Visual presentation equipment

A visual presentation apparatus which applies an illuminating light to an object placed on a stand, obtains an image of the illuminated object using a pick-up camera, transmits the image to a display whereat the image is displayed; wherein the front, back, left and right sides of the stand are open by using a flat plate as the stand, and by mounting the light source on an arm which also supports the pick-up camera and placing the arm outside the stand; and wherein the pick-up camera comprises a mechanism rotatable around the horizontal and vertical axes; and wherein sample clocks which are synchronized with color burst signals are generated by the apparatus and frame memories in which the images are stored are switched at the time of the sample clocks.

BACKGROUND OF THE INVENTION 
1. Field of Invention 
This invention relates to a visual presentation apparatus which obtains an 
image of an object to be displayed with a pick-up camera and displays the 
image on a display screen. 
2. Description of the Related Art 
A visual presentation apparatus is used to display samples or products on a 
screen. Some example of conventional visual presentation equipment and 
problems encountered thereby are discussed below. 
FIG. 1 shows an example of a conventional visual presentation equipment, 
wherein an object 1 to be displayed and having a three-dimensional shape 
is placed on an object stand 2 with external illuminators 3,4 irradiating 
the front and back of the object 1. The light is directed to the back and 
front of the object 1 in order to eliminate shadows created by the object. 
An image pick-up camera 5 obtains an image of the object 1 as the light 
source 3,4 illuminates the object. A display 6 shows an image of the 
object 1 on a screen provided therein by receiving video signals from the 
camera. The camera 5 may be, for example, a charge coupled device (CCD) 
camera. 
An operator faces the equipment in the direction "A" when carrying out a 
presentation. Since wall 7 is formed on one side of stand 2, a problem 
arises in that movement of object 1 is restricted by wall 7 when it is 
desired to move object 1 forward or backward. 
Also, another problem arises in that light sources 3,4 obstruct work to be 
done on the left or right side of the object 1, (See direction C--C), 
because the light sources 3,4 are positioned to the left and right of the 
object 1 to avoid shadows from the object. The work to be done may 
comprise writing with a marker to the left or right of the object during 
the presentation. 
Another conventional visual presentation equipment is shown in FIGS. 2 and 
3 and is provided with a head swinging mechanism which allows the camera 
to be turned forward, backward, left or right to display, for example, (a) 
observers of the presentation facing the visual presentation equipment, 
(b) a blackboard located behind the equipment operator, or (c) objects 
located to the left or right of the equipment. 
FIG. 2 shows a camera head 10 comprising an image pick-up camera, and a 
knob 11 linked to the camera. By turning knob 11, the camera is turned 
about an optical axis L. An arm 12 supports camera head 10 to rotate 
freely about the X-axis. A support means 13 is provided on arm 12 and 
supports camera head 10 to be freely rotatable about the Y-axis. Support 
means 13 comprises a hinge. 
When camera head 10 is rotated in the direction D around the Y-axis, the 
camera is turned to face toward X. When camera head 10 is rotated in 
direction D', the camera is turned to face toward -X. When camera head 10 
is rotated about the X-axis in direction E, the camera is turned to face 
toward Y. When camera head 10 is rotated in direction E', the camera is 
turned to face toward -Y. Hence, camera 5 may be turned in different 
directions, such as forward, backward, left, right. 
FIG. 3 shows the inside of camera head 10 of FIG. 2, and comprises an image 
pick-up camera 14. The same parts in FIGS. 1, 2, 3, have the same symbols. 
The same holds for the remainder of the figures. A hole 101 is provided on 
the side of camera head 10. A support means 15 supports camera head 10 to 
be rotatable freely about the X-axis. Support means 15 comprises a shaft 
151 inserted into hole 101, and a stopper 152 to prevent shaft 151 from 
slipping out of hole 101. Camera head 10 is supported by the foregoing 
components to be freely rotated around the X-axis. A plate member 102 is 
fixed on the inside of camera head 10 and a hole 103 is provided in plate 
member 102. The arrangement further comprises a support means 16 for 
supporting image pick-up camera 14 to be freely rotatable about the 
optical axis L and comprises a shaft 141 connected to pick-up camera 14 
and inserted into hole 103 and a stopper 161 for preventing shaft 141 from 
slipping out of hole 103. Camera 14 is supported by the foregoing 
components to be freely rotable about the optical axis L. 
