxiliary line image do not joint to form a solid line, in the image displayed on the recording facility. 
     In addition, in a display device comprising: an auxiliary line image storage means having pre-stored data about an auxiliary line image with a plurality of shapes; an OSD (On Screen Display) circuit part displaying the auxiliary lines; an image synthesis circuit weighting auxiliary line image data that are output from the OSD (On Screen Display) circuit part and display image data; an auxiliary line image display control part reading out auxiliary line image data from the auxiliary line image storage means, setting the aforementioned auxiliary line image data in the OSD circuit part, and controlling, so as to make be displayed, the desired auxiliary line image from the OSD circuit part; and a means displaying the image; the system is devised so that: the auxiliary lines are displayed weighted in the display image; the auxiliary lines are constituted by dashes; and the display of the dashes is carried out so as to move, at fixed time intervals or arbitrary time intervals, the dash display areas of the aforementioned auxiliary lines on the trajectory of the figure described by the aforementioned auxiliary lines. 
     Further, the system is devised, in a display device comprising a frame memory developing a prescribed auxiliary line image as a display image and a means of reading out and displaying the image data developed in the aforementioned frame memory; so that: the aforementioned auxiliary line image is constituted by background color and dashed auxiliary lines having pixels which have luminance or color that is different from that of the background color and pixels with have nearly identical luminance or color to that of the background color; and, with respect to an arbitrary position of the lines described by the aforementioned auxiliary lines, the aforementioned auxiliary line image is displayed with dashes by displaying the aforementioned dash display areas, at arbitrary time intervals. 
     Moreover, the system is devised to: comprise a light source provided with a light adjusting means adjusting the quantity of light of a display image; a fan carrying out the cooling of a heat generation block; and a fan drive circuit driving the aforementioned fan; and, during auxiliary line image display, to increase or decrease the quantity of light of the display image, with respect to an auxiliary line image, and, by associating it with a change in the aforementioned quantity of light, control the rotation rate of the aforementioned fan. 
     Also, the system is devised so as to comprise a distortion correction function correcting distortion by transforming an image displayed on a recording facility and so that, after execution of the aforementioned distortion correction function, the dashes of the aforementioned auxiliary lines are displayed with prescribed dash spacing. 
     In addition, the system is devised so as to comprise a distortion correction function correcting distortion by transforming an image displayed on a recording facility and so that, corresponding to the amount of distortion correction, the dashes of the aforementioned auxiliary lines are displayed with prescribed spacing. 
     Also, in a display device comprising: an auxiliary line image storage means having pre-stored data about an auxiliary line image with a plurality of shapes; an OSD (On Screen Display) circuit part displaying the auxiliary lines; an image synthesis circuit weighting auxiliary line image data that are output from the OSD (On Screen Display) circuit part and display image data; an auxiliary line image display control part reading out auxiliary line image data from the auxiliary line image storage means, setting the aforementioned auxiliary line image data in the OSD circuit part, and controlling, so as to make be displayed, the desired auxiliary line image from the OSD circuit part; and a display means displaying the image; the system is devised so that: the auxiliary line is displayed weighted in the display image; the auxiliary line is constituted by dashes and, with respect to an arbitrary position of the line described by the aforementioned auxiliary line, is displayed with dashes at arbitrary time intervals, by displaying the aforementioned dash display areas. 
     According to the present invention, it is possible to furnish an image display device that, more than conventionally, reduces the image persistence (burn-in) of display devices and makes possible the display of auxiliary lines in an identical position. In addition, it is possible, more than conventionally, to reduce image persistence (burn-in) of display devices without adding special circuits and make an implementation thereof at low cost. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a projection type image display device. 
         FIG. 2  is diagram showing auxiliary line images. 
         FIG. 3  is diagram explaining the drive control of a liquid crystal panel. 
         FIG. 4  is diagram explaining a display method of a registered auxiliary line image display. 