The arrangement further comprises knob 11 linked to camera 14, which 
rotates about axis L by the turning of knob 11. Camera 14 is made to be 
freely rotatable about optical axis L so as to return the image displayed 
back to the original position by turning camera. 14 when the image has 
been rotated by rotating camera head 10. 
However, there arises a problem in the conventional devices shown in FIGS. 
2 and 3, in that when arm 12 is bent to a dogleg position, such as when 
the camera 14 is turned toward X or -X, jamming is caused by the wiring 
contained in the arm 12. 
A further example of the conventional equipment is shown in FIGS. 4-6. High 
resolution, such as comparable to an overhead projector, is required in 
visual presentation equipment. Such equipment may incorporate frame 
memories for storing and subsequently displaying a preceding object when 
one object is replaced with another object. Since a high resolution image 
requires an extensive amount of data, the image data for one field are 
usually stored in more than one memory. 
FIG. 4 shows an example of a frame memory control system, used in the 
visual presentation apparatus, and comprises a synchronous separation 
circuit 20 which generates a horizontal synchronization signal and a field 
recognition signal from a luminance signal (Y signal) provided by a video 
camera, not shown, of a visual presentation equipment. A scanning line 
counter 21 is provided which counts the number of horizontal 
synchronization signals and outputs a memory switch signal by counting out 
at a predetermined number. Counter 21 identifies an odd number field and 
an even number field based on a field recognition signal and outputs a 
memory switch signal corresponding to the results of the identification. 
Counter 21 starts counting at the time of the field recognition signal 
changing points. 
A clock generator 22 is provided comprising a Phase Locked Loop (PLL) 
circuit and which generates sample clock signals which are synchronized 
with a color burst signal, and whose frequency is higher than the color 
burst signal, taking the color burst signal contained in color signals 
(i.e. C signals) sent from the camera, as a reference. 
Also shown in FIG. 4 are memories 231 to 233 and 241 to 243. Since the 
quantity of image data for one field is greater than the memory capacity, 
data forming images for one field are stored in more than one memory. When 
forming images for one field, the memories are switched in order to read 
the complete image data. Memories 231 to 233 and 241 to 243 are, for 
example, operated in a first in, first out (i.e. FIFO) manner. 
The arrangement further comprises A/D converters 25, 26, each carrying out 
A/D conversion of the Y and C signals, respective, and a control signal 
generating means 27 which (a) receives the memory switching signal, and 
(b) generates (i) an output enable signal, (ii) a write signal, and (iii) 
a reset signal, necessary for memory control. The generating means 27 (a) 
selects each data reading memory from the memories 231 to 233 and 241 to 
243; (b) permits and inhibits writing in memories 231 to 233 and 241 to 
243 with a write signal, and (c) clears the contents of memories 231 to 
233 and 241 to 243 with a reset signal. Since memories 231 to 233 and 241 
to 243 are used in a FIFO manner, and the data are continuously stored, a 
reset signal is used when the memory contents need to be renewed and the 
data need to be newly written therein. 
Generating means 27 outputs the data written in memories 231 to 233 and 241 
to 243 when a freeze mode is specified and does not write during such 
mode. This holds the displayed image. When a through mode is specified by 
a mode switch signal, generating means 27 writes data into memories 231 to 
233 and 241 to 243 in turn and immediately outputs the written data. The 
freeze mode and through mode are, for example, specified with a switch. 
The write signal level is changed to be high or low corresponding to the 
freeze mode or through mode. 
Connected to the memories are D/A (digital to analog) converters 28, 29 
which subject the image data from memories 231 to 233 and 241 to 243 to 
digital to analog conversion. A display control means 30 provides signals 
for displaying an image in display means 31 based on the signals received 
from the converters 28 and 29. 
Clock generator 22 supplies sample clock signals to the memories 231 to 233 
and 241 to 243; A/D (analog to digital) converters 25 and 26; control 
signal generating means 27,; and D/A converters 28 and 29. Note that the 
drawings may not show any direct connection between the clock generator 
and the using circuit, but, it is to be understood that the clock signals 
are directed thereto directly or indirectly through other circuits. 
FIGS. 5(a) and 5(b) show time charts for image signals outputted by the 
image pick-up camera, wherein H1 and H2 indicate horizontal 
synchronization signals; C1 and C2 indicate color burst signals; V1 and V2 
indicate video signals; and P indicates a memory switching point. If the 
phase of color burst signal C2 is shifted from that of color burst signal 
C1, the phase shifts between the display line of video signal V1 and the 
display line of video signal V2 thereby resulting in the generation of 
color shading in the displayed image. FIG. 5(a) shows signals having no 
phase shift while FIG. 5(b) shows signals having a phase shift. In FIG. 
5(b), a time shift of Dt is caused after switching of the memories. 
In the arrangement of FIG. 4, since the memories are switched based on the 
number of analog horizontal synchronization signals, the phase of the 
horizontal synchronization signals maybe shifted near the memory switching 
point due to aging or temperature change. This may generate undesired 
color shading in the displayed image. 
FIG. 6(a) and 6(b) show examples of a displayed image when a phase shift is 
generated in the color burst signals. As shown in FIG. 6(a) line L1 in 
field #1 and line L3 in field #2 are the switching points for the 
memories. The image for field .andgate.1 is formed with the image data 
from memories 231 and 232, and the image for field #2 is formed with the 
image data from memories 232 and 233. If the phase of the analog 
horizontal synchronizing signal is shifted due to temperature change or 
aging near the memory switching point, undesired color shading portions A1 
and A2 occur in the image, as shown in FIG. 6(b). 
Thus, a problem arises in that undesired color shading may occur in the 
displayed image due to shifting of phase resulting from aging or 
temperature changes. This problem arises because the memory switching time 
is based on an analog horizontal synchronizing signal. 
SUMMARY OF THE INVENTION 
Accordingly, an object of the invention is to overcome the aforementioned 
problem, disadvantages and deficiencies of the prior art. 
Another object is to provide a visual presentation apparatus wherein ease 
of use by an operator is enhanced; wherein jamming of wiring is eliminated 
regardless of which direction the image pick-up camera is turned; and 
wherein color shading due to aging and/or temperatures changes is 
substantially eliminated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
First Embodiment--Visual Presentation Apparatus 
FIG. 7 shows an object stand 40 formed in the shape of a substantially flat 
plate; an arm 41 having one end thereof supporting camera head 10 and 
another end thereof attached to a corner of stand 40; and an external 
light source 42 having a length dimension extending approximately to the 
left and right ends of the stand 40. Hence, the light source 42 irradiates 
object 1 from both sides and no shadows are produced by the object, which 
has three dimensions. The light source 42 is also mounted on arm 41 and is 
rotatable in direction F--F'. When source 42 is rotated in direction F, 
source 42 can be housed in arm 41 with its longitidinal direction 
coinciding with the longitudinal direction of arm 41. When source 42 is 
not required at a sufficiently bright place where the apparatus is used, 
the source may be housed in arm 41. 
A monitor display 43 is mounted on arm 41 and comprises a screen which 
faces in direction A, when the operator is facing the apparatus. Thus, the 
operator can simultaneously see in the monitor 43 that which is being 
displayed in display 6. 
The camera head 10, including the camera, obtains an image of object 1, 
which is illuminated by source 42, and sends video signals of the image to 
display 6. Display 6 then displays the image on its screen. At the same 
time, monitor display 43 also receives the same signals and displays the 
same image on the screen thereof. In this manner, the operator can monitor 
the presentation in an easy manner. 
Since stand 40 is formed as a substantially flat plate and hence no 
obstruction exists in the forward or backward direction, i.e. B--B' 
direction, the movement of object 1 is not restricted and object 1 can be 
readily moved in such directions. In addition, since source 42 is mounted 
on arm 41, no obstruction exists in the right or left direction and object 
1 can be readily moved in such right or left direction, and furthermore, 
various work can be performed readily about the object by the operator 
without any obstruction interfering with his work. Moreover, when source 
42 is housed in or adjacent to arm 41, the area about the stand 40 is free 
of further obstacles. Thus, the embodiment enhances the ease of use by an 
operator of the visual presentation apparatus, as compared with the prior 
art. 