         FIG. 5  is explanatory diagram in which the auxiliary line image intervals are adjusted. 
         FIG. 6  is explanatory diagram in which the background color of an auxiliary line image is adjusted. 
         FIG. 7  is diagram showing an example of a plurality of auxiliary line images pre-stored in a ROM. 
         FIG. 8  is explanatory diagram of the operation of adjusting the display size and position of an auxiliary line image. 
         FIG. 9  is diagram showing projected images that are projected when a projection type display device is directed obliquely upward on a vertically positioned screen. 
         FIG. 10  is diagram showing auxiliary line images on a liquid crystal panel. 
         FIG. 11  is a diagram showing an auxiliary line image on a liquid crystal panel in the case of displaying auxiliary lines so that the auxiliary lines do not become solid lines, taking into account the amount of trapezoid correction. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, an explanation will be given regarding the best mode of the present invention, using the drawings. Further, in each of the diagrams mentioned hereinafter, elements having common functions are designated with like reference numerals, and, regarding elements which have already been explained, the explanation thereof will be omitted. 
     1. The First Embodiment 
       FIG. 1  is a block diagram of a projection type image display device exhibiting Embodiment 1. In  FIG. 1 , ref.  101  is a projection type image display device,  109  is an input terminal into which a (not illustrated) video signal is input,  110  is an input signal processing part carrying out prescribed signal processing with respect to video signals input from input terminal  109 ,  111  is a frame memory temporarily storing video signals output from input signal processing part  110 ,  112  is a memory control part controlling reads to and from the frame memory,  113  is an image processing part carrying out scaling such as image enlargement and reduction as well as geometric distortion correction with respect to video signals read from the frame memory,  102  is a Central Processing Unit (below abbreviated as “CPU”) carrying out arithmetic control of the whole projection type image display device,  103  is a Read Only Memory (including a Flash ROM and below abbreviated as “ROM”) storing a program controlling CPU  102  and a processing program for generating auxiliary line image data or auxiliary line images for displaying auxiliary lines,  104  is a Random Access Memory (RAM) storing arithmetic results etc. used when the CPU is executing the program,  105  is a non-volatile memory storing selected information et cetera about a displayed auxiliary line image (below abbreviated as “non-volatile memory”),  115  is an OSD rendering part generating auxiliary line images and (not illustrated) adjustment menus on the basis of control from the CPU,  114  is an OSD memory in which are stored image data such as menu screens, fonts, and auxiliary line image auxiliary lines displayed with the OSD rendering part,  116  is an image synthesis part synthesizing image data output from the image processing part and OSD images output from the OSD rendering part,  117  is a drive circuit driving a liquid crystal panel, being a display element, on the basis of video data synthesized from video data and OSD images in the image synthesis part,  120  is a light source for displaying images which converts random polarized light into straight polarized light by means of a (not illustrated) polarization conversion element, irradiates light separated into the three colors red, green, and blue by means of a (not illustrated) dichroic mirror, and is provided with a function of adjusting the quantity of light,  121  is a liquid crystal panel controlling the transmitted quantity of light irradiated form the light source,  122  is a projection lens block magnifying and projecting images synthesized and generated from light transmitted through the liquid crystal panel,  123  is a screen reflecting projected images,  119  is a fan for cooling heat-generating components (below called “fan”),  118  is a cooling control part controlling the rotation rate of fan  119 ,  108  are operation buttons consisting of a plurality of buttons arranged on a cabinet of projection type image display device  101 ,  106  is a remote control (below called a “remote control”) remotely controlling the projection type image display device using an infrared remote control signal (below abbreviated as a “remote IR signal”), and  107  is an IR light reception part receiving remote IR signals from remote control  106 . 