FIG. 8 shows details of the display switching circuit of FIG. 7, comprising 
A/D converter 50 to sample video signals from camera 14, a frame memory 51 
for accumulating images taken from camera 14 by storing the video signals 
therefrom and sampled by A/D converter 50, and D/A converter 52 for 
converting digital data read from the frame memory 51 into analog data. 
A video switch 53 is switched from a connecting status (S1) in which the 
video signals from camera 14 are directly transmitted to display 6, to a 
connecting status (S2) in which an image read from the frame memory 51 is 
transmitted to display 6 and vice versa. 
A switching control circuit 54 controls frame memory 51 and video switch 53 
corresponding to the switching of memory switch 55. When memory switch 55 
is turned ON, control circuit 54 enables image data to be read from frame 
memory 51 as well as transfer video switch 53 to contact S2. When memory 
switch 55 is turned OFF, control circuit 54 transfers video switch 53 to 
contact S1 and transmits video signals from camera 14 directly to display 
6. Control circuit 54 also controls the writing into frame memory 51 while 
memory switch 55 is turned OFF, and at the time an image is being 
displayed. 
Operation of the ON and OFF states of memory switch 55 may also be done in 
a reverse manner. 
Operation of the FIG. 8 circuit is as follows, with objects "a" and "b" 
being used as examples. A default state exists when memory switch 55 is 
turned OFF and video switch 53 is transferred to contact S1. This enables 
an image obtained by camera 14 to be directly indicated in display 6. In 
this state, the operator puts object "a" on stand 40 and an image of 
object "a" is shown in display 6. The operator may orally discuss object 
"a" while showing such object. 
When the discussion of object "a" is completed, the operator turns ON 
memory switch 55. Control circuit 54 reads the image data from frame 
memory 51 and transfers video switch 53 to contact S2. The operator then 
replaces object "a" with object "b". During replacement, the image of 
object "a" is displayed subsequently. For this reason, the condition of 
stand 40 is not displayed during replacement. 
After object "a" is replaced on stand 40 with object "b", the operator 
turns OFF memory switch 55. This switches the image on display 6 from that 
of object "a" to object "b". Now, the operator discusses object "b" while 
showing object "b". When replacing one object with another, the same 
operation is followed. 
FIG. 9 shows the image processing circuit of FIG. 7 comprising a 
positive/negative inverting circuit 60 which changes an image obtained 
from camera 14 from positive to negative and vice versa. Signal processing 
circuit 61 processes image data read from frame memory 51 and transmits 
the data to display 6. Signal processing circuit 62 processes the image 
data read from frame memory 51 and transmits the data to display 6. Signal 
processing circuit 62 gives provides a higher quality signal processing 
than does circuit 61. In signal processing, a higher image quality is 
obtained by separating luminance signals from color signals, as compared 
with the process which mixes luminance signals with color signals. The 
signal processing circuit 62 carries out the former higher quality type of 
signal processing whereas the signal processing circuit 61 carries out the 
latter type of signal processing. Accordingly, depending on the image 
quality desired of display 6, the image data is connected to signal 
processing circuit 62 or 61, selectively. 
An RGB converting circuit 63 converts the image data read from frame memory 
51 to the three primary colors of read (R), green (G) and blue (B). When a 
visual presentation apparatus displaying an image by applying R,G and B 
light to the screen is used, display 6 is connected to RGB converter 
circuit 63. 
In the first embodiment of FIG. 7, the stand is flat in shape and the light 
source (also called "illuminator") is mounted on the arm which also 
support the camera. This provides an open area about the flat surface, 
forward, backward, left and right. Thus, the forward or backward movement 
of the object being displayed on the stand is not limited. Also, the light 
source does not obstruct any task performed to the right and left of the 
object disposed on the stand. When the source is housed in or adjacent to 
the arm, further open areas are provided about the flat surface of the 
stand. 
Accordingly, the first embodiment enhances the ease of use by an operator 
as compared with the prior art. 
Second Embodiment--Visual presentation apparatus 
FIG. 10 shows a second embodiment of the invention comprising a head 
support member 70 disposed between camera head 10 and arm 41; support 
means 71 which supports head support member 70 to be freely rotatable 
about the Z-axis (wherein the Z-direction is vertical) to arm 41; and 
support means 72 which supports camera head 10 to be freely rotatable 
about the X-axis to head support member 70. Accordingly, camera head 10 is 
supported to be freely rotatable about the X-axis (i.e. in the G--G' 
direction) and Z-axis (i.e. in the H--H' direction). The other components 
are explained elsewhere in the specification. 
FIG. 11 shows details of the head swinging mechanism, wherein support means 
71 comprises a shaft 711 inserted in hole 121 and a stopper 712 to prevent 
shaft 711 from coming out of hole 121. Shaft 711 is fixed to head support 
member 70. Support means 72 comprises a shaft 721 inserted into hole 101 
and a stopper 722 to pre-vent shaft 721 from slipping out of hole 101. 
Shaft 721 is fixed to head support member 70. Accordingly, camera head 10 
is supported to be freely rotatable about the X-axis and the Z-axis. In 
addition, support means 16, 71 and/or 72 maybe provided with detent 
mechanisms. 
FIGS. 12(a)-12(e) illustrate the operation of the embodiment of FIG. 10, 
wherein camera head 10 and head support means 70 are viewed from above the 
stand 11, for convenience of illustration. 
FIG. 12(a) shows the condition wherein camera 14 is oriented vertically 
downward to view an image of stand 40. FIG. 12(b) and FIG. 12(c) show 
conditions wherein camera head 10 is rotated about the X-axis either by 
90.degree. or by -90.degree.. In these conditions, camera is turned in the 
direction of Y or -Y, respectively. FIG. 12(d) shows the condition wherein 
head support member 70 is rotated by 90.degree. about the Z-axis and then 
camera head 10 is rotated by 90.degree. about the Y-axis from the 
condition of FIG. 12(a). In this condition, camera 14 is turned in the 
direction of X. In the condition of FIG. 12(a), because of the head 
support member 70, camera head 10 is freely rotatable about the X-axis. 
However, in the condition of FIG. 12(c), since the head support member 70 
is rotated by 90.degree. about the Z-axis, camera head 10 become freely 
rotatable about the Y-axis. FIG. 12(e) shows the condition wherein head 
support member 70 is rotated by 90.degree. about the Z-axis and then 
camera head 10 is rotated by -90.degree. about the Y-axis from the 
condition of FIG. 12(a). In this condition, camera 14 is oriented in the 
direction of -X. 
When an image is rotated because camera head 10 is rotated, camera 14 is 
rotated by turning knob 11 to restore the image to the original position. 
Camera 14 can be oriented in the X,-X, Y or -Y direction by causing camera 
head 10 to be in the positions shown in FIGS. 12(b) to 12(e), 
respectively. 
In the second embodiment, mechanism is provided for rotating the camera 
about the horizontal and vertical axes. Accordingly, the camera can be 
oriented in any direction, e.g. forward, backward, leftward or rightward, 
as desired, by combining the rotations about the horizontal and vertical 
axes, without bending the arm to be in a "dogleg" shape. This allows the 
visual presentation apparatus to be free from cluttered wiring regardless 
of whether the camera is oriented in the backward, forward, rightward or 
leftward position. 
Third Embodiment--Control Circuitry 
FIG. 13 shows a memory control circuit 80 which receives a field 
recognition signal and mode switch signal and provides an output enable 
signal, a write signal, and a reset signal to memories 231 to 233 and 241 
to 243. 
FIG. 14 shows details of the memory control circuit 80 comprising a counter 
81 which starts counting at the field starting point and counts the number 
of sample clocks generated by clock generator 22. The field starting point 
is detected from the changing points in the field recognition signal. 
Since a pixel is written when one sample clock is provided, counter 81 
counts the number of pixels which are written. A comparator 82 compares 
the number of counts in counter 81 with a reference value set in constant 
setting register 83, directs the switching of the memories with a memory 
switching signal when the number of counts in counter 81 reaches the 
reference value, and at the same time resets the counter 81. Whether the 
switching point for the memories is reached or not is checked by 
comparator 82. In addition, the capacity of memories 231 to 233 and 241 to 
243 may be of an arbitrary size. The settings of the constant setting 
register 83 are determined corresponding to the memory capacity. 