       FIG. 2  is an example of displayed auxiliary line images associated with the present invention. In  FIG. 2 , ref.  201  is an auxiliary line image,  202  shows an image pixel which a constituent element of the auxiliary line image,  203  is an auxiliary line,  204  is a pixel whose luminance or color differs from that of the background color constituting the auxiliary lines, and  205  is a pixel whose luminance or color is the same as that of the background color constituting the auxiliary lines. Auxiliary line image  201  is an auxiliary line image which, given an auxiliary line  203  being a horizontal line which has two pixels having a luminance or color that differs from that of the background color and two pixels having a luminance or color that is the same as that of the background color alternately arranged in the horizontal direction, has five horizontal auxiliary lines of the aforementioned constitution. The pixels other than those of the auxiliary lines are background pixels which have the same luminance or color. 
       FIG. 2 -( a ) is a display image occurring at an arbitrary time while an auxiliary line image is being displayed and auxiliary line image  206  of  FIG. 2 -( b ) shows an auxiliary line image displayed subsequently after displaying  FIG. 2 -( a ), after a fixed time or after an arbitrary time, and is an image in which the auxiliary lines have been moved one pixel in the left direction. 
       FIG. 3  is a diagram showing timing charts of the control voltage impressed on the liquid crystal panel from the drive circuit. The liquid crystal panel used in the present embodiment controls the transmitted amount of the irradiated light by applying a voltage to a group of oriented liquid crystals and changing the molecular axis of the liquid crystal molecules by means of the present impressed voltage. And then, in order to prevent degradation in liquid crystal quality, it is controlled with an inversion drive to invert the voltage for each fixed period. 
       FIG. 3 -( a ) shows the impressed voltage with respect to an arbitrary pixel within a liquid crystal panel during all-white display and shows the fact of inverting and impressing the impressed voltage for each screen. Moreover,  FIG. 3 -( b ) shows the impressed voltage with respect to an arbitrary pixel within a liquid crystal panel during all-black display and shows the fact of inverting and impressing the impressed voltage for each screen. 
     Next, there will be a mention regarding the operation. 
     In ROM  103 , there are pre-stored four types of auxiliary line images, the auxiliary line image of  FIG. 2 -( a ), the auxiliary line image of  FIG. 2 -( b ) in which the auxiliary lines of  FIG. 2 -( a ) have been moved one pixel leftward in the horizontal direction, an auxiliary line image (not illustrated) in which the auxiliary lines of  FIG. 2A  have been moved two pixels leftward in the horizontal direction, and an auxiliary line image (not illustrated) in which the auxiliary lines of  FIG. 2 -( a ) have been moved three pixels leftward in the horizontal direction. The aforementioned auxiliary line image data are constituted by the same number of pixels as the number of pixels of the liquid crystal panel, one pixel of an auxiliary line image corresponding one-to-one to a pixel of the liquid crystal panel. 
     CPU  102  carries out processing corresponding, respectively, to a (not illustrated) button out of operation buttons  108  or a remote IR signal received via IR reception part  107 . In case there is input a signal of an operation button associating an auxiliary line display, CPU  102 , via memory control part  112 , discontinues the read to frame memory  111  of the video signals that are output from input signal processing part  110  and permits a read to frame memory  111  from CPU  102 . 
     Next, CPU  102  reads out the pre-stored auxiliary line image data of  FIG. 2 -( a ) from ROM  103  and carries out a development of the same and a read to frame memory  111 . The auxiliary line image read into frame memory  111  is read to image processing part  113 , is scaled to an image size corresponding to the pixel number of liquid crystal panel  121  in image processing part  113 , and is input to drive circuit  117  via image synthesis part  116 . On the basis of the input image data, drive circuit  117  controls and impresses the impressed voltage corresponding to each pixel of liquid crystal panel  121 , as shown in  FIG. 3 . As for the light irradiated from light source  120 , the amount of transmitted light is controlled in liquid crystal panel  121  by means of the present control, the transmitted light is irradiated on screen  123  via projection lens block  122  to display the auxiliary line image on screen  123 . 