Operation of the system shown in FIG. 13 is as follows. The Y and C 
signals, which are transmitted from the camera, are subjected to an A/D 
conversion in A/D converters 25,26. Clock generator 22, which uses in one 
example, a PLL circuit, generates sample clock signals having frequencies 
which are higher than that of the color burst signal and which are 
synchronized with that signal using the color burst signal included in the 
C signal as a reference. Synchronous separating circuit 20 generates a 
field recognition signal at a logic level based on the Y signal. 
Memory control circuit 80 starts the counting at the changing point of the 
field recognition signal, and then counts the number of sample clocks with 
counter 81, and then switches the memories in which the data are to be 
written when the number of counts reaches the reference value. 
FIG. 15 shows the timing of each signal occurring in the visual 
presentation apparatus of FIG. 13 When an odd field is detected, the field 
recognition signal become high. When an even field is detected, the field 
recognition signal becomes low. 
When counter 81 counts out the first time, the first flip flop output FF1 
becomes high. When the counter 81 counts the second time, the second flip 
flop output FF2 becomes high. When counter 81 counts out the third time, 
the outputs of both flip flops FF1, and FF2 become low. Subsequently, the 
counter repeats the foregoing operation. 
When both flip flop outputs FF1 and FF2 are changed, the memories are 
switched. When both FF1 and FF2 are at the low level memories 231 and 241 
are selected. When FF1 is at the high level and FF2 is at the low level, 
memories 232 and 242 are selected. When FF1 is at the low level, and FF2 
is at the high level, memories 233 and 243 are selected. The memories are 
selected with decode signals which are obtained by decoding the flip flop 
outputs FF1 and FF2, using a decoder. 
FIG. 16 shows the connection of counter 81 to the flip flop circuits, 
wherein flip flop circuits 84 and 85 provided output signals FF1 and FF2, 
respectively. 
FIG. 17 shows an image displayed when using the embodiment of FIG. 13. In 
the embodiment of FIG. 13, since the number of image pixels is counted 
from the starting point of the field and the memories are switched at a 
point where the number of counts reaches a predetermined value, in 
principle, there is no discontinuity of the images. In the third 
embodiment, although the memory switching points are located at points P1 
and P2 in FIG. 17, the discontinuity cannot be entirely discriminated in 
the displayed image. When one sample clock is provided, one pixel is 
written. In addition, in the third embodiment, the image data comprising 
one field is stored in two memories. However, the data may be stored in 
three or more memories, as desired. 
In the third embodiment of FIG. 13, the memories are switched at the time 
the sample clocks in the digital signals are synchronized with the color 
burst signals, but, not by using horizontal synchronizing signals in 
analog form, as done in the prior art. Thus, the memory switching time or 
phase is not shifted because of aging or temperature change. Thus, in the 
invention, color shading in the displayed image is substantially prevented 
from occurring. 
Fourth Embodiment--Image Processing Circuit 
FIG. 18 shows another image processing circuit comprising a 
negative/positive inverting circuit 90 which changes a negative image, 
obtained by camera 14, to a positive image and vice versa. A 
negative/positive change over switch 91 operates the negative/positive 
inversion circuit. Y/C composing circuit 91 composes a Y signal and a C 
signal after passing negative/positive inverting circuit 90. The signal 
produced after composition is a composite signal. A buffer B provides 
signals Y and C. Thus, the image processing circuit of FIG. 18 generates 
separate Y and C signals and a Y/C composite signal. Accordingly, the 
image processing circuit of FIG. 18 can connect a display which receives 
separate Y and C signals as inputs for images and a display which receives 
the composite signals as inputs for the images to be displayed. 
FIG. 19 shows still another image processing circuit comprising frame 
memory 51 and RGB converting circuit 93. Frame memory 51 enables an image 
which has been displayed to be retained. RGB converting circuit 93 
converts the Y signal and the C signal to R, G, and B signals. The RGB 
converting circuit 93 enables a display, which receives the R,G and B 
signals as inputs for the images,. to be connected in addition to a 
display which is connected to any image processing circuit, such as shown 
in FIG. 18. A display which receives as inputs the R,G and B signals, for 
example, is a display which indicates the images by applying the R,G, and 
B signals to the screen of the display. SYNC shows a synchronous signal. 
The foregoing is illustrative of the principles of the invention. Numerous 
extensions and modifications thereof would be apparent to the worker 
skilled in the art. All such extensions and modifications are to be 
considered to be within the spirit and scope of the invention.