     Since the auxiliary line images developed and read to frame memory  111  have the same level of pixels as liquid crystal panel  121 , a pixel of an auxiliary line image corresponds one-to-one to a pixel of liquid crystal panel  121 , so a pixel  204  whose luminance or color differs from that of the background color is mapped onto a liquid crystal cell with an identical pixel position within the display area of liquid crystal panel  121  and a voltage corresponding to the luminance or color of pixel  204  is impressed. 
     Next, after displaying auxiliary line image  201  of  FIG. 2A , CPU  102  measures the time with a (not illustrated) timer and after a fixed time, or an arbitrary time, has elapsed, reads the data of auxiliary line image  206  of  FIG. 2 -( b ) from ROM  103 , carries out a development of the same in frame memory  111  and a read thereto. As a result, auxiliary line image  206  of  FIG. 2 -( b ) is displayed on the screen and, as for pixel  204  whose luminance or color differs from that of the background color, it comes about that the cell on the left horizontal side, in the liquid crystal panel controlled during the display of the image of  FIG. 2 -( a ), is controlled with a voltage corresponding to the luminance or color of pixel  204 , and, moreover, it comes about that the controlled cell corresponding to pixel  204  during the display of the image of  FIG. 2 -( a ) has impressed on it a voltage corresponding to the luminance or color of the right side of pixel  204  and is controlled therewith. 
     As stated above, by displaying the four types of auxiliary line images in order, an identical pixel of liquid crystal panel  121  is controlled so that a voltage with equal positive and negative levels that differ from those of the background color pixels is not impressed continually. 
     By means of the present control, the residual DC voltage component is reduced, image persistence (burn-in) is suppressed, and it is made possible to display an auxiliary line in an identical position. 
     In the present embodiment, an explanation was given using a means storing auxiliary images to be displayed as pre-stored image data in ROM  103 , but it is also acceptable to store in ROM  103  a program generating a displayed auxiliary image from data in which a displayed auxiliary image is divided up into background luminance or color, as well as the luminance or color, positional coordinates, and intervals of the auxiliary lines and the aforementioned displayed auxiliary image data; generate a display auxiliary image by means of the program whereby CPU  102  generates the aforementioned displayed auxiliary images; and develop the same in frame memory  111 , and read thereto, to display the auxiliary image. In addition, it is also acceptable to effectuate control so as to individually update the update time of each auxiliary line. 
     2. The Second Embodiment 
       FIG. 4  are diagrams explaining a display method for registered auxiliary line image display associated with the present invention. In  FIG. 4B, 401  is an auxiliary line image in which the display color of pixel  204 , whose luminance or color differs from the background color being a constituent element of auxiliary line  203  of auxiliary line image  201 , is taken to have the same luminance or color as that of the background color and pixel  205  is taken to have a display color whose luminance or color differs from the background color of pixel  204 . 
     Next, there will be a mention regarding the operation. 
     In ROM  103 , auxiliary line image  201  and auxiliary line image  401  are pre-stored. CPU  102  carries out processing corresponding, respectively to a (not illustrated) button out of operation buttons  108  or a remote IR signal received via IR reception part  107 . In case an operation button associating an auxiliary line display is input, CPU  102 , via memory control part  112 , discontinues the read to frame memory  111  of the video signals that are output from input signal processing part  110  and permits a read to frame memory  111  from CPU  102 , and CPU  102  reads pre-stored auxiliary line image  201  data from ROM  103 , and carries out a development of the same in frame memory  111  and a read thereto. 
     Next, after displaying auxiliary line image  201 , CPU  102  measures the time with a (not illustrated) timer and after a fixed time, or an arbitrary time, has elapsed, reads the data of auxiliary line image  401  from ROM  103 , and carries out a development of the same in frame memory  111  and a read thereto. 
     By carrying out a repetition of the aforementioned processing during auxiliary line display, an identical pixel of the liquid crystal panel is controlled so that a voltage with equal positive and negative levels that differ from those of the background color pixels is not impressed continually, the residual DC voltage component of the liquid crystal cell is reduced, image persistence (burn-in) is suppressed and it is made possible to display an auxiliary line in an identical position. 
     3. The Third Embodiment 
       FIGS. 5 -( a ) and ( b ) are explanatory diagrams in which the intervals in an auxiliary line image are adjusted. Ref.  502  indicates an auxiliary line interval. Ref.  501  is an auxiliary line image in which the auxiliary line interval is adjusted and  503  indicates the auxiliary line interval of auxiliary line image  501 . 
       FIGS. 6 -( a ) and ( b ) are explanatory diagram in which the background color of the auxiliary line image is adjusted. Ref.  601  is an auxiliary line image in which the background color of auxiliary line image  201  has been adjusted,  602  shows one background color pixel in which the display luminance or color has been adjusted, and  603  shows a pixel whose luminance or color, in conjunction with an adjustment of the luminance or color of the background pixels, is the same as the background color and which is a constituent element of auxiliary line  203  whose display luminance or color is nearly the same as the background color. 
     Embodiment 3 will be explained using  FIG. 1 . 
     In the case where a signal corresponding to an operation of adjusting the background color luminance or color inside the auxiliary line image and the luminance or color of an auxiliary line is received through a (not illustrated) button out of operation buttons  108  or IR reception part  107 , CPU  102  makes a (not illustrated) adjustment menu adjusting the aforementioned item be output from OSD rendering part  115 , synthesizes it in image synthesis part  116  with the auxiliary line image read from frame memory  111  and processed in image processing part  113 , and displays the same. The user operates an operation button  108  or remote control  106  in the aforementioned adjustment menu to adjust the aforementioned adjustment item. CPU  102  detects the aforementioned user input and, if what is concerned is an adjustment of the auxiliary line interval, e.g. in the case of detecting an adjustment of auxiliary line interval  502  to adjusted interval  503 , transforms auxiliary line image  201  into auxiliary line image  501 , and carries out a development of the same in frame memory  111  and a read thereto. Also, if what is concerned is an adjustment of the background luminance or color inside an auxiliary line image, it modifies the data of the pixels corresponding to the background of auxiliary line image  201  and carries out a development of the same in frame memory  111  and a read thereto, so that auxiliary line image  601  is displayed. Since the user can adjust the displayed auxiliary line image while checking it, the user can readily adjust the intended auxiliary line image. And then, after completion of the adjustment, CPU  102  stores the adjusted data in non-volatile memory  105  and, from the adjustment onward, CPU  102  operates to read the pre-stored auxiliary line image data from ROM  103  on the occasion of displaying the auxiliary line image, read the aforementioned adjustment data from non-volatile memory  105 , transform the auxiliary line image or modify the display luminance or color on the basis of the present adjustment data, carry out a development of the same in frame memory  111 , and cause it to be displayed. 
     4. The Fourth Embodiment 
       FIG. 7  shows an example of a plurality of auxiliary line images caused to be stored in ROM  103 . Ref.  701  is a lattice auxiliary line image,  702  is a lattice auxiliary line image with wide intervals, and  703  is a 5-line auxiliary line image in which five auxiliary lines are coupled. 
     Embodiment 4 will be explained using  FIG. 1 . 
     The data of a plurality of auxiliary lines are caused to be pre-stored in ROM  103  and, in case a signal corresponding to an operation of selecting an auxiliary line image to be displayed is received through a (not illustrated) operated button out of operation buttons  108  or IR reception part  107 , CPU  102  makes a (not illustrated) selection menu selecting a plurality of auxiliary line images caused to be pre-stored in ROM  103  be output from OSD rendering part  115 , the menu being synthesized in image synthesis part  116 , with the display image read from frame memory  111  and processed in image processing part  113 , and displayed. In the aforementioned selection menu, the user operates an operation button  108  or remote control  106  to select the auxiliary line image to be displayed. CPU  102  detects the input of the aforementioned user operation, reads the auxiliary line image data to be displayed from ROM  103 , carries out a development of the same in frame memory  111  and a read thereto, and displays the auxiliary line image. Also, CPU  102  stores, in non-volatile memory  105 , auxiliary line image identification data uniquely allocated to the selected auxiliary line image data and, from the selection onward, CPU  102 , on the occasion of displaying the auxiliary line image, reads the aforementioned auxiliary line image identification data from non-volatile memory  105  and selects and displays auxiliary line image data corresponding to the aforementioned auxiliary line identification data from the data of a plurality of auxiliary line images caused to be stored in ROM  103 . 
     5. The Fifth Embodiment 
       FIGS. 8 -( a ) and ( b ) is explanatory diagram of the operation of adjusting the display size and position of an auxiliary line image. 
     Embodiment 5 will be explained using  FIG. 1 . 
     The data of a plurality of auxiliary lines are caused to be pre-stored in ROM  103  and, in case a signal corresponding to an operation of displaying an auxiliary line image to be displayed is received through a (not illustrated) operated button out of operation buttons  108  or through IR reception part  107 , CPU  102  reads the auxiliary line identification data of auxiliary line image  801  to be displayed from non-volatile memory  105 , reads the corresponding auxiliary line image  801  from ROM  103  to display the same. Next, the user transmits a signal corresponding to an operation of adjusting the size or position of the display auxiliary line image with an operated button (not illustrated) out of operation buttons  108  or remote control  106 . CPU  102  detects the present signal and causes an adjustment menu (not illustrated) adjusting the size or position of the display auxiliary line image to be output from OSD rendering part  115  to display the same. The user adjusts the size or position of the display auxiliary line image in the aforementioned adjustment menu. As for the adjustment of the size of display auxiliary line image  801 , the size of the auxiliary line image is transformed by CPU  102  into display auxiliary line image  802  and is developed in frame memory  111 . Moreover, in the case of changing the position of the image data of display auxiliary line image  801 , CPU  102  operates to modify the position of reading to frame memory  111  so that an auxiliary line image  803 , in which the display image position is moved, is displayed, and carries out a read thereto. Also, CPU  102  stores the adjustment data of the adjusted size or position in non-volatile memory  105  and, on the occasion of displaying the aforementioned auxiliary line image  801 , CPU  102  reads the size or position data of the aforementioned auxiliary line image from non-volatile memory  105  and, using the size or position data of the aforementioned auxiliary line image, determines the read starting position of frame memory  111  of the displayed auxiliary line image, together with transforming it to the adjusted size, to carry out a read of the transformed auxiliary line image data from the aforementioned read starting position. 
     6. The Sixth Embodiment 
     Embodiment 6 will be explained using  FIG. 1 . 
     In case a signal corresponding to an auxiliary line image display operation is received through an operated button (not illustrated) out of operation buttons  108  or from remote control  106  through IR reception part  107 , CPU  102  reads the auxiliary line identification data from non-volatile memory  105 , selects auxiliary line image data corresponding to the aforementioned auxiliary line image identification data from a plurality of auxiliary line image data caused to be stored in ROM  103 , reads the aforementioned auxiliary line image data from ROM  103 , and carries out a read to frame memory  111 . In addition, CPU  102  outputs a light quantity adjustment signal to light source  120  so as to reduce the quantity of light of the light source and, with respect to fan  119  targeting the cooling of heat-generating parts generating heat in response to the quantity of light irradiated from light source  120 , lowers the rotation rate of the aforementioned fan  119  through cooling control part  118  so that the fan rotation rate becomes one corresponding to the reduced quantity of light. Since the quantity of heat generation diminishes by reducing the quantity of light, and since the air flow of the fan targeting the cooling of the heat-generating parts diminishes, it is self-evident that it is possible to lower the rotation rate. By means of the present control, the glare is alleviated, together with reducing the noise of the fan. 
     7. The Seventh Embodiment 
       FIGS. 9 -( a ) and ( b ) are projected images that are projected when a projection type display device is directed obliquely upward on a vertically positioned screen. Ref.  901  is a projected image in which trapezoid correction has not been carried out and  902  is a projected image in which trapezoid correction has been carried out. 
       FIGS. 10 -( a ) and ( b ) are diagrams showing auxiliary line images on a liquid crystal panel. Ref.  1001  is an auxiliary line image on a liquid crystal panel in the case where trapezoid correction has not been carried out and  1002  is an auxiliary line image in the case where trapezoid correction has been carried out. 
       FIG. 11  is a diagram showing an auxiliary line image on a liquid crystal panel in the case of displaying auxiliary lines so that the auxiliary lines do not become solid lines, taking into account the amount of trapezoid correction. 
     Embodiment 7 will be explained using  FIG. 1 . 
     Due to the tilt angle, with respect to screen  123 , of the optical axis of the (not illustrated) projection lens inside projection lens block  122  of the projection type display device, there arises trapezoidal distortion in the projected image of the projection type display device. E.g., in the case of projecting the projection type display device obliquely upward on a vertically positioned screen, the image becomes one having the trapezoidal distortion of projected image  901 . Because of this, it is common to have a device provided with a trapezoid correction function transforming this trapezoidal distortion on the liquid crystal panel into projected image  902 . In order to correct the aforementioned trapezoidal distortion on liquid crystal panel  121 , there is implemented an image transformation in image processing part  113  so as to inversely correct the aforementioned trapezoidal distortion and a projection on liquid crystal panel  121 . 
     As for the auxiliary line image, in order to develop it in frame memory  111  and read it thereto, and to display it, in the aforementioned case of carrying out trapezoid correction, the image is transformed in image processing part  113  so as to inversely correct the aforementioned trapezoidal distortion. In the case where the dash spacing of the auxiliary lines of the auxiliary line image read to frame memory  111  is narrow, it is easily anticipated that an auxiliary line on liquid crystal panel  121  becomes a solid line. In this case, since it comes about that a voltage with equal positive and negative levels that differ from those of the background color pixels is impressed continually on an identical pixel, the result is that image persistence (burn-in) occurs. 
     In order to solve the aforementioned problem, taking into account the amount of trapezoid correction, the auxiliary lines of the auxiliary line image are generated with spacing such that the dashes of the auxiliary lines do not become a solid line, even with trapezoid correction. Alternatively, the system is devised so that, in response to the amount of trapezoid correction, the corresponding position on liquid crystal panel  121  of each dash of an auxiliary line is computed with a calculation, the dash spaces are determined so that the dashes do not join, a read of the auxiliary line image data to frame memory  111  is carried out, and it is prevented, even during trapezoid correction, that a voltage with equal positive and negative levels that differ from those of the background color pixels is impressed continually on an identical pixel on liquid crystal panel  121 . 
     8. The Eighth Embodiment 
     Embodiment 8 will be explained using  FIG. 1 . 
     Auxiliary line image data are stored in OSD memory  114  and, with respect to OSD rendering part  115 , CPU  102 , during auxiliary line display, gives an instruction for displaying the auxiliary lines from auxiliary line data pre-stored in OSD memory  114 , OSD rendering part  115  reads the specified auxiliary lines from OSD memory  114  and renders the auxiliary line image, and the lines are synthesized with the input image in image synthesis part  116  and displayed. In a projection type display device provided with trapezoid correction, it is also acceptable to arrange image synthesis part  116  before the (not illustrated) trapezoidal distortion correction part inside the image processing part and for the trapezoid correction processing to be carried out after synthesizing the input image and the output image of OSD rendering part  115 . 
     It should be further understood by those skilled in the art that although the foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.